Environment Conservation Journal (Jun 2016)
Effect of irrigation regimes and cultivars on crop biomass and root length density of direct dry- seeded rice (Oryza sativa L.)
Abstract
The direct seeded rice is considered as an alternative to control ground water depletion and reducing cost of labour. To test this hypothesis the field investigation was carried out at research farm of the Department of Soil Science, Punjab Agricultural University Ludhiana, Punjab, India. The experiment comprised of 12 treatments combination viz; three cultivars in main plot (PR 114, PR 115 and PR 120) and four irrigation regimes (10, 20, 30 kPa and fixed 6 days interval) in sub plots. I. At 60 days after sowing (DAS) the average biomass across irrigation treatments was significantly higher in PR 120 and PR 115 over the cultivar PR 114. The biomass recorded with PR 120 was about 2.5 times and PR 115 was about 1.6 times higher than the PR 114 which recorded 0.98 t ha-1. The average biomass decreased progressively with increasing soil matric suction and it was lowest in 6 DI plots (0.9 t ha-1) and highest in 10 kPa plots (2.5 t ha-1). The cultivar PR 120 registered significantly highest number of tillers m-2 (492 No’s) than the cultivar PR 114 (452 No’s) and PR 115 (432 No’s). The numbers of tillers m-2 in different irrigation treatments varied from 425 to 481. The grain weight was significantly highest (22.1 g) in PR 120 as compared to PR 115 and PR 114 which were at par. The straw yield of rice varied from 6.5 t ha-1 to 7.3 t ha-1 in various irrigation regimes. The cultivar PR120 recorded significantly highest straw yield. The root length density (RLD) was highest (28.8 cm x106 cm-3) in PR 120 followed by PR 115 (21.6 cm x106 cm-3) and PR 114(19.2 cm x106 cm-3). The RLD was highest in 6 DI plots followed by 10, 20 and 30 kPa plots in the surface layer. However, the trend reversed in 15-30 cm soil layer where it was highest in 10 kPa plots and lowest in 6 DI plots.
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