Assessment of agro-morphological, physiological and yield traits diversity among tropical rice

Authors: KAKAR, NAQEEBULLAH - Mississippi State University; BHEEMANAHALLI, RAJA - Mississippi State University; JUMAA, SALAH - Mississippi State University; DIAZ REDOÑA, EDILBERTO - Mississippi State University; Warburton, Marilyn; REDDY, RAJA - Mississippi State University

Submitted to: PeerJ
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2021
Publication Date: 7/19/2021
Citation: Kakar, N., Bheemanahalli, R., Jumaa, S.H., Diaz Redoña, E., Warburton, M.L., Reddy, R.K. 2021. Assessment of agro-morphological, physiological and yield traits diversity among tropical rice. PeerJ. 9:e11752. https://doi.org/10.7717/peerj.11752.
DOI: https://doi.org/10.7717/peerj.11752

Interpretive Summary: Rice is an essential staple food crop, but in many countries, the per acre average rice yield is less than its substantial potential. Breeders can select the best rice plants in their experiments based on many methods, but a robust method that combines the best of several traits is preferred. Here, we show that breeders can select for rice plants that grow quickly and have large grain heads will automatically select higher yielding plants for Mississippi rice growing conditions. Several rice cultivars that have these beneficial traits were identified.

Technical Abstract: Rice (Oryza sativa L.) is an essential staple food crop, but in many countries, the per acre average rice yield is less than its substantial potential. Rice breeders and growers would benefit from a robust ideotype to understand morpho-physiological and yield-related traits better. Here, seventy-four new rice genotypes were phenotyped over two years for their gas exchange and yield potential-related traits under Mississippi rice-growing conditions. A wide range of variability was observed among genotypes for all measured traits. Detailed phenotyping of rice genotypes revealed two key relationships that function together to contribute to yield potential under the southern US climate. The first one, grain yield, grain number, and spikelet fertility, showed considerable correlation (r = 0.45 to 0.79, p<0.001) to harvest index. Conversely, days to anthesis had a high and negative correlation with harvest index (r = -0.79, p<0.001), which suggests that selection for short duration genotypes with efficient partitioning could improve the yields under southern US climatic conditions. Total response indices revealed a higher positive association with yield traits (R2=0.59) than physiological (R2 = 0.28) and morphological traits (R2 = 0.21). Compared with the commercial genotype Rex, 21.6% and 47.3% of the rice genotypes had higher gas exchange and yield response scores, respectively. IR08A172, IR07K142, and IR07F287 were ranked as high performers in physiological and yield response indices. Finally, our study highlights that selection for short duration yield-related traits with efficient sink capacity traits is desirable for future breeding programs.