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Bambara groundnut is an indigenous African legume, which is the third most important after peanut and cowpea in terms of consumption and socio-economic impact in semi-arid Africa. There is, therefore, the need for adequate research attention, especially with regard to yield improvement. In this study, nine genotypes of the Bambara groundnut (Cream with white eye, Black with white eye, Cream with brown eye, Cream with black eye, Cream with black eye and brown stripes, Cream with brown stripes, Deep-brown with white eye, Cream with black stripes and Brown white eye) were evaluated at Kuru, Nigeria (Lat. 09[degrees] 44'N, Long. 08[degrees] 47'E, altitude 1, 217 m above sea level) in 2018 in order to determine character associations and to analyse the pathways to grain yield. Results showed that emergence rate, plant height, number of leaves per plant, leaf area index, relative growth rate, harvest index, number of pods per plant and shelling percentage were positively correlated with total grain yield. The Results of the path coefficient analysis showed that the number of days to onset of flowering exerted the highest direct influence on total grain yield. Then followed by harvest index, emergence rate, 100-seed weight, net assimilation rate, shelling%, days to 50% flowering, relative growth rate, number of seeds per pod, and number of pods per plant. The highest total effect (0.988) was observed in 100-seed weight, followed by days to first flowering (0.837), days to 50% flowering (0.701), shelling% (0.658), emergence rate (0.574), number of pods per plant (0.557), relative growth rate (-0.375), net assimilation rate (0.226), harvest index (0.183) and number of seeds per pod (- 0.126) in that order. The study demonstrated that combining correlation and path coefficient analyses is important in determining reliable trait associations that can be used for developing superior genotypes. Therefore, days to first flower, days to 50% flowering, harvest index, emergence rate and 100-seed weight should be considered as major selection indices for the improvement of the Bambara groundnut in the Jos-Plateau environment in Nigeria. Key words: Correlation, direct effect, indirect effect, grain yield, Vigna subterranea (L.) Verdc., INTRODUCTION Bambara groundnut [Vigna subterranea (L.) Verdc] is an indigenous African legume, which is the third most important after peanut and cowpea in terms of consumption and socio-economic impact in [...]

The study analysed the efficiency of Watermelon (Citrullus lenatus) Production in Nigeria. A multi-stage sampling technique was used in selecting three hundred and sixty (360) respondents. Selection was done with purposive and simple random sampling, and data collected with a structured questionnaire. The objectives of the study were to identify the socio-economic characteristics of the respondents, determine the technical efficiency and measure the total resource productivity of watermelon production in the study area. The data were analyzed using descriptive statistics and quantitative analytical tool of stochastic frontier model (Cobb Douglas production function). Socio-economic attributes like age, farm size, educational status and farm experience were described to show their relationship with watermelon production in the study area. Results of the stochastic frontier model showed that all the estimated coefficients of the variables of the production function were positive except fungicide. They included: farm size (0.0795), labour (0.0201), number of seed grown (0.926) and fertilizer (0.0207). This implied that watermelon output increases with increase in these variables. It was also shown that labour (0.441), fertilizer (0.475) and fungicide (-1.662) did not exert any significant effect on watermelon output as shown by their t-ratio values. For the factors affecting technical inefficiency of watermelon farmers, age of farmers and farm size were negative and significant at 0.05 levels of probability, while household size, educational qualification and farming experience were all positive and significant at 5% levels of significance and type of cropping was positive and significant at 10% level of significance. Non-farm income was positive and significant at 5% level of probability. This means that one unit increase in these variables would increase technical inefficiency of the farmers and hence decreasing their technical efficiency. Finally, the return to scale parameter returned the value 0.967 which indicated that watermelon production in the study area was in the Stage II of the production surface. Based on the results of the analysis the following were recommended. Watermelon farmers should be provided and encouraged to take loans, be assisted with extension services and become members of farmer associations, in order to boost their production. Also inputs such as farm size, labour, seeds, fertilizer and fungicide should be increased for optimum production. Key words: Watermelon, production, stochastic frontier model, technical efficiency, Nigeria, INTRODUCTION Watermelon (Citrullus lenatus) is a warm season crop that is cultivated worldwide ostensibly for it numerous nutritional benefits [1,2]. The fruit contains nutrients and phytochemicals beneficial to human health [...]

The objective of this investigation was to evaluate the effect of different doses of nitrogen and potassium fertilizers on some production parameters of melon plants. The experiment was carried out in San Roque, which is 24 km from the city of Conception, Paraguay, at the coordinates 57[degrees]14'10.29' South and 23[degrees]19'12.05' West. The study design was the completely randomized block with three replications in a split plot scheme 4x4. The dose used in the main plot was of N (0, 50, 100 and 150 kg [ha.sup.-1]) and in the sub-plot, K (0, 95, 190 and 285 kg [ha.sup.-1]). A light harrow was carried out to prepare the soil, seedlings were produced in 1500 [cm.sup.3] pots of 60-micron thickness and the transplant was carried out when the seedlings had between 4 and 6 true leaves at 30 days after planting. Urea with 45% N was used as the source of nitrogen and potassium chloride 60% was used as the source of potassium. Fertilisation was carried out in September 2017 on two occasions: at 15 and 30 days after transplanting. The spacing used was of 1.5 m between rows and 1.5 m between plants, giving a total of 4356 plants [ha.sup.-1]. Harvesting began 90 days after planting and was carried out three times as the fruits reached commercial ripeness. The variables that were measured were average fruit weight (AFW), total soluble solids (TSS), polar diameter (PD), equatorial diameter (ED), fruit weight per plant (FWP). The data of the evaluated variables were subjected to the analysis of variance using the Fisher test where significant differences were found in: AFW, TSS, PD, ED and FWP. Subsequently, the regression analysis was performed (AFW, TSS and PD) and response surface (ED and FWP). The dose combination that produced the best values for equatorial diameter and fruit weight per plant was 71.9495 kg [ha.sup.-1] of N and 160.554 kg [ha.sup.-1] of K, 77.5921 kg [ha.sup.-1] of N and 147.369 kg [ha.sup.-1] of K, respectively. Key words: Cucumis melo L., fertilizer application, nitrogen, potassium, dose, weight, diameter, productivity, INTRODUCTION The melon plant (Cucumis melo L.) is a herbaceous species that is very well adapted to Paraguay's agroecological conditions. Production in Paraguay is highly seasonal: there is abundant supply [...]

Common bean (Phaseolus vulgaris) is the most consumed legume crop in the world, and one of the most consumed legume crops in Botswana. This study aims to identify constraints and opportunities in common beans production in order to enhance common bean production in the country. A survey was conducted among 287 farmers in two districts of Southern and Chobe with farmers selected by multi-stage sampling technique. The majority of farmers were female (66.1%), a few farmers planted common bean (11.5%). Slightly more than a quarter (27.8%) of farmers were above the age of 65 years. Constraints to production included pests and diseases, damage by animals, lack of labour, drought, and lack of seeds. Seven percent of farmers assumed that common bean was a drought tolerant crop and 33% of farmers said common bean taste better than other pulses. However, only 21% preferred to grow it. More farmers (13.2%) grew common bean in the Southern district than farmers in the Chobe district (7.0%). Farmers who grew common bean bought their seeds from Agro dealers (76%) with an average amount of 6kg of seed purchased at a time at an average price of $1.11 k[g.sup.-1]. Common bean was planted on 7% of the arable land that was planted. Most of the farmers (87%) were not trained in common bean production and received little or no assistance from extension officers resulting in little knowledge by farmers about the production of common beans. Strategies to create awareness are needed to facilitate access and mobilise farmers to adopt common beans to improve their livelihoods. This is particularly encouraged in agro-ecological zones such as Chobe with high yield producing potential. Development of seed systems and release of varieties tested in Botswana agro-ecological zones, would increase the production of common bean to improve food security and nutrition, and reduce import bill in Botswana. Key words: Common bean, Cropping systems, Marketing, Production, Phaseolus vulgaris, Agro-ecology, Multi-stage, Pulses, Drought, INTRODUCTION Common bean (Phaseolus vulgaris) is considered the most important food legume crop in human diet in the world [1]. It is an annual legume grown mainly for its rich [...]

