PRODUCTION POTENTIAL OF CYCLIC IRRIGATION AND MIXING OF SALINE AND CANAL WATER IN INDIAN MUSTARD (BRASSICA-JUNCEA) AND PEARL-MILLET (PENNISETUM-TYPHOIDES) ROTATION

Field experiments were conducted for two years on a sandy loam soil to evaluate various cyclic and mixing modes of irrigation with canal (0. 6 dS m-1) and saline (12 dS m-1) waters on salinity buildup, water use , and yields of Indian mustard (Brassica juncea L.) and pearl millet ( Pennisetum typhoides L.). Normalized to the treatment receiving canal water (100%), relative yield (RY) obtained with only saline irrigation averaged 56% in mustard. Application of canal water for presowing/fir st post-sowing irrigation (rossette stage) improved yields by 35 and 2 5%, whereas its application at later stages (siliquae formation) resul ted in lesser compensation (13%). Alternating irrigations with canal a nd saline water were superior (95% relative yields) compared to mixing the two supplies in equal proportions and then irrigating (87%). Sali nity-induced reduction in growth led to decreased branching and bearin g capacity (siliquae per plant), whereas effects on seed test weight a nd seeds per siliqua remained statistically nonsignificant. Stepwise l inear response function with time-averaged salinity (EC(e), dS m-1, 0- 0.3 m soil depth) could be described as RY = 100 - 8.5 (EC(e) - 3.8). Results also suggest increased salinity tolerance of mustard with agin g. Salts accumulated during irrigations to Indian mustard did not affe ct the yields of the following pearl millet crop.