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Adequate management of N supply, plant density, row spacing, and soil cover has proved useful for increasing grain yields and/or grain yield stability of rainfed crops over the years. We review the impact of these management practices on grain yield water-related determinants: seasonal crop evapotranspiration (ET) and water use efficiency for grain production per unit of evapotranspired water during the growing season (WUEG,ET,s). We highlight a large number of conflicting results for the impact of management on ET and expose the complexity of the ET response to environmental factors. We analyse the influence of management practices on WUEG,ET,s in terms of the three main processes controlling it: (i) the proportion of transpiration in ET (T/ET), (ii) transpiration efficiency for shoot biomass production (TEB), and (iii) the harvest index. We directly relate the impact of management practices on T/ET to their effect on crop light interception and provide evidence that management practices significantly influence TEB. To optimize WUEG,ET,s, management practices should favor soil water availability during critical periods for seed set, thereby improving the harvest index. The need to improve the performance of existing crop growth models for the prediction of water-related grain yield determinants under different management practices is also discussed.

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Inoculation with growth-promoting rhizobacteria inoculation and the addition of exogenous signaling molecules are two distinct strategies for improving heavy metal resistance and promoting growth in crops through several mechanisms. However, whether rhizobacteria and phyllosphere signaling molecules can act synergistically alleviate heavy metal stress and promote growth and the mechanisms underlying these effects remain unclear. Here, a novel strategy involving the co-application of growth-promoting rhizobacteria and an exogenous signaling molecule was developed to reduce cadmium (Cd) phytotoxicity and promote pak choi growth in Cd-contaminated soil. We found that the co-application of Azospirillum brasilense and hydrogen sulfide (H2S) resulted in significant improvements in shoot biomass and antioxidant enzyme content and a decline in the levels of Cd translocation factors. In addition, this co-application significantly improved pak choi Cd resistance. Furthermore, we observed a significant negative correlation between abscisic acid concentration and Cd content of pak choi and a positive correlation between H2S concentration and biomass. These findings revealed that the co-application of rhizobacteria and exogenous signaling molecules synergistically promoted the growth of vegetable crops subjected to heavy metal stress. Our results may serve as a guide for improving the food safety of crops grown in soil contaminated with heavy metals.

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Camelina sativa (L.) Crantz is an emerging oil seed crop and research information on its response to different levels of phosphorous (P) fertilizer is lacking. The two years study was performed to investigate the response of C. sativa to various rates of P fertilizer. The experiments were laid out in Randomized Complete Block Design (RCBD) with factorial arrangement having four replications. The P was applied in soil at the rate of 0, 30, 40 and 60 kg ha-¹ to two C. sativa accessions namely Canadian and Australian. Soil applied phosphorus rates had significant effects on the growth, yield and quality of C. sativa and two accessions were varied to each other. Australian accession performed better in terms of quality traits and Canadian was superior in terms of seed yield. An increase in P rate improved growth, yield and quality and 60 kg P ha-¹ resulted in maximal crop growth rate (6.79), seed yield (1239 kg ha-¹), total P uptake (0.67%) and oil contents (39.8%). The regression model estimated that each increment in P rate increased the seed yield by 11.5 and 11.2 kg ha-¹ in Canadian and Australian accessions, respectively. Conclusively, increases in P rates (0 to 60 kg ha-¹) impart a positive impact on C. sativa accessions and 60 kg P ha-¹ was most effective to achieve optimum yield and profitability.

