A study on the characterization of monsoon rainfall for sorghum (Sorghum Vulgare Pers) and its response to typical rainfall patterns

Abstract

Twenty eight years (1962-89) rainfall of Nagpur was analysed and the rainfall suitability at various probability levels for sorghum crop was studied. The total rainfall during kharif season (25-39^th MW) was 861.50 mm. Normal rainfall/week exceeded 50 mm during 12 weeks (25-36^th MW) which declined successively for three week (37-39^th MW). The coefficient of variation (CY) ranged between 74.3% (25^th MW), to 144.7% (39^th MW). The rainfall at 50% probability level was well distrturbed during 12 week (25-36^th MW)-ranging between 44.5 to 36.3 mm being adequate and sufficient (>20 mm/week) for sorghum crop considering its weekly demand (21-35 mm/week).

Typical rainfall patterns representing the situation were defined on the basis of their repetitiveness. Out of four typical rainfall patterns studied the one with lowest rainfall (458.4 mm /season and 30.56 mm/week) fetched the highest yield (865.0 kg/ha) which ensured adequate rains during the various growth stages except maturity. Excessive rainfall (>l00 mm/week) and deficient rainfall <20 mm/week) during every stage were inadequate. Rainfall atleast 30.56 mm/week was most adequate.