Biochar made from crop residues has been shown to improve soil texture, soil porosity and soil structure. It can enhance fertilizer utilization, reduce leaching loses and hence improve nitrogen supply for plant growth. Utilization of biochar in preparation of potting substrates can enhance growth and yields of greenhouse tomato. A study was carried out to test the influence of rice husks biochar on substrate properties, growth and yield of greenhouse tomato. The experiment was carried as a factorial in completely randomized design with two factors: four biochar levels and two soil types, replicated three times. The biochar levels were volume ratios of 0 biochar: 1 soil (OBiochar), 0.25 biochar: 0.75 soil (0.25Biochar), 0.5 biochar: 0.5 soil (0.5Biochar) and 0.75 biochar: 0.25 soil (0.75Biochar). The two soil types used were the well drained deep red friable soil and imperfectly drained dark brown clay soil obtained from the University farm. Tomato Anna F1 was grown in four-liter plastic pots containing about 3 kg of soil-biochar mixture. Data were collected on the plant growth parameters of plant height, number of leaves per plant and plant dry weight upto the 8th - 9th week after transplanting, when fruit ripening began. The chlorophyll index of the leaves were measured using the SPAD meter. At harvesting, fresh weight and number of the fruits were determined. Incorporating biochar into potting substrate at 0.25-0.75 levels significantly increased evapotranspiration during early vegetative growth. This was indicative of biochar changing substrate properties mainly through significant reduction of bulk density and possibly increasing porosity. Biochar levels of 0.25-0.75 resulted in significant increases in vegetative growth and fruit yield of tomato. Adding biochar to the pot substrate increased tomato plant height, plant dry weight and fruit fresh weight by 21-34%, 50-64% and 49%-56%, respectively. The increase in vegetative growth and fruit yield at 0.25-0.75 biochar levels was attributed to the positive effect of biochar on substrate physical properties. Plant height and number of leaves per plant had a significant linear relationship whose slope, the rate of increase in plant height with increase in number of leaves was not influenced by biochar levels. Biochar enhanced growth without changing the ratio of plant height to number of leaves of tomato. It is concluded that incorporation of biochar made from rice husks at 0.25 level can enhance greenhouse production in both red and clay soils. Key words: Bulk density, Dry weight, Fresh fruit weight, Number of leaves, Plant height, INTRODUCTION Biochar is a by-product of pyrolysis involving the thermal decomposition (exothermic) of biomass in an oxygen limited environment. Conversion of local bio-waste into biochar and its utilization as a [...]

Analysis of cereal production allows one to make decisions about the importance of certain products and the water resources. Improving cereal production is crucial in developing the standard of living in Algeria. Actually, it should be part of any future strategy for the country. Most of the arable land in Algeria is in a Mediterranean climate, where droughts are common and rainfall is distributed unevenly throughout the year. Research on the impact of climate variability and irrigation on cereal production is necessary due to the effects on the uneven performance of crops in Algeria. The study considered here is based on statistical methods to model the production of durum wheat, bread wheat, barley and oats. The first method used is principal component analysis. It was applied to classify the data in order to determine the relative importance of the various regions for the evaluation of cereal production. The results exhibit an increasing trend in the cereal production on the period from 2009 to 2012. The 2012 cereal harvest in Algeria proved to be the second highest ever recorded, after that of 2009, despite an unusual period of snow in February. It appears that durum wheat production was explained jointly by precipitation and irrigation. However, the variations in the production of the common wheat, oat and barley can only be explained by precipitation. Agriculture currently depends mainly on precipitation rather than irrigation. Modern irrigation systems could increase production. Therefore, if agricultural production is to be improved, important agricultural irrigation methods are needed to mitigate the impact of climate variability in each agricultural area, mainly in the southern regions of the country. Key words: cereal, irrigation, rainfall, regression, production, wheat, oat, barley, INTRODUCTION Agro-climatic constraints, combined with the recent effects of climate change, are weighing in on the development of Algerian agriculture. Research on the impact of climate change showed declining rainfall [...]

In the grain growing region of Queensland and New South Wales, Australia, crop production occurs predominantly under semiarid, rainfed conditions. Vertosols dominate the soils used and many are prone to structural problems. In this region, providing that crop nutrition is adequate, optimising yield is largely dependent on maximising the infiltration, storage and plant use of soil water. Soil constraints such as sodicity, salinity, acidity, subsoil compaction and surface sealing can limit these processes, leading to high yield losses. This review examines management options to treat these constraints, focusing on management where multiple constraints exist, and where these occur in the subsoil. The main strategies reviewed include (a) use of gypsum to treat sodicity and lime to treat acidity, which can lead to yield increases of >100% in some circumstances, (b) cultivation or deep ripping to break up compacted sodic layers and surface seals, (c) incorporating soil organic matter to improve conditions for plant growth and (d) selecting species, cultivars and management practices most appropriate for constrained sites. Future research must be directed to improving the profitability of ameliorant use for sodicity by increasing our understanding of how to identify soils responsive to ameliorants, and which combination of ameliorants will be cost effective when sodicity occurs in combination with other constraints. In addition, research needs to target ways to economically apply ameliorants in subsoil environments, and better identify which crop species or cultivars are productive on constrained sites, particularly those with multiple constraints.Additional keywords: acidity, gypsum, lime, salinity, sodicity, soil organic matter, subsoil.Received 9 August 2018, accepted 26 September 2018, published online 5 November 2018, IntroductionAustralia's grain growing area can be divided geographically into three broad agroecological regions - the northern region, encompassing Queensland (Qld) and New South Wales (NSW); the southern region, encompassing Victoria, [...]

Decline in soil organic carbon (SOC) content is considered a key constraint for sustenance of rice-wheat system (RWS) productivity in the Indo-Gangetic Plain region. We, therefore, studied the effects of fertilisers and manures on SOC pools, and their relationships with crop yields after 18 years of continuous RWS. Total organic C increased significantly with the integrated use of fertilisers and organic sources (from 13 to 16.03 g [kg.sup.-1]) compared with unfertilised control (11.5 g [kg.sup.-1]) or sole fertiliser (NPKZn; 12.17 g [kg.sup.-1]) treatment at 0-7.5 cm soil depth. Averaged across soil depths, labile fractions like microbial biomass C (MBC) and permanganate-oxidisable C (PmOC) were generally higher in treatments that received farmyard manure (PYM), sulfitation pressmud (SPM) or green gram residue (GR) along with NPK fertiliser, ranging from 192 to 276 mg [kg.sup.-1] and from 0.60 to 0.75 g [kg.sup.-1] respectively compared with NPKZn and NPK+cereal residue (CR) treatments, in which MBC and PmOC ranged from 118 to 170 mg [kg.sup.-1] and from 0.43 to 0.57 g [kg.sup.-1] respectively. Oxidisable organic C fractions revealed that very labile C and labile C fractions were much larger in the NPK + F YM or NPK+GR + F YM treatments, whereas the less-labile C and non-labile C fractions were larger under control and NPK + CR treatments. On average, Walkley-Black C, PmOC and MBC contributed 29-46%, 4.7-6.6% and 1.16-2.40% towards TOC respectively. Integrated plant nutrient supply options, except NPK + CR, also produced sustainable high yields of RWS. Additional keywords: cereal residue, FYM, green gram residue, Inceptisol, labile SOC, sulphitation pressmud., Introduction In the post-Green Revolution era, Indian agriculture encountered the problems of deterioration in soil health, stagnation in both food grain production and productivity growth rates and groundwater recession, resulting [...]

