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Biosolids are frequently used as organic soil additives. This 2-year field study investigated the effects of sewage sludge (SWS) application on maize (Zea mays L.) production, nitrogen accumulation, redistribution, and nitrogen use efficiency, as well as on grain element concentrations and soil properties. Treatments included three SWS rates (20, 40, and 80 Mg ha−1 year‒1), mineral fertilizer (300 kg N ha−1 year‒1 and 26 kg P ha−1 year‒1), and an unamended control. Plant samples were collected at silking and maturity in both years, while soil samples were taken following maize harvest in the second year. Maize grain yield increased by 143 kg ha−1 for every Mg increase in SWS rate. Sewage sludge application resulted in maize grain yield comparable to or even greater than that of mineral fertilizer. Nitrogen uptake and translocation to grains increased quadratically with increasing SWS rates. Nitrogen use efficiency increased with moderate SWS application (up to 40 Mg ha−1) but decreased with heavy application (80 Mg ha−1) compared to fertilizer, raising the risk of nitrogen losses. Compared to fertilizer, SWS resulted in similar or lower P and Cu concentration in the grain, as well as similar or higher K, but had no effect on N, Zn, Fe, and Mn concentration. Soil pH, NO3-N, and exchangeable K were similar in SWS and fertilizer, but soil Olsen P improved with SWS. There were no differences among treatments in DTPA-extractable Zn, Fe, and Cu, while Mn raised with SWS. Sewage sludge could be used to increase plant N reservoir at silking, N translocation to grains, and post-silking N uptake, allowing plants to meet their N requirements throughout the growing season. Even at 20 Mg ha−1, sewage sludge can successfully replace mineral fertilizer in maize crop.

Herbicides are the major method of weed control in most conventional cropping systems, but what affects farmers' intention to use herbicides has not been studied extensively. This study examined herbicide use among cereal farmers of northern Greece and tested for the first time whether the theory of planned behavior (TPB) can explain farmers' behavior in the adoption of herbicide use.Most farmers showed favorable attitudes towards herbicide use (71.2%), high levels of perceived behavioral control (PBC) of herbicide use (62.4%), and positive intention to use herbicides (67.6%). By contrast, most farmers (60.4%) were negative in following the advice of others in the adoption of herbicides. Finally, most farmers (82.8%) used herbicides in cereal production. The TPB explained 47.6% of the variation in farmers' intention to use herbicides. Logistic regression showed that intention and PBC positively affected (P 0.01) farmers' behavior in herbicide use, explaining 45.8-76.2% of the variation in farmers' behavior. Path analysis showed that attitudes, subjective norms, and PBC had a direct impact on intention. Gender had an indirect impact on intention through PBC, while age and farming as a main profession had an indirect impact on intention through attitudes and subjective norms. Furthermore, education had an indirect impact on intention through attitudes and PBC.Farmers' intentions and behavior in the use of herbicides in cereal production could be explained by the TPB. Attitudes showed the strongest total effect on the intention to use herbicides. © 2022 Society of Chemical Industry.

Knowledge of weed control practices and farmers’ awareness of herbicide resistance could be a basis for improving weed management programs with respect to herbicide resistance, but research on this topic is limited. This study reports current weed control practices and levels of awareness of herbicide resistance among cereal farmers of northern Greece. Face-to-face interviews were conducted with 250 cereal farmers of Evros district, based on a structured questionnaire. Most farmers (82.8%) used herbicides in cereal production, with one application per growing season. Farmers appeared divided with respect to using the same herbicide each year; the majority of the farmers (90.8%) applied crop rotation. Almost half of the farmers (47.2%) did not know what herbicide resistance is, but most farmers (75.1%) felt herbicide resistance would be a problem for them. According to their answers on nine knowledge questions about herbicide resistance, 66.8% of the farmers had good knowledge, and 33.2% had poor knowledge. Almost seven in 10 farmers (69.8%) did not consider herbicide resistance when purchasing an herbicide for use, and only 40.4% were willing to change common weed control practices to prevent herbicide resistance. Awareness of herbicide resistance did not differ by sex; poor awareness levels increased with advanced age, low education levels, and small farm size. Farmers who used chemical weed control had higher awareness levels of herbicide resistance than farmers who never used herbicides. Farmers who were keeping records of herbicide applications, those who observed low efficacy of herbicides in their field, and those who applied crop rotation had high awareness levels of herbicide resistance, whereas farmers who used the same herbicide each year had poor awareness. Findings shed light on inter-relationships between farmers’ awareness of herbicide resistance and current weed control practices that could be useful for targeted extension education.

A better understanding of crop and soil response to biosolids is necessary for optimizing their use as soil amendments. The present study examined the influence of sewage sludge application on N accumulation, partitioning, translocation, and N use in sunflower and on soil properties compared with mineral fertilizers. Treatments included the application of sewage sludge (9, 18, and 36 Mg dry weight ha−1 year−1), an inorganic fertilizer (138 kg N plus 55 kg P2O5 ha−1 year−1), and a non-amended control. Sewage sludge increased early crop growth rate and N uptake at levels similar to or even greater than those obtained with the inorganic fertilizer. Nitrogen translocation was correlated with nitrogen translocation efficiency (r = 0.66*); both parameters appeared to be associated with source and sink attributes. Nitrogen use efficiency and nitrogen uptake efficiency were decreased with increasing rates of sewage sludge following a quadratic response curve. The estimated nitrogen use efficiency of sewage sludge-added N was greater than that of the inorganic fertilizer when sewage sludge was applied at agronomically realistic rates (

Sowing time and cultivar choice have major effects on chickpea yield in the Mediterranean climate, but the effects on nutrient requirements are not well known. Information regarding nutrient requirements and utilization efficiency by crop species is necessary to optimize nutrient management in agricultural systems. Α two-year field study was conducted to examine the patterns of P and K uptake, translocation, utilization and removal across a wide-range of chickpea yield levels induced by sowing time (March and April) and cultivar [Zehavit-27 (Kabuli-type), Andros, Kassos, and Serifos (desi-type)], as well as to identify plant traits associated with efficient nutrient utilization. At all samplings throughout the growing period, P uptake was significantly correlated with that of K uptake with r values between 0.633 (P

