Soil microorganisms play important roles in nitrogen transformation.  The aim of this study was to characterize changes in the activity of nitrogen transformation enzymes and the abundance of nitrogen function genes in rhizosphere soil aerated using three different methods (continuous flooding (CF), continuous flooding and aeration (CFA), and alternate wetting and drying (AWD)).  The abundances of amoA ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), nirS, nirK, and nifH genes, and the activities of urease, protease, ammonia oxidase, nitrate reductase, and nitrite reductase were measured at the tillering (S1), heading (S2), and ripening (S3) stages.  We analyzed the relationships of the aforementioned microbial activity indices, in addition to soil microbial biomass carbon (MBC) and soil microbial biomass nitrogen (MBN), with the concentration of soil nitrate and ammonium nitrogen.  The abundance of nitrogen function genes and the activities of nitrogen invertase in rice rhizosphere soil were higher at S2 compared with S1 and S3 in all treatments.  AWD and CFA increased the abundance of amoA and nifH genes, and the activities of urease, protease, and ammonia oxidase, and decreased the abundance of nirS and nirK genes and the activities of nitrate reductase and nitrite reductase, with the effect of AWD being particularly strong.  During the entire growth period, the mean abundances of the AOA amoA, AOB amoA, and nifH genes were 2.9, 5.8, and 3.0 higher in the AWD treatment than in the CF treatment, respectively, and the activities of urease, protease, and ammonia oxidase were 1.1, 0.5, and 0.7 higher in the AWD treatment than in the CF treatment, respectively.  The abundances of the nirS and nirK genes, and the activities of nitrate reductase and nitrite reductase were 73.6, 84.8, 10.3 and 36.5% lower in the AWD treatment than in the CF treatment, respectively.  The abundances of the AOA amoA, AOB amoA, and nifH genes were significantly and positively correlated with the activities of urease, protease, and ammonia oxidase, and the abundances of the nirS and nirK genes were significantly positively correlated with the activities of nitrate reductase.  All the above indicators were positively correlated with soil MBC and MBN.  In sum, microbial activity related to nitrogen transformation in rice rhizosphere soil was highest at S2.  Aeration can effectively increase the activity of most nitrogen-converting microorganisms and MBN, and thus promote soil nitrogen transformation. 

Environmental conditions greatly affect the growth of rice. To investigate the geographic differences in yield formation of single-season high-yielding hybrid rice in southern China, experiments were conducted in 2017 and 2018 in the upper and middle–lower reaches of the Yangtze River with 10–30 main locally planted high-yielding hybrid cultivars used as materials. Compared with rice planted in the middle–lower reaches of the Yangtze River, rice planted in the upper reaches has a longer tillering duration, higher accumulated temperature (≥10°C) during tillering period, but lower accumulated temperature and solar radiation from initial booting to maturity. Yield traits comparison between the upper and the middle–lower reaches of Yangtze River showed that the former had 48.1% more panicles per unit area while the latter had 46.4% more grains per panicle; the rice yield in the former was positively correlated with the seed setting rate and the dry matter accumulation before heading, while the latter was positively correlated with grains per panicle and dry matter accumulation from booting to maturity. Comparison of the same variety Tianyouhuazhan planted in different regions showed there was a significant positive correlation between panicle number and the duration of and accumulated temperature during the tillering period (r=0.982**, r=0.993**, respectively), and between grains per panicle and accumulated solar radiation during booting period (r=0.952*). In the upper reaches of the Yangtze River, more than 90% of cultivars with an yield of greater than 11 t ha^–1 had an effective panicle number of 250–340 m^–2, and there was a significant negative correlation between seed setting rate and grains per panicle; therefore, the high-yielding rice production in these regions with a long effective tillering period (>40 d) should choose varieties with moderate grains per panicle, adopt crop managements such as good fertilizer and water measures during vegetative growth period to ensure a certain number of effective panicles, and to increase the dry matter accumulation before heading. While in regions with a short effective tillering period (<20 d) but good sunshine conditions during the reproductive growth period, such as the middle–lower reaches of the Yangtze River, high-yielding rice production should choose cultivars with large panicles, adopt good water and fertilizer managements during the reproductive growth period to ensure the formation of large panicles and the increase of dry matter accumulation after heading.

Rapeseed is a very important oil crop in China; however, its production is challenging due to the absence of effective weed management strategies.  This is predominantly because of a shortage of herbicide resistance genes.  Acetohydroxyacid synthase (AHAS) herbicides inhibit AHAS, a key enzyme involved in branched-chain amino acid synthesis that is required for plant growth.  A rapeseed line designated M342 with AHAS herbicide resistance was developed through seed mutagenesis and was studied to assess the level and mode of inheritance of the resistance and to identify the molecular basis of resistance.  M342 possessed a high level of cross-resistance to sulfonylureas (SUs) and imidazolinones (IMIs).  This resistance was due to AHAS insensitivity to these herbicides and was inherited as a dominant trait conferred by a single nuclear-encoded gene.  Molecular analysis revealed the presence of a Trp574Leu mutation in M342, and an allele-specific cleaved amplified polymorphic sequence (AS-CAPS) marker was developed and cosegregated with herbicide resistance in the F₂, BC₁, and BC₂ populations.  This mutation altered the transcript levels of BnAHAS1 and BnAHAS3 in M342 compared with those in the wild type, but it did not affect the agronomic or quality traits.  The simple genetic inheritance of this mutation and the availability of the cleaved amplified polymorphic sequence (CAPS) marker and herbicide resistance gene should facilitate the development of herbicide-resistant rapeseed cultivars for effective weed control in China.  

Effects of different polarity solvents on the ultrastructure and chemical composition of cuticular wax in Pingguoli pear as well as their bioactive role against Alternaria alternate were studied and the results showed that the highest wax content was extracted with chloroform, and its wax content was up to 322.2 μg cm-2. Long-chain fatty acids predominated in menthol extracts and n-alkanes were predominant in wax extracted with ether, chloroform and n-hexane. Pingguoli pear fruit surface was covered by a smooth and amorphous wax layer with small, scattered crystal. The morphology of recrystallized wax in vitro after removal with different solvents was not similar to that of the intact fruit surface. Removal of cuticular wax with various solvents significantly enhanced A. alternata infection, except for wax removed by methanol. The solvent extracts of methanol and chloroform stimulated the spore germination and mycelium growth of A. alternata, but the ether and n-hexane extracts showed antifungal activity.

Three different chlorophyll-deficient rice isogenic lines chl, fgl and pgl, and their recurrent parent zhefu802 (zf802) wereused to study effects of leaf color on photosynthesis, dry matter accumulation, yield, and quality in early season indicarice. Analysis showed that the chlorophyll (Chl.) a/b ratio of isogenic lines chl-8, pgl and fgl was 5.35, 10.00 and 15.46,respectively, among them, line fgl had higher leaf area index (LAI), higher net photosynthetic rate and higher grain-fillingrate than its recurrent parent zf802 at the later period of grain filling stage; while LAI, net photosynthetic rate and drymatter accumulated in lines chl-8 and pgl were lower than in zf802. Differences were found in the grain yield and qualityamong chlorophyll deficient isogenic lines, lines fgl, chl-8 and zf802 had similar grain yield, which was significantly higherthan that of pgl; the highest milling quality was observed in isogenic line fgl, with relatively high protein content. Thisstudy showed that isogenic line fgl would become a unique material for the development of high yield rice with high grainquality because of its slow aging process and relative steady grain-filling rate.