On 26 August, at VNUHCM–University of Science (HCMUS), doctoral researcher Trần Minh Hồng Lĩnh, 2019 intake, successfully defended a doctoral thesis in Plant Physiology entitled ‘Study on flower and fruit development to shorten the maturation phase in rice (Oryza sativa L.)’. The research was conducted under the scientific guidance of Associate Professor Bùi Trang Việt and Associate Professor Trần Thanh Hương.

The thesis focused on investigating the rice variety Oryza sativa L. cv. OM5451—a short-duration, high-quality variety widely cultivated in the Mekong Delta—aiming to shorten the growth cycle whilst maintaining yield under climate change conditions. Based on monitoring a 95-day growth cycle, the researcher analyzed morphological, anatomical, physiological, and biochemical changes, as well as plant hormone dynamics during development from germination to grain maturation.

Results indicated that cytokinins, auxins, abscisic acid (ABA), and gibberellins exhibited fluctuations across development stages, with ABA increasing sharply during the milky stage, associated with starch accumulation and embryo maturation. Quantitative real-time PCR (qRT-PCR) analysis also recorded that GA3 treatment increased the expression of two genes, Hd3a and RFT1.

Notably, treatment with 50 mg/L GA3 at the booting stage enabled grains to mature 9.1 days earlier, whilst increasing 1,000-grain weight. Treatment with 50 mg/L ethephon at the soft dough and hard dough stages reduced maturation time by 10.1 days and 6.2 days, respectively.

When combining 50 mg/L GA3 at the booting stage with 50 mg/L ethephon at the hard dough stage, grain maturation time was shortened by 12 days in experimental gardens and 13 days in field conditions, while simultaneously enhancing grain weight. The findings highlight the potential application of plant growth regulators in controlling the growth duration of rice.

The research provides additional scientific foundation regarding flower and grain development in the OM5451 variety, whilst opening directions for further investigation into the action mechanisms of plant growth regulators and applicability to other rice varieties in the Mekong Delta. During the study period, doctoral researcher Trần Minh Hồng Lĩnh published 01 domestic paper and 02 international papers.