Diverse Rice Accessions: Exploration for Germplasms with Important Agronomic Traits for Breeding Use
Rice (Oryza sativa) is the essential staple food eaten by 50% of the world’s population. The need to increase the yield of this crucial commodity has been prompted by the exponential growth rate of the world’s population. The functioning of each component of the plant is reflected in the yield, which is the culmination of many other qualities. In other words, each crop has a built-in physiological production system that utilizes the energy required for essential plant activity. Finding the phenotypic qualities that affect yield is crucial for improving the effectiveness of a plant breeding program. The current study was conducted to evaluate and identify agronomic traits that might be suitable for rice germplasm enhancement, identify rice lines with desired agronomic architecture for high yield potential and evaluate the interrelationships between desired agronomic traits. Results of the study showed that approximately 45.9% of all rice accessions had a plant height below the mean value, while 54.1% of the accessions had heights above the mean. Moreover, only 4% of the population fell within the range of 60 cm to 80 cm, and 20% had plant heights ranging from 90 cm to 100 cm. The flag leaf area (FLA) in the first year ranged from 7.2 cm to 65.1 cm. Similar results were observed in the second-year data, where the range was from 9.5 cm to 65.5 cm. Rice accessions 329B, IR-44595, Chacareiro Uruguay, Pergonil 15, WAB462-10-3-1, and Hatsunishiki exhibited the highest flag leaf areas, ranging from 40 cm to 65 cm. Notably, a small proportion, specifically 5.9% of the accessions, exhibited flag leaf lengths shorter than the reference check varieties, falling from 19 cm to 29cm. The Somewake variety has the longest flag leaf length from the overall rice accessions. The Edith variety stood out among the various rice accessions, boasting the widest flag leaves. In the initial year of the study, an analysis of primary branch counts across diverse plant varieties revealed a range extending from a minimum of 4 to a maximum of 15.3. The prevalence of a higher number of primary branches (PB) in check varieties was a consistent trend observed in both years. Additionally, the RU-903141 variety closely approximated the primary branch count of the Presidio variety. Secondary branches exhibited a range of values from 0.33 to 8.67, with an overall mean value of 2.6. Co-efficient analysis revealed that plant height exhibits noteworthy and statistically significant positive correlations with flag leaf area (r = 0.20*), and flag leaf length (r = 0.19*). Flag leaf area, on the other hand, exhibits markedly substantial and statistically significant positive correlations with both flag leaf length (r = 0.76***) and flag leaf width (r = 0.68***), with p values below 0.001. Flag leaf width displayed a significantly strong positive correlation with flag leaf area but had a nonsignificant negative correlation with the umber of primary branches (r = -0.01) and a moderately positive but non-significant correlation with the number of secondary branches (r = 0.08, p >= 0.05). The number of primary branches exhibited positive but non-significant lower correlations with flag leaf area and flag leaf length, and negative but non-significant correlations with plant height and flag leaf width. Intriguingly, it had a positive and significant correlation with the number of secondary branches (r = 0.14*, p < 0.05). In summary, our research demonstrates the utility of phenotypic data in the initial selection of rice lines with desirable traits, paving the way for subsequent genotypic analyses aimed at identifying the specific genes responsible for these qualities. However, breeders must exercise caution when choosing traits, as an improvement in one trait may have repercussions on others, as exemplified by the potential trade-off between flag leaf width and the number of primary branches.
rice accessions, correlation analysis, genetic variability, plant height, flag leaf length, width and area, number of primary and secondary branches
Chepuri, R. (2023). Diverse rice accessions: Exploration for germplasms with important agronomic traits for breeding use (Unpublished thesis). Texas State University, San Marcos, Texas.