Growth, yield components, and N utilization patterns of spring chickpea (Cicer arietinum L.) cultivars were investigated for 2 years under Mediterranean conditions, and the associations with seed yield were identified. Three desi-type cultivars (Andros, Kassos, and Serifos) and one kabuli-type cultivar (Zehavit-27) were assessed under March and April planting. April planting resulted in higher early dry matter and N accumulation, which were not reflected in increased seed yield compared with March planting. Chickpea growth was co-limited by both source and sink limitations induced by the environment during the seed filling period. Most of the variation (> 94%) in seed yield was accounted for by the variation in seeds m−2 rather than that in seed size. The seed number was reduced on average by 7–18.2 seeds m−2 day−1 of planting delay, with the penalty being higher the year with the greater yield potential. In addition, the number of seeds m−2 was reduced by 21% and by 18% for every degree Celsius increase in mean and maximum temperature during the early reproductive period, respectively. Biomass production efficiency (33.9–51.6 kg kg−1) was greater than nitrogen utilization efficiency (17.8–27.2 kg kg−1). The proportion of total plant N allocated to the seeds at maturity (i.e., nitrogen harvest index) was the limiting factor for enhanced N utilization. Overall, March planting may ameliorate growth limitations by bringing the reproductive stage earlier and, consequently, it may be more advantageous in terms of both seed yield and seed quality compared with April planting.

Woody rangelands are important forage resources for grazing goats in the Mediterranean basin. Goats are well adapted in these heterogeneous and complex ecosystems due to their particular anatomic characteristics, metabolic efficiency and browsing ability. However, the mechanism of grazing behavior and forage selection in goats is quite complex and depends on several factors. The present study deals with the seasonal changes of chemical composition in the selected forages and ingested diets as well as their effects on milk yield and composition of goats grazing in a Mediterranean woody rangeland. Hand plucked forage samples similar to those consumed by the goats were collected for chemical analysis. The nutritive value of consumed forages, in combination with the different feeding and grazing system per trial period, influenced milk quality and performance. The replacement of feed supplementation with an increase of the contribution of grazing in the rangeland could maintain the milk yield and quality at the late stage of lactation. In addition, this paper focuses on the influence of the chemical composition of selected forages on the diet selection of goats using a modeling approach. The model showed a high interpretative accuracy and explanatory value (R2 = 0.923) and was able to distinguish the goats' most important criteria for selecting among the forage plant species in relation to several factors. The results indicate that the dietary preferences of goats were influenced, not only by the seasonality of nutritive value and availability of forages in the rangeland, but also by the plant origin of each nutrient source. The selection of Quercus frainetto was highly correlated with its NDF content. Herbaceous species, Cistus creticus and other woody species were mainly selected due to their CP content. The ADL content seemed to have the lowest influence of all nutritive variables on the selection among groups of plant species. The modeling approach, apart from the understanding of grazing behavior of goats, offers additional information that can be useful to the shepherds in order to manage more effectively the feeding and grazing system of their goat's flock.

Chemical pesticides are an integral part of modern agriculture that may have serious side effects on human health and the environment. Assessing contribution of pesticides to potential environmental problems requires studies on eco-toxicological aspects of the pesticide products as well studies on the behavioural variable of the pesticide applicator, which can be critical for an accurate risk assessment, albeit often neglected. The study of human behaviour, i.e., the actions or reactions of an individual to external or internal stimuli, is a key prerequisite for improving environmental safety in pesticide use. The level of awareness and knowledge of pesticide risks among farmers is essential for improving safety in all aspects of pesticide handling, but knowledge is connected with deep understanding and sense of a concept, whereas awareness does not necessarily entail a deep understanding. Occupational safety and health studies show that safety behaviour among farmers can be affected by many factors, with perceptions, attitudes, and self-efficacy playing a major role.

In rainfed cropping systems, crops are typically subjected to terminal stresses, which diminish the assimilation process. Information regarding safflower (Carthamus tinctorius L.) dry matter dynamics during the seed-filling period and its association with yield-forming components is lacking. Field experiments over two years were conducted to assess the influence of nitrogen (N) fertilization levels (0, 100 and 200 kg ha−1), sowing time (autumn vs. spring) and genotype (two hybrids and an open-pollinated variety) on growth, assimilate remobilization, achene- and oil yield of safflower, and to identify early crop attributes as predictors of yield. Greater than 100 kg N ha-1 were required to optimize achene yield (> 4 Mg ha-1). On average, N promoted early growth and increased capitula and achenes per unit area compared with the non-fertilized control. The higher the availability of assimilates at the source, the greater their remobilization to sink (r = 0.823, P

In cooler Mediterranean areas autumn sowing of chickpea (Cicer arietinum L.) is avoided because of the increased frost risk. A 2-yr field study was conducted to investigate the potential effects of spring sowing date and cultivar on assimilate dynamics (i.e., dry matter and N accumulation, partitioning and translocation) and productivity of Mediterranean chickpea, and to assess possible N losses from plant foliage. Three local cultivars (i.e., Andros, Kassos, and Serifos) and one foreign cultivar (i.e., Zehavit-27) were evaluated under two sowing dates (i.e., March sowing and April sowing). March sowing resulted in higher dry matter, total N accumulation, and seed N content than April sowing. Seed yield up to 3320 kg ha–¹ was obtained with March sowing. April sowing resulted in a yield penalty of 22 to 50 kg ha–¹ d–¹ of sowing delay compared with March sowing. Seed yield was correlated negatively with dry matter translocation to the seeds and positively with dry matter accumulation during the seed-filling period. Dry matter and N translocation efficiency reached up to 77 and 96%, respectively. High N accumulation until the beginning of seed growth and low N accumulation thereafter enhanced N translocation to the seeds. However, when early aboveground N was high (>120 kg N ha–¹) and the seed demands for N were low (

Soil liming may increase phosphorus (P) availability, but this increase may also be achieved with generous P applications. However, it is not well known which practice has longer-term effects. Thus, in a pot experiment, an acidic soil (pH 4.57), limed to pH 6.5, was added with P and sown with Lolium perenne L. We conducted three cuttings (on Days 40, 80, and 120) in order to evaluate P dynamics in each of the treatments. As expected, biomass increased significantly with liming. We also found that plant P concentration increased in the liming treatment, but not in the P-added treatment, although the difference was reduced on Day 120. This shows that in severely acidic soils, liming should be preferred over P addition, although the beneficial effects may not last for a very long time, since in this experiment, they only lasted for 4 months. Similar conclusions were drawn from soil P extraction results.

