Flower organ identity in rice is mainly determined by the A-, B-, C- and E-class genes, with the majority encoding MADS-box transcription factors.  However, few studies have investigated how the expression of these floral organ identity genes is regulated during flower development.  In this study, we identified a gene named SUPER WOMAN 2 (SPW2), which is necessary for spikelet/floret development in rice by participating in the regulation of the expression of pistil identity genes such as OsMADS3, OsMADS13, OsMADS58 and DL.  In the spw2 mutant, ectopic stigma/ovary-like tissues were observed in the non-pistil organs, including sterile lemma, lemma, palea, lodicule, and stamen, suggesting that the identities of these organs were severely affected by mutations in SPW2.  SPW2 was shown to encode a plant-specific EMF1-like protein that is involved in H3K27me3 modification as an important component of the PRC2 complex.  Expression analysis showed that the SPW2 mutation led to the ectopic expression of OsMADS3, OsMADS13, OsMADS58, and DL in non-pistil organs of the spikelet.  The ChIP-qPCR results showed significant reductions in the levels of H3K27me3 modification on the chromatin of these genes.  Thus, we demonstrated that SPW2 can mediate the process of H3K27me3 modification of pistil-related genes to regulate their expression in non-pistil organs of spikelets in rice.  The results of this study expand our understanding of the molecular mechanism by which SPW2 regulates floral organ identity genes through epigenetic regulation.

Soil salinization is a critical environmental issue restricting agricultural production.  Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.  However, the legacy effects of straw added as an interlayer at different rates on soil organic carbon (SOC) and total nitrogen (TN) in saline soils still remain inconclusive.  Therefore, a four-year (2015–2018) field experiment was conducted with four levels (i.e., 0, 6, 12 and 18 Mg ha^–1) of straw returned as an interlayer.  Compared with no straw interlayer (CK), straw addition increased SOC concentration by 14–32 and 11–57% in the 20–40 and 40–60 cm soil layers, respectively.  The increases in soil TN concentration (8–22 and 6–34% in the 20–40 and 40–60 cm soil layers, respectively) were lower than that for SOC concentration, which led to increased soil C:N ratio in the 20–60 cm soil depth.  Increases in SOC and TN concentrations in the 20–60 cm soil layer with straw addition led to a decrease in stratification ratios (0–20 cm:20–60 cm), which promoted uniform distributions of SOC and TN in the soil profile.  Increases in SOC and TN concentrations were associated with soil salinity and moisture regulation and improved sunflower yield.  Generally, compared with other treatments, the application of 12 Mg ha^–1 straw had higher SOC, TN and C:N ratio, and lower soil stratification ratio in the 2015–2017 period.  The results highlighted that legacy effects of straw application as an interlayer were maintained for at least four years, and demonstrated that deep soil straw application had a great potential for improving subsoil fertility in salt-affected soils.

Grain filling is the physiological process for determining the obtainment of yield in cereal crops.  The grain-filling characteristics of 50 maize brand hybrids released from 1964 to 2014 in China were assayed across multiple environments.  We found that the grain-filling duration (54.46%) and rate (43.40%) at the effective grain-filling phase greatly contributed to the final performance parameter of 100-kernel weight (HKW).  Meanwhile, along with the significant increase in HKW, the accumulated growing degree days (GDDs) for the actual grain-filling period duration (AFPD) among the selected brand hybrids released from the 1960s to the 2010s in China had a decadal increase of 23.41°C d.  However, there was a decadal increase of only 19.76°C d for GDDs of the days from sowing to physiological maturity (DPM), which was also demonstrated by a continuous decrease in the ratio between the days from sowing to silking (DS) and DPM (i.e., from 53.24% in the 1960s to 49.78% in the 2010s).  In contrast, there were no significant changes in grain-filling rate along with the release years of the selected hybrids.  Moreover, the stability of grain-filling characteristics across environments also significantly increased along with the hybrid release years.  We also found that the exotic hybrids showed a longer grain-filling duration at the effective grain-filling phase and more stability of the grain-filling characteristics than those of the Chinese local hybrids.  According to the results of this study, it is expected that the relatively longer grain-filling duration, shorter DS, higher grain-filling rate, and steady grain-filling characteristics would contribute to the yield improvement of maize hybrids in the future.  

