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Zinc-oxide nanoparticles (ZnO-NP) effect on crop physiology and zinc recovery remains poorly studied for acidic-sandy soils. To address this, greenhouse pot (plastic-pots, 6 kg soil, maize) experiments with ZnO-NP (50, 100, 150, 200 mg kg−1) applied via different methods (soil-drench, seed-coating and foliar-spray) was conducted in a 60 days study. Results revealed that ZnO-NP via seed-coating (100 mg kg−1) and soil-drench (150 mg kg−1) enhanced shoot and total P uptake, while ZnO-NPs (foliar) (50 mg kg−1) enhanced maize growth (6–11%), with agronomic and physiological improvements ultimately resulted in greater biomass (16–20%), Zn agronomic efficiency and uptake. Compared to ZnSO4 treatment and the control, seed-coating with 100 mg kg−1 ZnO-NP increased leaf chlorophyll and pigment content by 12–127%. Principal component analysis revealed a close association among growth traits, plant pigments, fluorescence parameters, total Zn and P concentration, and uptake with total biomass as influenced by ZnO-NPs. Thus, compared to conventional ZnSO4 and higher dosages of ZnO-NPs, foliar-spray of ZnO-NP at 50 mg kg−1, seed-coating at 100 mg kg−1, or soil-drench at 150 mg kg−1 increased maize biochemical characteristics, growth, biomass, and Zn agronomic efficiency. These elucidate important implications of ZnO-NP application for increasing plant development and Zn biofortification in acidic-sandy soils. [ABSTRACT FROM AUTHOR]

Foliar application of Atonik (sodium nitrophenolate) at crop critical growth stages is expected to improve crop physiology, morphology, and productivity. The present field study was conducted at the University of Agriculture, Faisalabad in autumn season of 2018 and 2019. Water deficit conditions were imposed by skip irrigation method. Plants were treated with foliar application of Atonik 10 (mg L−1) to evaluate the physiological, morphological, yield, and yield causative attributes of maize grown under deficit irrigation treatments. Randomized complete block design (RCBD) with split plots arrangement was used to layout the experiment having three replications. It was revealed that application of Atonik improved the crop's physiological attributes: relative leaf water contents (RLWC by 10%), chlorophyll contents (14%), and carotenoids content (15%) under water deficit conditions. Similarly, Atonik application augmented the leaf length at maturity, the number of green leaves at harvesting, and the number of grains row−1 of maize by 7%, 20% and 12%, respectively. Moreover, the application of Atonik amended the 100-grains weight, grain yield, and biological yield by 8%, 9% and 20%, respectively. In crux, application of Atonik is an excellent strategy to alleviate the detrimental influence of water deficit on physiological, morphological, and yield causative attributes of maize. [ABSTRACT FROM AUTHOR]

Little is known about the photosynthetic physiology of guar (Cyamopsis tetragonoloba L. Taub), a legume crop, including how photosynthetic parameters intrinsically vary among germplasm and their recovery from water stress. To address this, two greenhouse studies were conducted: Study-1 to compare photosynthetic light response (AN–I) curves and related parameters in three contrasting guar genotypes under optimal and post-water deficit conditions; and Study-2 to quantify photosynthetic parameters in 44 guar genotypes and explore inter-relationships with plant growth parameters. In Study-1, the mean net photosynthetic rate (AN) statistically peaked with 1500 μmol (photons) m −2 s −1, though the maximum AN [33.29 μmol (CO2) m−2 s−1] was modeled to occur with 1950 μmol (photons) m −2 s −1. The light compensation point (Icomp), dark respiration rate (RD), and maximum quantum yield (Ф(I0)) were modeled to be 49.9 μmol (photons) m−2 s−1, 2.62 μmol (CO2) m−2 s−1, and 0.0526 μmol (CO2) μmol−1 (photons), respectively. Photosynthesis in guar was resilient to water stress. Despite reductions in growth, specific leaf area (SLA), and other growth parameters, persistently drought-stressed guar plants, on average, exhibited rapid and full recovery of photosynthetic functions when watered. Genotypes differed in their capacity to recover to some degree. In Study-2, AN differed only between two of the 44 genotypes tested, corresponding to the minimum and maximum AN values. There were no relationships between AN and most plant growth parameters. This finding suggested there is low potential to use point measurements of AN as a selection parameter for increased guar productivity. [ABSTRACT FROM AUTHOR]

Climate change has become a serious threat all over the world, which creates a negative impact on the growth, physiology and yield attributes of the crops. Drought stress is one of the major causes of climate change that contributes more to the reduction of yield of crops and its physiological aspects (i.e., stomatal conductance, leaf temperature, plant canopy temperature, membrane thermal stability index, total chlorophyll content, chlorophyll fluorescence). Pod shattering negatively affects the yield of canola under drought stress conditions. The control of shattering, caused by drought, has been difficult due to the lack of resistant cultivars. Drought at any stage of canola, either vegetative or reproductive, badly affects the canola crops in terms of growth, physiology, pod development and its shattering, which results in the reduction of yield. To overcome the pod shattering and its development, the Si plays an important role, which provides the strength to the pod when it was applied with their proper amount and proper time. Si is the beneficial element which helps in improving the growth and physiology of crop under drought stress conditions. Si helps for reducing the pod shattering in canola and improving its yield by mitigating the adverse effect of drought on canola. Molecular approaches also help to provide resistance in canola against pod shattering and improve its yield under drought stress conditions. Current review highlights the role of Si and current molecular developments to deal with constraints in pod development and it's shattering under drought stress. [ABSTRACT FROM AUTHOR]

Watermelon [Citrullus lanatus (Thunb.) & Nakai] is widely grown on plastic mulches in the southeast United States, but responses of plants to plastic mulch color are not well understood. The objectives of this study were to determine the effects of colored plastic mulches and changes in root zone temperature (RZT) on fruit yield of watermelon fruit. The mulches (152 cm wide) evaluated were: black, blue, gray, red, silver (metallic), and white. During the first weeks after transplanting, canopy development was more rapid on black, blue, and red than silver and white mulches. As the season progressed and temperatures increased, differences in canopy development among mulch treatments tended to decrease. Watermelon plant growth benefited from soil warming using plastic film mulches, mainly blue, black, and red. There were no differences in fruit yield among different colored mulches, indicating that under the temperature conditions of the present study, the RZTs during fruiting were within optimal range for watermelon which is estimated to be 28.3°C. [ABSTRACT FROM AUTHOR]

Though application of chemical fertilizers has contributed significantly to the huge increase in the world food production, the adverse impacts of it are well known. To develop an organic farming system an experiment was conducted on paddy, in old alluvial soil zone, with vermicompost prepared from screened municipality solid waste and different doses of bio-fertilizer and chemical fertilizer which is productive, profitable, enhances soil health and conserves the natural resource. We compared crop yields, crop morphological and morpho-physiological characters along with economical analysis obtained from three consecutive years experiment (2017 to 2019) along with long-term soil sustainability. It has been observed that 25% NPK fertilizer can safely be supplemented by low cost and natural resource-based vermicompost at 2.5 t ha−1 to achieve long-term sustainability in paddy cultivation that is more productive and profitable. [ABSTRACT FROM AUTHOR]

