Exploitation of Hybrid Vigour in Rice Hybrid ( Oryza sativa L.) Through Green Manure and Leaf Colour Chart (LCC) Based N Application

摘要

Field experiments were conducted during Kharif 2000 and 2001 in the wetland research farm of Tamil Nadu Agricultural University, Coimbatore to study the effects of green manuring and fertilizer N application based on LCC grades on the yield enhancement, nutrient uptake and economics of hybrid rice. Treatments consisted of two hybrids in the main plot and seven levels of N management practices during Kharif 2000 and eight sub-plot treatments during Kharif 2001. Among the hybrids, PA6201 registered significantly higher grain yield of 7363 and 7555 kg ha^-1 during Kharif 2000 and 2001 respectively with a yield advantage of 9.5% over CoRH2 in both the seasons. The N, P and K uptake at different growth stages revealed that rice hybrid PA 6201 was superior than CoRH2 in both the seasons. Application of green manure @ 6.25 t ha^-1 in combination with N application based on LCC critical value 5 recorded significantly higher grain yield compared to other treatments in both the seasons. The N, P and K uptake in green manure @ 6.25 t ha^-1 combined with LCC critical value 5 based N application (N₄) was significant at all the stages, however it was comparable with 200 kg N ha^-1 alone (N₁) except at tillering stage. In both the years PA6201 hybrid recorded high net returns of 15.05 and 14.60% over CoRH2. Application of green manure @ 6.25 t ha^-1 combined with LCC critical value 5 based N application (N₄) recorded higher net returns and B:C ratio during both the years and it was followed by application of 200 kg N ha^-1 alone (N₁). Therefore, the rice hybrid PA6201 with application of green manure 6.25 t ha^-1 combined with LCC critical value 5 based N applications significantly increased grain yield , nutrient uptake and in turn resulted in higher net return and B:C ratio.