The soybean rhizosphere has a specific microbial community, but the differences in microbial community structure between different soybean genotypes have not been explained.  The present study analyzed the structure of the rhizosphere microbial community in three soybean genotypes.  Differences in rhizosphere microbial communities between different soybean genotypes were verified using diversity testing and community composition, and each genotype had a specific rhizosphere microbial community composition.  Co-occurrence network analysis found that different genotype plant hosts had different rhizosphere microbial networks.  The relationship between rhizobia and rhizosphere microorganisms in the network also exhibited significant differences between different genotype plant hosts.  The ecological function prediction found that different genotypes of soybean recruited the specific rhizosphere microbial community.  These results demonstrated that soybean genotype regulated rhizosphere microbial community structure differences.  The study provides a reference and theoretical support for developing soybean microbial inoculum in the future.

The crown root system is the most important root component in maize at both the vegetative and reproductive stages.  However, the genetic basis of maize crown root traits (CRT) is still unclear, and the relationship between CRT and aboveground agronomic traits in maize is poorly understood.  In this study, an association panel including 531 elite maize inbred lines was planted to phenotype the CRT and aboveground agronomic traits in different field environments.  We found that root traits were significantly and positively correlated with most aboveground agronomic traits, including flowering time, plant architecture and grain yield.  Using a genome-wide association study (GWAS) coupled with resequencing, a total of 115 associated loci and 22 high-confidence candidate genes were identified for CRT.  Approximately one-third of the genetic variation in crown root was co-located with 46 QTLs derived from flowering and plant architecture.  Furthermore, 103 (89.6%) of 115 crown root loci were located within known domestication- and/or improvement-selective sweeps, suggesting that crown roots might experience indirect selection in maize during domestication and improvement.  Furthermore, the expression of Zm00001d036901, a high-confidence candidate gene, may contribute to the phenotypic variation in maize crown roots, and Zm00001d036901 was selected during the domestication and improvement of maize.  This study promotes our understanding of the genetic basis of root architecture and provides resources for genomics-enabled improvements in maize root architecture.

The red coloring of pear fruits is mainly caused by anthocyanin accumulation.  Red sport, represented by the green pear cultivar ‘Bartlett’ (BL) and the red-skinned derivative ‘Max Red Bartlett’ (MRB), is an ideal material for studying the molecular mechanism of anthocyanin accumulation in pear.  Genetic analysis has previously revealed a quantitative trait locus (QTL) associated with red skin color in MRB.  However, the key gene in the QTL and the associated regulatory mechanism remain unknown.  In the present study, transcriptomic and methylomic analyses were performed using pear skin for comparisons between BL and MRB.  These analyses revealed differential PcHY5 DNA methylation levels between the two cultivars; MRB had lower PcHY5 methylation than BL during fruit development, and PcHY5 was more highly expressed in MRB than in BL.  These results indicated that PcHY5 is involved in the variations in skin color between BL and MRB.  We further used dual luciferase assays to verify that PcHY5 activates the promoters of the anthocyanin biosynthesis and transport genes PcUFGT, PcGST, PcMYB10 and PcMYB114, confirming that PcHY5 not only regulates anthocyanin biosynthesis but also anthocyanin transport.  Furthermore, we analyzed a key differentially methylated site between MRB and BL, and found that it was located in an intronic region of PcHY5.  The lower methylation levels in this PcHY5 intron in MRB were associated with red fruit color during development, whereas the higher methylation levels at the same site in BL were associated with green fruit color.  Based on the differential expression and methylation patterns in PcHY5 and gene functional verification, we hypothesize that PcHY5, which is regulated by methylation levels, affects anthocyanin biosynthesis and transport to cause the variations in skin color between BL and MRB.

