High-yield rice varieties with a suitable growth duration are required for mechanical transplanting in multiple cropping systems.  Daily yield is an appropriate criterion for the selection of machine-transplanted rice varieties.  The aim of this study was to investigate the growth characteristics and grain production in machine-transplanted medium indica hybrid rice with a high daily yield.  We conducted a field experiment on 20 medium indica hybrid rice varieties in 2017 and 2018.  Grain yield decreased significantly with growth duration between jointing and heading, but it increased with dry matter accumulation, growth rate between jointing and heading, dry matter partitioning to the stem plus sheath at heading, daily yield, and number of spikelets per panicle.  Compared with the medium and low daily yield variety types, the high daily yield variety type increased shoot biomass by improving crop growth rate and dry matter accumulation amount between jointing and heading and after heading.  The high daily yield variety type decreased the growth duration pre-heading and the proportions of dry matter partitioned to the leaf lamina at heading and maturity, but it also increased the post-heading accumulated dry matter in the grain and the remobilization of dry matter stored in the vegetative organs.  Furthermore, the high daily yield variety type significantly increased the occurrence rate of tillers, which is beneficial for the formation of a larger panicle size and an increase in the grain-filling rate.  These changes contributed to a 6.51–23.16% relative increase in grain yield of the high daily yield variety type.  In conclusion, the selection of high daily yield indica hybrid rice varieties with shorter pre-heading growth duration, greater tiller occurrence rate and spikelet numbers per panicle, higher post-jointing growth rates and stem plus sheath dry matter accumulation at heading is suitable for machine-transplanted rice.

The present study investigates the chemical composition and antioxidant capacity of juice from the Gannan navel orange, which is harvested at one- to two-week intervals during the ripening period.  The total soluble solid (TSS), total polyphenol content (TPC), total flavonoid content (TFC), sucrose and hesperidin contents gradually increase with the ripening of the fruit, followed by slight declines at the late maturity stage.  Contrary to these observations, the contents of titratable acid (TA), vitamin C (Vc), and limonin trend downward throughout the ripening period.  However, the contents of fructose, glucose, and narirutin fluctuate throughout the harvest time.  Three in vitro antioxidant assays consistently indicate that the harvest time exerts no significant influence (P>0.01) on the antioxidant capacity.  Furthermore, principal component analysis (PCA) and Pearson’s correlation test are performed to provide an overview of the complete dataset. This study provides valuable information for evaluating the fruit quality and determining when to harvest the fruit in order to meet the preferences of consumers.  Meanwhile, our observations suggest that the fruits subjected to juice processing should be harvested at the late maturity stage to alleviate the “delayed bitterness” problem without compromising the antioxidant capacity and the flavonoid content in the juice.

Allopolyploidy has played an important role in plant evolution and heterosis.  Recent studies indicate that the process of wide hybridization and (or) polyploidization may induce rapid and extensive genetic and epigenetic changes in some plant species.  To better understand the allopolyploidy evolutionism and the genetic mechanism of Arachis interspecific hybridization, this study was conducted to monitor the gene expression variation by cDNA start codon targeted polymorphism (cDNA-SCoT) and cDNA high-frequency oligonucleotide-targeting active gene (cDNA-HFO-TAG) techniques, from the hybrids (F₁) and newly synthesized allopolyploid generations (S₀-S₃) between tetraploid cultivated peanut Zhongkaihua 4 with diploid wild one Arachis doigoi. Rapid and considerable gene expression variations began as early as in the F₁ hybrid or immediately after chromosome doubling.  Three types of gene expression changes were observed, including complete silence (gene from progenitors was not expressed in all progenies), incomplete silence (gene expressed only in some progenies) and new genes activation.  Those silent genes mainly involved in RNA transcription, metabolism, disease resistance, signal transduction and unknown functions.  The activated genes with known function were almost retroelements by cDNA-SCoT technique and all metabolisms by cDNA-HFO-TAG.  These findings indicated that interspecific hybridization and ploidy change affected gene expression via genetic and epigenetic alterations immediately upon allopolyploid formation, and some obtained transcripts derived fragments (TDFs) probably could be used in the research of molecular mechanism of Arachis allopolyploidization which contribute to thwe genetic diploidization of newly formed allopolyploids.  Our research is valuable for understanding of peanut evolution and improving the utilization of putative and beneficial genes from the wild peanut.