Investigation of Quantitative and Qualitative Traits of New Forage Sorghum Cultivars at Different Cuttings

In this study eight forage sorghum cultivars KFS1, KFS2, KFS3, Pacific BMR, Chopper, Nectar, Sweet Jumbo and Speed feed were evaluated on a randomized complete block design in four replications at Karaj during 2003-2004 growing season to determine the most suitable cultivar with the highest forage yield. Ammonium phosphate on the base of P2O5 was applied at 115 Kgha-1 and a total amount of nitrogen 183 Kgha-1 at four times, was used. Six traits including green fodder, dry matter, protein yield, plant height, stem diameter and tiller number were measured in each cutting. Harvesting was conducted from 7.8 m2 area. Two years data were analysed in simple and combined analysis, and the means were compared with Duncan's multipl range test (DMRT) method. Analysis of variance showed significant differences between cuttings for all traits (except for plant height) in each year. The green fodder, dry matter, protein yield and tiller number at second cut and stem diameter at first cut ranked first in each year. Combined analysis of variance showed significant differences between years (except for dry matter and tiller number), cultivars and year cultivar interaction (except for stem diameter). The means comparison with DMRT showed, green fodder with 150.5 tha-1, protein yield with 2.80 tha-1 in the first year, plant height with 196.9 cm and stem diameter 15.48 mm in the second year ranked in first group. Nectar and KFS2 produced the highest and lowest green fodder with 164.6 and 130.4 tha-1, respectively. Sweet jumbo produced the highest dry matter (36.38 tha-1), protein yield (2.88 tha-1) and tiller number (3.61 tillers). The highest plant hieght with 214.4 cm and stem diameter with 17.99 mm were produced by Speed feed and KFS2 respectively. The lowest dry matter (32.41 tha-1), protein yield (2.58 tha-1), plant height (172.2 cm) and tiller number (2.11 tillers) were produced by chopper and the lowest stem diameter (11.61 mm) by Speed feed. Nectar and Sweet Jumbo cultivars were determined as the most suitable cultivars for forage production in this study.