Numbers of vertebrae is an important economic trait associated with body size and meat productivity in animals.  However, the genetic basis of vertebrae number in donkey remains to be well understood.  The aim of this study was to identify candidate genes affecting the number of thoracic (TVn) and the number of lumbar vertebrae (LVn) in Dezhou donkey.  A genome-wide association study was conducted using whole genome sequence data imputed from low-coverage genome sequencing.  For TVn, we identified 38 genome-wide significant and 64 suggestive SNPs, which relate to 7 genes (NLGN1, DCC, SLC26A7, TOX, WNT7A, LOC123286078, and LOC123280142).  For LVn, we identified 9 genome-wide significant and 38 suggestive SNPs, which relate to 8 genes (GABBR2, FBXO4, LOC123277146, LOC123277359, BMP7, B3GAT1, EML2, and LRP5).  The genes involve in the Wnt and TGF-β signaling pathways and may play an important role in embryonic development or bone formation and could be good candidate genes for TVn and LVn.

Yield loss due to low precipitation use efficiency (PUE) occurs frequently in dryland crop production.  PUE is determined by a complicated process of precipitation use in farmland, which includes several sequential steps: precipitation infiltrates into the soil, the infiltrated precipitation is stored in soil, the soil-stored precipitation is consumed through transpiration or evaporation, transpired precipitation is used to produce dry-matter, and finally dry-matter is re-allocated to grains.  These steps can be quantified by six ratios: precipitation infiltration ratio (SW/SWe; SW, total available water; SWe, available soil water storage at the end of a specific period), precipitation storage ratio (SWe/P; P, effective precipitation), precipitation consumption ratio (ET/SW; ET, evapotranspiration), ratio of crop transpiration to evapotranspiration (T/ET; T, crop transpiration), transpiration efficiency (B/T; B, the increment of shoot biomass) and harvest index (Y/B; Y, grain yield).  The final efficiency is then calculated as: PUE=SWe/P×SW/SWe×ET/SW×T/ET×B/T×Y/B.  Quantifying each of those ratios is crucial for the planning and execution of PUE improvements and for optimizing the corresponding agronomic practices in a specific agricultural system.  In this study, those ratios were quantified and evaluated under four integrated agronomic management systems.  Our study revealed that PUE and wheat yield were significantly increased by 8–31% under manure (MIS) or biochar (BIS) integrated systems compared to either conventional farmers’ (CF) or high N (HN) integrated systems.  In the infiltration and storage steps, MIS and BIS resulted in lower SWe/P but higher SW/SWe compared with CF and HN.  Regarding the consumption step, the annual ET/SW under MIS and BIS did not increase due to the higher ET after regreening and the lower ET before regreening compared with CF or HN.  The T/ET was significantly higher under MIS and BIS than under CF or HN.  In the last two steps, transpiration efficiency and harvest index were less strongly affected by the agronomic management system, although both values varied considerably across the different experimental years.  Therefore, attempts to achieve higher PUE and yields in rainfed wheat through agronomic management should focus on increasing the T/ET and SW/SWe, while maintaining ET/SW throughout the year and keeping SWe/P relatively low at harvest time.

Perilipin1 (PLIN1) is a major phosphorylated protein that specifically coats the surface of neutral lipid droplets (LDs) in adipocytes and plays a crucial role in regulating the accumulation and hydrolysis of triacylglycerol (TG).  Mammalian studies have shown that Plin1 gene transcription is mainly regulated by peroxisome proliferator-activated receptor-gamma (PPARγ), the master regulator of adipogenesis.  However, the regulatory mechanism of the chicken Plin1 (cPlin1) gene is poorly understood.  The present study aimed to investigate whether Plin1 is regulated by PPARγ in chickens and identify its exact molecular mechanism.  Reporter gene and expression assays showed that PPARγ2, but not PPARγ1, activated (P<0.01) the cPlin1 gene promoter.  An electrophoretic mobility shift assay and mutational analysis revealed that PPARγ2 bound to a special site in the cPlin1 gene promoter to enhance its expression.  In summary, our results show that PPARγ promotes the expression of the cPlin1 gene and that PPARγ2 is the main regulatory isoform.

