Evaluation of rice genotypes for early- and mid-season vigor using morphological and physiological traits

Authors: JUMAA, SALAH - Mississippi State University; SEHGAL, AKANKSHA - Mississippi State University; KAKAR, NAQEEBULLAH - Mississippi State University; REDOÑA, EDILBERTO - Mississippi State University; CHASTAIN, DARYL - Mississippi State University; Warburton, Marilyn; REDDY, K - Mississippi State University

Submitted to: Journal of the Mississippi Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2020
Publication Date: 7/1/2020
Citation: Jumaa, S.H., Sehgal, A., Kakar, N., Redoña, E.D., Chastain, D., Warburton, M.L., Reddy, K.R. 2020. Evaluation of rice genotypes for early- and mid-season vigor using morphological and physiological traits. Journal of the Mississippi Academy of Sciences. 64(3):319-345.

Interpretive Summary: Rice (Oryza sativa L.) is a major staple crop consumed by more than half of the world’s population. Production of rice must increase to meet the requirements of the growing population in the twenty-first century and to maintain global food security. Rice plants that are very vigorous as seedlings suppress weeds, quickly put down deep roots, and can take advantage of the water and nutrients in the soil to grow large and high-yielding. This study determines which, of a panel of 36 rice cultivars and breeding lines, are the most vigorous as seedlings, and gives ways to most accurately and easily measure seedling vigor.

Technical Abstract: Rice (Oryza sativa L.) is a major staple crop consumed by more than half of the world’s population. Production of rice must be increased quantitatively and improved qualitatively to meet the requirements of the growing population in the twenty-first century and to maintain global food security. Early season vigor is a summation of the genotype’s ability to germinate uniformly, synchronize emergence, and grow rapidly. Developing quantitative methods and identifying traits for screening and classification of rice genotypes with early-season vigor could be valuable both for breeding as well as commercial rice production. We hypothesized that rice genotypes vary for seedling vigor, and relative scores could be used to identify genotypes with superior early stand establishment and canopy development. Therefore, a study was conducted using a sunlit pot-culture set-up to assess genetic variation among 36 rice genotypes for the shoot and root traits, and several physiological parameters at the seedling growth stage (26 DAS) and mid-grain filling stage (95 DAS). Individual (IVRI) and cumulative response indices (CVRI) were estimated for each trait for all genotypes. Genotypes were classified into different categories using CVRI values. Three genotypes, RU1204197 (inbred breeding line), XL753 (hybrid), and THAD (inbred released variety) showed the highest vigor indices and three genotypes (inbred varieties CL142-AR and SABINE and breeding line RU1304146) showed the lowest vigor indices at 26 DAS. Seven genotypes, including inbred breeding lines RU1204197 and RU1304122, hybrids CLX 745 and XL 753, and cultivars CLIZMN, LAKAST, and THAD, showed the highest vigor indices among the 36 genotypes at 95 DAS. There appeared to be no specific differences between hybrids and inbreds for early season vigor. Based on the results from the present study, rice producers could select either inbred varieties or hybrids to maximize rice production in their specific growing environments.