تأثیر زمان کاربرد پتاسیم بر عملکرد و محتوای پروتئین ‌دانه ارزن دم‌روباهی در ‌رژیم‌های متفاوت آبیاری

The research on reducing the water consumption in conventional cropping system is one of the important strategies to improve the water use efficiency in agriculture. In order to investigate the effect of time of potassium application under different irrigation regimes on millet grain yield and protein percent, a field experiment was carried out in Agricultural Research Center of Yasuj, Iran, in 2009. The experiment was conducted as split plot design in a randomized complete blocks design with 3 replications. Irrigation regime included 7, 14 and 21-day intervals as main factor and sub-plots included time of potassium fertilizer application in four stages: planting, tillering, stem development and flowering. The results showed that the effect of irrigation interval was significant on 1000-seed weight, grain and biological yield, number of grains per spike, harvest index, protein content, and chlorophyll a, b and total of leaves. By increasing the irrigation interval, all the above-mentioned traits decreased, except the protein percent that increased. The 1000-seed weight, grain and biological yield, harvest index and protein content were affected significantly by the time of potassium application. Maximum grain yield was obtained by interaction of 7- day irrigation interval and potassium application at the stem development stage. Maximum grain protein content was measured in potassium application at flowering stage. In general, increasing the irrigation interval, and subsequent water stress, reduced plant growth and yield components. Application of potassium fertilizer at early growth stages increased yield and yield components, while in reproductive stages increased seed quality.