Field and pot trials were conducted in two sites of northern Greece (Thermi and Lepti) to study selectivity and weed control in maize (Zea mays L.) with herbicide mixtures based on tembotrione. Treatments included tembotrione (plus isoxadifen-ethyl safener) applied alone at 100 g ai/ha and three mixtures of tembotrione with: (i) rimsulfuron at 10 g ai/ha, (ii) nicosulfuron at 40 g ai/ha and (iii) foramsulfuron at 60 g ai/ha (label rates for weed control in maize). Herbicides were applied at the 7- to 8-leaf growth stage of maize in Thermi and at the 6- to 7-leaf growth stage in Lepti. Six weeks after treatment, control of rhizomatous Sorghum halepense with tembotrione alone was 63% in Thermi and 60% in Lepti, with plants showing the typical bleaching symptoms of the HPPD-inhibiting herbicides. Control of rhizomatous S. halepense with the mixtures was improved from 63% to 86% in Thermi and from 60% to 82% in Lepti compared with the single treatment of tembotrione, with plants showing only the sympt...

A field study was conducted for two consecutive growing seasons to assess the effect of organic manure on the growth, productivity and nutrient dynamics of winter wheat (Triticum aestivum L.), as well as on the concentration of trace elements in soil and wheat plants. Treatments consisted of two rates of farmyard manure (16 and 32 Mg dry weight ha⁻¹ yr⁻¹), one rate of inorganic fertilizer (IF, 120 kg N ha⁻¹ yr⁻¹ plus 80 kg P₂O₅ ha⁻¹ yr⁻¹), and an unamended control. Manure improved wheat growth and productivity compared to the unamended control; the response was dependent on the application rate. The high manure rate increased the number of spikes m⁻² and resulted in grain yield similar to that of the IF. Manure application caused no changes in N, P, and K concentrations in plant tissues. At the high manure rate, N and P uptake was similar to that of the IF. Averaged across years, manure application resulted in nutrient translocation from vegetative parts to grain at a lower (for the N) or similar (for the P) rate to that of the IF. No differences among treatments in nutrient translocation efficiency were observed. Nitrogen and P translocation was correlated with total aboveground N or P accumulation at anthesis, respectively. The N use efficiency of manure-N was lower compared with that of inorganic fertilizer-N, mainly because of the corresponding differences in uptake efficiency. Trace elements did not increase with added manure either in soil or in wheat plant tissues.

Panicoid grasses are major weeds of maize and sugarcane as well as of several other important grains, including sorghum, pearl millet, and foxtail millet. Pot trials were conducted to study the activity and potential interactions of topramezone in mixture with recommended rates of rimsulfuron or nicosulfuron on three annual panicoid grasses (i.e. Echinochloa oryzoides,E.phyllopogon, and Panicum miliaceum). Target weeds were treated at the four- to five-leaf growth stage. On the basis of fresh weight reduction, topramezone alone provided 78% control of E.oryzoides, 68% control of E.phyllopogon, and 99% control of P.miliaceum. Topramezone plus rimsulfuron or nicosulfuron provided decreased control of both Echinochloa spp. compared with topramezone alone. The decreased control of E.oryzoidesand E.phyllopogon was more pronounced with rimsulfuron as a companion herbicide in the mixtures. Slightly decreased control of P.milaceum was observed with topramezone plus rimsulfuron compared with topramezone alone, but this was not the case for topramezone plus nicosulfuron. Increased topramezone rates mixed with rimsulfuron or nicosulfuron did not improve control of E.oryzoides and E.phyllopogon compared with the lowest topramezone rate. Also, increased topramezone rates mixed with rimsulfuron or nicosulfuron showed decreased control of both Echinochloa spp. when compared with either rimsulfuron or nicosulfuron alone, suggesting a two-way interaction between topramezone and the ALS-inhibiting herbicides. The above-mentioned interaction was not observed in P.miliaceum, probably related with species sensitivity to the herbicides tested. Newly introduced or naturalized panicoid grasses in maize fields may complicate selection of companion herbicides and rates for effective weed control.

Understanding differences in grain yield and nitrogen utilization efficiency (NUtE) between barley and triticale could be useful for designing more sustainable cropping systems. Field experiments were conducted to compare grain yield and dry matter accumulation as well as N accumulation, translocation, and utilization in barley and triticale under Mediterranean conditions with two N fertilization rates (0 and 100 kg ha−1). Overall, across years and N application rates, barley out-yielded triticale by 30% (6943 vs. 5339 kg ha−1). Differences in the grain number per m2 explained most of the variation between species in grain yield, with barley showing higher values than triticale. Barley showed higher early growth resulting in greater N accumulation in anthesis, and eventually in higher translocation to the grain than triticale. When no N was applied, barley showed a mean increase of 15% in NUtE. Triticale showed an advantage in biomass production efficiency in anthesis only in the drier year. From a practi...

Acidic soils typically suffer from high phosphorus (P) retention, a problem that can be dealt with using greater P fertilization, soil liming, or both. The aim of this work was to examine which of these practices bears the more beneficial result for Lolium perenne L. growth. In a pot experiment, five acidic soils were treated as follows: L0P0 (unamended control), L1P0 (liming only), L0P1 (P addition only), and L1P1 (both liming and P addition). We found that P amendment alone was sufficient to increase plant P levels when the initial soil P concentrations were low. Liming without P addition increased plant P satisfactorily only in the high-P soil. We conclude that P addition alone is a better practice than liming alone for improved plant growth conditions in acidic, low-P soils, unless there is relatively high P content in soil, in which case liming alone may be sufficient to increase P availability.