There is need for information on the general crop physiology and nitrogen (N) fertiliser responses of beetroot in New Zealand. We investigated the responses to N of beetroot grown in a silt loam near Hastings, Hawke's Bay. Four fertiliser treatments (0, 160, 320 or 480 kg N ha−1) were applied as urea, split evenly over four application times. The canopy light extinction coefficient averaged 0.64. Radiation use efficiency averaged 1.05 g MJ−1 for the treatments that received N fertiliser. Maximum yield occurred at an N fertiliser rate around 320 kg N ha−1. Published recommendations suggest only 225 kg N ha−1 would have been needed. This underestimation would have led to a yield penalty of only about 6%, but decreased the risk of significant mineral being N left in the soil. We discuss approaches to account for N supply from the soil when forecasting residual mineral N and N leaching risk. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum L.) grain yield is predicted to decrease in the future because of an increase in air temperature globally. To clarify the effects of the vernalization response gene in wheat to warmer winters, we compared dry matter production and grain yield between spring wheat 'Asakazekomugi' and its winter-type near-isogenic line (NIL) carrying different alleles of the vernalization response gene Vrn-D1 under early-, standard-, and late-sowing conditions. Under early-sowing conditions, dry matter production of the NIL carrying the winter allele of Vrn-D1, named Asa (Vrn-D1b), exceeded that of 'Asakazekomugi' from mid-March (after stem elongation in Asa (Vrn-D1b)) when the temperatures rose. Tiller number and leaf area index under early-sowing conditions were consistently higher in Asa (Vrn-D1b) than in 'Asakazekomugi' from mid-March onward. It was suggested that the early-sown 'Asakazekomugi' could not effectively absorb solar radiation to produce dry matter because of the acceleration of stem elongation caused by the Vrn-D1 gene during the cold season. The grain yield of Asa (Vrn-D1b) with early sowing was higher than with standard sowing. In contrast, the grain yield of 'Asakazekomugi' was lower in the early-sown crop than in the crop sown at the standard date. These results suggested that the higher grain yield of Asa (Vrn-D1b) than that of 'Asakazekomugi' under early-sown conditions could be due to Asa (Vrn-D1b) maintaining high dry matter production after the jointing stage by suppressing acceleration of growth caused by warm conditions after sowing. Abbreviations: CGR: crop growth rate; HI: harvest index; LAI: leaf area index; NIL: near-isogenic line; SNP: single-nucleotide polymorphism [ABSTRACT FROM AUTHOR]

Root growth into hypoxic or anoxic waterlogged soil relies on internal aeration in plants. The plant hormone ethylene helps adapt to waterlogging by inducing the formation of aerenchyma, which provides a low-resistance pathway for the transport of oxygen from the shoot to the root apex. Waterlogging-susceptible crops including barley start to form aerenchyma after suffering waterlogging stress. But waterlogging can be fatal if aerenchyma formation is not fast enough. Here, we investigated whether pre-treating barley with ethephon, an ethylene-releasing agrochemical, could improve its tolerance to mimicked waterlogging conditions (using stagnant deoxygenated agar nutrient solution). In barley growing in aerated nutrient solution, ethephon treatment enhanced aerenchyma formation at the root tips and induced the development of shorter and shallower roots. Pre-treating barley leaves also delayed waterlogging-caused whiting and increased the percentages of viable root-tips under waterlogging conditions. However, the pretreatment did not noticeably increase fresh weight or shoot length. Further studies are needed to optimize ethephon treatment conditions to improve barley production under waterlogged conditions. [ABSTRACT FROM AUTHOR]

Indigenous leafy vegetables play a major role in strategies to attain food and nutritional security for African households. However, the potential of these vegetables in meeting the nutritional requirements have not been adequately exploited. This study assessed effects of shadenets on nutritive value of African indigenous leafy vegetables. The vegetables African nightshade (Solanum scabrum Mill.) and spiderplant (Cleome gynandra L.) and net covers colored white, gray, blue, and yellow, with unnetted plants as a control were used. From the 7th week after sowing (spiderplant) and transplanting (African nightshade) and at 2-week intervals nutritive quality variables were determined. Compared to open field, white net produced higher leaf β-carotene at 13 weeks after planting by 6% and 17% for African nightshade and spiderplant, respectively. Use of blue net cover reduced leaf vitamin C content by 94.5% and 79% in African nightshade and spiderplant, respectively, compared to open field at 15 weeks after planting. Higher leaf calcium was consistently recorded for plants grown under yellow net cover for African nightshade and white nets for spiderplant; but was reduced under blue net for both species on most sampling dates. Leaf iron content was maximized under yellow net cover for both crops. Use of net covers reduced leaf crude fiber content compared to open field; high leaf phenolic content was obtained in crops grown under white net for both vegetables. The crop responses were attributed to spectral quality, light intensity, and environmental changes to which the crops were subjected. The different colored agronet covers differentially influenced crop leaf nutritive quality. [ABSTRACT FROM AUTHOR]

Air temperature is one of the most critical climatic factors controlling rice growth, development, and production in current and future climatic scenarii predicting increasingly frequent situations of extreme and/or fluctuating temperatures. With its large spectrum of geographical origins and cropping areas, one can credit tropical japonica rice subspecies of a probable genetic diversity of its response to air temperature, which is of major interest for the breeding of better adapted rice varieties. A panel of 195 rice accessions (175 japonica plus 20 reference cultivars) was studied in controlled environment to estimate cardinal (base, optimum, and maximum) temperatures based on the monitoring of the elongation rate (LERmax) of the sixth leaf on the main stem in response to six fixed thermal treatments ranging from 16 to 35 °C. A dedicated statistical framework was elaborated for estimating LERmax, cardinal temperature and related uncertainties. Developed statistical framework enhanced the precision of cardinal temperatures estimated compared to previously reported methods, especially for base temperature. Maximum temperature was trickier to estimate and will require further studies. A significant genotypic variability for base and optimal temperature was pointed out, suggesting tropical japonica subspecies represents a relevant genetic pool to breed for rice genotypes adapted to various thermal situations. These results also suggested that using genotype-dependent cardinal temperature values should enhance the way crop growth models account for genotype × environment interactions hence their predictive value in current and future climatic conditions. [ABSTRACT FROM AUTHOR]

Tachisuzuka, a rice cultivar for whole-crop silage, is characterized by a small panicle and high sugar content in the stem. Our previous study suggests that the high sugar content in the stem of Tachisuzuka is due to a factor other than the small panicle. To characterize sugar metabolism in the stem of Tachisuzuka, here we compared carbohydrate content, enzyme activity, and the expression of genes involved in sugar metabolism in the stem between Tachisuzuka and its parental variety, Kusanohoshi. Thinning the panicles of Kusanohoshi increased the starch content in the leaf sheath and internode but did not increase the sucrose content in the leaf sheath to the same level as that of Tachisuzuka. This suggests that Tachisuzuka has high potential to accumulate sucrose in its leaf sheath. Comparison of enzyme activity showed that the hexokinase activities in the leaf sheath tended to be higher in Tachisuzuka than Kusanohoshi or panicle-thinned Kusanohoshi, suggesting that glucokinase or fructokinase affects sugar accumulation in the stem of Tachisuzuka. Comparative transcriptome analysis revealed the differences in expression levels of carbohydrate-related genes between Tachisuzuka and Kusanohoshi. In particular, the expression levels of ISA2, which encodes starch-debranching enzyme, and TMT2, which encodes tonoplast monosaccharide transporter - both of which maybe involved in sugar accumulation in grass stems - were higher in Tachisuzuka than Kusanohoshi. Thus, these enzymes and transporters may contribute to the high sugar content in the stem of Tachisuzuka. [ABSTRACT FROM AUTHOR]

