Performance of intercrops and weed suppression in paired row planted rice in low land summer fallows

Abstract

A field experiment entitled “Performance of intercrops and weed suppression in paired row planted rice in low land summer fallows” was conducted at Department of Agronomy, College of Agriculture, Vellayani and Integrated Farming System Research Station, Karamana, Thiruvananthapuram, Kerala, during 2022 to 2024. The main objective was evaluation of intercrops in paired row planted rice in summer fallows of double cropped lowland rice field, in terms of weed dynamics, biological efficiency and economics. The field experiment was conducted during summer season of 2023-24 at Integrated Farming System Research Station (IFSRS), Karamana, Thiruvananthapuram, Kerala, India. The field experiment was laid out in randomized complete block design with ten treatments and three replications. The treatments were T1: Paired row of rice + grain cowpea, T2: Paired row of rice + finger millet, T3: Paired row of rice + Foxtail millet, T4: Paired row of rice + proso millet, T5: Sole crop of paired row rice, T6: Sole crop of grain cowpea, T7: Sole crop of finger millet, T8: Sole crop of foxtail millet, T9: Sole crop of proso millet, T10: Fallow. The varieties used for the study for rice, grain cowpea, finger millet, foxtail millet and proso millet were Uma, Bhagyalekshmi, Co 15, Co (Te)7 and TNAU 202, respectively. FYM and fertilizers were applied as per the recommendations (KAU, 2024 and TNAU, 2024) to rice, grain cowpea and millets, respectively. The growth attributes of rice and intercrops were recorded at monthly intervals. The analyzed data revealed that growth attributes of rice were significantly influenced by treatments. Among the treatments, the higher number of tillers m-2, and leaf area index were in sole crop of paired row rice (T5). Among the yield attributes, rice recorded the highest number of productive tillers m-2, grain yield and straw yield in the sole crop treatment(T5). The analyzed data showed that T5 recorded 8 to 15 per cent yield increase over intercropping treatments. The highest harvest index (0.48) of rice was obtained when intercropped with finger millet (T2). Sole crop of grain cowpea (T6) recorded the highest growth attributes when compared to intercropped treatments. Among the yield and yield attributes, number of pods per plant (15.87), grain yield (4526 kg ha-1), haulm yield (4526 kg ha-1) and harvest index (0.43) were the highest in sole crop of grain cowpea (T6). Analyzed data revealed that the plant height and number of tillers of finger millet, foxtail millet and proso millet were significantly influenced by intercropping treatments. The highest mean plant height and number of tillers m-2 were recorded in their sole crops. The sole crop yield of finger millet, foxtail millet and proso millet were higher than their intercropping treatments. Grasses were the predominant weed flora in the field. Total weed count and weed dry weight were significantly influenced by treatments. At 15 DAS, weed smothering efficiency (WSE) was highest in T4 (44.94%), while at 30 DAS and at 45 DAS, the highest efficiency of 43.79 and 40.57 per cent, were recorded in T1. The results on nutrient removal by weeds showed that significantly lower N, P and K were removed by weeds in T1 (Paired row of rice + grain cowpea). Total NPK uptake of crops were also influenced by the treatments. Higher nutrient uptake of all crops was seen in their sole cropping treatments. In rice, P uptake was significantly influenced by the treatments. The results on soil data revealed that the dehydrogenase activity (150.89 μg TPF g-1 soil d-1) was the highest in T1.The available N and P was higher in T6 and available K was higher in T9. The LER value was greater than unity in all intercropping treatments. Among the intercropping treatments, the highest RCC was observed in T1. Product of RCC was greater than one in all treatments. Aggressivity values were found positive in rice and negative in intercrops. Results indicated that rice equivalent yield from all intercropping system was significantly higher than sole crop of rice except in intercropping with proso millet. Highest monetary advantage was obtained from T1. Higher BCR and net income was observed in T1 (Rice + grain cowpea). Results revealed that net income of T1 was 39.27% higher than T5. The study on the performance of various intercrops in paired row planted rice in lowland summer fallows revealed that paired row planted rice intercropped with grain cowpea can be adjudged as the best treatment in case of weed control, biological efficiency and had higher net income and BCR.