Effect of oleiferous brassicas, their staggered sowing and fertility levels on potato (Solatium tuberosum) performance in potato-based intercropping systems

A field experiment was conducted during the winter (rabi) seasons of 1995–97 to assess the performance of potato (Solarium tuberosum L.) in potato-based intercropping systems (sole potato and 6 intercropping systems created by intercropping 3 Brassica spp. at the time of potato planting and 20 days after potato planting in 3:1 replacement series) under 5 fertility levels (N₀, N₇₅, N₁₅₀, N₇₅ + S₃₀ and N₁₅₀ + S₃₀ kg/ha). Irrespective of staggered sowing, intercrop caused significant reduction in leaf-area index (LAI), tubers/hill, proportion of A-grade tubers, tuber yield and green tubers (%) when compared with sole crop of potato, whereas plant height and shoots/hill remained unaffected. Among the intercropping systems, potato+staggeredly sown Brassica carinata A. Braun showed its superiority by recording relatively higher values of growth and yield attributes, yield of A-grade tubers and tuber yield/ha and minimum value of green tubers(%). Irrespective of time of sowing, Brassica carinata and its system with potato recorded the highest seed yield and tuber equivalent respectively. Nitrogen application induced significant increase in number of shoots and tubers/hill only up to 75 kg N/ha, whereas plant height, LAI, yield of A- and B-grade tubers and tuber, seed and tuber-equivalent yields/ha recorded significant increase up to 150 kg N/ha. Application N+S caused perceptible increase in the seed yield, B-grade tubers and tuber-equivalent yield over N alone.