RAINFALL ANALYSIS FOR PLANNING UPLAND RICE (ORYZA-SATIVA) CROP IN BIHAR PLATEAU

Rainfall data were collected from different meteorological observatori es of Chotanagpur plateau. Range, mean, standard deviation, and coeffi cient of variation of weekly, monthly, seasonal and annual rainfalls w ere calculated as per standard statistical procedures. Probability of rainfall was calculated. June-September received 78.4-85.5% of the ann ual rain fall. Dry spells of 5-12, 0-10 and 5-23 days were recorded du ring 11 June-10 July, 11 July-14 August and 15 August-14 October respe ctively, coinciding with seeding or seedling, vegetative growth and re productive stages of upland rice. Prediction of rainfall for different periods at 75-80% level of probability appeared more dependable than information in the form of annual or seasonal rainfall for planning up land rice (Oryza sativa L.). Variation in monthly rainfall was observe d in order of October > June > September > August > July. During June- September at least 826 mm rainfall was expected at 80% level of probab ility, which assures the success of upland rice crop. Analysis of rain fall data indicate that seeding of varieties with maturity period of 8 0-95 days should be completed in June. A variety of still shorter dura tion (75-85 days) could be chosen for seeding in late-monsoon year. Dr ought tolerance or resistance, particularly at reproductive phase, sho uld be the objective of upland rice breeding programme to stabilize yi eld.