Effect of plant density on yield and seed yield components of forage vetch in rain-fed and supplemental irrigation conditions

In order to study effect of plant density on yield and seed yield components of forage vetch in rain-fed and supplemental irrigation conditions، two separate experiments were conducted at the research filed of faculty of agriculture، Lorestsn University، during 2008-2009. Three species of forage vetch (Vicia narbonensis، V. sativa and V. dasycarpa) and in three plant densities (100، 150 and 200 plant/m2) were combined factorially based on a randomized complete block design in each experiment. The highest dry forage yield (4912 kg/ha) was found in V. sativa under rain-fed condition and 150 plant/m2. Also the lowest dry forage yield (1750 kg/ha) was found in V. dasycarpa under supplemental irrigation condition and 100 plant/m2. The highest and the lowest pods yield (4282 and 1426 kg/ha) were recorded under supplemental irrigation condition and 100، 150 plant/m2 for V. narbonensis and V. dasycarpa، respectively. The highest and the lowest seed yield (3352 and 3/870 kg/ha) were recorded under supplemental irrigation condition for 200، 150 plant/m2 for V. narbonensis and V. dasycarpa، respectively. The highest and the lowest 1000 grain weight (133. 10 and 29. 73 gr) were recorded under supplemental irrigation condition for 100، 200 plant/m2 for V. narbonensis and V. dasycarpa، respectively. The highest biological yield (8243 kg/ha) was found in V. sativa under rain-fed condition and 150 plant/m2. Also the lowest biological yield (3268 kg/ha) was found in V. dasycarpa under supplemental irrigation condition and 150 plant/m2. The maximum and the minimum harvest index (52/82% and 21/10%) were recorded under rain-fed condition for 100، 150 plant/m2 for V. narbonensis and V. dasycarpa، respectively. The 1000 grain weight of the two experiments were significantly different using T- test (P 1%) and dry forage yield and harvest index of the two experiments showed significant difference using T-test (P= 5%).