New plant type trait characterization and development of core set among indica and tropical japonica genotypes of rice

Abstract

This study was conducted to characterize new plant type (NPT) traits among 650 genetically diverse rice genotypes of tropical japonica and indica and to establish an initial core set for NPT traits. Analysis of variance revealed highly significant differences among the genotypes for all the traits assessed except flag length and width and leaf angles. Dendrogram categorized the genotypes into five distinct duration groups. Genotypes viz., Pumphamah, IRGC5097, IRGC37015, IRGC43741, IRGC50448, IRGC53089, IRGC39111, IRGC18021, Haorei Machang, IRGC44069, IRGC8269, Thangmoi, IRGC33130 and IRGC29772 were identified as possessing strong culm. Long panicles with a length of more than 35 cm were found in IRGC8269, IRGC9147, IRGC14694, IRGC19642, IRGC27435, IRGC39111, IRGC31051, IRGC26011and IRGC25892. Ideal leaf angle of NPT genotypes of 5°, 10° and 20° of flag leaf, 1st and 2nd leaves was not found in any genotype but with a combination of 5°, 10° and 10° was observed in IRGC63102 and IRGC66644. NPT flag leaf length and width of 50 and 2 cm, respectively, was seen in ‘Kemenya Kepeu’ and ‘IRGC29772’. High grain number of more than 350 was observed in IRGC53089, IRGC31063 and Azhoghi. A total of 72 genotypes were found with a combination of one or more ideal plant type traits of which, hierarchical cluster analysis based on genetic distances selected 32 as NPT core set. This core set will serve as an ideal genetic resource for breeding programs aimed at NPT development.

Identification of Newer Stable Genetic Sources for High Grain Number per Panicle and Understanding the Gene Action for Important Panicle Traits in Rice

“…From the PCA biplot, the group 2 and group 5 genotypes exhibit low tillering, low TGW, and high panicle trait value and grain yield per plant, and genotypes in group 1 exhibit desirable panicle characters along with high TGW and high grain yield per plant. The selection of low tillering and higher panicle characters leads to a plant type similar to IRRI’s new plant type verities, which had thick and strong culm, low tillers and 100% productive tillers, large panicles, vigorous root system, and high yield [ 46 ]. The high tillering in rice is related to increased biomass and exhibited dense canopy, which facilitates the microenvironment and is amenable to pests and diseases.…”

Population Structure of a Worldwide Collection of Tropical Japonica Rice Indicates Limited Geographic Differentiation and Shows Promising Genetic Variability Associated with New Plant Type

“…Excess tillers or late tillers may divert the key metabolites to growth instead of grain formation, which may render panicles under development or may reduce the number of spikelets [ 35 ]. Therefore, NPT is an optimized combination of tiller number, panicle length, and grain number leading to high grain yield [ 36 ]. Other traits such as spikelet fertility could also play a significant role in yield; hence, high spikelet fertility among NPT lines is the most desirable trait for recruitment into breeding.…”

Overview of developed core and mini core collections and their effective utilization in cultivated rice and its related species (Oryza sp.)—A review

“…A core set of 72 genotypes was developed from 650 diverse genotypes of indica and japonica rice with a combination of one or more ideal plant type traits. Of these, hierarchical cluster analysis based on genetic distances selected 32 as a new plant type (NPT) core set (Jyothi et al, 2018). A collection of 552 aromatic rice ( O. sativa ssp.…”

“…indica subgroups. Another NPT rice core set of 41 accessions (Jyothi et al, 2018) was analysed for genetic diversity employing 52 yield‐related and 12 randomly chosen markers (Bagudam et al, 2019). These were further characterized for agromorphological traits using seven gene‐specific functional markers related to culm strength, grain number and grain weight (Bagudam et al, 2021).…”

“…indica subgroups. Another NPT rice core set of 41 accessions (Jyothi et al, 2018) was analysed for genetic diversity employing 52 yieldrelated and 12 randomly chosen markers (Bagudam et al, 2019).…”