اثر تنش آبی بر ویژگی‌های مورفوفیزیولوژیک ارزن نوتریفید و سورگوم اسپیدفید در چین‌های مختلف

To study the effects of delayed irrigation on growth and ratoon of millet (Pennisetum americanum cv. Nutrifeed) in the first harvest  and sorghum (Sorghum bicolor cv. Speedfeed), a field experiment was conducted as split plot based on a randomized complete blocks design with three replications in Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Iran, at summer 2014. Factors consisted of irrigation regime at three levels, including irrigation after 80 (control), 120 and 160 mm evaporation from a Class A evaporation pan as main plots, crop species at two levels, including Nutrifeed (millet) and Speedfeed (sorghum) as subplots and  harvest number ( at two levels) as sub-sub plots. At regrowth, all treatments were irrigated as control regime (80 mm evaporation). At 1st harvest, delayed irrigation decreased leaf photosynthetic pigments contents, LAI, SLA, LWR, leaf and stem dry weight and forage yield and increased proline, sucrose and leaf soluble sugars contents at both species. Similar effects of delayed irrigation were observed at regrowth. The highest forage yield belonged to normal irrigation of Speedfeed (9376 kg/ha), however, Nutrifeed showed a better performance at regrowth (4250 and 3816 kg/ha of forage, respectively). Nutrifeed had a better forage quality, owing to a higher leafiness index at both harvests (46.7% and 45.0%, respectively).