Enhancing rice yield in upland rice systems through genetic improvement remains a major challenge in the tropics. This review aims to provide the trends on upland rice cultivation over the last 30 years and recent distribution of upland rice in the tropics, and to report progress in studies on genetic improvement for enhancing productivity in Africa, Asia, and Latin America. While upland rice cultivation area has reduced in Asia and Latin America over the last 30 years, the area in Africa has increased. The current share of upland rice area in total rice area is related to rainfall and gross national income per capita, especially in Africa, and higher share is associated with lower rice selfsufficiency at national level. Breeding programs in Asia and Latin America have developed highyielding varieties using indica materials as parents. In Africa, New Rice for Africa (NERICA) varieties were developed from crosses between improved tropical japonica and Oryza glaberrima. However, recent studies report that there is scope for improving existing NERICA using upland indica materials from Asia. In highlands of Africa, there are ongoing breeding programs using japonica varieties, such as the Nepalese Chhomrong Dhan. Key important plant traits used in the breeding programs are not largely different across regions, especially intermediate plant height and tillering capacity (which may be related to weed-suppressive ability), and high harvest index. In conclusion, we propose an international network for breeding upland rice with accelerating seed exchange across regions that could enhance upland rice productivity through genetic improvement. [ABSTRACT FROM AUTHOR]

C4plants show higher photosynthetic capacity and resource use efficiency than C3plants. However, the genetic variations of these traits and their regulatory factors in C4plants still remain to be resolved. We investigated physiological, biochemical, and structural traits involved in photosynthesis and photosynthetic water and nitrogen use efficiencies (PWUE and PNUE) in 22 maize lines and four teosinte lines from various regions of the world. Net photosynthetic rate (PN) ranged from 32.1 to 46.5 μmol m−2s−1.PNwas positively correlated with stomatal conductance, transpiration rate, and chlorophyll, nitrogen and soluble protein contents of leaves, but not with specific leaf weight.PNwas positively correlated with the activities of ribulose-1,5-bisphosphate carboxylase/oxygenase and the C4-acid decarboxylases, NADP-malic enzyme and phosphoenolpyruvate carboxykinase, but not with the activity of phosphoenolpyruvate carboxylase. Leaf structural traits (stomatal parameters, leaf thickness, and interveinal distance) were not correlated withPN. These data suggest that physiological and biochemical traits are involved in the genetic variation ofPN, but structural traits are not directly involved. PWUE is in the lower class of values reported for C4plants, whereas PNUE is in the highest class of values reported for C4plants. PNUE was negatively correlated with leaf nitrogen content but not significantly correlated withPN. PWUE was not correlated withδ13C values of leaves, indicating difficulty in usingδ13C values as an indicator of PWUE of maize. In general, teosinte lines showed lowerPNbut higher PWUE than maize lines. [ABSTRACT FROM PUBLISHER]

Rice production needs to increase in the future in order to meet increasing demands. The development of new improved and higher yielding varieties more quickly will be needed to meet this demand. However, most rice breeding programmes in the world have not changed in several decades. In this article, we revisit the evidence in favour of using rapid generation advance (RGA) as a routine breeding method. We describe preliminary activities at the International Rice Research Institute (IRRI) to re-establish RGA on a large scale as the main breeding method for irrigated rice breeding. We also describe experiences from the early adoption at the Bangladesh Rice Research Institute. Evaluation of RGA breeding lines at IRRI for yield, flowering time and plant height indicated transgressive segregation for all traits. Some RGA lines were also higher yielding than the check varieties. The cost advantages of using RGA compared to the pedigree method were also empirically determined by performing an economic analysis. This indicated that RGA is several times more cost effective and advantages will be realized after 1 year even if facilities need to be built. Based on our experience, and previous independent research empirically testing the RGA method in rice, we recommend that this method should be implemented for routine rice breeding in order to improve breeding efficiency. [ABSTRACT FROM PUBLISHER]

Production of bioethanol from rice straw has attracted attention from the point of effective use of agricultural residue. Starch content is an important determinant for bioethanol production from rice straw. The overexpression ofCO2-responsive CCT protein(CRCT), which is the positive regulator of starch synthesis in vegetative organs, notably increased the starch content in rice straw. To produce the bioethanol from rice straw, the dilute acid pretreatment is a general pretreatment method. Importantly, the glucose yields in liquid hydrolyzate after dilute acid pretreatment was markedly increased in theCRCToverexpression lines compared with non-transgenic rice. In addition, the overexpression ofCRCTenhanced the biomass production. In contrast,CRCTdid not affect on the glucose yields from cellulose in acid-insoluble residue obtained after dilute acid pretreatment. With respect to byproduct in liquid hydrolyzate which inhibits the fermentation, the formic acid content was increased, whereas the furfural, 5-hydroxymethylfurfural and acetic acid contents were unchanged by the overexpression ofCRCT. These results demonstrate that genetic engineering ofCRCTis an effective method to increase the bioethanol production from rice straw. [ABSTRACT FROM PUBLISHER]

Mixed cropping is a cultivation method widely practiced in tropical regions. The newly developed close mixed planting technique mitigates the flood stress of drought-adapted upland cereal species by co-growing rice (Oryza sativa) plants under field flood conditions. We tested the hypothesis that O2was transferred from rice to upland crops using the model system of hydroponic culture. To confirm the hypothesis, the phenomena of O2absorption and release by plants were evaluated in a water culture condition without soil. Experiments were conducted in a climate chamber to estimate the amount of O2released from the roots of rice and pearl millet (Pennisetum glaucum) under both O2-rich (20.0 ± .0% conc. in phase I) and O2-free dark (.8 ± .0% conc. in phase II) conditions. The total O2change (between the two phases) in a single planting of rice and pearl millet was significantly higher than that of the mixed planting of rice and pearl millet, which indicated that O2was transferred from rice to pearl millet under a water culture condition. The result indicated that approximately 7 μM O2 g fresh root weight−1 h−1was transferred between the two plant species. O2transfer was confirmed between the two plant species in a mix cultured in water, implying its contribution to the phenomenon that improved the physiological status of drought-adapted upland crops under field flood conditions. [ABSTRACT FROM PUBLISHER]

To explore the zinc stress response in eddo, plants were grown for 15 d in hydroponic solutions containing 1 (control), 200, and 1000 μM zinc, and the hydathode function and changes in the contents of various elements in these plants were investigated. Under 1000 μM zinc, the dry weights of leaf blades and roots are decreased by 17 and 42%, respectively. The zinc contents in leaf blades, petioles, corms, and roots increased with increasing zinc levels in the solution. The zinc content in roots was 6.57 mg g−1dry weight, which was 2.8–4.3 times higher than in other plant parts under 1000 μM zinc. These results demonstrate that the severe root damage occurring under 1000 μM zinc is due to higher zinc content in the roots. Under zinc stress, the contents of iron and copper in roots increased, but the contents of magnesium and calcium in petioles, corms, and roots, iron in leaf blades and corms, and manganese in petioles and corms decreased. In the guttation fluid, the concentrations of zinc, magnesium, and potassium increased, while the iron concentration decreased under 1000 μM zinc. Thus, elemental changes occurred in the guttation fluid as well as in different plant parts in eddo. In the 200 and 1000 μM zinc treatments, the amount of zinc eliminated via guttation was 2.8 and 8.5 times higher, respectively, than in the control. The results indicate that guttation partly contributes to the excretion of excess zinc under zinc stress conditions. [ABSTRACT FROM PUBLISHER]