Rain-harvesting planting can improve crop biomass and enhance precipitation use efficiency in rainfed semiarid areas. In this study, field trials were conducted during summer 2007-2010 to determine the impacts of different mulching patterns in rainfall harvesting planting on spring com growth and development in a typical semihumid dryland farming area of the Loess Plateau in China, which is characterised by spring droughts. Rain-harvesting ridges and planting furrows were mulched with 8% biodegradable film ([RC.sub.SB]), liquid film ([RC.sub.SL]), or not mulched ([RC.sub.SN]), and bare land drilling without mulching served as the control (CF). We found that the rain-harvesting effects of ridges and the evaporation-inhibiting and moisture-conserving effects of mulching materials during the spring com growing season significantly increased water storage in the 0-100 cm soil layer (P 0.05) of the treatments on water storage. During 2007-2010, the average plant height increased by 26.6%, 15.4%, and 11.1% under [RC.sub.SB], [RC.sub.SL], and [RC.sub.SN] relative to CF respectively, whereas the per plant biomass increased by 26.6%, 15.4%, and 11.1% under these treatments, and the grain yield increased by 32.3%, 17.5%, and 15.0%. Therefore, in the semihumid dryland fanning areas of the Loess Plateau, rain-harvesting planting greatly increased the growth, development, and dry matter accumulation by spring com, thereby enhancing its biomass yield, whereas the plastic-covered ridges and furrows mulched with biodegradable films substantially increased the yield-enhancing effects. Additional keywords: furrow mulching, Loess Plateau of China, rain-harvesting planting, soil temperature, soil water storage, yield., Introduction The semihumid dryland farming areas of China have a vitally important role in the development of arid agriculture (Yao and Yin 1999). In these areas, particularly in recent years, [...]

ABSTRACT Dry areas are vulnerable to climate change and are commonly hit by drought, which makes the inhabitants to rely on food aid. Mushroom cultivation is a profitable agribusiness that [...]

Sustainable fanning practices are required to address the persistent problems of land degradation and declining crop productivity in Sub-Saharan Africa. Approaches such as reducing tillage and retaining crop residues as mulch are potential entry points for smallholder farmers to move towards sustainability. In this study, we assessed the impact of reduced tillage (RT) compared with conventional tillage (CT), each combined with crop residue reapplication, on soil quality indicators and crop yields under an 8-year trial in western Kenya. Our results indicate that RT combined with crop residue reapplication enhanced soil physical quality through increased macroaggregate (>2000 pm) proportions and mean weight diameter. Similarly, lower respiratory quotient values indicate that soil microbes under RT have better substrate-use efficiency than those under CT. Nevertheless, soil organic carbon (C), potentially mineralisable C, microbial biomass C and mineral nitrogen contents were all higher under CT with crop residue incorporated into the soil. Maize grain yield and aboveground biomass were also higher under CT. Thus, despite RT showing potential to improve soil physical properties, CT performed better. A stepwise approach is proposed towards the practice of conservation agriculture under resource-constrained smallholder farming conditions, starting with increased biomass production to provide crop residue for soil cover, followed by RT approaches. Additional keywords: aggregate stability, labile SOC fractions, nutrient management, qC[O.sub.2], smallholder farming systems, soil quality indices. Received 6 May 2015, accepted 20 November 2015, published online 4 July 2016, Introduction Declining soil fertility is one of the major challenges facing smallholder farming communities in Sub-Saharan Africa (SSA), and is often associated with extractive farming practices (Lai 2011). The situation [...]

A controlled traffic no-till system is a cropping system that has a significant potential to improve soil health, sustainability and crop yield. A pilot experiment was conducted to compare soil chemical properties and crop yields between controlled traffic no-till and random traffic in an annual double-cropping area of the North China Plain from 2005 to 2010. The experiment was performed using three treatments: (1) controlled traffic no-till (NTCT); (2) random traffic no-till (NTRT); and (3) conventional tillage (CT). The NTCT treatment significantly improved soil organic matter and total N compared with both NTRT and CT treatments and remarkably increased available P compared with CT treatment in the surface soil layer (0-10 cm), but no significant differences were found in soil pH compared with both NTRT and CT treatments. However, in the 10-20- and 20-30-cm soil profiles, soil organic matter, total N and available P were reduced after NTCT treatment when compared with those obtained after CT treatment. At 0-10 cm soil depths, soil bulk density under NTCT and NTRT was higher than in CT, whereas the opposite was true at soil depths of 10-30 cm. Overall, it was found that the 6-year mean maize yield of NTCT and NTRT treatments was 10.9% and 1.1% higher respectively than the CT treatment, whereas the winter wheat yield was 1.1% and 3.0% higher respectively compared with the CT treatment. NTCT appears to be an improvement over current farming systems in an annual double-cropping area of the North China Plain. Additional keywords: available P, bulk density, C/N ratio, conventional tillage, pH, soil organic matter, total nitrogen. Received 29 August 2012, accepted 27 October 2015, published online 12 July 2016, Introduction Soil organic matter (SOM) represents the mineral and organic characteristics of soil (Alexandra and Jose 2005). It is also considered as a primary component of sustainable soil management and [...]

Integration of trees with forage and livestock production (silvopastoralism) could increase productivity of forest and range resources in western North America. Pre-commercial thinning (PCT) and fertilization are two silvicultural practices that could enhance silvopasture. We tested two hypotheses (H): that yield and quality of forage would be enhanced by ([H.sub.1]) heavy thinning (PCT) to Key words: cattle grazing, crude protein, forage, forest fertilization, silvopasture, thinning. L'integration d'arbres a la production de fourrage et de betail (sylvopastoralisme) pourrait augmenter la productivity des ressources forestieres et des paturages dans l'ouest de l'Amerique du Nord. L'eclaircie precommerciale (EPC) et la fertilisation sont deux pratiques sylvicoles pouvant accroitre le sylvopaturage. Nous avons teste les hypotheses (H) que la production et la qualite du fourrage seraient ameliorees par une eclaircie forte (EPC) laissant moins de 1000 tiges-[ha.sup.-1] ([H.sub.1]) et par des fertilisations repetees dans des peuplements de pin tordu latifolie (Pinus contorta var. latifolia Engelm.) ([H.sub.2]). Les aires d'etude etaient situees pres de Summerland et de Kelowna, dans le centre-sud de la Colombie-Britannique, au Canada. Chaque aire d'etude comprenait six traitements : trois paires de peuplements eclaircis a des densites approximatives de 500 (faible), 1000 (moderee) et 2000 (forte) tiges-[ha.sup.-1] dont un peuplement de chaque paire a ete fertilise cinq fois a intervalles de deux ans. La production de fourrage a ete amelioree par l'EPC, mais seulement dans les peuplements fertilises. La qualite du fourrage n'a generalement pas ete influencee par l'EPC, sauf pour les proteines brutes des herbacees dont la quantite etait moins elevee dans les peuplements fortement eclaircis. La fertilisation tendait a augmenter la production et la qualite du fourrage dans les peuplements fortement eclaircis. L'augmentation significative de la qualite du calamagrostis rougissant (Calamogrostis rubescens Buckley) indique que la fertilisation repetee, jumelee a une eclaircie forte, peut allonger la periode pendant laquelle du fourrage de bonne qualite est disponible, permettant ainsi d'augmenter la densite de bovins (Bos taurus L.) et peut-etre d'etendre la saison de paturage durant l'automne. [Traduit par la Redaction] Mots-cles: paturages pour bestiaux, proteine brute, fourrage, fertilisation forestiere, sylvopaturage, eclaircie., Introduction Silvopastoralism (the intentional integration of trees with forage and livestock production) has long been successfully practiced throughout the world (Knowles et al. 1973; Msika and Etienne 1989; Sibbald et [...]

Field experiments were conducted at Abubakar Tafawa Balewa University, Fadama Farm Bauchi, during the rainy seasons of 2006 and 2007 to study the effects of variety, seeding rate and row spacing on growth and yield of rice. Two varieties of rice; Ex - China (Indigenous and upland/lowland) and NERICA-1 (improved and upland), three seeding rates (32, 54 and 75 kg/ha) and four row spacings (15, 20, 25 and broadcast) were used during the study. The treatments were combined and laid in a split - split plot design with three replications. Variety was placed in the main plot, seeding rate in the sub plot while row spacing was placed in sub -sub plot. Data were collected on parameters such as plant height, number of tillers per plant, spikes per hill, spikelets per spike and number of seeds per spike, seed weight per hill, 1000 grain weight and yield kg [ha.sup.-1] and analyzed using analysis of variance procedure for split - split plot and significant differences among the treatment means were separated using the Duncan multiple range test (DMRT). Variety Ex-China produced significantly (P [less than or equal to] 0.05) higher numbers of tillers per plant and spikes per hill. However, NERICA-1 produced significantly (P[less than or equal to]0.05) higher numbers of spikelets per spike, seeds per spike, weight of seed per spike, weight of seed per hill, 1000 grain weight and yield in kg [ha.sup.-1] than Ex-China. Row spacings of 15, 20 and 25cm also had significant effects on the number of tillers per plant, number of spikes per hill, number of spikelets per spike, number of seeds per spike, weight of seed per spike, weight of seed per hill, 1000 grain weight and yield kg [ha.sup.-1] over the control. From the factors studied, seeding rate did not show any significant difference during the two years of investigation. Interactions were also observed among the factors studied. Therefore, row spacings irrespective of the method used, or hole planting of rice could be more appropriate for optimum grain yield., Key words: Seed rate, Row spacing, Spikes INTRODUCTION Over the past decades, rice has shifted from a luxury to a staple food crop in Nigeria, produced by subsistence farmers. As [...]