Agricultural sustainability has benefited from the broad adoption of conservation agriculture (CA) practices for decades, in which the reduction of mechanical disturbances to soil (also known as reduced tillage, RT) is one of the most essential principles for CA implementation.  Many studies have recommended the advantages of CA practices in the promotion of biodiversity, but the integrated impacts on crop productivity and biodiversity remain unclear.  Since CA has been applied in rice production in the subtropical area of southern China for several years, the effects of CA, particularly the RT methods, need to be evaluated for the local and long-term adoption.  In this study, we established an integrated network to illustrate how the reduction of tillage intensity influenced organisms including invertebrates (such as rice pests and their predators), pathogens and weeds, and then led to an impact on rice yield.  The two-year study demonstrated that major rice pests, such as rice planthoppers, stem borers and apple snails, were effectively controlled by RT practice.  Similarly, the occurrence of common diseases declined with less tillage.  Compared to the conventional tillage (CT) treatment, the density of weeds in paddy fields deceased significantly in the RT treatment.  In addition, the diversity and richness of pest predators increased remarkably in paddy fields where either reduced or no tillage was applied, which highlighted the significance of a CA strategy for the promotion of biodiversity in the agroecosystem.  More importantly, the rice yield gradually increased after the two-year reduction of tillage.  Taken together, our results suggest that the reduction of tillage intensity is beneficial for the protection of rice crops from various pests, and facilitates the sustainability of the agroecosystem and rice yield, which provides a solid basis and novel insights for the establishment of sustainable agroecosystems by CA-related practices in rice production in southern China.

Improving the production of broiler chicken meat has been a goal of broiler breeding programs worldwide for many years.  However, the genetic architectures of skeletal muscle production traits in chickens have not yet been fully elucidated.  In the present study, a total of 519 F₂ birds, derived from a cross of Arbor Acres broiler and Baier layer, were re-sequenced (26 F₀ individuals were re-sequenced at a 10-fold depth; 519 F₂ individuals were re-sequenced at a 3-fold depth) and the coupling of genome-wide association study (GWAS) and selection signatures (F_ST (fixation index) and θ_π (nucleotide diversity)) was carried out to pinpoint the associated loci and genes that contribute to pectoral muscle weight (PMW) and thigh muscle weight (TMW).  A total of 7 890 258 single nucleotide polymorphisms (SNPs) remained to be analyzed after quality control and imputation.  The integration of GWAS and selection signature analyses revealed that genetic determinants responsible for skeletal muscle production traits were mainly localized on chromosomes 1 (168.95–172.43 Mb) and 4 (74.37–75.23 Mb).  A total of 17 positional candidate genes (PCGs) (LRCH1, CDADC1, CAB39L, LOC112531568, LOC112531569, FAM124A, FOXO1, NBEA, GPALPP1, RUBCNL, ARL11, KPNA3, LHFP, GBA3, LOC112532426, KCNIP4, and SLIT2) were identified in these regions.  In particular, KPNA3 and FOXO1 were the most promising candidates for meat production in chickens.  These findings will help enhance our understanding of the genetic architecture of chicken muscle production traits, and the significant SNPs identified could be promising candidates for integration into practical breeding programs such as genome-wide selection (GS) to improve the meat yield of chickens.