Paclobutrazol (PBZ), a well-known growth retardant of the triazole family, is mostly used for controlling plant size and growth, resulting in more desirable compact plants for floricultural purposes; however, limited experimental data are available for use of PBZ in field sunflower. The objective of this study was to evaluate the effect of repeated foliar applications of PBZ at rates of 50 + 50 g ha-1(double application) and 50 + 50 + 50 g ha-1 (triple application) on sunflower morphology and productivity. PBZ applications corresponded to growth stages of four to five, five to six, and six to eight true leaves of sunflower plants, respectively. The double foliar application of PBZ reduced sunflower plant height at maturity by 4.4% (or by 11.7 cm). The triple foliar application of PBZ reduced sunflower plant height at maturity by 14.4% (or by 49.2 cm). However, PBZ either in the double or the triple application reduced achene yield per plant by 25.6% and 22.5% and the 100-achene weight by 11.4% and 25.0%, respectively, compared with the non-treated control. Overall, the repeated foliar applications of PBZ at the rates tested in this study, apart from providing a reduction of sunflower plant height, had major adverse effects on achene yield and weight. Thus, different application schemes of PBZ or perhaps different growth regulators should be investigated to control plant height in sunflower.

A field experiment with wheat (Triticum aestivum L.) was established over two growing seasons where farmyard manure and sewage sludge, along with conventional fertilizer, were added to soil. We found that ammonium N was at greater concentrations in the organic amendments treatments, indicating more beneficial dynamics (i.e., it can be taken up by plants for a greater amount of time) and thus a longer lasting effect as a nutrient for the test crop. We found that nitrogen (N), phosphorus (P), and potassium (K) uptake increased with added organic amendments. This means that when organic matter along with nutrients are added to soil, productivity may increase beyond preset targets because soil conditions greatly improve, not only chemically but also physically. Nitrates left over at the end of the growing season (residual N) were greater in the high sewage sludge and manure treatments, but not proportionally.

Summary Common burdock (Arctium minus) is a common biennial weed of non-arable land in typical rural settings of Orestiada, Greece. The aim of this study was to describe the basic morphological traits of this species throughout the main phenological stages of its life cycle and to obtain some insight into its growth and productivity in Orestiada. Based on our observations, the plants occurred most commonly in moist and fertile soils, usually as isolated individuals or in small patches near the parent plants. The species is characterized by its large basal ‘elephant-ear’ leaves during the vegetative stage, appearing in alternate arrangement, with irregularly wavy and non-toothed edges, as well as with long hollow stalks forming a noticeable furrow on the top. By monitoring individual plants, it was found that fl owering (in the second year of growth) mostly occurred from late June up to early August. The fl owers were purple, occurring in bristly heads at the top of the stem. The bristly heads formed a fruit, containing small black seeds. The average number of capitula per plant, from randomly selected populations in Orestiada, was found to be 69.7 and 57.7 respectively, whereas the mean seed number per capitulum reached 30.3 and 33.3 seeds, respectively

The application of sewage sludge (SS) to agricultural land can improve soil fertility and physical properties, and enhance crop production. This field study was conducted for two consecutive growing seasons to investigate the influence of SS application on winter wheat growth, grain yield, N accumulation, translocation and use, and on trace elements concentrations in soil and wheat plants under Mediterranean conditions. Treatments consisted of three rates of SS, i.e. 20, 40, and 60 Mg dry weight ha−1 year−1, one rate of inorganic fertilizer (IF, 120 kg N ha−1 year−1 plus 80 kg P2O5 ha−1 year−1), and an unamended control. The application of SS resulted in tall plants with high early dry matter and N accumulation similar to or significantly higher than those obtained with IF. The lowest SS application rate resulted in grain yield similar to that obtained with IF. Nitrogen use efficiency (NUE) in SS treatments was mainly determined by uptake efficiency, which decreased with increasing SS application rate. Values of NUE and biomass production efficiency with the lowest SS rate were similar to those obtained with IF. SS application resulted in increased concentrations of total and DTPA-extractable trace elements in the soil after the first year, but concentrations were much lower than the regulation limits. Concentrations of Cu, Mn and Zn in wheat plants did not exceed those obtained with IF. Overall, SS could be considered for use as a fertilizer in wheat production systems in the area, serving also as an alternative method of SS disposal.

Information about pesticide use and perceptions of their risks among farmers is important for identifying problems associated with pest-control decisions and developing appropriate management practices in given crops. In tobacco, a plant sensitive to many pests and diseases, such information is lacking. The patterns of pesticide use in oriental tobacco, as well as the most important factors for farmers’ decisions relating to chemical pest control were studied among randomly selected farmers in northern Greece on the basis of self-reported information acquired through a pre-tested questionnaire. High reliance of farmers on pesticides and field use of all well-known classes of chemical pesticides were reported. While all the active ingredients reported were registered for pest control in tobacco, they differed considerably in terms of toxicity. A normal cropping season received at least 14–16 pesticide applications for soil disinfection, pest control, and weed control. Most farmers stated that they usually ...

