Evaluation of transplanted and ratoon crop for double cropping of rice (Oryza sativa L.) under organic input management in mid altitude sub-tropical Meghalaya.

摘要

In mid-altitude of the North Eastern Hill (NEH) region of India, a second crop of rice following the harvest of main kharif (July to mid-November) rice is not possible due to early onset of low temperature (<15 degrees C) from November onwards, which causes spikelet sterility in rice. A field experiment on double cropping of rice was conducted under mid-altitude subtropical wetland valley ecosystem of Meghalaya from 2004-05 to 2005-06 at Umiam (950 m amsl), Meghalaya. Out of the six varieties tested, IR-64 (43.2 q/ha), Aerobic rice IR 72176 (42.1 q/ha) and Krishna Hamsha (40.5 q/ha) performed well during pre-kharif season. Double cropping (main+ratoon) of IR-64 produced 75.4 q/ha of grain yield compared to 40.5 q/ha under improved monocropping of rice variety Sahsarang-1. Ratooning could save time (nursery and field preparation, transplanting, etc.), resources (labour, seeds, etc.) and gave higher productivity. The ratooning ability of Sahsarang-1 (33.0 q/ha) and IR-64 (32.2 q/ha) was found to be highly promising. The sequence IR-64 in pre-kharif followed by its ratoon also gave 86 and 202% higher productivity over improved (40.5 q/ha) and local practice (25.0 q/ha) of monocropping respectively. It was found equally good with the best combination of IR-64 in pre-kharif followed by late kharif transplanted crop of Vivek Dhan-82 (system productivity of 80.4 q grain/ha). Duration of main crop varied from 135 to 158 days, whereas in case of ratoon it varied from 70 to 95 days. Therefore, it was concluded that ratooning has ample opportunity, especially in the NER region of India, where climatic conditions and non-availability of resources restrict the double cropping of rice by the farmers. The practice of double cropping would not only add to the national food basket, but would also increase the farmers' income and generate more employment in the region.