Genetic analysis of rice seedling traits related to machine transplanting under different seeding densities

Abstract

Background: Due to the diversity of rice varieties and cropping systems in China, the limitation of seeding density and seedling quality makes it hard to improve machine-transplanted efficiency. Previous studies have shown that indica and japonica varieties varied in machine transplanting efficiency and optimal seeding density. In this study, a RIL population derived from ‘9311’ and ‘Nipponbare’ were performed to explore the seedling traits variations and the genetic mechanism under three seeding densities. Results: The parents and RIL population exhibited similar trends as the seeding density increased, including seedling height and first leaf sheath length increases, shoot dry weight and root dry weight decreases. Among the 37 QTLs for six traits detected under the three seeding densities, 12 QTLs were detected in both three seeding densities. Five QTL hotspots identified clustered within genomic regions on chromosomes 1, 2, 4, 6 and 11. Specific QTLs such as qRDW1.1 and qFLSL5.1 were detected under low and high seeding densities, respectively. Detailed analysis the QTL regions identified under specific seeding densities revealed several candidate genes involved in phytohormones signals and abiotic stress responses. Whole-genome additive effects showed that ‘9311’ contributed more loci enhancing trait performances than ‘Nipponbare’, indicating ‘9311’ was more sensitive to the seeding density than ‘Nipponbare’. The prevalence of negative epistasis effects indicated that the complementary two-locus homozygotes may not have marginal advantages over the means of the two parental genotypes. Conclusions: Our results revealed the differences between indica rice and japonica rice seedling traits in response to seeding density. Several QTL hotspots involved in different traits and specific QTLs (such as qRDW1.1 and qFLSL5.1) in diverse seeding densities had been detected. Genome-wide additive and two-locus epistasis suggested a dynamic of the genetic control underlying different seeding densities. It was concluded that novel QTLs, additive and epistasis effects under specific seeding density would provide adequate information for rice seedling improvement during machine transplanting.

A MOF-based pH-responsive dual controlled-release system for herbicide pretilachlor and safener AD-67 delivery that enhances the herbicidal efficacy and reduces side effects

“…Rice is one of the most widely planted crops, with over 158 million hectares planted globally and an annual output of more than 700 million tons, which is critical for food production safety. 15,16 However, as common weeds in paddy fields, weeds such as barnyard grass can cause yield losses of 40-60% in competition with rice, and even up to 90% if not properly controlled. 17 Pre (2-chloro-N-(2,6-diethylphenyl)-N-(2propoxyethyl) acetamide), belongs to the class of chloroacetanilide herbicides and is widely used as a preemergence herbicide for the control of weeds such as barnyard grass in the paddy field.…”

“…In this study, we aimed at the acidic conditions of paddy fields (pH 5.0-pH 6.5), based on the CRF strategy and increased drug utilization, by using the acid-responsive material ZIF-67, a Co-based MOF, as the carrier, the small molecule pesticide Pre was encapsulated inside, and the safener AD-67 was self-assembled on the surface to form a pH double controlled release system AD-67@Pre@ZIF-67 (Scheme 1), which achieved the characteristics of partially releasing AD-67 first and then disintegrating the material to release Pre. Studies have shown that pH values between 5.0-6.5 can ensure the normal growth of rice, 16 and the growth of seedlings in this pH range results in good nutrient absorption capacity and strong photosynthesis, and physiological metabolism. 42 In this study, the pH range of the paddy field was simulated.…”