Correlation of plant height and crop age with yield potential in Sri Lankan traditional rice accessions of <em>Ma wee</em>: a comparative study in Kamburupitiya with selected new improved rice varieties

Abstract

Generating knowledge about agronomic and yield characters of Ma wee is important for breeding. Therefore, this experiment aimed to determine the selected agronomic characteristics and yield components in accessions 8541 and 8543 (Maha Ma wee) and 4561 (Ma wee samba) varieties in comparison to new improved rice varieties (NIVs) of Bg 38, Bg 300 and Bg 366. Rice varieties were grown in pots in a completely randomized design in the greenhouse with 5 replicates for two consecutive Maha seasons of 2021/2022 and 2022/2023 in ecological zone of WL2. Daily daytime temperature (DT) inside the greenhouse and daily photoperiod were recorded during the experimental period. Selected agronomic characteristics and yield components were measured. During 2021/2022, DT varied from 250C to 30.250C, while in 2022/23, DT varied from 27.50C to 330C. DT during 2022/2023 was significantly higher compared to that of 2021/2022. Days to fifth leaf (DFL), plant height at fifth leaf (HFL), plant height at flowering (HF), number of grains per first panicle (GPP) and effective tiller number at harvest (ETH) varied from 24.00±.40 to 30.4±32, 40.00±1.14 to 60.90±2.75, 95.80±.96 to 235.6±11 and 2.00±.31 to 3.80±.37 during 2021/22 while variations were from 27.00±.70 to 32.60±.40, 39.20±.97 to 73.25±1.60, 81.75±4.11 to 239.00±2.91, 135.25±4.87 to 225.80±3.54 and 2.20±.20 to 3.60±.24 respectively during 2022/2023. DFL was influenced by the season, with significantly higher DFL during the 2022/2023 season having significantly higher DT. In 2021/2022, DFL, HFL, DF, HF and GPP were significantly higher in Ma wee accessions in contrast to those of NIVs. Except for Bg 38, which is bred with a traditional rice ancestor, NIVs produced significantly lesser GPP in contrast to Ma wee accessions. Although Bg 38 had the highest DF (145±1.15), and produced a higher GPP (213.5±9.97), HF (87.8±1.06) was significantly lower than that of Ma wee. Strong correlations were observed for DFL and DF (0.571), DFL and ETH (0.414), DF and GPP (0.599) and, HF and GPP (0.855). Our results suggest that the challenge of incorporating Ma wee accessions into breeding programmes for increased yield with an ideal plant structure must overcome the coincidence of high GPP with tall PH and the extended DF efficiently through molecular breeding strategies.