Yield response of cotton, maize, soybean, sugarbeet, sunflower and wheat to deficit irrigation

Results of several field experiments on deficit irrigation programs in Turkey are discussed. Deficit irrigation of surgarbeet with water stress imposed (i.e. irrigation omitted) during ripening stage saved nearly 22% water, yet with not significant yield decrease. An experiment, conducted in Trakya Region the European part of Turkey, and aimed at studying water production functions of sunflower (i.e. yield versus water consumption) revealed that water stress imposed at either head forming or seed filling stages influences yield the least with 40% savings of irrigation water supply compared with traditional practices in the region. Water stress imposed at vegetative and flowering stages of maize hindered the yield most significantly. The results showed that deficit irrigation can be a feasible option under limited supply of irrigation if stress occurs during yield formation stage. A four year field experiment aiming at developing deficit irrigation strategies for soybean showed that soybean was most sensitive to water stress during flowering and pod filling stages, and irrigation during these stages would ensure high yields. Results of experiments on cotton showed that irrigations omitted during flowering and yield formation stage did not significantly hinder the yield. Similarly, wheat gives good yield response depending on weather conditions if irrigated at booting, heading and milking stages. In areas where rainfall at planting is limited, supplementary irrigation during this period can ensure good establishment of a wheat crop. (author). 58 refs, 9 figs, 1 tab