With the increased cultivation of Bt crops in China, Apolygus lucorum and other mirid bugs have emerged as important agricultural pests because they are insensitive to the Bt proteins.  In addition, the reduction of pesticide applications after planting Bt crops also increases the severity of mirid bug outbreaks.  Peristenus spretus is a parasitoid of mirid nymphs, but its sensitivity to Bt proteins is not known.  In the current study, we developed a dietary exposure assay to assess the effects of Bt proteins (Cry1Ab, Cry1Ac, Cry1F, Cry2Aa, and Cry2Ab) on P. spretus adults using a diet consisting of a 10% honey solution with or without Bt proteins at 400 µg g^–1 diet.  The results showed that the survival and reproduction of P. spretus adults were reduced by the cysteine protease inhibitor E-64 (a positive control) but were not affected by any of the five Bt proteins.  The activities of digestive, detoxifying, and antioxidant enzymes in P. spretus were also unaffected by diets containing the Cry proteins, but they were significantly affected by the diet containing E-64.  We then developed a tri-trophic bioassay to determine the effects of the five Bt proteins on P. spretus larvae and pupae.  In this assay, A. lucorum nymphs fed an artificial diet containing Cry proteins were used as the hosts for P. spretus.  The results of the tri-trophic assay indicated that neither the pupation rate nor the eclosion rate of the P. spretus parasitoids were significantly affected by the presence of high concentrations of Bt proteins in the parasitized A. lucorum nymphs.  The overall results indicate that these two assays can be used to evaluate the toxicity of insecticidal compounds to P. spretus and that the tested Cry proteins are not toxic to P. spretus.  

Domestication and genetic improvement of maize improve yield and stress tolerance due to changes in morphological and physiological properties, which likely alter rhizosphere microbial diversity.  Understanding how the evolution of maize germplasm impacts its rhizobacterial traits during the growth stage is important for optimizing plant-microbe associations and obtaining yield gain in domesticated germplasms.  In this study, a total of nine accessions representing domestication and subsequent genetic improvement were selected.  We then sequenced the plant DNA and rhizobacterial DNA of teosinte, landraces and inbred lines at the seedling, flowering and maturity stages in a field trial.  Moreover, the soil chemical properties were determined at the respective stages to explore the associations of soil characteristics with bacterial community structures.  The results showed that domestication and genetic improvement increased the rhizobacterial diversity and substantially altered the rhizobacterial community composition.  The core microbiome in the rhizosphere differed among germplasm groups.  The co-occurrence network analysis demonstrated that the modularity in the bacterial network of the inbred lines was greater than those of teosinte and the landraces.  In conclusion, the increased diversity of the rhizobacterial community with domestication and genetic improvement may improve maize resilience to biotic stresses and soil nutrient availability to plants. 

MicroRNA (miRNA) has vital regulatory effects on the proliferation, differentiation and secretion of ovarian granulosa cells, but the role of miR-99a-5p in goat ovarian granulosa cells (GCs) is unclear.  Both miR-99a-5p and Frizzled-5 (FZD5) were found to be expressed in GCs in goat ovaries via fluorescence in situ hybridization and immunohistochemistry, respectively, and FZD5 was verified (P<0.001) as a target gene of miR-99a-5p by double luciferase reporter gene experiments.  Furthermore, FZD5 mRNA and protein expression were both found to be regulated (P<0.05) by miR-99a-5p in GCs.  Moreover, the overexpression of miR-99a-5p or knockdown of FZD5 suppressed (P<0.05) estradiol and progesterone secretion from the GCs, as determined by ELISA.  In summary, miR-99a-5p inhibits target gene FZD5 expression and estradiol and progesterone synthesis in GCs.  Our study thus provides seminal data and new insights into the regulatory mechanisms of follicular development in the goat and other animals.

