Effects Of Plant Density And Cultivar On Yield Of Forage Sorghum

To determine the effect of plant density on yield of a forage sorghum cultivar (Speedfeed) and two promising lines (MFS2 and KFSI), two separate experiments were conducted in 2001 and 2002 at Birjand Agricultural Research Station. A factorial experiment based on randomized completely block design with four replications was used. Different levels of plant density including (20,25,30,35 and 40 plants m-2)were used, and characteristics such as plant height, total leaf number, diameter of stem, stem percentage, number of tillers number of nodes, length of internode, dry forage yield in the first and second harvest and total dry forage yield were recorded. The results from combined analysis of data of two years showed that cultivars were significantly different in all traits except leaf number. The highest internode length and plant height were observed in Speedfeed, the highest nod number, stem percentage and stem diameter in KFS1, and the highest tiller number in MFS2. KFS1 line had the highest dry forage yield in the first and second harvests with yield of 14.7 ton ha-1 and 7.8 ton ha-1, respectively, and 22.52 ton ha-1 total dry forage yield. Different plant densities were significantly different at 1% probability level for stem percentage and stem diameter. Stem percentage and in some cases, stem diameter decreased with increase of density. Interaction between density and cultivar was significant for dry forage yield in the second harvest and total dry forage yield at %5 level. As Speedfeed had the highest wet forage yield in density of 40 plantsm-2 with yield of 8.5 ton ha-1, and KFSl had the highest dry forage yield in density of20 plants m-2with yield of 10.39 ton ha-1 in 2nd hervest. In density of20 plants m-2, SKFl, and in density of 40 plants m-2speedfeed had the highest total dry forage yield with means of 26.2 and 22.3 ton ha-1, respectively. According to the results, the density of 20 plants m-2is recommended for KFS1 and density of 40 plants m-2for Speedfeed.