Genotypic-phenotypic relationship between grain yield, leaf biochemicals and anthesis quality traits in rice under reproductive stage drought

• Main Authors: Salleh, Mohd Syahmi, Nordin, Mohd Shukor, Yusop, Mohd Rafii, Abd. Aziz Shamsudin, Noraziyah, Ab Ghaffar, Mohamad Bahagia
• Format: Article
• Language: English
• Published: Malaysian Society For Biochemistry & Molecular Biology (MSBMB) 2022
• Subjects: S Agriculture (General)
• Online Access: http://irep.iium.edu.my/102419/1/102419_Genotypic-phenotypic%20relationship.pdf; http://irep.iium.edu.my/102419/; https://msbmb2010.wixsite.com/mjbmb/ipbc-2022
• Institution: Universiti Islam Antarabangsa Malaysia

Reproductive stage drought (RSD) significantly reduces the harvestable grain yield of rice. The grain yield (GY) is commonly used as a direct selection criterion in breeding drought-tolerant rice, while the leaf relative water content (LRWC) as a secondary selection criterion. The aim of this study was to compare the degree of association between leaf biochemicals (LB) and anthesis quality traits (AQT) with the harvestable GY under RSD. The pot-trial experiment was conducted using randomized complete block design (RCBD) with three replications. A total of 18 rice genotypes consisting of selected cultivars, breeding lines and landraces were used in this study. Quantitative assessment of LB and AQT was conducted under RSD at -60 kPa. The GY was recorded at harvest maturity. Genotypic correlation analysis was conducted to determine the general association of the studied traits while the path coefficient analysis was to determine the direct and indirect effects of LRWC and AQT (independent variables) on the GY (dependent variable). The level of lipid peroxidation and proline content were not significantly correlated with AQT, LRWC, and GY. In contrast, spikelet moisture content (SMC) was positively and significantly correlated with all of the AQT particularly spikelet opening (SO), anther exertions (AE), apical dehiscence length (ADL), apical dehiscence width (ADW), basal dehiscence length (BDL), basal dehiscence width (BDW), number of pollen grains (NPG) and pollen load on stigma (PLS) at 0.624, 0.746, 0.786, 0.799, 0.735, 0.789, 0.724, and 0.701 except for the rate of pollen viability (RPV) at 0.506. The SMC was also positively and significantly correlated with the LRWC (0.949) and GY (0.836). Results of the path-coefficient analysis revealed that the direct and indirect effects of the SMC towards GY were higher than the LRWC and other AQT. This indicated that the SMC was highly associated and contributed to higher GY under RSD. The LRWC, in contrast, recorded a negative direct effect with GY (-0.912) under RSD. These results suggested that SMC might be used as a better secondary selection criterion in breeding drought-tolerant rice compared to LRWC. However, further field trials are necessary to confirm finding of the present study.