Rice breeding for multi-canopy system: Estimations of genetic parameters and response to selection

One strategy currently being developed to increase rice (Oryza sativa L.) productivity is using a multi-canopy cropping system in rice cultivation. This method involves planting tall and short rice genotypes in the same hill. The objective of this experiment was to estimate the genetic parameters and response to selection in multi-canopy rice. Each experiment was arranged in an augmented randomized complete block design with five replications for the checks. In the first planting season, 200 F₃ families from IPB196 and IPB197 populations were planted in monoculture and multi-canopy as the short genotypes. IPB187-F-40-1-1 was used in multi-canopy as the tall genotype. Selection of 25% based on grain weight per hill of short genotype in multi-canopy was performed, and 50 families were selected and their F₄ seeds were planted in the second season along with the same tall genotype. The results indicated the genotype × cropping system was significant for grain weight per hill in the F₃ and F₄ generations. Grain weight per hill has a similar realized h²_ns in the multi-canopy (0.58) with monoculture (0.54). Meanwhile, the response to selection in multi-canopy (3.60) was higher compared to monoculture (2.09), and therefore the selection of rice lines for a multi-canopy system should be conducted in the multi-canopy environment. A selection percentage of 5% resulted in a higher response to selection. These findings may provide insight into the acceleration of breeding rice varieties for the multi-canopy system.