Camelina sativa (L.) Crantz é uma cultura de sementes oleaginosas emergente e faltam informações de pesquisa sobre sua resposta a diferentes níveis de fertilizante de fósforo (P). O estudo de dois anos foi realizado para investigar a resposta de C. sativa a várias doses de fertilizante P. Os experimentos foram dispostos em blocos casualizados em arranjo fatorial com quatro repetições. O P foi aplicado em solo na proporção de 0, 30, 40 e 60 kg ha-¹ em dois acessos de C. sativa, canadenses e australianos. As doses de P aplicadas no solo tiveram efeitos significativos sobre o crescimento, rendimento e qualidade de C. sativa e dois acessos foram variados entre si. O acesso australiano teve melhor desempenho em termos de características de qualidade e o canadense foi superior em termos de rendimento de sementes. O aumento na taxa de P melhorou o crescimento, rendimento e qualidade e 60 kg P ha-¹ resultou em taxa máxima de crescimento da cultura (6,79), rendimento de sementes (1239 kg ha-¹), absorção total de P (0,67%) e teor de óleo (39,8 %). O modelo de regressão estimou que cada incremento na dose de P aumentou a produtividade de sementes em 11,5 e 11,2 kg ha-¹ nos acessos canadense e australiano, respectivamente. Conclusivamente, aumentos nas doses de P (0 a 60 kg ha-¹) conferem um impacto positivo sobre os acessos de C. sativa e 60 kg P ha-¹ foram mais eficazes para atingir rendimento e lucratividade ideais.

Assuntos

RESUMO

Camelina sativa (L.) Crantz is an emerging oil seed crop and research information on its response to different levels of phosphorous (P) fertilizer is lacking. The two years study was performed to investigate the response of C. sativa to various rates of P fertilizer. The experiments were laid out in Randomized Complete Block Design (RCBD) with factorial arrangement having four replications. The P was applied in soil at the rate of 0, 30, 40 and 60 kg ha-¹ to two C. sativa accessions namely Canadian and Australian. Soil applied phosphorus rates had significant effects on the growth, yield and quality of C. sativa and two accessions were varied to each other. Australian accession performed better in terms of quality traits and Canadian was superior in terms of seed yield. An increase in P rate improved growth, yield and quality and 60 kg P ha-¹ resulted in maximal crop growth rate (6.79), seed yield (1239 kg ha-¹), total P uptake (0.67%) and oil contents (39.8%). The regression model estimated that each increment in P rate increased the seed yield by 11.5 and 11.2 kg ha-¹ in Canadian and Australian accessions, respectively. Conclusively, increases in P rates (0 to 60 kg ha-¹) impart a positive impact on C. sativa accessions and 60 kg P ha-¹ was most effective to achieve optimum yield and profitability.(AU)

Camelina sativa (L.) Crantz é uma cultura de sementes oleaginosas emergente e faltam informações de pesquisa sobre sua resposta a diferentes níveis de fertilizante de fósforo (P). O estudo de dois anos foi realizado para investigar a resposta de C. sativa a várias doses de fertilizante P. Os experimentos foram dispostos em blocos casualizados em arranjo fatorial com quatro repetições. O P foi aplicado em solo na proporção de 0, 30, 40 e 60 kg ha-¹ em dois acessos de C. sativa, canadenses e australianos. As doses de P aplicadas no solo tiveram efeitos significativos sobre o crescimento, rendimento e qualidade de C. sativa e dois acessos foram variados entre si. O acesso australiano teve melhor desempenho em termos de características de qualidade e o canadense foi superior em termos de rendimento de sementes. O aumento na taxa de P melhorou o crescimento, rendimento e qualidade e 60 kg P ha-¹ resultou em taxa máxima de crescimento da cultura (6,79), rendimento de sementes (1239 kg ha-¹), absorção total de P (0,67%) e teor de óleo (39,8 %). O modelo de regressão estimou que cada incremento na dose de P aumentou a produtividade de sementes em 11,5 e 11,2 kg ha-¹ nos acessos canadense e australiano, respectivamente. Conclusivamente, aumentos nas doses de P (0 a 60 kg ha-¹) conferem um impacto positivo sobre os acessos de C. sativa e 60 kg P ha-¹ foram mais eficazes para atingir rendimento e lucratividade ideais.(AU)

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The data in this article includes 300 simulated two-way data tables with 200 genotypes in the rows and 12 environments in the columns each. The yield data was obtained from a genotype-to-phenotype crop growth model that was adapted for pepper. The genotypes were characterized by 237 markers covering all the 12 chromosomes, and the environments were obtained as a combination of: (i) two levels of radiation based on historical data; (ii) three levels of daily average temperatures, 15, 20 and 25 °C; and (iii) two countries, Spain and The Netherlands. 100 two-way data tables were obtained for each of the three levels of heritability in the environments, 0.3, 0.5 and 0.8. The data is available as supplementary material of this paper.