Milk thistle (Silybum marianum [L.] Gaertn.) and cardoon (Cynara cardunculus L.) are energy plants. However, no studies have been conducted to investigate which of these crops could provide sufficient biomass under reduced inputs (regarding irrigation, fertilization and weed management), although this knowledge is essential for the farmers for decision-making. A 3-year field study was conducted in central Greece to compare the productivity of milk thistle (native ecotype) with that of cardoon (var. C12) under weedy and weed-free conditions, without fertilization and irrigation. During the 3 years of cultivation, cardoon and milk thistle produced a total of 24.56 t ha−1 and 20.89 t ha−1 dry biomass, respectively, in weed-free treatments. Weed competition slightly reduced the productivity of both crops. Therefore, the corresponding biomass yields in weedy treatments were 19.70 and 15.49 t ha−1. The gross calorific value of milk thistle and cardoon biomass ranged from 15.5 to 16.1 MJ kg-1 and 16.5 to 17.3 MJ kg−1, respectively. The average across-year potential energy yield in weed-free treatments was 111,870 MJ ha-1 for the milk thistle and 135,330 MJ ha-1 for the cardoon. The corresponding potential energy yields in weedy treatments were 80,130 MJ ha-1 and 113,550 MJ ha−1. Conclusively, milk thistle and cardoon could provide satisfactory dry biomass for energy use in semi-arid Mediterranean fields without irrigation or weed control inputs (assisted by their high allelopathic potential). Additionally, the cardoon outperformed the milk thistle in productivity.

SUMMARYThe identification of factors determining the adaptation and nitrogen (N) utilization of spelt wheat is important for the successful introduction of the crop to a new environment. The present study was carried out to investigate the relative importance of grain-filling rate and duration of grain growth and to analyse the nitrogen utilization efficiency (NUtE) and biomass production efficiency of spelt under Mediterranean conditions. The performance of spelt was evaluated in relation to a well-adapted bread wheat cultivar. Three spelt cultivars (Ressac, Poème and Cosmos) and one bread wheat cultivar (Centauro) were grown for two growing seasons on a silty clay soil under two N levels (0 and 100 kg N/ha). Grain-filling parameters were estimated using the cubic polynomial model. This model provided good fit to the grain-filling data of spelt cultivars, with high coefficients of determination (R2) that ranged from 0·868 to 0·999. Cultivar differences were found for all grain-filling parameters studied, and these differences accounted for most of the variation observed within each particular grain-filling component in both years. Grain filling of spelt plants took place under adverse environmental conditions, mainly high temperatures, which led to a shortening of the grain-filling period. This fact was not fully compensated by the increase in the grain-filling rate, and eventually resulted in a reduction of the final spelt grain weight. Selection for early-flowering cultivars could be a successful strategy to moderate the influence of the environment on grain filling and improve the adaptation of spelt under Mediterranean conditions. The mean grain-filling rate was positively correlated with dry matter translocation, suggesting the crucial role of reserve assimilates in the vegetative tissues for the grain growth of spelt. The efficiency of N utilization to produce biomass was greater during the grain-filling period than the vegetative period. Averaged across N application rates, NUtE in spelt ranged from 20·1 to 29·5 g grain/g plant N. Cultivar differences in NUtE were observed in both years. Grain yield per unit grain N (grain DM/grain total N at maturity) contributed more to the total variation in NUtE among spelt cultivars compared with N harvest index (NHI). Spelt showed lower NUtE values, probably due to its higher grain N concentration and lower NHI compared with wheat. Low straw N concentration at maturity may be an indicator of improved NUtE in spelt, as evidenced by the negative relationship detected between the two variables. These results provide a better understanding of factors related with the adaptation and N utilization of spelt under Mediterranean conditions.

The importance of stored assimilates for grain development in cereals has been widely recognized, particularly in conditions exposed to abiotic and/or biotic stresses during the grain filling period. This study was conducted to investigate dry matter and N accumulation and translocation in spelt cultivars in a Mediterranean environment and to identify possible N losses from the plant foliage during the grain filling period. Three spelt cultivars (Ressac, Poeme and Cosmos) and one bread wheat cultivar (Centauro) were grown in a silty clay soil in 2003 and 2004 under two N rates (0 and 100 kg ha−1). Spelt plants were taller, showed higher early crop growth rate and accumulated more dry matter and total N compared to wheat plants at both anthesis and maturity. Spelt cultivars had significantly lower harvest index and N harvest index, suggesting a lower rate of partitioning of assimilates and N into the grain compared to wheat. N application increased dry matter and N accumulation and resulted in higher grain yield. Post-anthesis N uptake was on average lower for spelt compared to that for wheat. Dry matter translocation in spelt ranged from 0.1 to 6 Mg ha−1 and N translocation efficiency from 62.1 to 81.1%. Spelt showed higher values for all dry matter and N translocation related parameters compared to wheat. N losses by plants during the grain filling period were observed and were associated with the total N accumulated up to anthesis. High amounts of N (>189 kg N ha−1) at anthesis combined with low grain yield resulted in net N losses by plants. Results indicated than spelt could be used as alternative crop in cooler Mediterranean areas. The major constrain for growing spelt, however, was the severe lodging observed irrespective of N rate applied. Thus, lodging resistance should be a major goal of spelt breeding to sustain its future production. Moreover, the development of early-maturing varieties is necessary to improve spelt adaptation under Mediterranean conditions.

Safflower ( Carthamus tinctorius L.) plants grown under Mediterranean environments are subjected to several biotic and abiotic stresses during the seed filling period that limit their production. The genotypic and seasonal variation in seed filling parameters and their association with agronomic traits were investigated in field experiments conducted for 2 years. A set of 10 safflower genotypes, which included hybrids and open pollinated varieties, was used. Seed filling rate (mg head −1 day −1 ) and duration (days) were calculated by using the cubic polynomial model. Data obtained indicated that this model could be successfully used to simulate the seed growth and to estimate the seed filling parameters in safflower genotypes with high coefficients of determination ( r 2 ) that ranged from 0.901 to 0.999. Seasonal differences were observed only for seed filling duration that was mainly determined by the sink size, as it was specified by the number of seeds per head. Greater sink size induced by higher head fertility (number of seeds per head) resulted in a longer seed filling duration. Genotypes differed greatly in seed filling rate. Seed yield and seed oil yield were significantly correlated with seed filling rate. More than 57% of the variation among genotypes in seed yield was due to the corresponding variation in seed filling rate. Increased seed filling rate improved dry matter partitioning to the seeds contributing to a higher harvest index. Results indicate that selection of genotypes with high seed filling rate could be a successful strategy to increase production of safflower grown under Mediterranean environments.