Drought stress which often occurs during early growth stage is one constraint in sugarcane production. In this study, the response of sugarcane to drought and nitrogen application for physiological and agronomical characteristics was investigated. Two water regimes (well-watered and drought stress from 60 to 120 day after transplanting) and four nitrogen levels (0, 4.4, 8.8 and 13.2 g pot−1equivalent to 0, 90, 180 and 270 kg ha−1, respectively) were assigned in a Split-plot design with three replications. The results showed that photosynthetic responses to light intensity and intercellular CO2concentrations of sugarcane were different between fertilized and non-fertilized treatments. Photosynthetic rates of 180 and 270 N treatments, normally, were significantly higher than that of 90 N, but not significant at drought conditions. Photosynthetic rates of 0 N treatment were the lowest under both conditions. Higher nitrogen application supported higher photosynthetic rate, stomatal conductance, and chlorophyll content because of higher nitrogen concentration accumulated into the leaf. Drought significantly reduced the potential photosynthetic rate, stomatal conductance, SPAD, leaf area, and biomass production. Higher nitrogen applications with larger root system could support higher photosynthetic activities to accumulate more dry mass. Strong positive coefficient between photosynthetic and biomass nitrogen use efficiency and drought tolerance index may suggest that higher nitrogen use efficiency could help plants have higher ability to tolerate drought stress. [ABSTRACT FROM PUBLISHER]

Seed coating with molybdenum compounds improves seedling establishment for rice, wheat, barley, and soybean when such seeds were sown under flooded conditions. Tungsten belongs to the same chemical group as molybdenum in the periodic table, and similar to molybdenum, inhibits the generation of sulfide ions. Here, the effects of tungsten and molybdenum containing seed coatings on seedling establishment under flooded conditions were compared using rice, wheat, barley, and soybean. In rice, the effects of tungsten compounds on seedling establishment varied. Tungsten trioxide had little effect but tungstic acid and ammonium phosphotungstate significantly improved seedling establishment when the amounts were at least .1–.2 mol W kg−1. Although the effect of tungsten coating varied depending on the compound used, ammonium phosphotungstate, along with other tungsten compounds, improved seedling establishment in a manner comparable with that of molybdenum compounds. For wheat and barley, ammonium phosphotungstate treatment resulted in a significant increase in establishment that was only slightly less than the results observed using molybdenum compounds. Tungstic acid and ammonium phosphotungstate treatments improved soybean establishment in a significant manner that was comparable with those of molybdenum compounds. Collectively, these results suggest that tungsten compounds, as well as molybdenum compounds, improve seedling establishment under flooded conditions. [ABSTRACT FROM PUBLISHER]

The effect of soil exchangeable (plant-available) potassium (ExK) content on cesium (Cs) absorption and translocation in buckwheat was evaluated in a field contaminated with radioactive Cs (134Cs and137Cs, RCs) in 2013. The RCs concentration in buckwheat was significantly positively correlated with the naturally occurring stable Cs (133Cs, SCs) concentration, and was lower at higher soil ExK content. The RCs and SCs were actively absorbed by buckwheat until the flowering stage. The soil ExK content was significantly negatively correlated with soil exchangeable RCs and SCs (ExRCs and ExSCs) concentrations. Greater RCs and SCs absorption by buckwheat in soils with low ExK contents was mainly due to higher soil ExRCs and ExSCs concentrations. Reproductive organs showed the largest differences in SCs concentration between low-ExK and high-ExK plots. The root–shoot and shoot–reproductive organs translocations of SCs markedly decreased with increasing soil ExK content. In the root–shoot and shoot–reproductive organs translocations, the discrimination of SCs and K decreased with decreasing soil ExK content. Our main findings were as follows: (1) because RCs are mainly taken up at the earlier growth stage, potassium should be applied as a basal fertilizer to decrease the RCs concentration in buckwheat; (2) lower soil ExK content led to higher soil ExRCs concentrations, resulting in greater RCs absorption by buckwheat; (3) the high Cs absorption and translocation and weaker discrimination between Cs and K in low ExK content soil may be due to the expression of K transporter(s) with weak discrimination between Cs and K. [ABSTRACT FROM PUBLISHER]

The present study investigated the effects of elevated carbon dioxide concentration ([CO2]) and air temperature on the germination of seed bulbils and the seedling vigour of two Chinese yam lines. Plants were grown under two [CO2] levels, ambient and elevated (ambient + 200 μmol mol−1), and two mean air temperature regimes, 22.2 °C (ambient + 1.4 °C) and 25.6 °C (ambient + 5.2 °C). Elevated [CO2] did not affect bulbil germination under both air temperature regimes. During the early growth stage, the dry weight (DW) of leaves, vines, shoots, roots, belowground parts (roots + tubers) and whole plants were higher under elevated [CO2] than ambient [CO2] for both lines under the low- and high-temperature regimes. The values of vigour indexes (index I = germination % × seedling length and index II = germination % × seedling DW) were also higher under elevated [CO2] than ambient [CO2] for both lines. These results indicated that Chinese yam seedlings respond positively to elevated [CO2] during the early growth stage. The above:belowground DW ratios were lower under elevated [CO2] than ambient [CO2] in seedlings with very small new tubers for both yam lines, indicating that elevated [CO2] strongly affected the root growth in the early growth stage. The DWs of post-treatment seed bulbils were higher in the elevated [CO2] under both air temperature regimes. The results showed that Chinese yam used a smaller amount of the reserves in seed bulbils under elevated [CO2] than under ambient [CO2]. [ABSTRACT FROM AUTHOR]

Soil salinity is a major environmental stress causing significant loss of crop productivity. Barley (Hordeum vulgareL.) is one of the few field crops that can grow in salt-affected fields and varietal differences in productivity under salinity conditions were known. To clarify the trait most responsible for grain production under salt stress, barley cultivars that were salt tolerant (OUE812) or salt sensitive (OUC613) were grown from seedling to harvest stage in vermiculite containing various concentrations of NaCl. Dry weight of aboveground parts and grain weight decreased significantly with increasing NaCl concentration. The dry weight of the aboveground parts and grain weight decreased more significantly in OUC613 than in OUE812 for plants treated with 150 mM and 200 mM NaCl. A marked reduction in ripening percentage caused significantly decreased grain production in OUC613 as compared with OUE812. In plants treated with 200 mM NaCl, the photosynthetic rate decreased three weeks after starting the NaCl treatment, but a significant difference between cultivars in photosynthetic rate did not appear until seven weeks of NaCl treatment. OUE812 kept a higher photosynthetic rate during ripening than did OUC613 and dry matter production during the period from ripening to harvest was significantly larger in OUE812 than in OUC613. Keeping a higher photosynthetic rate might have contributed to higher grain production in OUE812. Higher ripening percentage and higher rate of photosynthesis during ripening might be target traits in breeding to improve the tolerance of barley to long-term salt stress. [ABSTRACT FROM PUBLISHER]

C4 plants show higher photosynthetic capacity and productivity than C3 plants owing to a CO2-concentrating mechanism in leaves, which reduces photorespiration. However, which traits regulate the photosynthetic capacity of C4 plants remains unclear. We investigated structural, biochemical, and physiological traits associated with photosynthesis and resource use efficiency in 20 accessions of 12 species of Amaranthus, NAD-malic enzyme-type C4 dicots. Net photosynthetic rate (PN) ranged from 19.7 to 40.5 μmol m−2 s−1. PN was positively correlated with stomatal conductance and nitrogen and chlorophyll contents of leaves and was weakly positively correlated with specific leaf weight. PN was also positively correlated with the activity of the C3 enzyme ribulose-1,5-bisphoshate carboxylase/oxygenase, but not with the activities of the C4 enzymes phosphoenolpyruvate carboxylase and NAD-malic enzyme. Structural traits of leaves (stomatal density, guard cell length, leaf thickness, interveinal distance, sizes of mesophyll and bundle sheath cells and the area ratio between these cells) were not significantly correlated with PN. These data suggest that some of the biochemical and physiological traits are involved in interspecific PN variation, whereas structural traits are not directly involved. Photosynthetic nitrogen use efficiency ranged between 260 and 458 μmol mol−1 N s−1. Photosynthetic water use efficiency ranged between 5.6 and 10.4 mmol mol−1. When these data were compared with previously published data of C4 grasses, it is suggested that common mechanisms may determine the variations in resource use efficiency in grasses and this dicot group. [ABSTRACT FROM AUTHOR]

