Effect of seed treatments and shade on seedling growth dynamics of pongamia pinnata (Linn.) Pierre in the nursery

Abstract

The present study entitled “Effect of seed treatments and shade on seedling growth dynamics of Pongamia pinnata (Linn.) Pierre in the nursery” was carried out in College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur during the period of 2007-2009.

In the first phase, seeds were subjected to six pre-sowing treatments. GA3 treated seeds recorded highest Germination percentage, Final Mean Daily Germination (FMDG), Germination Value (GV) and Peak Value (PV). The effect of seed treatments were observed on various biometric parameters like height, collar diameter, number of leaves and primary branch. GA3 treated seeds recorded better height and collar diameter during the initial stage of seedling growth. At the end of study cold water seed treatment was found to be effective in enhancing seedling growth. However, none of the pretreatments was observed to cast a significant effect on biomass production and root growth parameters in Pongamia pinnata seedlings.

In the second phase, to evaluate seedling growth under different shade conditions, seedlings were placed under 25 per cent shade, 50 per cent shade, 75 per cent shade and full sunlight situations. Shade treatments did not significantly influence height and collar diameter growth of Pongamia pinnata seedlings in the nursery. The maximum leaf production and primary branch production was observed in seedlings kept under full sunlight and 50 per cent shade respectively. Under seventy five per cent shade seedlings produce maximum shoot and root dry weight. The shoot: root ratio and total biomass was also maximum for seedlings kept under 75 per cent shade. Root length and spread were maximum under 50 per cent shade. However, shade did not significantly effect secondary root production. Shade levels also did not influence Pongamia pinnata seedlings with respect to relative growth rate and leaf area. However, Specific leaf area and Leaf area ratio was higher under 25 per cent shade. Highest Specific leaf weight was observed for seedlings under full sunlight. Shade had no significant effect on leaf weight ratio of seedlings. Maximum stomatal number was recorded under 25 per cent shade. In the nursery stage shade is casting an overriding influence with regards to various growth parameters of Pongamia pinnata.