The 'degree of compactness' is a useful parameter to study soil compaction and represents the current bulk density in relation to the bulk density of the same soil in a reference state. The objectives of this study were to: (i) determine the best compression stress to establish the reference bulk density in the uniaxial compression test using undisturbed samples; (a) quantify the effect of texture on degree of compactness, and (Hi) evaluate the influence of degree of compactness on selected soil physical properties and crop yield. Six soils under no-tillage from southern Brazil were used and the reference bulk density was evaluated on soil samples equilibrated to the matric suction of 33 kPa and subjected to uniaxial compression test. Soil macroporosity, mechanical penetration resistance, root growth, and yield of soybean were also evaluated. For undisturbed soil samples, stresses ≥ 800kPa (particularly the stress of 1600kPa) arc appropriate to determine the reference bulk density. Degree of compactness is independent of clay content and is associated with changes in soil physical properties. A degree of compactness ~100% restricted root growth of soybean, whereas the highest soybean yield was obtained with a DC of 82% for Alfisols and Ultisol, and 85% for Oxisols. Additional keywords: reference bulk density, relative compaction, soil compaction, uniaxial compression., Introduction Soil compaction is defined as the process of decreasing total porosity (especially air-filled porosity), with a consequent increase in bulk density and soil penetration resistance and decrease in water [...]

Soil water repellency (SWR) caused by organic coatings on soil particles can lead to serious loss in crop production and turfgrass quality. In laboratory experiments, we tested the novel concept of direct application of enzymes to alleviate SWR. In a biofuel research project on fungal pre-treatment of switchgrass (Pemicum virgatum L.) for improved saccharification, enzymatic co-products (mainly laccase mixed with other trace enzymes) were produced based on fermentation periods of 18, 36, 54, and 72 days. We characterised enzyme activities of the 18-72-day crude enzyme extracts (CEE) and applied undiluted or diluted solutions (dilutions of 5-, 10-, and 100-fold) to eight air-dried, SWR soils from several golf courses. These soils exhibited water drop penetration times (WDPT) of 345-7439 s (i.e. moderately to very strongly hydrophobic) and all showed a large decrease in SWR to WDPT Additional keywords: soil water repellency, laccase, Co-product, bioremediation., Introduction Soil water repellency (SWR) is the phenomenon in which a soil does not spontaneously wet when a drop of water is applied to the surface, indicating that the soil [...]

A project aimed at improving bean production in Kigoma Region was carried out from 2008/09 to 2010/11 in Kasulu and Kibondo districts. Soils at trial sites varied from sandy clay loams to clay, mostly acidic with pH water varying from 4.5 to 6.3 (mean 5.5 ± 0.5) with low to medium (1.86% [+ or -] 0.57%) organic carbon (OC), low (0.15 ± 0.05) total nitrogen (N), and low to medium (5.27 ± 5.4 mg/kg) available phosphorus (P). Five improved cultivars, Jesca, Lyamungo 90, Selian 97, Uyole Njano and Uyole 98 were evaluated for yield in farmers' fields, and assessed for farmer acceptability through a questionnaire. The varieties were compared to Kigoma Yellow, a local variety known also as Mburamutwe. The experimental design was Randomized Complete Block with farmers as replicates. Plot size was 10 m by 10 m and spacing was 50 cm by 20 cm. Yield data were analyzed using MS X-Cel and GenStat Discovery edition. Farmers' assessment data were analyzed by SPSS (V 11.5). There were positive significant (p Key words: Bean varieties, yields, farmers' assessment, INTRODUCTION Beans are a warm season crop that does not require an excessive amount of moisture. Depending on the soil and climatic factors, the requirement is met with 300-600 mm [...]

Pumpkin (Cucurbita pepo Linn.) is a vegetable crop often grown without fertilizer by peasant farmers in Nigeria. With the increased pressure on land resources for other competing uses, farmers have adopted the use of fertilizers to boost crop productivity. This study was carried out for the purpose of evaluating the influence of NPK fertilizer on fruit yield and fruit yield parameters of pumpkin. The experiment was carried out under open field conditions in 2010 for two seasons at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife, Nigeria. The farm is located on latitude 07°28'N and longitude 04°33'E about 244-m above sea level. NPK 15:15:15 compound fertilizer was applied as ring/side dressing at the rates of (0, 50, 100, 150, 200, 250 kg/ha). The experiment was a randomized complete block design and was replicated six times. Each plot size was10 m X 12 m and consisted of 7 rows. Alley was 3 m, while the plants were spaced 2 m x 2 m. Data were taken on yield and yield parameters such as: fruit height, fruit circumference, fruit fresh weight, fruit dry matter, fruit yield, seed number and seed weight. The fresh fruit yield was 21 t/ha and 7t//ha for early and late seasons, respectively. Fruits number/ha significantly (p=0.05) increased from 7000 in control to over 10,000/ha at fertilizer rates between 100 and 250 kg NPK/ha. Fruit weight also increased from 9 to 17t/ha between control and higher fertilizer rates. Seed yield from the application at 100 to 250 kg/ha were similar and significantly better than control and 50 kg/ha NPK application. Mean seed yield between 100-250 kg NPK was 460 kg/ha. The value was 37% higher than at 50 kg NPK and 57% higher than in control. Increasing fertilizer above 100 kg NPK/ha did not significantly (p=0.05) increase the fruit yield nor the seed yield. Key words: NPK fertilizer, Fruit yield, Pumpkin, INTRODUCTION Pumpkin fruits are rich in carotenoids, minerals and vitamins. Recent studies have shown that they are a veritable source of antioxidants. Antioxidants are required to boost the human body [...]

Sorghum (Sorghum bicolor L. Moench) is an important crop that enhances food security in a region. As a food crop, sorghum is nutritious, containing starch (75-79%) as the major component, followed by protein (6.0-16.1%) and oil (2.1-5.0%). Despite the crop's versatility, it is regrettable that sorghum yields are still fairly low in Bomet District of Kenya. One of the constraints associated with low yields is the accessibility to good quality seeds by farmers. It was assumed in this study that use of low quality seed was among the factors that could be significantly affecting the low production of sorghum in the district. This study focused on the physiological quality of seed which refers to the germination capacity, viability, characteristics related to dormancy and vigour of the seed. A total of 100 farmers were interviewed and 80 seed samples were obtained from 80 farmers. The seeds were subjected to viability and vigour quality tests. These tests included germination (as a viability test); mean germination time and electrical conductivity tests (as vigour tests). About 29% of the seed samples taken for germination test were below the laboratory standards as stipulated in the seeds and Plant Varieties Act (CAP 326). Critical electrical conductivity values and critical mean germination time values were derived during the study. In accordance with the critical values arrived at in this study, 27.5% of the seed samples showed relatively high electrical conductivity readings and 36.3% of the seed samples showed longer mean germination time. However, 11.3% of the seed samples showed high germination percentages of above 90%. Since about 29% of farmers seeds were of bad physiological quality, it was concluded that this proportion of seed can result in poor yields and hence cause food insecurity to the people of the society, and thus requires further consideration for improvement. This study recommends that further research be conducted on the genetic, physical and sanitary quality aspects of seed planted by farmers in Bomet District so that a definite conclusive statement about the quality of seed planted by farmers in the District can be made. Key words: sorghum, viability, vigour, germination, quality., INTRODUCTION Sorghum is one of the world's major food crops, particularly in areas of low and unreliable rainfall such as in arid and semi-arid regions [1, 2]. In Kenya, sorghum [...]