We investigated changes in the developmental duration of rice cultivars with a wide range of maturities in response to late planting. Elucidating the relationship between cropping season and the progress of growth stages is important for establishing direct-seeded cultivation and creating growth models. Late planting of the intermediate to late maturing cultivars Akidawara and Hoshijirushi decreased the time from emergence to panicle formation and decreased the cumulative effective temperature (CET) and cumulative effective soil temperature (CEST). In the very early maturing cultivars Ichibanboshi and Fusakogane, the changes in number of days, CET, and CEST from emergence to panicle formation with late planting were small. From emergence to heading and maturity, the number of days, CET, and CEST of many cultivars tended to increase until mid-May and then decreased. The changes in the number of days, CET, and CEST caused by late planting were greater for the intermediate to late maturing cultivars than for the very early maturing cultivars. The differences between cultivars were greatest with early May sowing, and then decreased with later planting. Short-day condition revealed significant differences in the duration of vegetative growth and CET among cultivars, but long-day condition erased these differences. These results demonstrate that the photosensitivity and thermosensitivity of cultivars are especially important in crop planning and for creating growth models of direct-seeded rice. [ABSTRACT FROM AUTHOR]

Hydraulic resistance in plants is one of the most important factors responsible for changes in leaf water potential that is an indicator of plant water stress. Although the hydraulic resistance to passive water transport (Rpa) is a robust index in paddy rice (Oryza sativa), measurement is both time-consuming and labour-intensive. Here, we describe on a quick method to measure hydraulic resistance to osmotic water transport (Ros) by measuring the xylem sap exudation rate and osmotic water potential. In a greenhouse experiment, Ros responded significantly to soil temperature, but under field conditions soil temperature varied considerably less than air temperature. In the field experiment, Ros of six rice cultivars at two growth stages was strongly positively correlated with Rpa. We conclude that measuring Ros could be used to evaluate root water transport capacity in paddy rice under conditions with adequate soil water. [ABSTRACT FROM AUTHOR]

Henna (Lawsonia inermisL.) is naturally cultivated from north-east Africa to India as a medicinal-industrial plant. The objective of this study was to evaluate the possible role of salicylic acid (SA) for mitigating the salinity stress. For this purpose, we evaluated the effect of three concentrations of SA (0, 40 and 80 μM) and salinity (0, −3 and −6 bar) on photosynthetic pigments, protein content, catalase (CAT, EC 1.11.1.6) activity, electrolyte leakage and leaf relative water content (RWC). The experiment was carried out with a factorial arrangement based on complete randomized design in triplicates at University of Kerman, Iran. The results revealed that salinity caused a significant decrease in photosynthetic pigments, protein content, RWC and quantum yield of henna. By increase in salinity levels from 0 to −6 bar, the mean values of mentioned traits were reduced. CAT activity, electrolyte leakage,F0andFmwere elevated significantly with increasing the salinity concentration. Application of SA under salinity stress increased the photosynthetic pigments, protein content, CAT activity, leaf RWCs and quantum yield, while it decreased electrolyte leakage,F0andFm. It can be concluded that SA alleviated the stress generated by NaCl possibly through the ameliorated antioxidant defense system. [ABSTRACT FROM AUTHOR]

Chinese yam (‘yam’) was grown at different carbon dioxide concentrations ([CO2]), namely, ambient and elevated (ambient + 200 μmol mol−1), under low- and high-temperature regimes in summer and autumn, separately. For comparison, rice was also grown under these conditions. Mean air temperatures in the low- and high-temperatures were respectively 24.1 and 29.1 °C in summer experiment and 20.2 and 24.9 °C in autumn experiment. In summer experiment, yam vine length, leaf area, leaf dry weight (DW), and total DW were significantly higher under elevated [CO2] than ambient [CO2] in both temperature regimes. Additionally, number of leaves, vine DW, and root DW were significantly higher under elevated [CO2] than under ambient [CO2] in the low-temperature regime. In autumn experiment, tuber DW was significantly higher under elevated [CO2] than under ambient [CO2] in the high-temperature regime. These results demonstrate that yam shows positive growth responses to elevated [CO2]. Analysis of variance revealed that significant effect of [CO2] × air temperature interaction on yam total DW was not detected. Elevated-to-ambient [CO2] ratios of all growth parameters in summer experiment were higher in yam than in rice. The results suggest that the contribution of elevated [CO2] is higher in yam than in rice under summer. Yam net photosynthetic rate was significantly higher under elevated [CO2] than under ambient [CO2] in both temperature regimes in summer. Elevated [CO2] significantly affected on the rate in yam but not in rice in both experiments. These findings indicate that photosynthesis responds more readily to elevated [CO2] in yam than in rice. [ABSTRACT FROM AUTHOR]

The influence of seed priming with sorghum water extract (SWE) and benzyl amino purine (BAP) on germination metabolism and early seedling growth of wheat was evaluated in this study. For priming, wheat seeds were soaked in SWE (5%), BAP (5 mg L−1) alone and mixed with nonionic surfactant Tween-80 (0.05%). All the seed priming treatments significantly (p ≤ 0.05) improved the germination metabolism and early seedling growth as compared with dry seeds. Seed priming with combination of SWE, BAP and Tween-80 was the most effective treatment in improving the final germination percentage (34%), number of tillers per pot (50%), fresh weight (32%), dry weight (63%), chlorophyll contents (7%) and total phenolic contents (36%) over dry seed control. Similarly, maximum total soluble proteins, total soluble sugars and α-amylase activity were observed from the combined priming with SWE, BAP and Tween-80. Total soluble proteins were maximum in growing seedlings followed by germinating seeds than primed seeds. The germination and growth improvement by priming with SWE was comparable to BAP which makes it a cost-effective natural growth regulator. Combined applications are more effective, which may be due to enzymatic regulation in a synergistic manner. [ABSTRACT FROM PUBLISHER]

Crop classification is needed to understand the physiological and climatic requirement of different crops. Kernel-based support vector machines, maximum likelihood and normalised difference vegetation index classification schemes are attempted to evaluate their performances towards crop classification. The linear imaging self-scanning (LISS-IV) multi-spectral sensor data was evaluated for the classification of crop types such as barley, wheat, lentil, mustard, pigeon pea, linseed, corn, pea, sugarcane and other crops and non-crop such as water, sand, built up, fallow land, sparse vegetation and dense vegetation. To determine the spectral separability among crop types, theM-statistic and Jeffries–Matusita (J–M) distance methods have been utilised. The results were statistically analysed and compared usingZ-test andχ2-test. Statistical analysis showed that the accuracy results using SVMs with polynomial of degrees 5 and 6 were not significantly different and found better than the other classification algorithms. [ABSTRACT FROM PUBLISHER]

