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1651985 2015 Research ReportsThe publications in this series cover a wide range of subjects-from computer modeling to experience with water user associations-and vary in content from directly applicable research to more basic studies, on which applied work ultimately depends. Some research reports are narrowly focused, analytical and detailed empirical studies; others are wide-ranging and synthetic overviews of generic problems.Although most of the reports are published by IWMI staff and their collaborators, we welcome contributions from others. Each report is reviewed internally by IWMI staff, and by external reviewers. The reports are published and distributed both in hard copy and electronically (www.iwmi.org) and where possible all data and analyses will be available as separate downloadable files. Reports may be copied freely and cited with due acknowledgment. About IWMIIWMI's mission is to provide evidence-based solutions to sustainably manage water and land resources for food security, people's livelihoods and the environment. IWMI works in partnership with governments, civil society and the private sector to develop scalable agricultural water management solutions that have a tangible impact on poverty reduction, food security and ecosystem health.

The response of chlorophyll fluorescence, photosynthetic CO 2 assimilation (PN), stomatal conductance (gs), electrolyte leakage, and transpiration (E) was observed in Jatropha curcas seedlings subjected to soil flooding. A strong reduction in growth, leafarea expansion (64%), and stomatal conductance (45%) impaired photosynthetic CO 2 assimilation (66%), which eventually reduced biomass yield. The ratio between variable-to-initial chlorophyll fluorescence (Fv/Fo) and the maximum quantum yield efficiency of the photosystem II (Fv/Fm) was used to explore damage associated with the functioning of the photosynthetic apparatus. A strong, nonlinear correlation between physiological parameters and soil flooding duration was found. Our study primarily revealed consequences of epigenetics, i.e. stagnant soil flooding, which affected growth, development, and performance of Jatropha curcas significantly. The activities of catalase (CAT), ascorbate peroxidase (APx), glutathione reductase (GR), and glutathione peroxidase (GPx) in leaves increased, implying an integrated pathway involving CAT, APx, GR, and GPx for protection against the detrimental effects of reactive oxygen species (ROS) during soil flooding.

Background Water stress is one of the serious abiotic stresses that negatively influences the growth, development and production of sugarcane in arid and semi-arid regions. However, silicon (Si) has been applied as an alleviation strategy subjected to environmental stresses. Methods In this experiment, Si was applied as soil irrigation in sugarcane plants to understand the mitigation effect of Si against harmful impact of water stress on photosynthetic leaf gas exchange. Results In the present study we primarily revealed the consequences of low soil moisture content, which affect overall plant performance of sugarcane significantly. Silicon application reduced the adverse effects of water stress by improving the net photosynthetic assimilation rate (Anet) 1.35–18.75%, stomatal conductance to water vapour (gs) 3.26–21.57% and rate of transpiration (E) 1.16–17.83%. The mathematical models developed from the proposed hypothesis explained the functional relationships between photosynthetic responses of Si application and water stress mitigation. Conclusions Silicon application showed high ameliorative effects on photosynthetic responses of sugarcane to water stress and could be used for mitigating environmental stresses in other crops, too, in future.

Sufficient water and fertilizer inputs in agriculture play a major role in crop growth, production, and quality. In this study, the response of sugarcane to limited water irrigation and foliar application of potassium salt of active phosphorus (PSAP) for photosynthetic responses were examined, and PSAP's role in limited water irrigation management was assessed. Sugarcane plants were subjected to limited irrigation (95−90 and 45−40% FC) after three months of germination, followed by a foliar spray (0, 2, 4, 6, and 10 M) of PSAP. The obtained results indicated that limited water irrigation negatively affected sugarcane growth and reduced leaf gas exchange activities. However, the application of PSAP increased the photosynthetic activities by protecting the photosynthetic machinery during unfavorable conditions. Mathematical modeling, a Skewed model, was developed and compared with the existing Gaussian model to describe the photosynthetic responses of sugarcane leaves under the limited irrigation with and without PSAP application. The models fitted well with the observed values, and the predicted photosynthetic parameters were in close relationship with the obtained results. The Skewed model was found to be better than the Gaussian model in describing the photosynthetic parameters of plant leaves positioned over a stem of limited water irrigation and applied PSAP application and is recommended for further application.

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