Interactive Effect of Conservation Tillage, Potassium and Magnesium Sulphate Fertilization on Dry Matter Production, Physiological and Yield Parameters, and Yield of Grain Cowpea

This study conducted in Kerala, evaluated the role of conservation tillage (zero tillage (ZT), minimum tillage (MT), and conventional tillage (CT)) with five treatment combination of potassium (12 kg/ha, 20 kg/ha, 40 kg/ha) and magnesium sulphate (60 kg/ha and 80 kg/ha) on total DMP, physiology and grain yield of the test variety Anaswara (cowpea). In pot culture study, application of K: MgSO4, 10:80 kg/ha resulted in highest total chlorophyll content. While higher chlorophyll a content was obtained with the levels 20:60 kg/ha, and highest total DMP was recorded with the application at 40:100 kg/ha. Different levels of K and MgSO4 nutrition positively influenced 100 seed weight and grain yield, while there found no significant difference on chlorophyll b content, days to flowering, and grains/pod with any of the treatments imposed. Higher values for test weight and grain yield were recorded with K: MgSO4 40:60 kg/ha. In field experiment, tillage practices failed to produce notable difference in chlorophyll a, chlorophyll b, total chlorophyll contents, chlorophyll a/b ratio, grains per pod and test weight. Early flowering (45 DAS) and highest total DMP up to 75 DAS were recorded under CT. ZT produced highest LAI, while highest grain yield was noted under MT practice (734.5 kg/ha). Nutrient treatments failed to produce significant differences in chlorophyll b and chlorophyll a/b ratio. However, application at 40:80 kg/ha produced highest LAI, and higher content of chlorophyll a and total chlorophyll content (1.34 mg/g). K:MgSO4 applied at 40:60 kg/ha recorded highest grain yield. LAI was recorded highest under ZT with K:MgSO4 at 40:80 kg/ha. MT + K:MgSO4 at 40:60 kg/ha reported highest chlorophyll a/b ratio (4.71). K: MgSO4 applied at 40:60 kg/ha produced highest grain yield (806 kg/ha). In interactions, MT + K: MgSO4 at 40:60 kg/ha registered highest grain yield (914.8 kg/ha). Overall, in terms of grain yield, the test crop responded well to MT with application of K: MgSO4 at 40:60 kg/ha.