The effect of supplemental irrigation in five chickpea varieties under Mediterranean conditions. Field evaluation and modelling study.

Abstract

Chickpea (Cicer arietinum L.) is one of the most important pulse crops in the world, cultivated on a wide range of environments. In Mediterranean regions, it is traditionally grown as a spring sown rainfed crop, thus very dependent on rainfall. Supplemental irrigation can sometimes be a strategy to overcome the deficiency in rainfall, especially in very dry years. The objective of this study was to evaluate the effects on crop yield and water productivity (WP) with the use of supplemental irrigation in both dry and wet years. Field tests were carried out over two cropping seasons, in Southern Portugal, using three kabuli type and two desi type chickpea varieties, and four irrigation treatments, corresponding to full (100%) crop irrigation requirements (IR), 50 % of IR, 25 % of IR and rainfed. Crop physiological parameters were measured during the cropping season in order to evaluate crop development. Results showed that all chickpea varieties had a positive response to supplemental irrigation, with a significant increase in the number of pods, seeds and the weight of the seeds, leading to higher grain and above ground biomass yields. The Elixir variety showed the best results in grain and biomass yield as well as harvest index and water productivity. In 2009, a dry year, the highest WP values were achieved at the 50% IR treatment. In 2010, due to heavy rain, crop sowing had to be delayed. This shortened the crop growth cycle, affecting crop growth and yield, leading to lower yield values and higher WP values in the rainfed treatment. Field data was used in the SALTMED model to evaluate the capabilities of the model to simulate chickpea yield in these conditions. It was possible to verify that the calibration of the model using a single chickpea variety was enough to simulate the other varieties. The results of the calibration and validation of the model, recently published in Silva et al. (2012), showed that, providing enough and reliable data, the model can simulate very accurately grain yield and total dry mass of different chickpea varieties with supplemental irrigation, in both wet and dry year conditions.