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The diseases that attack the tomato crop are a limiting factor for its production and are difficult to control or eradicate. Stem and fruit rot and leaf blight caused by Alternaria solani causes severe damage and substantial yield losses. Carbon nanotubes (CNTs) could be an alternative for the control of pathogens since they have strong antimicrobial activity, in addition to inducing the activation of the antioxidant defense system in plants. In the present study, multi-walled carbon nanotubes were evaluated on the incidence and severity of A. solani. Moreover, to the impact they have on the antioxidant defense system and the photosynthetic capacity of the tomato crop. The results show that the application of CNTs had multiple positive effects on tomato crop. CNTs decreased the incidence and severity of A. solani. Furthermore, CNTs increased the fruit yield of tomato crop and dry shoot biomass. The antioxidant system was improved, since the content of ascorbic acid, flavonoids, and the activity of the glutathione peroxidase enzyme were increased. The net photosynthesis and water use efficiency were also increased by the application of CNTs. CNTs can be an option to control A. solani in tomato crop, and diminish the negative impact of this pathogen.

RESUMO

Chitosan is a natural polymer, which has been used in agriculture to stimulate crop growth. Furthermore, it has been used for the encapsulation of nanoparticles in order to obtain controlled release. In this work, the effect of chitosan-PVA and Cu nanoparticles (Cu NPs) absorbed on chitosan-PVA on growth, antioxidant capacity, mineral content, and saline stress in tomato plants was evaluated. The results show that treatments with chitosan-PVA increased tomato growth. Furthermore, chitosan-PVA increased the content of chlorophylls a and b, total chlorophylls, carotenoids, and superoxide dismutase. When chitosan-PVA was mixed with Cu NPs, the mechanism of enzymatic defense of tomato plants was activated. The chitosan-PVA and chitosan-PVA + Cu NPs increased the content of vitamin C and lycopene, respectively. The application of chitosan-PVA and Cu NPs might induce mechanisms of tolerance to salinity.

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Warm nights are a widespread predicted feature of climate change. This study investigated the impact of high night temperatures during the critical period for grain yield determination in wheat and barley crops under field conditions, assessing the effects on development, growth and partitioning crop-level processes driving grain number per unit area (GN). Experiments combined: (i) two contrasting radiation and temperature environments: late sowing in 2011 and early sowing in 2013, (ii) two well-adapted crops with similar phenology: bread wheat and two-row malting barley and (iii) two temperature regimes: ambient and high night temperatures. The night temperature increase (ca. 3.9 °C in both crops and growing seasons) was achieved using purpose-built heating chambers placed on the crop at 19:000 hours and removed at 7:00 hours every day from the third detectable stem node to 10 days post-flowering. Across growing seasons and crops, the average minimum temperature during the critical period ranged from 11.2 to 17.2 °C. Wheat and barley grain yield were similarly reduced under warm nights (ca. 7% °C(-1) ), due to GN reductions (ca. 6% °C(-1) ) linked to a lower number of spikes per m(2) . An accelerated development under high night temperatures led to a shorter critical period duration, reducing solar radiation capture with negative consequences for biomass production, GN and therefore, grain yield. The information generated could be used as a starting point to design management and/or breeding strategies to improve crop adaptation facing climate change.

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With devastating increase in population there is a great necessity to increase crop productivity of staple crops but the productivity is greatly affected by various abiotic stress factors such as drought, salinity. An attempt has been made a brief account on abiotic stress resistance of major cereal crops viz. In spite of good successes obtained on physiological and use molecular biology, the benefits of this high cost technology are beyond the reach of developing countries. This review discusses several morphological, anatomical, physiological, biochemical and molecular mechanisms of major cereal crops related to the adaptation of these crop to abiotic stress factors. It discusses the effect of abiotic stresses on physiological processes such as flowering, grain filling and maturation and plant metabolisms viz. photosynthesis, enzyme activity, mineral nutrition, and respiration. Though significant progress has been attained on the physiological, biochemical basis of resistance to abiotic stress factors, very little progress has been achieved to increase productivity under sustainable agriculture. Therefore, there is a great necessity of inter-disciplinary research to address this issue and to evolve efficient technology and its transfer to the farmers' fields.

