Incorporating oilseed-rape straw in soil is one of the effective methods for enhancing the use efficiency of agricultural resources in the rape-rice rotation system. However, the impacts of oilseed-rape straw incorporation on root growth and dynamic changes in soil are still unclear. In order to provide a deeper understanding of the oilseed rape straw return on rice growth and productivity, the experiment was conducted in the field and in a specially-designed pots system from 2016 to 2017 by means of two straw returning methods and four straw returning amounts. In the early stage of rice growth (0–36 days after rice transplanting) the straw returning treatments decreased 1.0–8.6 mg/plant in bleeding density and 0.10–6.11, 0.06–0.31, and 0.52–0.84 μmol/(g h) in the activity of glutamine synthetase (GS), glutamic-oxalacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT), respectively. Oilseed rape straw returned by mulching induced negative impacts on new germinating roots in 0–10 cm of soil, while the negative impacts were observed on roots in 10–30 cm of soil for straw returned by plowing. In the later stage of rice growth (56–75 days after rice transplanting), oilseed rape straw returning produced some positive impacts on rice roots, which enhanced the yield of rice. Conclusively, our findings suggested that dynamic root growth and the activity of root enzymes are two major factors behind the slow reviving of rice after transplanting in the straw returning field. Plowing is a more appropriate method of straw returning than mulching in the rape-rice rotation system in the Sichuan basin area, with a straw incorporation rate of 3.0 t/hm².

A few plant species are recognized for uranium bioaccumulation, particularly as upper accumulator. Uranium has a dynamic impact on the physiological, biochemical, and photochemical reactions. Therefore, the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), soluble sugar, protein, photochemical reactions, and accumulation of uranium characteristics were studied in Bidens pilosa L. while applying altered concentrations of uranium in the form of C₄H₆O₆U. It was done to measure the capacity of B. pilosa L. to remediate uranium from wastewater. In this study, the results showed that B. pilosa L. not only has the ability of uranium accumulation but it can accumulate in the upper parts i.e. leaves and stem. Overall it can accumulate as much as 1538 mg/kg on a dry weight basis. Uranium accumulation is a complex process which changes both physiological and biochemical index in plant species under different treatments. SOD decreased in leaves and stem in response to all treatments whereas POD and CAT increased at treatment 3 and 72 h up to 1335 μ/g-FW and 47 μ/g-FW at 72 h, respectively. This increase was followed by a downward trend. The correlation coefficient between fluorescence ratio F_v/F_m and the concentrations of uranium treatment were significantly negative i.e. −0.928. The Fourier transform infrared spectroscopy (FTIR) analysis also highlighted that uranium does not change the basic chemical composition of B. pilosa L., but has an effect on the contents of chemical constituents. From the study, it is concluded that B. Pilosa L. has shown a capacity for uranium enrichment, especially as an upper accumulator.

Drought is one of the major factors limiting rice yield worldwide. A total of 46 hybrid rice varieties were chosen to investigate their root distribution and their response to drought. A field experiment was carried out in a dry shed building to evaluate the drought tolerance capacity of hybrid rice varieties on the basis of CTIRDE (complex tolerance index of rice under drought environment) values. Next, the experiment was conducted in a specially designed pot system and seed bags to analyze the root distribution and activity of antioxidant enzymes in different rice varieties. Moreover, the DEEPER ROOTING 1 (DRO1) gene was sequenced to elucidate its role in the root distribution of typical rice varieties. On the basis of CTIRDE values, the 46 hybrid rice varieties were classified as tolerant (CTIRDE ≥ 0.75), semi-tolerant (0.75 > CTIRDE > 0.65), or sensitive (CTIRDE ≤ 0.65) to drought stress. The tolerant varieties (Chuanguyou208 and Deyou4727) displayed a significantly larger length, had higher number and weight of roots in the 30–50 cm soil layer, and exhibited a significantly higher activity of Superoxide dismutase (SOD) and Peroxidase (POD) enzymes in roots during the drought stress period. The DRO1 gene sequencing results revealed that the tolerant and sensitive varieties exhibited a single-nucleotide polymorphism (SNP) in the 3-exon region, and the tolerant varieties (Chuanguyou208 and Deyou4727) exhibited a larger root growth angle with the horizontal axis, hence developing a deeper root system as compared with the other two group varieties. A significant correlation was found not only between the DRO1 gene and root distribution but also between DRO1 and the activity of SOD and POD enzymes. Conclusively, as a key feature, a deep root system enabled tolerant rice varieties (Chuanguyou208 and Deyou4727) to avoid drought stress by absorbing more water stored in deep soil layers. The root distribution, activity of POD and SOD enzymes in roots, and DRO1 gene can be used to screen tolerant rice varieties that can survive better under drought stress during the seedling stage of rice growth.

The seed-to-seedling transition represents a key developmental and metabolic switch in plants. Catabolism of seed storage reserves fuels germination and early seedling emergence until photosynthesis is established. The seed-to-seedling developmental transition is controlled by Polycomb repressive complex 2 (PRC2). However, the coordination of PRC2 activity and its contribution to transcriptional reprogramming during seedling establishment remain unknown. By analyzing H3K27me3 re-distribution and changes in gene transcription in the shoot and root tissues of heterotrophic and photoautotrophic Arabidopsis (Arabidopsis thaliana) seedlings, we reveal two phases of PRC2-mediated gene repression. The first phase is independent of light and photosynthesis and results in the irreversible repression of the embryo maturation program, marked by heterotrophy and reserve storage molecule biosynthesis. The second phase is associated with the repression of metabolic pathways related to germination and early seedling emergence, and H3K27me3 deposition in this phase is sensitive to photosynthesis inhibition. We show that preventing the transcription of the PRC2-repressed glyoxylate cycle gene ISOCITRATE LYASE promotes the vegetative phase transition in PRC2-depleted plants. Our findings underscore a key role of PRC2-mediated transcriptional repression in the coordinated metabolic and developmental switches that occur during seedling emergence and emphasizes the close connection between metabolic and developmental identities.