اثر کاهش میزان سطح برگ گندم و مصرف نیتروژن بر خصوصیات روزنه‌ای برگ پرچم و عملکرد تحت شرایط کم آبیاری

To study the effects of below leaves excision and nitrogen application on stomatal characteristics of wheat flag leaf, grain protein, dry matter remobilization, grain yield and yield component, leaf area of winter wheat (T. aestivum cv. Ghods) was artificially reduced under filed condition. The experimental design was a factorial on a RCB with 3 replications, a combination of three levels of defoliation (D0= control or intact plants, D1= excision of all leaf blades except flag leaf at booting stage, D2= as D1 but at anthesis stage) and two levels of nitrogen treatment (none and 250 kg ha-1 urea fertilizer at jointing stage) were randomly assigned to plot units. Deficient irrigation was induced from late booting stage until plant maturity. Results showed that defoliation increased the photosynthesis rate (Pn), photosynthetic water use efficiency (WUEp) and dry matter remobilization from stem. The highest photosynthesis rate was observed in defoliated plants at anthesis stage with application of nitrogen. Defoliation significantly decreased the grain protein. Nitrogen application in all defoliation levels significantly could improve Pn, chlorophyll content, grain protein percentage and dry matter remobilization. Leaf area manipulation could not affect grain yield significantly. However nitrogen application could increase fertile spike number per square meter as a yield component.