We investigated the alleviative effects of mixed cropping using ice plant, which is one of the salt-accumulating halophytes, on the damage and growth inhibition of cowpea, which is not tolerant to high salinity. Three cropping patterns (mono cropping of cowpea and ice plant and their combination) were tested. The plants were treated with 0, 100, 200 and 300 mM NaCl for 14 days (consecutive NaCl). The plants were also treated with NaCl for 3 days, followed by 2 weeks (short-term recovery) and 1 month (long-term recovery) recovery. Salinity levels for short-term recovery were similar to those of the consecutive experiment, while the concentration of long-term recovery was 250 mM. The alleviative effects of mixed cropping in the consecutive NaCl experiment were observed at 200 and 300 mM NaCl. Mixed cropping significantly reduced the Na content in the cowpea leaves at 200 and 300 mM NaCl compared with mono cropping. In addition, the Na content in the soil of mix-cropped cowpea at 200 and 300 mM NaCl was statistically lower than that of the mono cropping. Mixed cropping was effective to recover from high concentration of NaCl in the experiments of short- and long-term recovery. These results indicate that mixed cropping with a halophyte could be effective in mitigating the damage and growth inhibition of a glycophyte not only under salinity but also under recovery periods. [ABSTRACT FROM PUBLISHER]

Sugarcane (Saccharumspp.) is an economical crop in the tropical and subtropical countries. However, because of global climate change, flooding has become problematic, particularly during the rainy season, in Thailand. We investigated the effects of floods on three commercial sugarcane cultivars, namely NiF8, U-thong 6 (UT6), and U-thong 9 (UT9), as well asErianthus spp. Growth was assessed using a pot experiment in a glasshouse with two treatments: (1) control and (2) 60 d of flooding followed by 30 d of normal conditions. In comparison with control, during prolonged flooding,Erianthusshowed greatly decreased CO2assimilation, whereas NiF8, UT6, and UT9 showed slightly declined CO2assimilation. Growth in plants subjected to 60 d of flooding was less influenced by floods while sucrose content was not affected except in UT6. During flooding, some roots died, resulting in plants compensating adventitious roots to offset the negative effects of root death and to assist them in maintaining their growth, which appeared from the submerged nodes, with different characteristics for each cultivar. However, 30 d after draining, roots remained damaged, while adventitious roots died, resulting in lesser growth as compared with the control, but it did not significantly affect sucrose content and sugar yield. This study suggests that sugarcane plants need to produce the adventitious roots to compensate their roots’ death during flooding and require time to recover their root system after flooding for obtaining the optimum yield and quality at harvest. [ABSTRACT FROM PUBLISHER]

Tachisuzuka, a rice cultivar grown for whole-crop silage, is characterized by the small-panicle trait and high-stem sugar content. To investigate the interrelationship between the two features, we attempted to identify the gene responsible for the small-panicle trait in Tachisuzuka, and also to examine the function of the gene using a knockout mutant line. A functionally disruptive deletion of the nucleotide sequence was found in the geneSP1(Short-Panicle 1; Os11g0235200) in Tachisuzuka, which has been reported as a candidate gene for the small-panicle trait. A gene knockout mutant ofSP1obtained from the cultivar Nipponbare showed a small-panicle phenotype similar to that observed in Tachisuzuka. However, soluble sugar content in the stem did not increase in the knockout line, whereas starch content increased significantly. Overall, disruption ofSP1is responsible for the small-panicle phenotype of Tachisuzuka, but it is only partially associated with the high-stem sugar content. [ABSTRACT FROM PUBLISHER]

While many plants accumulate the majority of their photoassmilates as starch during the daytime, some plants accumulate sucrose. Although the existence of these high-sucrose leaves, called ‘sugar leaves’, has long been known, the physiological characteristics of sugar leaves compared to ‘starch leaves’ remain unclear. In this study, the physiological roles of starch accumulation in rice, which has typical sugar leaves, were investigated using a mutant with suppressed leaf-starch biosynthesis. When grown under controlled conditions with light intensity of 400 μmol m−2s−1, the initial growth of the mutant was similar to that of the wild-type plant, even with a 6-h-light/18-h-dark photoperiod in which carbon resources for growth are required during the night. This finding indicates that rice does not rely on leaf starch as a carbon resource during the night. By contrast, under field conditions, the grain yields of the mutant were significantly lower than those of the wild type only when the plants were exposed to full sunlight during the ripening period. These results may indicate that starch accumulation in sugar leaves plays an important role in maintaining a high source capacity under sufficient light conditions rather than as a carbon resource for the plant’s growth at night. [ABSTRACT FROM PUBLISHER]

Foxtail millet grains usually contain carotenoids, which are yellow pigments that are important for human health. Yellow grains are preferred by distributors and consumers, and special cultivars and cultivation methods are desired for a stable supply of yellow millet. We investigated the level of pigment fluctuation in several foxtail millet accessions, including the yellow grain cultivar ‘Yuikogane’ from Iwate Prefecture, using high-performance liquid chromatography. Most yellow grains primarily contained xanthophylls, including approximately 1 mg/100 g lutein and 0.2 mg/100 g zeaxanthin. These pigments were rare in the bran and grain husks but were readily detected in polished grains, indicating that xanthophylls accumulate in the endosperm. We examined ‘Yuikogane’ to investigate the relationship between xanthophyll accumulation and grain ripening. During the ripening stage, xanthophyll levels gradually increased, but they rapidly decreased in response to over-ripening. Xanthophyll accumulation was estimated using a colorimetric assay of yellow pigmentation, which could be a useful method for determining the proper harvesting time for foxtail millet. [ABSTRACT FROM PUBLISHER]

The role of ascorbic acid on acute O3-induced inhibition of photosynthesis in solution-cultured paddy rice was evaluated. As pre-treatment, ascorbic acid (0, 5, and 10 mM) was added to the culture solution for 5 d before 5 h of O3exposure (0, .1, and .3 cm3m−3O3) during daytime. O3decreased photosynthesis-related parameters, total ascorbic acid content, and the redox state (RDS) of ascorbic acid. Ascorbic acid treatment enhanced the total ascorbic acid contents and its RDS level of rice leaves, but scarcely ameliorated O3-induced inhibition of photosynthesis-related parameters. Inhibition of net photosynthetic rate (PN) by O3was slightly ameliorated by exogenous ascorbic acid only at 1 d after O3exposure. These results indicate that ascorbic acid is a component of protection from O3injury but has a marginal role in the acute inhibition ofPNby O3in rice leaves. [ABSTRACT FROM PUBLISHER]

Early vigor is important for crop establishment in rice. This study was conducted to determine the seed and seedling traits in relation to early vigor in rice. Laboratory tests and pot experiments were carried out in 2013 and 2014. Morphological and physiological traits of seeds and seedlings were compared between two contrasting rice cultivars, Yuxiangyouzhan with superior early vigor and Huanghuazhan with general early vigor. For seed traits, Yuxiangyouzhan had lower seed hull weight but higher seed amylose content, seed amylase activity, and plumule–radicle ratio than Huanghuazhan, and consequently, Yuxiangyouzhan had about 10% higher germination percentage and velocity and 37% longer plumule than Huanghuazhan. For seedling traits, leaf area, specific leaf weight, leaf chlorophyll and soluble protein contents, leaf net photosynthetic rate, and shoot–root ratio were higher in Yuxiangyouzhan than in Huanghuazhan, and as a result, seedling shoot biomass was 23–32% higher in Yuxiangyouzhan than in Huanghuazhan. These results indicate that Yuxiangyouzhan has both superior seed and seedling vigor. The former is attributed to the low mechanical strength of seed hull, high conversion efficiency of seed reserve, and high mobilization of seed reserve to plumule, while the latter is due to large leaf area, high leaf photosynthetic capacity, and high partitioning of dry matter to shoot. This study enriches the physiological understanding of superior early vigor in rice. [ABSTRACT FROM PUBLISHER]

