Growth, yield, and water use of okra ( Abelmoschus esculentus

Many experiments are conducted in simulated confined spaces to provide controlled environments where plants are grown in pots with limited rooting volume to characterise fundamental physiological responses of plants to stress conditions such as soil water, soil salinity, irrigation water salinity, and plant nutrition. However, rooting volume in the pots can have a limiting effect on overall plant growth to varying degrees. This study was undertaken to quantify the effects of widely differing rooting volume on growth, yield, and water use of eggplant (Solanum melongena) and okra (Abelmoschus esculentuts). Eggplant and okra experiments were conducted similarly, but as separate experiments. Both plants were grown in 3.6-litre (P1), 16-litre (P2), 36-litre (P3), and 52-litre (P4) pots. For eggplant and okra, evapotranspiration (ET) and all of the growth parameters including plant height, stem diameter, root and vegetative dry weight, root length, number of branches and fruit, and fruit yield significantly increased with increasing rooting volume. Pot volume started to affect plant height and ET after 3 weeks from transplanting. For both experiments, the highest yield and the highest yield based water-use efficiency (WUE(yield)) were obtained from the P4 and P3 treatments, respectively. The highest WUE based on total biomass (WUE(biomass)) was obtained from the P4 and P3 treatment of eggplant and okra, respectively. Both experiments exhibited similar morphological changes such as decreases in plant height, stem diameter, branching, root and vegetative dry weight, and root length to root restriction. As a result of this study it can be concluded that a pot size of 36 litres (P3) may be enough for okra growth, but even a 52-litre (P4) pot size may not provide unrestricted rooting volume for eggplant growth

The effect of deficit irrigation with treated wastewater on sweet corn: experimental and modelling study using SALTMED model

This study investigated the impact of using treated wastewater and deficit irrigation on yield, water productivity, dry matter and soil moisture availability. The experiment included six treatments of deficit irrigation with treated wastewater during the 2010 and 2011 seasons and two deficit irrigation treatments combined with 3 organic amendment levels during the 2012 season. The experimental and SALTMED modelling results indicated that regulated deficit irrigation when applied during vegetative growth stage could stimulate root development, increase water and nutrient uptake and subsequently increase the yield. The organic amendment has slightly improved yield under full irrigation but had relatively small effect under stress conditions. The SALTMED model results supported and matched the experimental results and showed similar differences among the different treatments. The model proved its ability to predict soil moisture availability, yield, water productivity and total dry matter for three growing seasons under several deficit irrigation strategies using treated wastewater. The high values of the coefficient of determination R 2 reflected a very good agreement between the model and observed values. The SALTMED model results generally confirm the model’s ability to predict sweet corn growth and productivity under deficit irrigation strategies in the semi-arid region