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El objetivo de este estudio fue caracterizar fisicoquímicamente la corriente Las Cintas, afluente al lago de Tota, ubicado en el departamento de Boyacá. Se determinaron los parámetros de temperatura, pH, conductividad, oxígeno disuelto, DQO, DBO5, concentración de especies de nitrógeno (nitratos y nitritos) y concentración de especies de fósforo (fósforo total, fósforo hidrolizable total, ortofosfato total y fósforo orgánico total), para lo cual se efectuaron seis muestreos entre septiembre y noviembre del 2009, en cinco puntos seleccionados sobre la corriente. Estos análisis se realizaron siguiendo metodologías normalizadas para el análisis de aguas. En los resultados se observan comportamientos de poca variabilidad en los parámetros de temperatura, pH, conductividad y oxígeno disuelto; en cuanto al aporte de nitratos, se determinó que el desarrollo de cultivos en las proximidades de la corriente aumenta la concentración de estos iones, que pueden ser arrastrados al lago. Respecto a las diferentes especies de fósforo evaluadas permiten establecer la escasa contribución de fósforo orgánico hacia el cuerpo de agua, además del aporte significativo de fósforo por detergentes vertidos en la corriente. Basándose en la caracterización efectuada, se puede establecer que la actividad agrícola aporta nutrientes que probablemente favorecen el desarrollo del proceso de eutrofización en el lago de Tota.

The aim of this study was to characterize physicochemically “Las Cintas” stream located at Tota Lake, Boyacá department. Temperature, pH, conductivity, dissolved oxygen, COD, BOD5, concentration of nitrogen (nitrates and nitrites) and phosphorus (total phosphorus, total hydrolysable phosphorous, total orthophosphate and total organic phosphorus) were measured. To perform the characterization, samples were collected in six sampling dates, between September and November of 2009, at five points selected along the stream. The analyses were carried out following normalized procedures for water analysis. The results obtained show little changes in temperature, pH, conductivity and dissolved oxygen behavior; Nitrate values indicating that the proximity of the crops to the stream, rises the concentration of these ions, which can be carried to the Lake by run off; The different phosphorous species evaluated allow to establish the highest contribution of organic phosphorus towards the water body, and the input of phosphorous by detergents spilled in the stream. With results it can be established that onions crops provides nutrients which probably support eutrophication processes at the Lake Tota.

O objetivo deste estudo foi caracterizar aphysicochemically afluente do Lago Tota localizada no departamento de Boyacá, e afluente do Lago Tota. Para determinar os parâmetros de temperatura, pH, condutividade elétrica, oxigênio dissolvido, DQO, DBO5 concentração de espécies de nitrogênio (nitrato e nitrito) e da concentração de fósforo de espécies (fósforo total, fósforo hidrolisável total, fósforo total e ortofosfato orgânico total) para os quais seis amostras foram realizadas entre setembro e novembro de 2009 em cinco pontos selecionados no fluxo. Estes testes foram realizados de acordo com metodologias padronizadas para análise de água. Os resultados de comportamento, de pouca variabilidade nos parâmetros de temperatura, pH, condutividade e oxigênio dissolvido na ingestão de nitrato, foi determinado que o desenvolvimento das culturas nas proximidades do córrego aumenta a concentração destes íons pode sendo jogado no lago, enquanto que as diferentes espécies de fósforo possível estabelecer a baixa contribuição de fósforo orgânico o corpo de água, além de significativa contribuição das descargas de fósforo em detergente no córrego. Com base na caracterização realizada, você pode definir que a agricultura fornece nutrientes que estimulam o desenvolvimento da eutrofização no Lago Tota.