The potato cyst nematodes (PCN) Globodera rostochiensis (Wollenweber) Skarbilovich, 1959 is considered the most damaging nematode pest of potato worldwide that causes significant yield losses, and this nematode is recognized and listed as a quarantine nematode in many countries (EPPO 2017).  China is currently the largest producer of potato in the world, while the total production is also the highest (Guan and Cai 2019).  The survey for cyst nematodes on potato were conducted in Yunnan and Sichuan provinces of China during 2018–2020, numerous cysts were observed on potato roots in Huize County and Ludian County of Yunnan Province, Zhaojue County and Yuexi County of Sichuan Province.  Cysts and second-stage juveniles (J2s) were isolated from each soil sample using the Cobb decanting and sieving method.  The morphology of cysts and J2s and molecular analysis established the identity of this species as golden cyst nematode Globodera rostochiensis (Subbotin et al. 2010).  For morphological analysis, the cysts were characterized by smoothly rounded with a small projecting neck, brown and golden color, terminal cone was absent and circumfenestrate.  The key morphometrics of cysts (n=25) were: length excluding neck 705±24 (689–747) μm, width 698±28 (678–759) μm, number of cuticular ridges between anus and vulval fenestra 17.3±1.7 (14–19); fenestral diameter 13.6±1.1 (12.25–15.45) μm; distance from anus to the edge of fenestra 63.7±11.3 (48.23–79.14) μm; Granek’s ratio 4.7±0.7 (3.92–5.75).  The key morphometrics of J2s (n=25): body length 453.9±16.6 (440–496) μm, stylet length 21.9±1.0 (20.3–24.3) μm, tail length 51.1±3.2 (45.5–55.5) μm, and hyaline region length 24.4±2.5 (21.7–29.9) μm.  Morphology of the cysts and J2 were consistent with those of G. rostochiensis (Subbotin et al. 2010; EPPO 2017).  Moreover, the identification result was confirmed by PCR using universal primers TW81 (5´-GTTTCCGTAGGTGAACCTGC-3´) and AB28 (5´-ATATGCTTAAGTTCAGCGGGT-3´) for ITS region and D2A (5´-TTTTTTGGGCATCCTGAGGTTTAT-3´) D3B (5´-AGCACCTAAACTTAAAACATAATGAAAATG-3´) for rDNA-28S region, respectively.  The ITS rDNA sequences (GenBank accessions MZ042365, MZ042366, MZ042369, and MZ042370) exhibited 99.83% identity match to G. rostochiensis sequences available in the GenBank (GQ294513).  Sequence from the 28S region (GenBank accessions MZ057595, MZ057596, MZ057599, and MZ057600) was 99.33% similar to those of G. rostochiensis isolate from MF773722.  The species was also confirmed with species-specific primers ITS5 (5´-GGAAGTAAAAGTCGTAACAAGG-3´) and PITSr3 (5´-AGCGCAGACATGCCGCAA-3´) (Bulman and Marshall 1997), a single 434-bp fragment was obtained from Huize, Ludian, Zhaojue and Yuexi populations.  The pathog enicity testing of Huize, Ludian, Zhaojue and Yuexi, three weeks-old potato plants (cv. Qinshu 9)

were inoculated with 2 000 eggs, and cultured in an incubator at 23°C/20°C with a 16 h/8 h light/dark photoperiod.  After three months inoculation, 36±7.2 cysts and females were extracted from the infested potato roots, no females and cysts were observed on control plants.  

This is the first report of potato golden cyst nematode G. rostochiensis in China.  

Understanding yield potential, yield gap and the priority of management factors for reducing the yield gap in current intensive maize production is essential for meeting future food demand with the limited resources. In this study, we conducted field experiments using different planting modes, which were basic productivity (CK), farmer practice (FP), high yield and high efficiency (HH), and super high yield (SH), to estimate the yield gap. Different factorial experiments (fertilizer, planting density, hybrids, and irrigation) were also conducted to evaluate the priority of individual management factors for reducing the yield gap between the different planting modes. We found significant differences between the maize yields of different planting modes. The treatments of CK, FP, HH, and SH achieved 54.26, 58.76, 65.77, and 71.99% of the yield potential, respectively. The yield gaps between three pairs: CK and FP, FP and HH, and HH and SH, were 0.76, 1.23 and 0.85 t ha^–1, respectively. By further analyzing the priority of management factors for reducing the yield gap between FP and HH, as well as HH and SH, we found that the priorities of the management factors (contribution rates) were plant density (13.29%)>fertilizer (11.95%)>hybrids (8.19%)>irrigation (4%) for FP to HH, and hybrids (8.94%)>plant density (4.84%)>fertilizer (1.91%) for HH to SH. Therefore, increasing the planting density of FP was the key factor for decreasing the yield gap between FP and HH, while choosing hybrids with density and lodging tolerance was the key factor for decreasing the yield gap between HH and SH.

