Calcium (Ca²⁺) plays an important role in determining plant growth and development because it maintains cell wall and
membrane integrity. Therefore, understanding the role of Ca2+ in carbon and lipid metabolism could provide insights
into the dynamic changes in cell membranes and cell walls during the rapid elongation of cotton fibers. In the present
study, we found that the lack of Ca²⁺ promoted fiber elongation and rapid ovule expansion, but it also caused tissue
browning in the ovule culture system. RNA-sequencing revealed that Ca²⁺ deficiency induced cells to be highly oxidized,
and the expression of genes related to carbon metabolism and lipid metabolism was activated significantly. All gene
members of nine key enzymes involved in glycolysis were up-regulated, and glucose was significantly reduced in Ca²⁺
deficiency-treated tissues. Ca²⁺ deficiency adjusted the flowing of glycolysis metabolic. However, low K⁺ recovered
the expression levels of glycolysis genes and glucose content caused by Ca2+ deficiency. Electrospray ionizationtandem
mass spectrometry technology was applied to uncover the dynamic profile of lipidome under Ca²⁺ and K⁺
interacted conditions. Ca²⁺ deficiency led to the decrease of fatty acid (FA), diacylglycerol (DAG), glycolipid and the
significant increase of triacylglycerol (TAG), phospholipid phosphatidylethanolamine (PE), phosphatidylglycerol (PG),
and PC (phosphatidylcholine). Low K⁺ restored the contents of FA, phospholipids, and glycolipids, effectively relieved
the symptoms caused by Ca²⁺ deficiency, and recovered the development of fiber cells. This study revealed dynamic
changes in transcript and metabolic levels and uncovered the signaling interaction of Ca²⁺ deficiency and low K⁺ in
glycolysis and lipid metabolism during fiber development.

Cereal and legume intercropping has been widely adopted to increase crop productivity in sustainable farming systems worldwide.  Among different intercropping combinations, millet and peanut intercropping can be adapted to most water-limited areas.  However, there are few studies on the differences in yield characteristics and nitrogen use efficiency between millet/peanut intercropping and monocultures under different nitrogen (N) application rates.  The objective of this study was to determine the yield advantages and economic benefits, as well as the appropriate N application rate, of millet/peanut intercropping.  A two-year field experiment was conducted with three cropping patterns (monoculture millet, monoculture peanut and millet/peanut intercropping) and four N rates (0, 75, 150 and 225 kg ha⁻¹).  The results showed that the land equivalent ratio (LER) and net effect (NE) of the intercropping system reached their highest levels at the N input of 150 kg ha⁻¹ in 2018 and 2019 (1.04 for LER, 0.347 Mg ha⁻¹ for NE, averaged across two years).  Millet was the dominant crop in the intercropping system (aggressivity of millet and peanut (Amp)>0, competitive ratio of millet and peanut (CRmp)>1), and millet yields achieved their highest values at N inputs of 225 kg ha⁻¹ for monoculture and 150 kg ha⁻¹ for intercropping.  NUE reached its highest levels with N inputs of 150 kg ha⁻¹ for all planting patterns over the two years.  Intercropping combined with an N input of 150 kg ha⁻¹ achieved the highest net income of 2 791 USD ha⁻¹, with a benefit-cost ratio of 1.56, averaged over the two years.  From the perspective of economics and agricultural sustainable development, millet/peanut intercropping at 150 kg N ha⁻¹ seems to be a promising alternative to millet or peanut monoculture.

Rice, the main food crop in China, has been sporadically reported to suffer from weedy rice infestation.  However, the overall occurrence and distribution pattern of Chinese weedy rice remains unclear because a systematic survey has not been conducted.  In order to reveal the infestation of Chinese weedy rice, a field survey was conducted in 999 sampling sites all over the rice-growing regions in China from 2009 to 2016 using seven-scale visual scoring of the level of weed infestation.  Weedy rice was found 39% occurrence incidence in a total of 387 sites.  The sampling sites with 50% or higher overall weedy rice infestation index mainly radiated from Jiangsu, Heilongjiang, Ningxia and Guangdong to the whole East China, Northeast China, Northwest China and South China.  A total of 45 morphological characters from 287 populations (collected simultaneously with the field survey) out of those occurred sites were observed and analyzed using multivariate analysis in common gardens with the same cultivation conditions in 2017 and 2019.  Canonical correlation analysis showed that 45 morphological characters were significantly related to the latitude, mean temperature, minimum temperature, precipitation and mean diurnal range factors.  The 287 weedy rice populations were divided into three morphological groups with climate-dependent geographical differentiation: strong tiller type only in Jiangsu, large leaf type in South China and Central China and large grain type mainly in North China.  Weedy rice seriously infested rice fields and had a geography, climate and cultivated rice type-dependent morphological and biotype differentiation in China.  It is suggested to pay attention to the harmfulness of weedy rice and adopt comprehensive control strategies.

