Since the founding of the People’s Republic of China in 1949, significant achievements have been made in cotton production in China.  China has maintained its position as the world’s largest cotton producer for 33 years (1983–2015), with average annual increases of 3.5 and 3.9% in the unit yield and total output of cotton, respectively.  Cotton production has played an extremely important role in the development of the national economy and the improvement of living standards.  Although the cotton planting area has been reduced in recent years, the total output has remained relatively unchanged due to the continuous increase in the unit yield.  China’s dominant position in global cotton production is undoubtedly attributed to the progress and development of cotton cultivation technology.  Over the past 70 years, China has established a high-yielding and high-efficiency cotton cultivation mode that corresponds to its national conditions, including a large population and a limited land area.  Furthermore, cotton cultivation technology is constantly being innovated and developed to keep pace with the times.  In this paper, we review the development of cotton production and cultivation in China over the past 70 years, with a particular focus on the innovation and development of cotton cultivation technology with Chinese characteristics.  This review is intended to provide guidance for the sustainable development of China’s cotton production in the future and to provide a reference for global cotton production.

    Crop growth and yield depend on canopy light interception (LI). To identify a low-cost and relatively efficient index for measuring LI, several color attributes of red-green-blue (RGB), hue-saturation-intensity (HSI), hue-saturation-value (HSV) color models and the component values of color attributes in the RGB color model were investigated using digital images at six cotton plant population densities in 2012–2014. The results showed that the LI values followed downward quadratic curves after planting. The red (R), green (G) and blue (B) values varied greatly over the years, in accordance with Cai’s research demonstrating that the RGB model is affected by outside light. Quadratic curves were fit to these color attributes at six plant population densities. Additionally, linear regressions of LI on every color attribute revealed that the hue (H) values in HSI and HSV were significantly linearly correlated with LI with a determination coefficient (R²)≥0.89 and a root mean square error (RMSE)=0.05. Thus, the H values in the HSI and HSV models could be used to measure LI, and this hypothesis was validated. The H values are new indexes for quantitatively estimating the LI of heterogeneous crop canopies, which will provide a theoretical basis for optimizing the crop canopy structure. However, further research should be conducted in other crops and under other growing and environmental conditions to verify this finding.

Foxtail millet (Setaria italica (L.) P. Beauv) is a naturally stress tolerant crop.  Compared to other gramineous crops, it has relatively stronger drought and lower nutrition stress tolerance traits.  To date, the scope of functional genomics research in foxtail millet (S. italic L.) has been quite limited.  NAC (NAM, ATAF1/2 and CUC2)-like transcription factors are known to be involved in various biological processes, including abiotic stress responses.  In our previous foxtail millet (S. italic L.) RNA seq analysis, we found that the expression of a NAC-like transcription factor, SiNAC110, could be induced by drought stress; additionally, other references have reported that SiNAC110 expression could be induced by abiotic stress.  So, we here selected SiNAC110 for further characterization and functional analysis.  First, the predicted SiNAC110 protein encoded indicated SiNAC110 has a conserved NAM (no apical meristem) domain between the 11–139 amino acid positions.  Phylogenetic analysis then indicated that SiNAC110 belongs to subfamily III of the NAC gene family.  Subcellular localization analysis revealed that the SiNAC110-GFP fusion protein was localized to the nucleus in Arabidopsis protoplasts.  Gene expression profiling analysis indicated that expression of SiNAC110 was induced by dehydration, high salinity and other abiotic stresses.  Gene functional analysis using SiNAC110 overexpressed Arabidopsis plants indicated that, under drought and high salt stress conditions, the seed germination rate, root length, root surface area, fresh weight, and dry weight of the SiNAC110 overexpressed lines were significantly higher than the wild type (WT), suggesting that the SiNAC110 overexpressed lines had enhanced tolerance to drought and high salt stresses.  However, overexpression of SiNAC110 did not affect the sensitivity of SiNAC110 overexpressed lines to abscisic acid (ABA) treatment.  Expression analysis of genes involved in proline synthesis, Na⁺/K⁺ transport, drought responses, and aqueous transport proteins were higher in the SiNAC110 overexpressed lines than in the WT, whereas expression of ABA-dependent pathway genes did not change.  These results indicated that overexpression of SiNAC110 conferred tolerance to drought and high salt stresses, likely through influencing the regulation of proline biosynthesis, ion homeostasis and osmotic balance.  Therefore SiNAC110 appears to function in the ABA-independent abiotic stress response pathway in plants.

     Yield and fiber quality of cotton even varies within locules in a boll, but it is not clear how yield components and quality parameters are altered across seed positions of a locule (SPL). A field experiment was arranged in a split plot design with transgenic insect resistant Bt (Bacillus thuringiensis) cotton hybrid cultivar CRI75 and conventional cultivar SCRC28 as the main plots, and three plant densities (15 000, 51 000 and 87 000 plants ha^–1) as the subplots in 2012 and 2013 at Anyang, Henan Province, China. Cotton was hand harvested by node and fruiting position, and then seeds of the first fruiting position bolls from nodes 6–10 were separated by SPL. The effects of plant density on lint yield, fiber quality, especially across SPL were determined. It was showed that plant densities of 51 000 and 87 000 plants ha^–1 increased lint yield by 61.3 and 65.3% in 2012 and 17.8 and 15.5% in 2013 relative to low plant density (15 000 plants ha^–1), however, no significant difference was observed between 51 000 and 87 000 plants ha^–1. The number of bolls (boll density) increased while boll weight decreased as plant density raised, and no significant changes occured in lint percentage in 2013 but increased with plant density in 2012. The number of bolls in upper nodes and distal fruiting positions, the number of seeds per boll, seed area (SA) and seed vigor index increased with decreasing plant density. Seed area was found to be greater from the base to the middle compared to the apex of a locule. Mote frequency (MF) increased as plant density increased, and fiber quality was the best at the middle of the locule regardless of plant density. As the number of fibers per seed area is genetically determined, adjusting plant density to produce more seeds and greater seed area can be a potentially promising alternative to improve lint yield in cotton. These findings might be of great importantance to cotton breeding and filed management.