ZEA MAYS L اثرا تنش خشكي ، مقادير فسفر و روي بر توزيع عمودي سطح برگ ، نفوذ نور در سايه انداز و رابطه آن ها با عملكرد دانه ذرت

Effects of drought stress, amounts of phosphorous and zinc contents on vertical distribution of leaf area, light interception in canopy and their relationships with maize (Zea mays L.) grain yield

Leaf area distribution which determines the interception of radiation for photosyntesis is affected by environmental conditions, specially drought stress and nutrients contents. The shape of the polynomial reflected the bell shape of individual leaf area versus leaf number curves, with the highest leaf area in the mid-portion of the canopy. A third-order polynomial accurately described the relationship between leaf area index (LAI) and plant height at tasseling stage. This study was conducted as a split-factorial in Randomaized Complete Block Design with four replications. Drought treatments were the plant irrigation after soil water reached 70% (without stress) , 60% (medium stress), and 50% (high stress) of field capacity (FC) as main plots. Zn (0, 10 and 20 kg/ha) and P (0 and 150 kg/ha P205) were randomely assigned to sub-plots. The results showed that all traits were affected by drought stress. By increasing in drought stress, PAR interception increased at the bottom of the canopy. Increasing had also similar effects on all characteristics but with lower seventy than drought stress. No significant effects of Zn were seen. Interactions between treatments were not significant. The results of this experiment showed that grain yield increased linearly with increase in total LAl, LAI above ear, and LAI below ear; but decreased linearly by increase in PAR interception at the bottom of the canopy