Understanding the characteristics of rice productivity is of great importance for achieving high yield formation.  However, such traits have not yet been studied for different ages of hydroponically grown long-mat rice seedlings (HLMS), which constitutes a new method of seedling cultivation.  Field experiments were conducted to evaluate the effects of seedling age on the growth stage, photosynthesis characteristics, dry matter production, and yield of HLMS.  A conventional japonica rice cultivar (Wuyunjing 24) and an indica hybrid rice cultivar (6 Liangyou 9368) were used as test materials.  The results showed that the whole phase was shortened by 13–15 days for young seedlings (13-day-old) compared with old seedlings (27-day-old), which occurred because the growth process accelerated with the transplantation of young seedlings.  As seedling age increased, the dry matter weight of stems of individual plants and of the population increased at the transplanting stage but decreased at the maturity stage (MS).  Compared with that of 27-day-old seedlings, the average ratio of panicle weight to total plant dry weight of 13-day-old seedlings during a 2-year period increased by 3.71% for Wuyunjing 24 and by 3.78% for 6 Liangyou 9368 at the MS.  Moreover, as seedling age increased, the leaf area index and photosynthetic potential decreased for both cultivars, and the photosynthetic rate markedly decreased at the heading stage (HS).  With the exception of that of Wuyunjing 24 from the jointing stage to the HS in 2014, the crop growth rate was higher for young seedlings than for old seedlings.  Grain yield significantly decreased with seedling age, but no significant difference was detected between the 13- and 20-day-old seedlings for either cultivar.  Therefore, equilibrious and high biological yield formation, vigorous growth in the late stages, and high photosynthetic production capacity are important characteristics and causes of the efficient and sustainable output of photosynthetic systems and for achieving high yield formation in young transplanted seedlings (13–20-day-old).

The cotton direct seeding after wheat (rape) harvested is under trial and would be the future direction at the Yangtze River Valley region of China.  The objective of this study was to quantify the effects of branch and stem architecture on cotton yield and identify the optimal cotton architecture to compensate the yield loss due to the reduction of individual production capacity under high planting density in the direst seeding after wheat harvested cropping system.  The characteristics of the stem and branch architecture and the relationships between architecture of the stem and branch with yield formation were studied on eight short season cotton cultivars during 2015 and 2016 cotton growth seasons.  Based on the two years results, three cultivars with different architectures of stem and branch were selected to investigate the effect of mepiquat chloride (MC) application on the architecture of the stem and branch, boll retention, and the yield in 2017.  Significant differences were observed on plant height, all fruiting nodes to branches ratio (NBR) in the cotton plant, and the curvature of the fruiting branch (CFB) among the studied cultivars.  There were three types of stem and fruiting branch structures: Zhong425 with stable and suitable plant height and NBR (about 90 cm and 2.5, respectively), high CFB (more than 10.0), and high boll retention speed and seed cotton yield; Siyang 822 with excessive plant height and NBR, low CFB, and low boll retention speed and seed cotton yield; and other studied cultivars with unstable structure of stem and branch, boll retention speed, and seed cotton yield across years.  And MC application could promote the appropriate plant height and NBR and high CFB and thus resulted in high boll retention speed and the yield.  The results suggested that the suitable plant height and NBR (about 90 cm and 2.5 respectively), and high CFB (more than 10.0), which was related to both genotype and cultural practice, could promote the higher boll retention speed and seed cotton yield.