All India Co-ordinated Rice Improvement Project, Rajendranagar, Hyderabad-500030
Relationship of different aged seedlings (20 to 70 days) at planting with crop efficiency and productivity was assessed with varied combinations of density of population, growth duration of varieties, normal and late planting and seasons. The studies indicated that for the production of a single leaf during the nursery period, rabi grown seedlings have taken double the number of days (8 days) than kharif grown ones (4 days) under Rajendranagar conditions. Although the duration from planting to flowering decreased with increase in age of seedlings at planting, the period varied with varieties (30–80 days) which was adequate enough for manipulations to get desired tiller number.
More number of leaves, higher dry matter of seedlings and more tillers at planting upto a level were found to be associated for vigorous growth of tillers (with aged seedlings) which compensated for age and matched with panicle number produced by younger (A-l) seedlings. Even under normal and late planted conditions, the panicle number did not differ with age of seedlings at planting while the potential was expressed only under favourable climatic conditions. The increase in total duration of crop when planted with aged seedlings was found to be due to the extension of primordial initiation stage. The study indicated that age per se upto 40–50 days in kharif and 60–70 days in rabi did not corrode the production potential in the modern varieties with 120–150 days duration. The findings were discussed in the light of the current literature.