This experiment was conducted to study the effect of high ozone concentrations on two cotton (Gossypium hirsutum L.) cultivars. Two cotton cultivars (Romanos and Allegria) were exposed to control (CF In comparison to control plants, plants exposed to O3 showed chlorotic and necrotic patches on their leaves, increased stomatal or epidermal cell density and yellowness of cotton fibers. Elevated ozone concentration did not have a significant effect on stomatal width, total leaf thickness and thickness of histological components of leaves. Exposure to ozone concentration reduced non-glandular hair density of main leaf veins, plant height, mainstem internode length, chlorophyll content, net photosynthetic rate, stomatal conductance and length and area of bracts and petals. Elevated ozone treatment reduced the maximum length of staminal tube, anther number, pollen grain germination, leaf area, leaf dry weight, boll number, raw cotton weight, total branch length, dry weight of the mainstem–branches–bracts–carpophylls and of root dry weight. Furthermore, exposure to O3 reduced the seed weight, the lint weight, the yield, the ratio of lint weight to seed weight, the fiber strength, the micronaire, the maturity index and the fiber uniformity index values. This study shows that the exposure to high ozone concentrations mainly affected the rate of photosynthesis, raw cotton weight and strength of cotton fibers.

Safflower (Carthamus tinctorius L.) growth and productivity are influenced by many factors like genotype, environment and agronomic practices. This field study was conducted to investigate the effects of phenotypic variation in physiological traits on development and yield of spring sown safflower under Mediterranean conditions. Twenty-one genotypes of varying origin were grown for two growing seasons without irrigation. Data were recorded on phenological development stages and seed yield, seed oil content, harvest index (HI) and, seed growth rate (SGR), biomass growth rate (BGR) and economic growth rate (EGR) were determined. Seed yield varied greatly among genotypes and ranged from 1333 to 2870 kg ha−1. There were large variations in SGR and EGR, which were linearly and positively related to seed yield and explained a large amount of the variation in yield, with r2 values between 0.83 and 0.99. The relative contribution of biomass and HI to the variation in seed yield among genotypes appeared to be dependent on the growing season. When the environmental conditions allowed the genetically controlled variation in biomass production to become more apparent, most of the variation (87%) among genotypes in seed yield were due to the differences in biomass and were not resulted by genotypic differences in HI. Genotypes differed in seed oil content that ranged from 26.7% to 35.8%. Oil yield was mainly determined by seed yield in both seasons. Results indicated that spring sown safflower could be considered as an alternative rainfed crop in cool Mediterranean areas where winter kill is a problem. In conclusion, SGR, BGR and EGR were found to be important physiological determinants of seed yield, which could be used as additional selection criteria for yield improvement.

SUMMARYChickpea (Cicer arietinum L.) is an important legume of rainfed farming systems, contributing to the sustainability of production and reducing the need for nitrogen (N) fertilization through fixing atmospheric N2. The relative importance of factors causing variations in growth, seed yield, N accumulation and N utilization efficiency among spring chickpea varieties grown in a Mediterranean-type climate was investigated in field experiments conducted in 2003 and 2004. Five chickpea varieties were grown in a silty clay soil in the farm of the Democritus University of Thrace in Orestiada, Greece. Yearly differences in plant growth and productivity were observed and were mainly associated with the variations in the weather parameters between the growing seasons. Nitrogen utilization efficiency (NUE) for biomass production during the seed-filling period was higher compared with that during the vegetative period. NUE for seed yield (SY) ranged from 18·3 to 24·5 g dry matter (DM)/g N and was positively correlated with seed yield, suggesting that high SY was associated with more efficient exploitation of N. When the environmental conditions favoured high early N accumulation, the differences among varieties in NUE were mainly due to the differences in N partitioning at maturity, e.g. the nitrogen harvest index (NHI). The amount and the efficiency of N content at the beginning of seed growth (growth stage (GS) R5) that was translocated to the seed differed among varieties and ranged from 7·0 to 16·6 g N/m2 and from 68·2 to 86·8 g DM/g N, respectively. Most of the variation (0·96) between varieties in N translocation could be accounted for by the differences in total N content at GS R5. N losses from the plant foliage between 0·61 and 9·92 g N/m2 were detected during the seed-filling period when SY was low and N content at GS R5 was high.

The identification of the factors determining nutrient utilization of safflower (Carthamus tinctorius L.) is useful for the successful introduction of the crop to the cropping system of a region. A field study was conducted to compare and analyze the relative importance of the various component traits causing variation in nitrogen utilization efficiency (NUE) of safflower under Mediterranean conditions. Ten genotypes, four hybrids and six open-pollinated varieties, were grown for two growing seasons without irrigation, on a silty clay (Typic Xerorthent) soil. Seed yield varied greatly among genotypes and ranged from 923 to 3391 kg ha−1. Hybrids showed a mean seed yield superiority of 12.5% against varieties. Seed yield was the most important component of seed N yield and its contribution to the total variation in seed N yield among genotypes was at least 53%. NUE for biomass production during the seed-filling period was lower compared to that during the vegetative period. Genotypes differed in NUE for seed production (NUEs) and the differences followed those of nitrogen harvest index (NHI). The contribution of NHI to the total variation in NUEs among genotypes was much greater compared to that of yield per unit seed nitrogen and accounted for more than 79%. NUEs is positively correlated with seed yield, suggesting that high yield was probably associated with more efficient exploitation of nitrogen. NUEs is negatively correlated with (leaf + stem) N concentration at maturity, meaning that low straw N concentration may be indication of higher NUEs. Results indicated that selection for NUE in safflower should be based on multiple criteria rather than just one criterion and also should be accompanied by evaluation for seed yield to ensure an improvement in both traits.

