Direct seeding (DS) of rice gained much attention due to labor scarcity and unavailability of water. However, reduced emergence and poor seedling establishment are the main problems of DS which causes significant yield losses. Herein, DS-associated seedling traits of three major rice groups, i.e., Indica (Ind), Japonica (Jap), and aus-type (Aus), were evaluated by using an improved mesocotyl elongation assay. The associations among different traits at the seedling and maturity stage were also studied. Significant variation was observed among the cultivars of different rice groups. The Aus group cultivars showed higher mean values for coleoptile (C, 3.85 cm), mesocotyl (MC, 4.17 cm), shoot length (SL, 13.64 cm), panicle length (PL, 23.44 cm), tillers number (T, 15.95), culm length (CL, 105.29 cm), and plant height (PH, 128.73 cm), while the Indica and Japonica groups showed higher mean values of grain length (GL, 8.69 mm), grain length/width ratio (GL/WR, 3.07), and grain width (GW, 3.31 mm), with 1000 grain weight (TGWt, 25.53 g), respectively. Pairwise correlation analysis showed that MC, C, and SL were positively correlated among themselves and with PL, CL, and PH. Moreover, based on principal component analysis (PCA), C, MC, SL, CL, and PH were identified as the major discriminative factors in the rice cultivars. This study describes the development of desired DS rice variety with long MC and semidwarf in height and suggests that Aus group cultivars can be used as the donor parents of favorable DS-associated traits in rice breeding programs.
Background Effective tiller number (ETN) has a pivotal role in determination of rice (Oryza sativa L.) grain yield. ETN is a complex quantitative trait regulated by both genetic and environmental factors. Despite multiple tillering-related genes have been cloned previously, few of them have been utilized in practical breeding programs. Results In this study, we conducted a genome-wide association study (GWAS) for ETN using a panel of 490 rice accessions derived from the 3 K rice genomes project. Thirty eight ETN-associated QTLs were identified, interestingly, four of which colocalized with the OsAAP1, DWL2, NAL1, and OsWRKY74 gene previously reported to be involved in rice tillering regulation. Haplotype (Hap) analysis revealed that Hap5 of OsAAP1, Hap3 and 6 of DWL2, Hap2 of NAL1, and Hap3 and 4 of OsWRKY74 are favorable alleles for ETN. Pyramiding favorable alleles of all these four genes had more enhancement in ETN than accessions harboring the favorable allele of only one gene. Moreover, we identified 25 novel candidate genes which might also affect ETN, and the positive association between expression levels of the OsPILS6b gene and ETN was validated by RT-qPCR. Furthermore, transcriptome analysis on data released on public database revealed that most ETN-associated genes showed a relatively high expression from 21 days after transplanting (DAT) to 49 DAT and decreased since then. This unique expression pattern of ETN-associated genes may contribute to the transition from vegetative to reproductive growth of tillers. Conclusions Our results revealed that GWAS is a feasible way to mine ETN-associated genes. The candidate genes and favorable alleles identified in this study have the potential application value in rice molecular breeding for high ETN and grain yield.
The primary purpose of this paper is to recognise the essential factors that contribute to women farmer involvement in training events which, was used to determine significant independent variables for the five provinces of Central Division Fiji adding to 120 women farmers. The sampling was done in concern with any form of training provided in the agricultural, animal and crop sector alike. Considering the independent variables used to indicate the significant contributing factors influencing women participation in training, Marital status, age, tertiary education, extension services, access to market and the size of owned land played active roles. More interestingly, the variables that played insignificant influencers were the number of family members in the farmer household and the reason for farming. A logit analysis was used to display the results of significant and insignificant determining variables. Thus, the overall understanding of these variables through this study carried out in Fiji can lead to better decision making in regards to training programmes for women farmers and consequently producing positive agricultural development in Fiji which can become an efficient tool for agricultural ministry. Moreover, better agricultural policies for women farmers can be adopted based on their determinants to agricultural involvement.
Rice inflorescence is one of the major organs in determining grain yield. The genetic and molecular regulation on rice inflorescence architecture has been well investigated over the past years. In the present review, we described genes regulating rice inflorescence architecture based on their roles in meristem activity maintenance, meristem identity conversion and branch elongation. We also introduced the emerging regulatory pathways of phytohormones involved in rice inflorescence development. These studies show the intricacies and challenges of manipulating inflorescence architecture for rice yield improvement.
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