Responses of Weedy Rice to Drought Stress at Germination and Seedling Stages

Abstract

Drought is a world-spread problem seriously influencing grain production and quality, the loss of which is the total for other natural disasters, with increasing global climate change making the situation more serious. Rice is the staple food for more than 23% of world population, so rice anti-drought physiology study is of importance to rice production and biological breeding for the sake of coping with abiotic and biotic conditions. Much research is involved in this hot topic, but the pace of progress is not so large because of drought resistance being a multiple-gene-control quantitative character. On the other hand, stress adaptive mechanisms are quite different, with stress degree, time course, materials, soil quality status and experimental plots, thus increasing the complexity of the issue in question. Additionally, a little study is related to weedy rice.In order to investigate the effects of drought stress on germination and early seedling growth of weedy rice (Oryza sativa f. spontanea L.) and cultivated rice (Oryza sativa L.), polyethyleneglycol-6000 (PEG-6000) are used to generate -1.33MPa and 0MPa water stress in a laboratory condition (28±3°C). Complete randomized design with three replications is used in the study. After 10 days of germination, shoot length, the longest root length, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight and root numbers are measured; germination percentage, and root to shoot ratio are calculated. Germination index (GI), shoot length stress index (SLSI), root length stress index (RLSI) and dry matter stress index (DMSI) are used to evaluate the response of different genotypes to PEG-induced water stress. Results of ANOVA analysis show that responses of weedy rice accessions and cultivated rice varieties to water stress are significant different, demonstrating the germplasm of weedy rice and cultivated rice are diverse which enables us to screen the germplasm tolerant to drought stress.

Carbon Nanodots for Enhancing the Stress Resistance of Peanut Plants

“…Meanwhile, they are inserted, nonpenetrating, water-solution, and nonionic polymers. So PEG-6000 has been frequently used to induce water stress and maintain a uniform water potential throughout the experimental period. − The simulated drought stress experiment of the peanut is shown in Figure . The peanut plants treated by PEG-6000 (20%) exhibit obvious growth inhibition.…”

Enhanced photosynthesis endows seedling growth vigour contributing to the competitive dominance of weedy rice over cultivated rice

“…It belongs to the same biological taxon as cultivated rice ( O. sativa L.) and occurs in most rice‐growing regions worldwide. Weedy rice is similar to cultivated rice in morphology, physiology and biochemistry, but usually exhibits many weedy traits such as enhanced stress tolerance and competitive ability, seed shattering and dormancy that facilitate seed dispersal and persistence in the field, and seed longevity . These traits and con‐specificity with cultivated rice make controlling weedy rice very difficult compared to other weeds.…”

“…Weedy rice can reduce the rice crop yield by 20% to 90% and even cause total crop failure depending on infestation levels, relative proportion to crop plants, duration of crop interference, and the type of rice cultivar or biotype of weedy rice involved . Its success as a competitor can be attributed to weedy rice being often taller than the crop and producing more tillers, tolerance to stress including deep sowing, cold stress and drought, and having greater N‐use efficiency than cultivated rice …”

Competition between Rice and Weedy Rice under Different Water Regimes

“…This is important to strengthen the drought breeding program in rice by considering additional root morphological and physiological plasticity traits that are not just water uptake enhancers but also competitor-specific. Furthermore, given the competitive nature of WR over cultivated rice (Pantone and Baker 1991), it could also be considered as raw genetic materials for rice breeding programs aimed at improving tolerance to drought (Ding et al 2013;Chen and Suh 2015), as well as competitive (weed suppressive) ability (Shreshta et al 2020). Using transcriptomic and proteomic analyses, Han et al (2020) identified six proteins related to drought tolerance in WR accessions, in which four of the proteins formed a combined defense system to respond to drought stress in WR.…”