This study was designed to observe physiological indices of a spring maize response with the integration of beneficial microorganism, organic and inorganic nitrogen (N) fertilizer, and N levels. Field experiments were conducted in three replications during 2014 and 2015 at Agronomy Research Farm, the University of Agriculture Peshawar, Pakistan. Different beneficial microbes (BM) (with BM and without BM), organic (farm yard manure, FYM) and inorganic (ammonium nitrate) N ratios (0:100, 25:75, 50:50, 75:25, and 100:0), and nitrogen levels (N) (100, 150, and 200 kg ha−1). Beneficial microorganism, 50:50 ratio of organic and inorganic N, and 200 kg N ha−1seem better in terms of improving SPAD value, plant height (cm), leaf rea (cm2), and leaf area index (LAI) of spring maize. Therefore, the application of BM, 50:50 ratio of organic and inorganic N, and 200 kg N ha−1were recommended for enhancing crop physiology in agro-climatic condition for Peshawar, Pakistan. [ABSTRACT FROM AUTHOR]

Field screening of wheat (Triticum aestivumL.) lines for zinc (Zn)-use efficiency (ZUE) is a time consuming exercise. In the present experiment, we examined some important and early crop stage phenotypic and physiological trait(s), which could be used for a rapid screening of a large number of wheat lines for ZUE. Four wheat cultivars of varying ZUE (‘UP2628ʹ, ‘UP262ʹ, ‘PBW175ʹ, and ‘UP2554ʹ) were screened for dry matter accumulation, root characteristics, tissue partitioning of Zn, and kinetic parameters of Zn uptake under Zn-deficient (–Zn) and Zn-sufficient (+Zn) conditions in a sand culture. Under –Zn condition, ‘UP262ʹ (Zn-use inefficient) had maintained relatively higher pH (>6.6) around roots in contrast to ‘UP2628ʹ (Zn-use efficient) that maintained relatively lower pH (<6.2) and also produced relatively finer roots with higher number of forks and crossings and had higher cation exchange capacity as compared to other cultivars. Under –Zn, ‘UP262ʹ accumulated more dry matter and Zn in roots with poor translocation to shoots than under +Zn. Time-dependent uptake of Zn in the roots and shoots of all wheat cultivars conformed to the first-order kinetic equation and the computed intercepts and slopes were also related to their Zn uptake and translocation behavior. In contrast to ‘UP262ʹ cultivar, ‘UP2628ʹ showed higher translocation of Zn to the shoots under –Zn condition. In short-term sand cultures, Zn translocation index (Zn uptake in shoot/Zn uptake in roots) could be used as an important criterion for selection of Zn-use efficient wheat lines. [ABSTRACT FROM AUTHOR]

Chalky rice (Oryza sativaL.) grains are induced by high temperature during the grain-filling period. Plant nitrogen status also affects the occurrence of basal- and back-white grains (BBWG). The objective of this study was to elucidate the relations between nitrogen availability per spikelet during the grain-filling period (NGF) and each of the percentage ofBBWGand grain protein content (GPC). We further compared the effect of the components ofNGFdetermined before heading (NBH) and after heading (NAH) onBBWGandGPC. We grew the rice cultivar ‘Koshihikari’ in pots in 2012 and 2013, and top-dressed nitrogen at the panicle formation and heading stages, under two (2012) or three (2013) temperature regimes during the grain-filling period.GPCwas explained well byNGF, butBBWGwas not.BBWGwas best explained in a multiple-regression equation by mean air temperature after heading and byNBHandNAH. The partial correlation coefficients forNBHwere 1.6 and 3.0 times those forNAHin 2012 and 2013, respectively. On the other hand, in a multiple-regression equation forGPC, the partial correlation coefficients forNBHwere 0.91 and 0.71 times those forNAHin 2012 and 2013, respectively. These results suggest that rice grains are most sensitive to plant nitrogen status before heading forBBWGbut after heading forGPC, and that there is an optimal timing for nitrogen top-dressing that would maximize the reduction inBBWGper unit increment ofGPC. [ABSTRACT FROM AUTHOR]

We investigated the change in seed shape and weight as well as the accumulation and distribution of anthocyanins, melanin, and flavonoids during tartary buckwheat seed development. Pericarp dry weight increased slowly while the increase in flour dry weight was much greater. Increases in the dry weight of the embryo and endosperm were associated with change in seed shape. The highest anthocyanin content was observed in stage two while the highest melanin content occurred in stage five. There was a considerable decrease in total flavonoids, rutin, quercetin and kaempferol in mature seeds relative to seeds that were still developing. Additionally, there were significant correlations (correlation coefficient > .900,p < .05) among the changes in rutin, quercetin and kaempferol between flour and the pericarp. In mature seeds, 95% of the flavonoids were present in flour. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the reliability of pot-based screening method for iron (Fe) toxicity tolerance in rice using soils from hot spots. Five lowland rice varieties with known reaction to Fe toxicity were grown in pots in a screen house for three seasons. Fe-toxic soils from two hot spot fields – Edozighi, Nigeria and Niaouli, Benin were used and soil from Africa Rice Center (AfricaRice) experimental farm, Cotonou, Benin was included as control. Leaf bronzing score (LBS) was determined at different stages, and grain yield was determined at maturity. Heritability was estimated using data across the three seasons. High heritability was recorded for LBS and grain yield. Grain yield reduction in stress treatment relative to control varied from 15 to 56% depending on the variety and soil. Bao Thai, Suakoko 8, and WITA 4 had better performance under Fe toxicity in terms of LBS, yield and relative yield reduction, whereas Bouake 189 and IR64 had poorer performance. Grain yield and LBS were significantly correlated but negatively at 60 days after sowing (DAS). Overall, the results found in this experiment were consistent with previous field studies. Therefore, pot screening using soils from hot spots can be used by rice breeding programs to reliably assess Fe toxicity toleranceex situ. [ABSTRACT FROM AUTHOR]

We tested whether exposing rice plants to abiotic stress (salt or shade) during vegetative growth affects the chilling tolerance of reproductive organs, which is one of the most important traits for rice growing in a cool climate; we used two rice cultivars with different tolerance in two growing seasons. We divided the vegetative growth into three phases to clarify the most sensitive period: 7–22 days after transplanting (DAT), 23–38 DAT and 39–54 DAT. Chilling tolerance of the pre-stressed plants was based on the male sterility induced by low temperatures. Shade and salt stress during all three vegetative growth phases significantly reduced stomatal conductance. Shade decreased the specific leaf weight and the leaf sugar and starch contents, but salt had no significant effect, despite causing leaf damage. Low temperatures during the reproductive stage induced spikelet sterility in all plants, but the magnitude was greater in the salt- and shade-stressed plants of both cultivars, especially those stressed late during vegetative growth. The increased spikelet sterility caused by chilling was closely related to the reduction of the total spikelet number per panicle. This is the first study to show that salt and low light stress during vegetative growth increased the susceptibility of rice plants to chilling damage during panicle development. [ABSTRACT FROM AUTHOR]

