RESPONSE OF TILLAGE, RESIDUE MANAGEMENT, AND SEED RATES ON PRODUCTIVITY OF WHEAT

Abstract In Nepal, the lack of appropriate agronomic practices and soil health maintenance are major factors contributing to low wheat yield. Utilizing suitable agronomic practices not only enhances wheat productivity but also helps sustain soil health. A field experiment was conducted during the winter season of 2019 and 2020 at the National Wheat Research Program (NWRP), Bhairahawa, Rupandehi, Nepal, to assess the effect of tillage practices, residue management, and seed rates on wheat growth, yield attributes, yield, and soil health. The experiment was conducted in a strip-split plot design with three replications. Three tillage practices (conventional tillage, reduced tillage, and zero tillage) were assigned to the vertical factor, two residue levels (residue removal, and residue retention at 30 cm) were assigned to the horizontal factor, and seed rates of 80, 120, and 160 kg ha-1 were used as subplots. The recommended dose of fertilizers at the rate of 100: 50: 50 N: P2O5:K2O kg ha-1 was applied. The experimental plot was 12 m2 with a 25 cm row spacing. The released variety Vijay was planted, and data on growth, yield attributes, and yield were collected and analyzed using the Genstat 15th Edition. Results showed a significant difference in plant height and number of tillers per square meter between tillage practices in 2019 but were significantly higher for zero tillage in 2020. Residue management treatments showed similar effects on plant height, number of tillers per square meter, dry matter production, and leaf area index in both years. Seed rates were not significant for plant height but significantly increased the number of tillers per square meter, dry matter production, and leaf area index due to the increase of seed rate up to 160 kg ha-1 during both years of experimentation. Days to flowering and maturity days were not influenced by tillage and residue management treatments in both years. In 2020, zero tillage resulted in longer spikes and more grains per spike than conventional and reduced tillage, though tillage had no effect in 2019. Residue management had no significant impact on spike length, grains per spike, and 1000-grain weight. The lower seed rate (80 kg ha-1) produced significantly longer spikes only in 2020, and more grains per spike only in 2019, compared to higher rates (120 and 160 kg ha-1). Zero tillage also showed lower sterility percentages than other tillage methods, while residue levels and seed rates did not affect sterility. Grain yield was significantly affected by tillage practices and seed rates but not by residue management. Zero tillage produced a higher grain yield than conventional tillage and reduced tillage. The higher levels of seed rate 160 kg ha-1 registered more grain yield than its lower levels of 80 and 120 kg ha-1. The harvest index was not influenced by different tillage and residue levels but seed rates affected the harvest index during 2019. The lower levels of seed rate 80 kg ha-1 produced more harvest index. Zero tillage resulted in higher organic matter compared to conventional and reduced tillage. Residue retention increased organic matter and reduced bulk density compared to residue removal. Based on two years' results, it can be concluded that adopting zero tillage, retaining residue, and using a recommended rate of seed rate of 120 kg ha-1 can enhance wheat yield and sustain soil fertility.