Effects of thermally gasified pig manure ash (GA) and lime-free gasified ash (LF-GA) on properties of an acidic soil (pH 4.5) and the growth and elemental uptake of ryegrass (Lolium rigidum Gaudin) were investigated. The GA was an effective liming agent (2% addition raised soil pH from 4.5 to 7.9); both GA and LF-GA increased soil electrical conductivity and bicarbonate-extractable phosphorus (P). Soil fertilised with LF-GA supported slightly higher plant dry matter (DM) yield than GA (1.5-1.7 v. 1.2-1.5g DM/kg soil) for the first harvest, due to greater initial P availability at pH 6. However, plant yields for the subsequent two harvests were similar, as soil acidity dissolved lime in untreated ash (GA) over time. Maximum yields for ash-treated soil and soil treated with mono-calcium phosphate (MCP) were similar. Relative agronomic effectiveness of P sources for three harvests, based on plant P content compared with values for MCP, were 6, 11, and 12% for GA and 19, 10, and 33% for LF-GA. Internal efficiency of P utilisation was similar for all three P sources for each harvest, indicating that differences in yield were mostly a consequence of differences in P supply. Heavy metal concentrations in plants fertilised with ash were minor and within regulatory limits. In general, application of ash did not systematically affect the concentrations of elements (A1, B, Cd, Mg, Mn, Fe, Pb, S, Se) in plants. Additional keywords: animal manure, available P, gasifier ash, lime content, phosphate fertiliser, soil acidity. Received 21 March 2012, accepted 1 June 2012, published online 3 August 2012, Introduction Soil acidity is a major problem in agriculture worldwide, including Australia, North America, China, India, and Europe. It restricts nutrient availability and may cause metal toxicity for plants, especially [...]

Precipitation is the major factor limiting crop growth in the semi-arid Loess Plateau region of China. Ridgeand-furrow rainfall harvesting systems (RFRHS) with mulches are used to increase water availability to crops, thereby improving and stabilising agricultural production in the semi-arid region of China. We conducted a field experiment from 2007 to 2010 in the Weibei Highlands of China, to determine the influence of RFRHS with different mulching patterns on soil water content, temperature, water-use efficiency, and maize yield (Zea mays L.). Ridges were covered with standard plastic film in all RFRHS treatments, while different furrow treatments were mulched with standard plastic film (PP), biodegradable film (PB), maize straw (PS), or liquid film (PL), or left uncovered (P). A conventional flat treatment without mulching was used as the control. In the early stage of maize growth, the topsoil temperature (5-20 cm) under PP and PB was significantly (P Additional keywords: mulch, ridge and furrow rainwater harvesting, spring maize, soil temperature, soil water, yield., Introduction The Weibei Highlands, in the southern Loess Plateau of China, is a semi-humid agricultural area that is liable to drought. Precipitation is the major water resource used for agricultural [...]

: Root and butt rot is the most destructive disease of conifers in the Northern Hemisphere, but little is known about the dynamics of yield loss in stands of different ages, site types, and species composition. This study aimed to estimate butt rot incidence, causal fungi, and related wood yield loss in Picea abies (L.) H. Karst. stands in Latvia. A total of 24 745 stumps were examined on 318 forest sites, and 21.8% of them contained rot. There was a positive correlation between stand age and butt rot frequency. Proportion of other tree species in a stand had no influence on incidence of the rot, but significant differences were observed among different forest site types. The length of decay columns in 114 stems analysed was 6.6 ± 2.6 m on average. Based on the observed butt rot frequencies in Latvian P. abies stands of different age classes, volumes of decay-degraded wood in a fully stocked stand would comprise about 19.7 [m.sup.3] * [ha.sup.-1] at the age of 40 years, 57.4 [m.sup.3] * [ha.sup.-1] at 60 years, 54.9 [m.sup.3] * [ha.sup.-1] at 80 years, 63.1 [m.sup.3] * [ha.sup.-1] at 100 years, and 91.8 [m.sup.3] * [ha.sup.-1] at 120 years, corresponding to 6%-16% of a total standing volume. Resume: Le pourridie est la maladie la plus dommageable chez les coniferes dans l'hemisphere nord mais la dynamique des pertes de rendement selon l'?ge, le type de station et la composition en especes est peu connue. Cette etude visait a determiner l'incidence du pourridie, les champignons responsables et la perte de rendement en matiere ligneuse dues a cette maladie dans les peuplements de Picea abies (L.) H. Karst. en Lettonie. Au total, 24 745 souches ont ete examinees dans 318 stations et 21,8 % contenaient de la carie. Il y avait une correlation positive entre l'age du peuplement et la frequence du pourridie. La proportion d'especes compagnes dans le peuplement n'avait pas d'influence sur l'incidence de la carie mais des differences significatives ont ete observees entre les differents types de station. La colonne de carie avait une longueur moyenne de 6,6 ± 2,6 m dans les 114 tiges qui ont ete analysees. En se basant sur la frequence observee du pourridie dans les peuplements de P. abies de differentes classes d'?ge en Lettonie, le volume de bois carie dans un peuplement avec une densite relative adequate serait respectivement d'environ 19,7, 57,4, 54,9, 63,1 et 91,8 [m.sup.3] * [ha.sup.-1] a l'?ge de 40, 60, 80, 100 et 120 ans, ce qui correspond a 6-16 % du volume sur pied. [Traduit par la Redaction], Introduction Butt and stem rots are the most economically important diseases of Picea abies (L.) H. Karst. in Europe, especially in managed forests where cut stumps and wounds on living [...]

BACKGROUND: Global climate change is anticipated to reduce future cereal yields and threaten food security, thus potentially increasing the risk of undernutrition. The causation of undernutrition is complex, and there [...]

Much of the fertiliser nitrogen (N) used in agriculture is lost to the atmosphere as nitric oxide and nitrogen dioxide (collectively referred to as N[O.sub.x]), ammonia (N[H.sub.3]), and nitrous oxide ([N.sub.2]O). The lost N is not only an economic problem for the farmer; it also contaminates the environment and affects human health. Because the values obtained for N[O.sub.x] and N[H.sub.3] loss to the atmosphere from agriculture in Monsoon Asia have been questioned, we quantitatively determined, using new techniques, the emission of these gases from a maize crop fertilised with urea in northern China. The fertiliser was deep-placed by traditional farmers' practice and emissions of N[O.sub.x] and N[H.sub.3] were determined with a chemiluminescence analyser and a backward Lagrangian stochastic dispersion technique. The emission measurements indicate that 1.2% of the applied N was lost as N[O.sub.x]. This loss is far greater than measured or derived by other researchers, and we suggest that this is because our measurements were made continuously rather than as spot measurements with static chambers. The results for N[H.sub.3] show that, although the fertiliser was placed below the soil surface, a small amount (7% of the applied N) was still lost to the atmosphere. Soil analyses indicate that the rate of nitrification in this soil was low, and the maximum nitrate (N[O.sub.3.sup.-]) concentration found in the soil (31.4 µg N/g) was only 3.9% of the fertiliser N added. Thus, there is little potential for N[O.sub.3.sup.-] to be leached down the profile. A study using soil cores and acetylene inhibition to measure denitrifying activity suggested that the rate of denitrification in this soil was also very low. The results suggest that in this soil with slow nitrification and denitrification rates and little potential for leaching, deep placement of the urea to limit N[H.sub.3] volatilisation is an effective method for increasing fertiliser use efficiency. Additional keywords: bLs method, deep placement, fertiliser, micrometeorological techniques., Introduction Agriculture in China is highly intensive and, with the aid of new technology and high input of fertiliser, is very productive and meets the demands by the rapidly increasing [...]

