Effect of different irrigation regimes on yield, water use efficiency and quality of potato (Solanum tuberosum L.) in the lowlands of Tashkent, Uzbekistan: A field and modeling perspective

In the lowlands of Central Asia, summer grown potato is increasingly affected by soil moisture deficit due to inadequate irrigation and high evaporative demand. Many farmers cannot apply irrigation schedules that fully respond to the water demand because of reduced water availability throughout the Aral Sea basin, caused by global warming, and the competing use of irrigation by the cotton crop. The effects of different irrigation regimes were evaluated on ten potato clones in the lowlands of Tashkent, Uzbekistan, during the summer cropping season (July–October) of three consecutive years (2008, 2009 and 2010). The applicability of a growth model to predict yield under the different water regimes was tested. Significant treatment and genotype effects on yield and yield components were observed. The significant correlation for tuber yield among treatments suggested that yield under water limitation was driven more by potential yield than water restriction tolerance. Tuber yield was more associated to tuber weight than to tuber number, a component already largely determined when the different water treatments were initiated. The reduction of water supply after tuberization had a limited effect on yield and consequently drastically enhanced water use efficiency. It increased starch and dry matter content, but decreased vitamin C content. Some clones maintained high yield across years and treatments and appeared as good candidates for being recommended to farmers. Others showed interesting quality traits and are proposed for use as progenitors in breeding programs targeting at the improvement of the nutritional value of potato. A good prediction of yield was obtained using the growth model except for year 2009 when trials were heavily affected by weed infestation. The present study contributes to the improvement of water management and the identification of clones with high tuber yield and quality for the lowlands of Tashkent. Additional experiments are required to address the constraints to potato cultivation in other agro-climatic zones of Central Asia.