Tillage represents an important practice that is used to dynamically regulate soil properties, and affects the grain production process and resource use efficiency of crops. The objectives of this 3-year field study carried out in the Huang-Huai-Hai (HHH) Plain of China were to compare the effects of a new deep vertical rotary tillage (DVRT) with the conventional shallow rotary tillage (CT) on soil properties, winter wheat (Triticum aestivum L.) grain yield and water and nitrogen use efficiency at different productivity levels, and to identify a comprehensive management that optimizes both grain yield and resource use efficiency in the HHH Plain. A split-plot design was adopted in field experiments in the winter wheat growing seasons of 2016–2017 (S1), 2017–2018 (S2) and 2018–2019 (S3), with DVRT (conducted once in June 2016) and CT performed in the main plots. Subplots were treated with one of four targeted productivity level treatments (SH, the super high productivity level; HH, the high productivity and high efficiency productivity level; FP, the farmer productivity level; ISP, the inherent soil productivity level). The results showed that the soil bulk density was reduced and the soil water content at the anthesis stage was increased in all three years, which were due to the significant effects of DVRT. Compared with CT, grain yields, partial factor productivity of nitrogen (PFP_N), and water use efficiency (WUE) under DVRT were increased by 22.0, 14.5 and 19.0%. Path analysis and direct correlation decomposition uncovered that grain yield variation of winter wheat was mostly contributed by the spike numbers per area under different tillage modes. General line model analysis revealed that tillage mode played a significant role on grain yield, PFP_N and WUE not only as a single factor, but also along with other factors (year and productivity level) in interaction manners. In addition, PFP_N and WUE were the highest in HH under DVRT in all three growth seasons. These results provided a theoretical basis and technical support for coordinating the high yield with high resource use efficiency of winter wheat in the resource-restricted region in the HHH Plain of China.

    Pepper (Capsicum spp.) is an important vegetable crop in the world. Now the pepper in China contributes one-third of the world’s peppers production. Genetic diversity of the pepper germplasm of China is expected interesting to know. To explore the structure of genetic diversity in Chinese pepper germplasm resources and possible relationship with cultivar types or geographic origin, we sampled and compared 372 GenBank pepper accessions (local cultivars and landraces) from 31 provinces, autonomous regions and municipalities of China and 31 additional accessions from other countries. These accessions were genotyped using 28 simple sequence repeat (SSR) markers spanning the entire pepper genome. We then investigated the genetic structure of the sampled collection using model-based analysis in STRUCTURE v2.3.4 and examined genetic relationships by the unweighted pair-group method of mathematical averages (UPGMA) in MEGA. In addition to geographic origin, we evaluated eight plant and fruit traits. In total, 363 alleles were amplified using the 28 SSR primers. Gene diversity, polymorphism information content and heterozygosity of the 28 SSR loci were estimated as 0.09–0.92, 0.08–0.92 and 0.01–0.34, respectively. The UPGMA cluster analysis clearly distinguished Capsicum annuum L. from other cultivated pepper species. Population structure analysis of the 368 C. annuum accessions uncovered three genetic groups which also corresponded to distinct cultivar types with respect to the plant and fruit descriptors. The genetic structure was also related to the geographic origin of the landraces. Overall results indicate that genetic diversity of Chinese pepper landraces were structured by migration of genotypes followed by human selection for cultivar types in agreement with consumption modes and adaptation to the highly diversified agro-climatic conditions.

Fruit set and development are affected by many phytohormones, including gibberellin.  Little is known regarding molecular mechanism underlying gibberellin mediated fruit set and development especially in Capsicum.  Three gibberellin receptors, CaGID1b.1, CaGID1b.2 and CaGID1c, and a DELLA protein, CaGAI, have been identified in Capsicum annuum L.  During the fruit development, the expression level of CaGID1c was low, and the expression fold change is mild.  However, CaGID1b.1 and CaGID1b.2 were relatively higher and more acute, which indicates that CaGID1b.1 and CaGID1b.2 may play an important role in fruit pericarp, placenta and seed.  Ectopic expressions of CaGID1b.1, CaGID1b.2 and CaGID1c in Arabidopsis double mutant gid1a gid1c increased plant height, among which CaGID1b.2 had the most significant effect; CaGAI reduced plant height in double mutant rga-24/gai-t6, having a similar function to AtGID1 and AtGAI in stem elongation.  Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays indicated that CaGID1b.1 and CaGID1b.2 interact with CaGAI in a GA-dependent manner, while CaGID1c interacts with CaGAI in a GA-independent manner.  Our study reveals the key elements during gibberellin signaling in Capsicum and supports the critical importance of gibberellin for Capsicum fruit set and development.

SSR markers are useful in pepper linkage mapping and gene location. 446 SSR markers have been reported, but they are insufficient. It is costly to develop SSR markers from DNA library, whereas it seems much easy to find in EST sequences in the GenBank of pepper through internet. In this study, attempts have been made to develop SSR markers in the EST sequences by using bioinformatics. EST sequences were trimmed by ‘est-trimmer.pl’ software, while 116915 EST sequences were obtained without poly ‘A’ or poly ‘T’, ranged between 100 and 700 bp. Using ‘e-PCR’ and ‘del.pl’ softwares, SSR sequences were identified. 2 508 microsatellite loci (larger than 20 repeats) were established and 755 SSR primers were designed using SSR finder software and Primer 3 software. There were 498 (0.43%) mono-, 1 026 (0.89%) di-, 518 (0.45%) tri-, 245 (0.21%) tetra-, 114 (0.10%) penta-, and 107 (0.09%) hexa-nucleotide SSRs. The estimated frequency of SSRs was approximately 1/25.12 kb. According to the distribution of SSRs in pepper, the mean length of pepper SSRs was 22.68 bp and the adenine rich repeats such as A/T, AG, AT, AAG, AAAT, and AAAC were predominant in each type of SSRs (mono-, di-, tri-, tetra-, penta-, and hexa-), whereas the C/G, CG, CCG repeats were less abundant. 210 primers were tested in 8 pepper cultivars and the PCR result revealed the existence of polymorphism among 127 (60.48%) SSR primers within 8 pepper cultivars. It is confirmed that pepper EST database could be efficiently exploited for availability of SSR markers.