Research was performed during the 2010 and 2011 growing seasons to investigate the effect of zeolites and zinc foliar application on the physiological characteristics of canola cultivars at different moisture regimes. A factorial split-plot experiment was performed on the basis of the randomized complete block design with three replications in the Seed and Plant Improvement Institute, Karaj, Iran. The treatments were as follows: (1) irrigation (I), complete (I1), and restricted (I2) at the pod formation stage, (2) zeolite (Z), 0 (Z1), and 15 t ha−1 (Z2), and (3) (Zn), zinc sulfate concentrations of 0%, 0.1%, and 0.2% (Zn1, Zn2, and Zn3) at the pod formation stage. These treatments were applied on Licord, RGS003, and Opera cultivars. Although applying Z and Zn had positive effects on the quality of canola, the highest performance and the best results were obtained using a combination of Z and Zn. The combined application of Z and Zn increased the relative water content, yield, and oil yield and decreased the stomatal resistance and canopy temperature. Therefore, with the low cost of natural Z and moderate Zn intake, these treatments can be used to enhance the performance of canola, especially in regions frequently subjected to water stress. [ABSTRACT FROM AUTHOR]

Waterlogging is the constraint for soybean growth and yield, because soybean is often cultivated in upland fields converted from paddy in Japan. However, efficient cultivation techniques for alleviating the adverse effects have not been developed. We have proposed the new soybean cultivation technique named crack fertilization which enables yield increase due to enhancing new root growth and N acquisition by increasing nodulation. Waterlogging induces N deficiency due to the suppression of nutrient uptake by the inhibition of root growth and nodule activity. Thus, it is hypothesized that crack fertilization would be effective to alleviate the inhibition of soybean growth and yield. The soybean cultivar of Sachiyutaka was planted in 1/5000 a Wagner pots and root boxes. Two separate waterlogging treatments were imposed to soybean plants at different growth stages, V1 and R4, and crack fertilization was done at V3. After these treatments, soybean plants were sampled at R5 in 2012 and 2013 experiments, respectively. Waterlogging at V1 and R4 inhibited the growth and yield of soybean and nodule growth, and the decreases in physiological parameters of soybean such as photosynthesis, chlorophyll content, and xylem sap exudation rate were observed. The adverse effects of waterlogging at V1 were alleviated by crack fertilization at V3, whereas crack fertilization could not alleviate the adverse effects of waterlogging at R4. Thus, crack fertilization after waterlogging at early vegetative stage would be the cultivation technique that enables to alleviate the adverse effects. [ABSTRACT FROM AUTHOR]

The plasticity in root system development (RSD) is a key trait for the adaptation of rice to mild drought. However, the enhanced RSD due to the plasticity may not be always a sole function of promoted lateral root (LR) production, but also of the integrated responses of nodal root (NR) development. In this study, we aimed to evaluate the effects of mild drought intensities on the development of the NR and LR, and their contribution to the entire RSD. We used six genotypes including KDML105 (indica, lowland adapted), a high lateral rooting ability genotype. The plants were grown up to heading or maturity stage for two years under soil with limited soil depth (20 cm) assuming the presence of the hardpan and at different moisture gradients generated by the line source sprinkler system. The effects of drought intensities generally differed between the development of NR and LR. In both years, all genotypes showed highest LR development under mild drought stress intensities. However, in some genotypes including KDML105, NR development was maintained in a limited soil moisture range only, which was narrower and wetter than that in which LR plasticity was expressed. Furthermore, the entire RSD was maintained only when both the NR and LR were simultaneously promoted or maintained. These results suggest that the NR have less plasticity than the LR in response to drought and the contribution of the plasticity in LR development to the entire RSD is dependent on both the soil moisture and nodal rooting ability. [ABSTRACT FROM AUTHOR]

The effects of putrescine was studied on the growth, physiology, and yield of wheat (Triticum aestivumL.) exposed to salinity stress. Foliar spray of putrescine at the rate of 0.24 g/l was made to plants grown in saline-sodic soil of the field and also to plants grown under axenic condition in pots. The foliar spray was made twice at 14 and 30 d after seed germination. Under salt stress, putrescine application decreased the Na accumulation concomitant with the increase in the accumulation of potassium (K), calcium (Ca), and magnesium (Mg). The putrescine-induced salt tolerance was mediated by the enhanced production of proline, stimulation in the activities of antioxidant enzymes, superoxide dismutase and peroxidase, and modulating the endogenous level of phytohormones such that increased abscisic acid (ABA) (70%), indole acetic acid (IAA), and gibberellic acid (GA) (40–50%) were produced. It is inferred that putrescine application can be a strategy to mitigate salinity stress in plants. [ABSTRACT FROM AUTHOR]

In the present study, the effectiveness of biofertilizer containing plant growth promoting rhizobacteria was evaluated on growth and physiology of cotton under saline conditions. Cotton plants were exposed to different levels of NPK (50%, 75%, and 100% of recommended levels) along with coating with biofertilizer under saline (15 dS m−1) and non-saline conditions. It was observed that the biofertilizer seed coating improved growth, physiological (relative water content and chlorophyll content index), and ionic (K+/Na+) characteristics under saline and non-saline conditions. However, shoot growth (shoot fresh and dry weight) and leaf gas exchange characteristics (CO2assimilation rate,A; intercellular CO2concentration,Ci; transpiration rate,E; stomatal conductance,gs) were decreased by biofertilizer coating under saline condition. Increasing levels of NPK fertilizer increased shoot growth, whereas root growth was maximum at 75% NPK level under saline conditions. The results of the study indicate that the biofertilizer application was very effective for cotton plant in non-saline conditions but not very effective in saline conditions. [ABSTRACT FROM PUBLISHER]

This study aims to assess radiation-based models versus the FAO Penman–Monteith (FPM) model to determine the best model using linear regression under different weather conditions. The reference evapotranspiration was estimated using 22 radiation-based methods and was compared with the FPM. The results showed that the Stephens method estimates the reference evapotranspiration better than other methods in the most provinces of Iran (nine provinces). However, the values ofR2were more than 0.9930 for 24 provinces of Iran. The radiation-based methods estimated the reference evapotranspiration near the Caspian Sea better than other regions. The most precise methods were the Berengena–Gavilan, Modified Priestley–Taylor, and Priestley–Taylor methods for the provinces ES (center of Iran), GI and GO (north of Iran) and the Stephens–Stewart method for IL (west of Iran). Finally, a list of the best performance of each method has been presented to use other regions and next research steps according to the values of mean, maximum, and minimum temperature, relative humidity, solar radiation, elevation, sunshine, and wind speed. The best weather conditions to use radiation-based equations are 23.6–24.6 MJ m−2day−1, 12–20°C, 18–24°C, 5–13°C, and <180 hour month−1for solar radiation, mean, maximum, and minimum temperature, and sunshine, respectively. [ABSTRACT FROM PUBLISHER]

The improvement of plant growth and productivity under biotic and abiotic stress conditions, as well as the reduction of post-harvest losses, are of paramount significance to meet the increasing demand for food by a growing World population. Hydrogen sulphide (H2S) has recently appeared as a key contributor towards this goal through its bioactive role in the regulation of plant defence responses. In this review, we provide an up-to-date overview of recent literature concerning the biosynthesis and regulation of H2S within plant cells, as well as its involvement in a series of plant physiological processes. More specifically, H2S is actively associated with several horticultural plant growth and developmental processes, tolerance responses following exposure to stress factors, as well as in post-harvest fruit physiology. The H2S-mediated enhancement of tolerance to several abiotic stress factors is highlighted, with particular emphasis on the priming effects of H2S on the anti-oxidant capacity, redox regulation and signalling and transcriptional regulation of cellular defence components in plants. Moreover, H2S has been reported to be associated with seed germination, increased growth, and root organogenesis, while also enhancing the post-harvest performance and anti-oxidant capacity of fruit. The present review proposes a practical role for H2S in horticultural crop physiology, further supporting the notion that H2S acts as a key signalling molecule in plants, possibly acting by "cross-talk" with other secondary plant cell messengers. [ABSTRACT FROM AUTHOR]