اثر تنش خشكي، كود شيميايي نيتروژن و كود آلي بر قرائت كلروفيل متر، عملكرد دانه و اجزاي عملكرد ذرت دانه اي سينگل كراس 704

Effect of drought stress, nitrogen fertilizer and manure on chlorophyll meter reading, grain yield and yield components in grain maize cV. SC 704

In order to investigate effects of water stress, nitrogen fertilizer and manure and mixed nitrogen fertilizer and manure on chlorophyll meter reading, grain yield and yield components of grain maize cv. SC 704, a field study was conducted in 2005 and 2006 cropping seasons. A randomized complete block design with factorial arrangement with three replications was used. Treatment consisted of four levels of nitrogen fertilizer (0, 92, 184 and 276 kg N ha-l ) , mixed nitrogen fertilizer and manure (46 kg N ha· 1+ 2.5 tons !la· 1 farm yard manure (FYM), 92 kg N 11a· 1 + 5 tons haoJ FYM and 138 kg N ha·] +7.5 tons ha-] FYM) and Farm Yard Manure (5.10 and 15 tons ha· 1 FY~l ) three levels of irrigation (optimum irrigation (control), water stress 75% crop water requirement and water stress 50% crop water requirement). Results showed that decreasing in nitrogen with water stress reduced plant growth. Maximum growth was observed when nitrogen and adequate water for maize crop was applied. Chlorophyll meter readings were significantly higher when water stress and nitrogen increased. and had a linear relationship with kernel nitrogen percentage and was affected by water supply. The results also showed the maximum grain yield was obtained in 138 kg N ha-I + 7.5 tons ha-I FYM with an average of7555 and 7912 kg ha-1 in the first and second years. respectively. Maximum grain yield was observed when optimum irrigation was applied with an average grain yield of ~756 and 9462 kg ha- I in the first and second years. respectively. When water stress was applied at 50 and 75% of optimum irrigation, grain yield was decreased by 63 and 41% in first year and by 66 and 41% in second year. The maximum grain yield was obtained in 13S kg N ha-I + 7.5 tons ha- I FYM and optimum irrigation with an average grain yield of \ 1790 and [2360 kg ha- I in the first and second years, respectively. Results indicated that adequate nitrogen fertilizer slightly increased grain yield under water stress. Integrated nitrogen and FYM application increased gram yield under water stress but optimum irrigation increased grain yield. Under severe water stress condition nitrogen applied as integrated nitrogen fertilizer and manure increased grain yield. Integrated nitrogen fertilizers and manure, reduced the needs for chemical fertilizers and produced higher grain yield. It is concluded that application of 138 kg N ha-I + 7.5 tons FYM ha· 1 at optimum irrigation decreased the needs for chemical N fertilizer by 50%. It also increased the grain yield and water productivity by 6.2 and 6~..o, respectively in the first year and by 4.1 and 4.2% in the second years. as compared to the 276 kg N haʹ].