The reliability and the effectiveness of three field experimental designs for the assessment of varietal resistance to Pyricularia oryzae was studied for 2 years. Plants were arranged in the field using two sets of three designs: randomized compete block (RCB), adjacent control (AC) and honeycomb (HC). In the first set, plants were inoculated with the fungus and in the second one, plants were naturally infected. Four varieties were used, Maratelli (susceptible control), Roxani, Selenio and Senia (main varieties). Disease progress was recorded as leaf and neck blast. The number of plants of the main varieties required in each design was higher for RCB (90) and lower for AC and HC (30 and 32, respectively). Results showed that disease severity was significantly different in the varieties studied and it was consistent and not affected by the plant arrangement in the field. All experimental designs were reliable and effective for the assessment of leaf and neck blast under inoculation or natural infection. AC and HC designs had the advantage of requiring fewer plants over RCB one. This could be important in cases where seed availability is a limiting factor.

In crops grown under Mediterranean environments, translocation of pre-anthesis assimilates to the seed is of great importance for seed growth, because hot and dry conditions during the seed filling period diminish photosynthesis and crop nitrogen uptake. This field study was conducted to assess the genetic and seasonal variation in the amount of pre-anthesis dry matter and nitrogen accumulated and translocated to seed by safflower ( Carthamus tinctorius L.) plants, and the possible N losses occurring between anthesis and maturity. Ten genotypes, 4 hybrids and 6 open pollinated cultivars, were grown for 2 growing seasons without irrigation, on a silty clay (Typic Xerorthent) soil. The proportion of dry matter and N content at anthesis that was translocated to seed differed among genotypes and ranged from 14.9 to 39.6 and from 24.8–59.3%, respectively. Genotypic differences in dry matter and N translocation were mainly associated with dry matter and N accumulated during the vegetative growth of the plants. Greater amounts of dry matter and N content at anthesis resulted in a greater dry matter and N translocation to seed during the filling period. When the N contents of aboveground plant parts at anthesis and maturity were compared, both gains and losses were observed, and were mainly related to the sink size. No N losses were detected when yield was high. When yield was low, N losses depended on N content at anthesis; high N content resulted in N losses, otherwise no N losses were observed. The contribution of pre-anthesis accumulated reserves to seed weight ranged from 64.7 to 92.2%, indicating the importance of pre-anthesis storage of assimilates for attaining high safflower yield.

The improved grain yield per unit area of modern maize ( Zea mays L.) hybrids is due to the increased optimum plant population rather than the improved grain yield per plant. Traits associated with tolerance to various stresses, including high plant populations, and the efficiency of capture and use of resources rendered modern hybrids more productive. As a consequence of the improved tolerance to high plant populations and the low yield potential per plant, modern hybrids are strongly population-dependent as their maximum grain yield is achieved only under a narrow spectrum of high plant populations, followed by adverse effects on hybrids’ productivity and stability. Missing plants and unevenness in the plant emergence constitute common problems in the field. Grain yield loss due to missing plants is poorly compensated by the increased yield of the surrounding plants, so grain yield per unit area decreases. Unevenness in the plant emergence leads to increased plant-to-plant variability, the impact being stronger under higher plant populations. Plant-to-plant variability is associated with decreased resource use efficiency, and therefore with reduced grain yield. At higher plant populations reduced grain yield also results from the increased pollen-to-silking interval and the following barrenness. Consequently, maize breeding should seek hybrids that combine population-tolerance and improved yield potential per plant, so that a wider range of optimum plant populations insure both high productivity and stable performance.

The identification of the factors that determine grain yield and nitrogen utilization in rice production systems is necessary to optimize their productivity and reduce the pollution risk for the environment. A field study was conducted to analyze the various component traits that cause variation in grain yield, grain nitrogen yield and nitrogen utilization efficiency (NUE) of direct water-seeded Indica and Japonica rice, using yield and yield component analysis. Five rice cultivars, Olympiada and L-202 (Indica type) and Ispaniki A′, Melas and Dion (Japonica type), with contrasting traits were grown in a silty loam soil (Aquic Xerofluvents) in 1999 and 2000. Grain yield ranged from 6045 (Melas) to 8310 kg/ha (Olympiada). More than 50% of the total variation in grain yield among cultivars was explained by the variation in panicles per square meter, suggesting the importance of tillering ability of a given cultivar in obtaining high yields. The relative contribution of grains per panicle was moderate (35.2% in 1999 and 34.1% in 2000), while that of grain weight the lowest. Grain yield was significantly correlated with N concentration in vegetative parts at anthesis. NUE for biomass accumulation during grain filling period was generally similar or lower compared to that during vegetative period. Indica cultivars had lower NUE for biomass accumulation and higher nitrogen utilization efficiency for grain yield (NUE g ) compared to Japonica cultivars, mainly due to the higher NHI. For a reliable comparison among cultivars, the agronomic traits of each cultivar should be taken into account. Short and late maturing cultivars had significantly higher NUE g than the tall and early or mid-season cultivars, respectively. NUE g was negatively correlated with grain and straw N concentration at maturity, suggesting that low grain or straw N concentrations may be indications of higher NUE g .

Part of the dry matter and N accumulated by rice (Oryza sativa L.) plants until anthesis is translocated to grain during the grain filling period. A field study was conducted to assess the dry matter and N accumulation and translocation of direct water-seeded rice and examine their association with grain yield. Five rice cultivars, Olympiada and L-202 (Indica type) and Ispaniki A′, Melas and Dion (Japonica type), with contrasting characteristics were grown in a silty loam soil (Aquic Xerofluvents) in 1999 and 2000. Cultivar dry matter translocation efficiencies ranged from 8.5 to 39.3% and N translocation efficiencies from 44.7 to 66.7%. Differences among Indica and Japonica cultivars in translocation efficiencies were found, but these differences depended mainly on the agronomic characteristics of each cultivar. Dry matter and N translocation were greater for short and late maturing cultivars compared to the tall and early maturing or mid-season cultivars, respectively. Greater amounts of dry matter and N content at anthesis resulted in a greater dry matter and N translocation to grain. Grain yield was positively and significantly correlated with dry matter and N translocation efficiency, suggesting that the sink strength could be involved in the translocation efficiency. The contribution of pre-anthesis accumulated reserves to grain weight ranged from 9.1 to 42.2%, indicating the importance of pre-anthesis storage of assimilates for attaining high grain yield of rice under Mediterranean conditions.

