Effect of seedling age on main stem leaf appearance rate and total leaf number in transplanted rice

Seedling age at transplanting time have a great impact on seedling establishment, plant growth and development. The correct age of seedlings used for transplanting is of primary importance for uniform stand. Number of leaf on main stem and Leaf appearance rate (LAR) is one of the most important indicators for determination of physiological development stage and development rate of rice plant. To examine the effect of seedling age on leaf appearance rate and total leaf number of rice, a two yearʹs experiment has conducted at Caspian Sea coastal area in Iran. The research has conducted as a split plot under randomized complete block design with three replications. Main plot include three rice cultivars and subplot consist of three different seedling ages consist of young seedling (3-3.5 leaf stage); middle seedling (4-4.5 leaf stage) and mature seedling (5.5-6.5 leaf stage). To raising seedling with different ages, cultivars were sown in 10 days interval starting 21st April 2008 at three seeding dates applied in box nursery and transplanted at the same time, 25th May. Seedling ages influenced leaf appearance rate (LAR) decreasing the total number of leaves on the main culm at mature seedling. LAR after transplanting was negatively linearly correlated with seedling age ranged from 0.0105 to 0.0136 leaves -1 GDD.