Field capacity (FC) and permanent wilting point (PWP) are two critical input parameters required in various biophysical models. There are limited published data on FC and PWP of dryland cropping soils across north-western Victoria. Direct measurements of FC and PWP are time-consuming and expensive. Reliable prediction of FC and PWP from their functional relationships with routinely measured soil properties can help to circumvent these constraints. This study provided measured data on FC using undisturbed samples and PWP as functions ofgeomorphological unit, soil type, and soil texture class for dryland cropping soils of north-western Victoria. We used a balanced, nested sampling strategy and developed functional relationships of FC and PWP with routinely measured soil properties using residual maximum likelihood based mixed-effects regression modelling. Using the data, we also tested the adequacy of nine published pedotransfer functions (PTFs) in predicting FC and PWP. Significant differences were observed among the three soil types and nine texture classes for most soil properties. FC and PWP were higher for Grey Vertosols (FC 43.7% vol, PWP 29.1% vol) than Hypercalcic Calcarosols (38.4%, 23.5%) and Red Sodosols (20.2%, 9.2%). Of the several functional relationships developed for prediction of FC and PWP, a quadratic single-predictor model based on dg (geometric mean particle size diameter) performed better than other models for both FC and PWP. It was nearly bias-free, with a root mean square error (RMSE) of 3.18% vol and an [R.sup.2] of 93% for FC, and RMSE 3.47% vol and [R.sup.2] 89% for PWP. Another useful model for FC was a slightly biased, two- predictor quadratic model based on clay and silt, with RMSE 3.14% vol and [R.sup.2] 94%. For PWP, two other possibly useful, though slightly biased, models included a single-predictor quadratic model based on clay (RMSE 3.45% vol, [R.sup.2] 89%) and a three-predictor model based on clay, silt, and [σ.sub.g] (geometric standard deviation of particle size diameter) (RMSE 3.27% vol, [R.sup.2] 90%). We observed a strong quadratic relationship of FC with PWP (RMSE 1.61% vol, [R.sup.2] 98%). This suggests the possibility to further improve the prediction of FC indirectly through PWP. These predictive models for FC and PWP, though developed for the dryland cropping soils of north-western Victoria, may be applicable to other regions with similar soil and climatic conditions. Some validation is desirable before these models are confidently applied in a new situation. Of the nine published PTFs, the multiple linear regression and artificial neural network based NTh5 for FC and NTh3 and CAM for PWP performed better on our data for the prediction of FC and PWP. The root mean square deviation of these PTFs, for both FC and PWP, was higher than the RMSE of our models. Our models are therefore likely to perform better under the dryland cropping soils of north-western Victoria than these PTFs. As a safeguard against arriving at optimistic inferences, we suggest that the modelling of functional relationships needs to account for the hierarchical structure of the sampling design using appropriate mixed effects regression models. Additional keywords: mixed effects regression, nested sampling design, plant-available water capacity, PTFs, residual maximum likelihood, soil texture, soil type, soil water retention., Introduction The most important soil factor that controls yield in much of the Australian grain-production regions is the quantity of plant-available water (e.g. Rab et al. 2009). Prediction of the [...]

Coffee (genus Coffea L.) is one of the most critical global agricultural crops. Many studies have focused on coffee plants and their associated insects. This review will summarize work specifically relating to coffee plant--pollinator interactions. We review the current status of coffee as a worldwide commodity, botanical aspects of coffee, and insects associated with coffee pollination, and we assess the current understanding of the role of different pollinator taxa in increasing fruit set and yield. Le cafe (le genre Coffea L.) represente une des cultures agricoles globales les plus importantes. Plusieurs etudes se sont interessees aux cafeiers et aux insectes qui leur sont associes. Notre retrospective resume les travaux relies specifiquement aux interactions cafeiers-pollinisateurs. Nous examinons le statut actuel du cafe comme denree mondiale, les aspects botaniques du cafe et les insectes associes a la pollinisation du cafe et nous evaluons la comprehension actuelle des roles des differents taxons de pollinisateurs dans l'augmentation de la nouaison et du rendement. [Traduit par la Redaction], Introduction With approximately 2.28 billion cups consumed every day (Dicum and Luttinger 1999; Bacon 2005), coffee is the world's second most important legally traded commodity after oil (Daviron and Ponte [...]

ABSTRACT Organic wastes have been reported to reduce saturation of the exchange complex by Al in Al-rich acid soils. For 3 years, the main soil fertility properties were studied in [...]

The leaves, shoots, immature pods and dry seeds of okra are used extensively in vegetable food preparations in the tropics. The fruit is rich in minerals and vitamins, which are essential for body functions. The soft and succulent nature of the leaves make them vulnerable to attack and subsequent damage by a range of leaf eating insects, animal pests and man. Such damage results in remarkable yield loss and reduced market value. Identification of the critical stages of attack and extent of loss taking place at each stage of development of the plant could aid in planning strategies for prevention and/or control. Thus, two field experiments were conducted to determine the effect of leaf removal on the growth and marketable yield of okra. The treatments on leaf defoliation at different stages of development consisted of removal of leaves at 4 weeks after sowing (WAS) as early vegetative stage, 6WAS (at floral budding stage) and 8 WAS (at early fruiting stage). The treatments on the degrees of defoliation included the control (no leaf removal), removal of a quarter ([D.sub.25]), half (D50), three quarter ([D.sub.75]) or total removal ([D.sub.100]) of every fully expanded leaf. Different proportions of every leaf were removed with sharpened scissors. Each treatment was replicated four times. The experiment was 3x5 factorial with randomized complete block design. Current market price was used to value the yields. The removal of up to a quarter of each leaf did not affect the fruit yield significantly but the yield was significantly reduced by 39, 79 and 86% when 1/2, 3/4 of each leaf and complete leaf were defoliated, respectively. In money terms, the losses were [begin strikethrough]N[end strikethrough]26,390($175.93), [begin strikethrough]N[end strikethrough]52,780($351.87), and [begin strikethrough]N[end strikethrough]57,876($385.84) per hectare, respectively for these various defoliation levels. Removal of okra leaves during the early fruiting stage led to 82% marketable yield reduction. Complete leaf defoliation was detrimental to fruit yield. The results suggested that okra could tolerate 25% defoliation as might occur from leaf eating insects, human predators or foliage pathogenic infections but beyond this level, it would be detrimental. A programme of control of leaf predators in okra management should therefore commence prior to or at the early fruiting phase in order to realize yields of good value. Further research on commercial uses of okra and the economics of pest control on okra fields is recommended. Key words: Agro-economic, Defoliation, Fruiting, Yield, Commercial, INTRODUCTION Okra (Abelmoschus esculentus (L) Moench) is a popular vegetable in the tropics, cultivated for its immature pods and dry seeds [1, 2]. It is a flowering plant in the [...]

Pearl millet (Pennisetum glaucum (L.) R. Br.) is an important cereal in semi-arid tropics in Africa and India. Conventionally, millet has good amounts of grain minerals compared to other cereals. Estimation of genetic parameters would be useful in developing appropriate breeding and selection strategies. The present study was conducted to evaluate the local pearl millet accessions to assess the magnitude of variability and to understand the heritable component of variation present in the yield and nutritional characters. A field trial was laid under the complete randomized block design (RCBD) with three replications; observation were recorded on eight morphological and seven nutritional characters (as detailed in material and methods) including anti-nutritional properties such as phytate content among 61 genotypes collected from millet collection. The phenotypic co-efficient of variation (PCV) was greater than genotypic co-efficient of variation (GCV) for all the characters studied; this shows the influence of environmental factors on the characters. The phosphorus content had expressed the highest phenotypic and genotypic variances (845.30 and 772.08, respectively). The magnitudes of phenotypic and genotypic variances were low for the 100 grain weight (0.001 for both phenotypic and genotypic variance). High estimates of genetic co-efficient of variation, heritability and genetic advance were exhibited by iron and crude fat content. Heritability is a measure of possible genetic advancement under selection. High heritability was observed for all the traits under study except seed weight which had moderate heritability. High value of heritability coupled with high genetic advance as per cent of mean were recorded for number of productive tillers, crude protein, crude fat, phytate, phosphorus, calcium, iron and zinc content, indicating the important role of additive gene action for the expression of these characters. Therefore, selection based on these characters could bring about desired improvement in yield as well as nutritional quality of pearl millet cultivars. Key words: Genetic-advance, Heritability, Variability, Micronutrients, Malnutrition, INTRODUCTION Biofortification, a new approach that relies on conventional plant breeding and modern biotechnology to increase the micronutrient density of staple crops holds great promise for improving the nutritional status [...]