We tested the hypothesis that, in competition for nutrients, the plant species using more efficiently the limiting nutrient will tend to dominate in plant communities. Two experiments were conducted. In the first, plant communities consisting of perennial herbaceous species were grown in large boxes filled with soil enriched with all necessary nutrients, except for nitrogen (N) in half of the boxes and phosphorus (P) in the other half. It was expected that N or P, respectively, would become progressively limiting. In the second experiment, five perennial species, in monocultures and in mixtures of the five species, were grown in nutrient solutions of the combination of 3 levels of potassium (4, 16 and 64 µg ml−1) × 2 levels of phosphorus (1 and 4 µg ml−1) with all the other necessary nutrients at adequate concentrations for plant growth. In the first experiment, changes of the proportions of species biomass duration to community biomass duration between the second and the third years of the experiments were negatively related to species P shoot concentrations, but they were not related to species N shoot concentrations, probably because N did not become limiting. The second experiment showed that the species use efficiency of a particular nutrient (measured as the quantity of dry matter produced per g nutrient) was highest when the availability of this nutrient was lowest; the species with the highest use efficiency of a particular nutrient tended to have the highest relative abundance when this nutrient was limiting. The results of both experiments suggest that nutrient competition is important in low-nutrient environments and the species that use more efficiently the limiting nutrients have a competitive advantage and tend to dominate in the plant community. Zusammenfassung Wir untersuchten die Hypothese, das im Hinblick auf die Konkurrenz um Nahrstoffe Pflanzenarten, die effizienter in der Nutzung limitierter Nahrstoffe, den Pflanzenbestand dominieren. Es wurden daher zwei Experimente durchgefuhrt, in dem ersten wurden Pflanzenbestande aus perennierenden krautigen Arten in grosen Behaltern angezogen, die mit einem Boden, angereichert mit allen notwendigen Nahrstoffen mit Ausnahme von Stickstoff in der Halfte der Behalter und Phosphor in der anderen Halfte, gefullt waren. Es wurde erwartet, das N oder P zunehmend limitierend sein wurden. Im zweiten Experiment wurden funf perinnierende Arten in Monokulturen und in Mischungen der funf Arten in Nahrlasungen angezogen, in denen eine Kombination von drei Konzentrationen von Kalium (4, 16 und 64 µg ml −1) sowie zwei Konzentrationen von Phosphor (1 und 4 µg ml−1) mit allen anderen notwendigen Nahrstoffen in ausreichender Konzentration fur das Pflanzenwachstum vorhanden waren. In dem ersten Experiment waren Anderungen in dem Anteil der Biomassedauer der Arten zur Biomassedauer der Bestande zwischen dem zweiten und dritten Jahr des Experimentes negativ korreliert mit der P-Spros-Konzentration der Arten, aber nicht mit der N-Sproskonzentration; wahrscheinlich wurde N nicht limitierend. Das zweite Experiment zeigte, das die Nutzungseffizienz eines einzelne Nahrstoffes (gemessen als die Menge der Trockenmasse je Gramm Nahrstoff) der Arten am hochsten war, wenn die Verfugbarkeit dieses Nahrstoffes am niedrigsten war; die Arten mit der hochsten Nutzungseffizienz eines einzelnen Nahrstoffs tendierten dazu, den hochsten relativen Uberschus aufzuweisen, wenn dieser Nahrstoff limitierend war. Die Ergebnisse der beiden Experimente weisen darauf hin, das die Kon-kurrenz um Nahrstoffe in Umwelten mit niedrigem Nahrstoffangebot bedeutend sein kann und das Arten, die limitierende Nahrstoffe effizienter nutzen, einen Konkurrenzvorteil aufweisen und damit den Pflanzenbestand dominieren.

Field experiments were conducted in 1996 and 1997 to evaluate barnyardgrass (Echinochloa crus-galli) control, rice (Oryza sativa) yield, and grain quality with cyhalofop-butyl applied early postemergence (EPOST) or late postemergence (LPOST) in drained or flooded plots at rates of 0.15 to 0.4 kg ai/ha and standard treatments of molinate or propanil. Control with cyhalofop-butyl at 0.15 and 0.2 kg/ha applied in drained plots was greater compared to propanil and generally increased when treatments were applied EPOST to plots reflooded 2 d after treatment. Barnyardgrass control with cyhalofop-butyl at 0.15 and 0.2 kg/ha applied in flooded plots was similar to or better than the control obtained with molinate. Rice yields generally reflected differences in barnyardgrass control and were greatest with cyhalofop-butyl applied EPOST in drained plots. The 0.4 kg/ha rate of cyhalofop-butyl resulted in rice foliar injury and significant reductions in grain yield. Grain qualitative characteristics (total m...

A field study was conducted to assess the effect of irrigation on castor (Ricinus communis L.) and to define the water requirements of the crop. Three irrigation regimes, corresponding to 0.0, 0.5 and 1.0 fractions (kd) of the evapotranspiration (ETm) in the area were compared, factorially combined with the varieties Pronto and Negus in 1995. In 1996 and 1997 one more irrigation treatment corresponding to 0.75 of the ETm was included, and Negus was replaced by HD912. Irrigation was found necessary for castor production since seed and oil yields obtained with irrigation were much higher compared to yields of rainfed plants, and also castor could not be competitive to winter cereals in rainfed areas. In 1995 seed yield increased to kd = 1.0, but the response of both varieties was curvilinear. In 1996 kd = 0.50 was enough for the maximum yield by both varieties, while in 1997 higher amounts of water were needed (kd = 1.00 and 0.75 for Pronto and HD912, respectively). The beneficial effect of irrigation was mainly due to the increased number of secondary racemes. Oil yield was mainly determined by seed yield. Thus, the aim of the growers should be to increase the seed yield. The suggested amount of water for the irrigation of castor in the Northern Greece is equal to 75 % of the evapotranspiration of the plant in the area. With this amount the yield is satisfactory and the management of water resources is doing in a rational way.