Soilless closed cycle production of green bean (Phaseolus vulgaris L.) using subirrigation: effects on yield, fruit quality, substrate and nutrient solution parameters

A soilless closed system experiment was conducted at MAIB greenhouse during the 2008 spring using subirrigation (trough bench system) for growing green bean. The effects of two substrates (peat+perlite and peat+sand 1:3, v/v) and two nutrient solution (NS) concentrations (100% and 50% of the macro-elements concentration normally used for growing this crop in soilless conditions) on yield, pod quality (categories, mineral composition), water use efficiency, and nutrients concentration into substrate and NS of two cultivars (‘Saporro’ and ‘Venda’) were evaluated. Trough bench technique allowed the realization of a continuous closed system with a major stability of the chemical parameters of the NS. It proved to be more effective than open soilless system since it saved water and fertilizers, allowing to obtain yield comparable to that obtained with traditional techniques (22 t/ha, on average). The reduction of the NS concentration (50% of the fertilizer concentration) reduced plant growth and consequently the total production by 15%. The use of different substrates did not affect the cultivars productivity. Concerning quality, ‘Saporro’ plants produced a high percentage of pods in the category “Extra” than ‘Venda’ plants (92 % vs. 89%, respectively). Sand can be an alternative of perlite given that it costs 30 times less

The SALTMED model calibration and validation using field data from Morocco

The objective of this study was to calibrate and validate the SALTMED model using field data of three growing seasons of quinoa (Chenopodium quinoa Willd.), chickpeas (Cicer arietinum) and sweet corn (Zea mays Saccharata) which were grown in the south of Morocco and subjected to six treatments of deficit irrigation with treated wastewater. The calibration focussed primarily on soil moisture related to quinoa in the field, measured yield and dry matter. The validation process of biomass production was based on use of the calibrated photosynthesis efficiency value of the control treatment. Plant parameters such as plant height and rooting depth, duration of each growth stage, sowing date, harvesting date, harvest index and leaf area index were based on field measurements and records. Crop coefficients Kc, Kcb, Fc were based on FAO56 paper. Soil parameters such as water retention curves were based on laboratory measurements. Initial soil water content and salinity were based on measurements either in the laboratory or in the field. Fine tuning of some crop and soil parameters was carried out in order to obtain a good calibration. Following successful calibration and validation, the SALTMED model proved its ability to predict soil moisture, yield and total dry matter for three growing seasons under several deficit irrigation strategies using treated wastewater. The model showed a very good agreement between the observed and simulated data, as well as being able to reveal the same difference between deficit irrigation strategies in terms of measured yield and total dry matter