In cold and semi-arid Northeast China, insufficient soil accumulative temperature and low water use efficiency (WUE) are the limiting factors for the further development of agriculture. Ridge tillage (RT) has been proposed to improve soil temperature and water conservation. Data from a 3-year field experiment conducted at two locations (Sujiatun and Lanxi) in Northeast China were used to compare RT, no-tillage (NT), and conventional tillage (CT) in a spring maize cropping system. At both sites, RT and NT significantly (P< 0.05) increased mean soil temperature to 0.10 m depth, relative to CT, by 0.7-2.4°C in the cold season during the spring maize growing stage. Mean soil moisture depletion in the RT treatment was greater by 1.2-4.1% (Sujiatun) and 0.6-3.0% (Lanxi) than in NT and CT, respectively. Mean maize yields over 3 years for RT were -9.9% greater than for CT, whereas the yield advantage in the NT treatment was only slight. In Sujiatun, WUE was 8.0% and 8.6% greater under RT than under NT and CT, respectively, and in Lanxi, WUE was 7.7% and 9.6% greater under RT than NT and CT. Ridge tillage is recommended to the farmers to obtain higher crop yield and WUE in Northeast China. Additional keywords: maize, ridge tillage, soil temperature, water use efficiency, yield., Introduction In cold and semi-arid Northeast China, spring maize is one of the most important grain crops in terms of area and output. The cropping areas and annual total yields [...]

Heterosis has been extensively exploited in maize (Zea mays L.), but the underlying molecular basis remains poorly understood. Identification of molecular markers in the inbred parental lines, which is reliably associated with heterosis, is of apparent breeding interest. We report here that a specific type of cytosine-methylation-based epigenetic difference, that is, CHG methylation (H is A, C, or T) at the 5'-CCGG sites of randomly sampled genomic loci, is positively correlated with grain yield (GY) heterosis in maize (P < 0.01). This conclusion was reached based on an analysis of cytosine methylation differences for 12 maize parental inbred lines by methylation-sensitive amplification polymorphism analysis and on field trials for GY of the inbred parental lines together with 132 [F.sub.1] hybrids produced by complete diallel crossing. Multiple regression analysis showed that the parental difference in CHG methylation level (relative amount) was positively correlated with both midparent heterosis and better-parent heterosis in GY. In contrast, no correlation with GY heterosis was detected for parental differences in CG or total (CG+CHG) methylation levels. Also, no significant correlation was obtained between the amplified fragment length polymorphism-based genetic difference and heterosis in GY for the same set of inbred lines and hybrids. We conclude that parental difference in CHG methylation is a promising molecular marker for grouping germplasms into heterotic groups in maize. doi: 10.2135/cropsci2010.01.0023

The soybean cyst nematode (Heterodera glycines Ichinohe) is the main yield limiting pathogen of soybean [Glycine max (L.) Merr.] in the USA. Resistant cultivars are the most efficient management tool today. Our research studied the physiological basis of yield differences between H. glycines-susceptible and H. glycines-resistant cultivars developed from the Hartwig, PI 88788, and Peking sources of resistance at two locations in Iowa during 2005 and 2006. Supplementing resistance with chemical control may improve soybean yield and/or nematode control, so nematicide application {aldicarb[2-methyl-2 (methylthio) propionaldehyde O-(methylcarbamoyl) oxime]} was included as an experimental factor. Aldicarb increased total plant biomass by 9% during R1-R5 soybean growth stages, but there was no increase in seed yield. Yields of the resistant cultivars were greater than those of the susceptible cultivars, except for the Peking source. Compared with the susceptible cultivars, cultivars with H. glycines resistance from PI 88788 had a 13% increase in yield associated with a 15% increase in growth during R1-R5. In cultivars with resistance from Hartwig, a 6% increase in yield was associated with a 4% increase in R1-R5 duration and increased seed-set efficiency. This work demonstrates that yield increases due to resistance to H. glycines can be attained by different physiological mechanisms associated with the different resistance sources and probably are controlled by different genes. This opens the possibility of pyramiding genes conferring resistance by different mechanisms. doi: 10.2135/cropsci2009.12.0724

To exploit the heterosis for yield and yield-related traits expressed in indica x japonica [F.sub.1] hybrids of rice (Oryza sativa L.), a set of 64 chromosome segment substitution lines (CSSLs) was constructed, with each line selected to carry one or a few chromosome segments of the japonica cv. C418 in a genetic background of indica cv. 9311. The CSSLs were crossed one by one with the recipient parent to generate a set of 64 corresponding [F.sub.1] hybrids (CSSLHs). These materials were field tested over 2 yr for six yield and yield-related traits. A total of 48 (in 2008) and 55 (in 2009) quantitative trait loci (QTL) were detected, with most individually explaining only a modest proportion of the phenotypic variance. In 2008, 72.9% of the QTL were overdominant, whereas in 2009, this proportion was only 54.5%, indicating that overdominance is important in determining heterosis in japonica x indica rice hybrids, and chromosome segments substitute technology is effective in the utilization of heterosis from intersubspecific cross between indica and japonica rice. Moreover, some of the CSSLs harbored QTL associated with heterosis in both years; these should represent potential candidates as parents of [F.sub.1] hybrids along with cv. 9311 or other indica lines. doi: 10.2135/cropsci2010.05.0242

Forage availability and quality during the dry and cool season is a major constraint to dairy development in the Highlands of Madagascar. The objective of the present study was to determine optimal seeding of oat and common vetch mixtures for increased production and quality of forage. The study was conducted under irrigated conditions in two agro-ecological zones of the Vakinankaratra region in the Highlands of Madagascar. Seed proportions studied were oat-vetch 100:0; 0:100; 50:50 and 50:75. Pure stands of oat and vetch were seeded at the rate of 100 and 60kg [ha.sup.-1], respectively. Standard fertilization for forage oat production was uniformly applied on each plot. Pure stands and mixtures were given two successive cuts at flag leaf stage of oat. For both sites and their average, dry matter (DM), feed unit for lactation (UFL), crude protein (CP), and protein digested in the small intestine (PDI) yields were not significantly (p>0.05) different among mixtures and pure stands. The highest yields were obtained from the 50:50 mixture at the first site and from the 50:75 mixture at the second site. According to the two sites' results' average, the highest DM (7.71 t [ha.sup.-1]), UFL (6.08 x [10.sup.3] units [ha.sup.-1]), CP (1.64 t [ha.sup.-1]) and PDI (597.1kg [ha.sup.- 1]) yields were obtained from 50:50 mixture. There were no significant differences (p>0.05) in forage quality characteristics except for CP and protein digested in the small intestine when rumen-fermentable nitrogen is limiting (PDIN). Mean CP concentration varied from 15.20% for pure stand of oat to 27.01% for pure stand of vetch. The highest value (178.8 g/kg DM) and the lowest value (103.5g/kg DM) in PDIN content were obtained from pure stand of oat and pure stand of vetch, respectively. Mixtures had 4.6 to 6.3% more CP content and 15.6 to 39.1% more PDIN content than pure stand of oat. Combined land equivalent ratio values exceeded unity in both mixtures which showed an advantage of intercropping over sole system in terms of the use of environmental resources. As intercropping of oat with vetch at 50:50 (50:30 kg [ha.sup.-1]) mixture achieved maximum yield advantage and forage quality, it could be used as alternative practice of oat sole cropping for high forage and protein production in the Vakinankaratra region. Key words: mixture, forage, quality, oat, vetch, INTRODUCTION Small-scale dairy production is an important smallholder farming system in the Highlands of Madagascar [1]. The promotion of livestock breeding and improved management practices for zero grazing has resulted [...]

