Investigation of the effect of row spacing and seed rate on quantitative and qualitative yields of Crimson clover (Trifolium incarnatum L.) as second crop in paddy fields.

In order to evaluate the effect of row spacing and seed rate on yield of Crimson Clover (Trifolium incarnatum L.) as second crop after rice, a factorial experiment based on the complete randomized block design with three replications was conducted at Rice Research Institute of Iran (Rasht, Iran) during 2010-2012 for two years. Experimental factors were row spacing in three levels of 20, 30 and 40 cm and seed rate in three levels of 20, 30 and 40 kg.ha-1. In this experiment, some important agricultural plant charactristics such as seedling emergence, days to flowering, growth duration, plant height, number of axillary branches, plant density, leaf to stem ratio, yields of fresh and dry forages were studied. The results of analysis of variance showed significant differences between the years, row spacing and seed rate in most traits. The first year had more fresh and dry forages yields (35228 and 6268.8 kg.ha-1, respectively) than the second year (27122 and 5709.3 kg.ha-1, respectively) due to high plant height and density and higher number of axillary branches. Among row spacing, row spacing of 20 cm produced maximum yields of fresh and dry forages with averages of 34222 and 6425.7 kg.ha-1, respectively. Among seed rates, 40 kg.ha-1 had maximum yields of fresh and dry forages with averages of 34794 and 6732.6 kg.ha-1, respectively. The treatment of 40 kg.ha-1 with 20 cm row spacing produced maximum yields of wet and dry forages with averages of 38166.7 and 7358.7 kg.ha-1, respectively. Based on the results of the present experiment, planting Crimson Clover with row spacing of 20 cm and seed rate of 40 kg.ha-1 is recommended in paddy fields of Guilan area due to maximum yields of fresh and dry forages yield. Key words: Row spacing, Seed rate, Crimson clover, Forage yield, Second crop