Crop lodging management in rice (Oryza sativa L.)

Abstract

The research programme entitled “Crop lodging management in rice (Oryza sativa L.)” was conducted with the objective of standardizing the agronomic practices for crop lodging management in upland rice. The experiment was carried out in the Agronomy farm of the College of Agriculture, Vellanikkara during the period from June 2020 to September 2020. The upland variety used was Vaishak. The experiment was laid out in Randomized Block Design (factorial) and replicated thrice. The treatment consisted of two levels of growth regulator application viz., 50 ppm paclobutrazol and control, three levels of planting method viz., dibbling at 15 × 10 cm, dibbling at 20 × 15 cm and broadcasting and three levels of nutrient application viz., soil-test based N: P2O5: K2O, 75% N, 100% P2O5, 125% K2O, 20 kg/ha Si and 50% N, 100% P2O5, 150% K2O, 20 kg/ha Si. Biometric parameters like plant height, culm length and leaf area of rice were significantly reduced by the foliar spray of 50 ppm paclobutrazol. But the effect was significant only up to 60 DAS indicating the low persistence of the chemical in the plant. Dibbling resulted in the overall improvement of biometric parameters compared to broadcasting. The plant height and number of tillers per hill were high from dibbling at 20×15 cm spacing at 30 and 90 DAS. The number of tillers per hill was on par with dibbling at 15 × 10 cm spacing. Even with a lower plant population than broadcasting, the dry matter production from dibbling at 20×15 cm spacing was on par with broadcasting. The plants which got soil-test-based N: P2O5: K2O had taller plants at 60 and 90 DAS as well as high dry matter production at harvest due to the effect of high N. The number of tillers per hill was also higher from this treatment and on par with 75% N, 100% P2O5 125% K2O, 20 kg/ha Si level. The plants which received 75% N, 100% P2O5 125% K2O, and 20 kg/ha Si recorded the thickest culms at 60 DAS and the plants which received 50% N, 100% P2O5, 150% K2O and 20 kg/ha Si application recorded the thickest culms at 60 and 90 DAS. The Si control had lower culm thickness at all the stages. Application of soil-test-based N: P2O5: K2O resulted in the highest culm length at 90 DAS. At 60 DAS, the lodging index was significantly influenced by the planting method and at 90 DAS by nutrient management. The lodging index from dibbling at 15 × 10 cm was high and on par with broadcasting at 60 DAS. The lodging index was low from dibbling at 20×15 cm spacing at all the stages. The application of soil-test-based N: P2O5: K2O resulted in the highest lodging index. The highest number of panicles per square meter was obtained from 50 ppm paclobutrazol foliar spray, dibbling at 15 × 10 cm spacing and the application of 75% N, 100% P2O5, 125% K2O and 20 kg/ha Si. The number of grains per panicle was high from dibbling at 20×15 cm spacing. The other yield attributing parameters did not register any significant variation among treatments. The grain yield was not influenced by paclobutrazol application. However, the straw yield was significantly reduced and hence harvest index was increased from the treatment. Dibbling at 20×15 cm spacing resulted in the highest grain yield and the highest harvest index due to reduced lodging. Straw yield was highest from dibbling at 15 × 10 cm due to the high plant population compared to dibbling at 20×15 cm spacing. Application of 75% N, 100% P2O5 125% K2O and 20 kg/ha Si recorded the highest grain yield and harvest index. The straw yield was highest from soil-test based recommendation N: P2O5: K2O. When N dose was reduced to half, even though lodging was less, grain yield was significantly affected. Hence a nutrient level of 75% N, 100% P2O5 125% K2O of soil-test-based recommendation and 20 kg/ha Si can be considered optimum both in terms of lodging and grain yield. The application of different N: P2O5: K2O: Si levels had a significant influence on the uptake of N and Si at harvest. The highest and superior nitrogen uptake was recorded in the plants that got 100 % N: P2O5: K2O of soil-test based recommendation. The Si uptake from the nutrient level 75% N, 100% P2O5, 125% K2O, 20 kg/ha Si was higher and on par with that from 50% N, 100% P2O5, 150% K2O and 20 kg/ha Si level and was 56 % higher compared to Si control. The gross return from rice cultivation recorded no significant variation among paclobutrazol treated and control plants because the treatment had no significant impact on grain yield. Hence, the net return and B:C ratio were significantly higher in the control. Dibbling at 20cm × 15cm spacing and application of 75% N, 100% P2O5, 125% K2O and 20 kg/ha Si resulted in the highest gross return, net return and B:C ratio. Planting of rice at 20cm × 15cm spacing and application of 75% N, 100% P2O5, 125% K2O of soil test-based recommendation and 20 kg/ha Si resulted in reduced lodging, increased yield and net return of upland rice variety Vaishak