During three consecutive years of field trials conducted in northwestern New Jersey on a Quakertown silt loam soil (fine-loamy, mixed, active, mesic Typic Hapludult), a calcium silicate, steel slag by-product (CSS), was added as an effective liming agent to long winter wheat (Triticum aestivum L.) and evaluated for its suppressive effects on powdery mildew disease (Erysiphe graminis DC. f. sp. tritici Era. Marcha/ Blumeria graminis (DC.) E.O. Speer = E. graminis DC. Oidium monilioides (Nees) Link [anamorph]). Limestone was used as the control in a completely random design, consistent for treatment during all trial years. Plots were split for one fungicide, propiconazole (1-[[2(2,4-Dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl] 1-H-1,2,4-triazole), application per year. The field was allowed to become naturally inoculated. In 2006 disease symptoms did not appear until late in the season. Although no significant grain yield response was exhibited in 2006, powdery mildew lesions were reduced by 29% on the flag leaves of wheat plants in the CSS treated plots, in 2007, powdery mildew was not diagnosed, but nonpathogenic Alternaria spp. leaf blotch was observed late season. Leaf blotch lesions were reduced 25% on flag leaves in the CSS-treated plots. During 2008, powdery mildew lesions on flag leaves were 44% less and yields were 10% greater in plots treated with CSS. Our results suggest that the use of CSS as an effective neutralizer of soil acidity may have the added benefit of suppressing powdery mildew in field grown winter wheat. doi: 10.2136/sssaj2010.0134

The ability of soil tests to identify nutrient-deficient soils and recommend fertilizer rates that optimize agronomic yield is essential for profitable soybean [Glycine max (L.) Merr.] production. Our objectives were to correlate relative soybean yield to Mehlich-3 and 1 mol [L.sup.-1] HN[O.sub.3]-extractable soil K and trifoliolate-leaf K concentration at the R1 to R2, development stage and calibrate the K rates for Mehlich-3-extractable soil K. Experiments were established on silt loams at 34 site-years planted with a Maturity Group IV or V cultivar and fertilized at five K rates (0-148 kg K [ha.sup.-1]). Mehlich-3-extractable soil K ranged from 46 to 167 mg K [kg.sup.-1] and produced relative soybean yields of 59 to 100% when no K was applied. Eleven sites had Mehlich-3-extractable K < 91 mg K [kg.sup.-1] and all responded positively to K fertilization. Soybean grown in soil having 91 to 130 mg K [kg.sup.-1] responded positively at nine of 15 sites. Mehlich-3 soil K explained 76 to 79% of the variability in relative yields and had critical concentrations of 108 to 114 mg K [kg.sup.-1], depending on the model. The linear-plateau model predicted the critical HN[O.sub.3]-extractable soil K to be 480 mg K [kg.sup.-1]. Trifoliolate-leaf K concentration increased significantly, positively, and linearly as Mehlich-3- and HN[O.sub.3]-extractable soil K increased, but Mehlich-3 soil K explained only 49 to 53% of the variation in trifoliolate-leaf K. Mehlich-3-extractable K is an excellent predictor of soil K availability for soybean grown on silt loams in eastern Arkansas. doi: 10.2136/sssaj2009.0197

New bahiagrass (Paspalum notatum Flugge) genotype PCA Cycle 4 is more productive than existing bahiagrass cultivars during the cool season, but it may not persist as well when defoliated frequently or to short stubble. Characterizing tiller dynamics forms a basis for understanding mechanisms of grass yield and persistence responses to defoliation. A 2-yr field experiment studied the effects of two stubble heights (4 and 8 cm) and two harvest frequencies (7 and 21 d) on tiller dynamics of diploid (PCA Cycle 4, 'Pensacola', and 'Tifton 9') and tetraploid ('Argentine' and Tifton 7) bahiagrass. Tiller number of highly persistent Argentine and Pensacola was unaffected by defoliation treatment and generally greatest among cultivars. Tiller number of Tifton 9 and PCA Cycle 4 varied by up to 970 and 730 tillers [m.sup.-2], respectively, among defoliation treatments and was greatest with frequent harvests at short stubble. PCA Cycle 4 tiller mass was relatively low. Net tiller appearance rate was positive in spring and early summer, and was nearly zero or negative throughout the remainder of the growing season. This study showed that Tifton 9 and PCA Cycle 4 responded to frequent, close defoliation by increasing tiller number, but tiller mass was the least or not different from the least among entries tested. Very small tillers may indicate a weakening stand under frequent, close defoliation, and management practices such as rotational stocking may be necessary for PCA Cycle 4 to persist. doi: 10.2135/cropsci2010.01.0002

Data from USDA-coordinated winter wheat (Triticum aestivum L.) regional performance nurseries collected over the time period 1959 to 2008 were used to estimate genetic gain (loss) in grain yield, grain volume weight, days to heading, and plant height in winter wheats adapted to the Great Plains of North America. In both the Southern Regional (SRPN) and Northern Regional Performance Nurseries (NRPN), linear regression revealed significant positive relationships between relative grain yields of advanced breeding lines and calendar year of the nursery trial. The estimated genetic gain in grain yield potential since 1959 was approximately 1.1% (of the control cultivar Kharkof) [yr.sup.-1] for all entries in the SRPN, and 1.3% [yr.sup.-1] if only the most productive entry was considered. For the NRPN, the estimates of genetic gain in grain yield were 0.79% [yr.sup.-1] for all entries, and also 0.79% [yr.sup.-1] for the most productive entry. Linear regressions of relative grain yields vs. year over the time period 1984 to 2008, however, showed no statistically significant trend in the SRPN. For the same time period in the NRPN, a statistically significant positive slope of 0.83 was observed, though the coefficient of determination ([R.sup.2]) was only 0.28. Relative grain yields of Great Plains hard winter wheats may have peaked in the early to mid-1990s, and further improvement in the genetic potential for grain yield awaits some new technological or biological advance. doi: 10.2135/cropsci2009.11.0685

Wisconsin Quality Synthetic (WQS) is a maize population that has undergone four cycles of [S.sub.2]-topcross selection for increased silage yield and feed quality. This study evaluated forage yield and quality for each cycle of WQS per se as well as testcrosses to two Stiff Stalk-type testers. Linear improvement was seen in whole-plant yield, stover yield, and whole-plant quality both in the population per se and in testcrosses. Stover quality has not improved through selection. Starch content has increased while crude protein has decreased. Milk yields on a Mg dry matter and hectare basis have increased with selection. Changes in silage dry matter yield have been greater on a percent basis than changes in silage quality, suggesting that the current selection protocol of selecting [S.sub.2]-top-crosses first for yield then for quality may be more efficient at improving yield than quality. Selection directly focused on stover quality may be necessary if more rapid improvement in stover composition is desired. doi: 10.2135/cropsci20009.12.0725

The Canal Point (CP) sugarcane (Saccharum spp.) breeding program has developed high-yielding cultivars for the organic soils of South Florida, but cultivar development has not been as successful for sand soils in this region. Our objectives were to improve final-stage (Stage 4) selection efficiency of this program by assessing interactions among genotypes, soils, and locations and other sources of variation and by comparing the relationship between repeatability and number of replications as a measure of precision for testing sugarcane genotypes on sand and muck soils. Sources of variation were partitioned for plant-cane, first-ratoon, and second-ratoon data, from 7 yr and five CP series in Stage 4 tested at eight locations on muck soils and two locations on sand soils. Variation related to genotype x location (soil) was highly significant for cane and sugar yields for all series and crops, but most genotype x soil interactions were nonsignificant. This suggested that planting more Stage-4 tests on sand may improve genotype selection for these soils. The six replications used routinely in Stage 4 provided elevated levels of precision for both soil types. All locations with muck and sand soils in Stage 4 have ample testing resources for discriminating among genotypes. Our results indicate that, to improve sugarcane genotype selection for sand soils, increasing the number of sand locations would be a more successful strategy than increasing replications within locations. doi: 10.2135/cropsci2009.09.0539

Striga hermonthica (Del.) Benth threatens maize (Zea mays L.) production in sub-Saharan Africa. In an extra-early population, [S.sub.1] families derived from four cycles of recurrent selection for grain yield and Striga resistance were evaluated with and without Striga infestation at three locations in Nigeria for 2 yr to determine relative changes in genetic variances, heritabilities, and genetic correlations for yield and other traits. Under infestation, yield was not correlated with other traits at Co but was significantly correlated with ears per plant (EPP), Striga damage, and emerged Striga plants in advanced cycles. Genetic correlations between yield and most traits were significant in [C.sub.0] when Striga-free but was reduced in advanced cycles. Genetic variances and heritabilities for yield and ear aspect increased in advanced cycles. Genetic variances decreased with selection for emerged Striga counts and EPP under infestation. A response to selection for improved yield, Striga emergence and EPP is expected in subsequent cycles. Low genetic variances and heritabilities for Striga damage and low predicted gain [cycle.sup.-1] for all traits except numbers of emerged Striga plants suggest a need to introgress novel resistance genes into the population for faster progress from selection for increased yield. doi: 10.2135/cropsci2009.09.0523