Effects of Planting Density and Harvesting Date on Total Yield and Yield Components of some Potato Cultivars in Behbahan

For determination of optimum planting density and harvesting date for potato cultivars, a split split plot experiment in basis of RCBD design with four replications was conducted for two years (2001-03) at Behbahan Agricultural Research Station. Main plot consisted of three cultivars Arinda. Piccaso and Sante. Sub plot were three planting densities 5.3, 7.6 and 8.9 plants per square meter (15 75, 20 75 and 25 75 cm) and sub sub plot were three harvesting dates of 30 April, 15 May and 30 May. Combined analysis of variance showed significant effects of cultivar, planting density and harvesting date on total yield, marketable yield and yield components. Effects of cultivar and harvesting date on unmarketable yield and its components (small tubers, rotted tubers and secondary growth) were also significant. Effect of planting density on small and rotted tubers were not significant. Cultivar Sante produced the heighest total and marketable yield. Increase in planting density decreased mean of tuber weight and tuber number per plant. Planting density of 8.9 plants per square meter produced the highest total and marketable yield. The highest total yield was produced in the latest harvesting date, but unmarketable yield was high in this harvesting date. Based on the results, cultivar Sante, density of 8.9 palnts per square meter and harvesting date of 15 May can be recommend for Behbahan region.