[Objective] An elite germplasm resource of sea-island cotton with outstanding traits was mined in order to accelerate the breeding process of new varieties. [Method] The core collections of sea-island cotton germplasm consisted of 178 accessions were used as experimental materials in this study. Analyses of variability and diversity were performed through detecting phenotypic data of six main breeding-targeted traits, including boll weight, boll number per plant, lint percentage, fiber length, fiber strength, and micronaire. The elite germplasm of sea-island cotton was selected according to 10% optimal sampling strategy based on the phenotypic value of each trait. The 120 pairs of polymorphic simple sequence repeat (SSR) primers were used to analyze the polymorphism of 178 accessions of the core collections. Then, we conducted the population structure and clustering analysis based on the genotyping results. According to the results of cluster analysis, the primary elite germplasm was further selected, and the final elite germplasm of sea-island cotton was identified. [Result] The results showed that there was a high variability and abundant genetic diversity in the 6 studied traits. In 178 accessions of sea-island cotton, 262 alleles were detected by 120 pairs of SSR primers, with an average of 2.18 loci. The average polymorphism information content (PIC) was 0.067 8-0.630 0, with an average of 0.296 0, showing moderate polymorphism. The cluster analysis showed that the core collection of sea-island cotton was divided into six groups. twenty-three elite germplasm resources of sea-island cotton were identified based on phenotypic value and cluster analysis of SSR markers. [Conclusion] The germplasm of sea-island cotton can be analyzed and evaluated based on the phenotyping and SSR markers, and then the elite germplasm of sea-island cotton can be identified. These results provided the material basis for the genetic breeding of sea-island cotton, as well as the important reference and basis for the mining and identification of crop elite germplasm.
[Objective] The present study aimed to investigate how sucrose metabolism in the leaf subtending to cotton boll, within-boll yield components and fiber quality respond to varying planting dates. [Method] Two upland cotton lines A705 and A201 differing in cotton boll traits were field tested in 2016-2017. Two different planting dates were designed with early planting on April 12, 2016, and April 15, 2017, and late planting on May 6, 2016, and May 28, 2017, respectively. Dynamics of non-structural carbohydrates (sucrose, hexose, starch) and key sucrose metabolism enzymes in the leaf subtending to cotton boll were examined including vacuolar acid invertase, cell wall acid invertase, sucrose phosphate synthase and sucrose synthase. The differences between two planting dates were compared for within- boll yield components, fiber quality and sucrose metabolism related characteristics. [Result] Late planting lengthened the period of cotton boll maturation relative to early planting. Boll weight, seed mass per boll, seed index and fiber length were increased, and lint percentage and micronaire were decreased. Late planting reduced the activities of cell wall acid invertase and sucrose synthase responsible for sucrose degradation, and in turn led to the increment of sucrose concentration in the subtending leaves which might enhance the carbon supply to the opposite bolls. [Conclusion] Lower temperature due to late planting could contribute to the more full development of cotton bolls. Late planting is an alternative consideration in improvement of fiber quality in cotton cultural practices.
[Objective] Analyze the influence of climate change on cotton potential productivity in Shihezi region by using decision support system for agrotechnology transfer (DSSAT) model, so as to provide thoughts for sustainable development of cotton planting management. [Method] Based on the field test data in Shihezi area, this study verified the applicability of DSSAT V4.7 model, simulated cotton light and temperature potential productivity and climate production potential, and analyzed the impact of climate change on potential productivity on cotton. [Results] After the adjustment of variety parameters, the simulated value of the model is in good agreement with the experimental measured value, so the model can be used in the study of cotton in Shihezi. In the past 51 years, the average temperature and total solar radiation in the growth period of cotton in Shihezi have shown a very significant trend of increasing, while the rainfall change is not significant and the trend of climate change is partly various in different growth stages of cotton. The actual yield and light and temperature potential productivity of cotton have shown a very significant improving trend; the average value of production potential was 3.6 times than the actual yield, and due to the lack of precipitation in this area, the simulation results of climate production potential are not good. Cotton light and temperature potential productivity has a strong correlation with the meteorological factors in the growth period, and has a very significant positive correlation with the monthly average minimum temperature and the monthly total solar radiation. But the potential productivity has no significant correlation with most monthly rainfall and some monthly average maximum temperature. Therefore, the increasing of temperature and total solar radiation are conducive to the production of cotton. [Conclusion] Climate change has a positive effect on cotton yield and production potential in Shihezi.
[Objective] Cotton(Gossypium hirsutum L.) production was largely affected by soil salinity via inhibiting root growth and its ability of nutrient acquisition, especially phosphorus from soil in Xinjiang. In order to explore the way to improve root growth, nutrient efficiency and cotton yield in saline soil by altering application method of phosphate fertilizer(P) and nitrogen form. [Method] A 3-year experiment was conducted in a drip-irrigated cotton field in Xinjiang, to test the effects of P as broadcast fertilizer, P plus ammonium sulfate as starter fertilizer and P as starter fertilizer combining with application of ammonium at flowering and boll stage. [Result] At seedling stage, cotton shoot biomass and nutrient uptake were enhanced by increasing root length density (RLD) and root surface area (RSA) by 114.3% and 93.7% in 10-20 cm layer and decreasing soil pH in rhizospere by 0.41 units with application of P plus ammonium sulfate (AP34.5) as starter fertilizer compared with P plus ammonium sulfate broadcast (PB34.5) or P plus urea as starter fertilizer (UP34.5). Furthermore, fertigation with ammonium sulfate at flowering and boll stage further decreased rhizosphere pH by 0.64 units, and increased RLD, RSA in 10-20 cm layer. Thereby cotton yield was increased by 11.9% on average for 3 years, and nitrogen fertilizer partial productivity and P use efficiency were increased by 28.5% and 9.2 units compared with PB34.5, respectively. While application with ammonium sulfate plus high P rate (P2O5 69.0 kg·hm-2) as starter fertilizer had no positive effect on the root growth and AM fungi, but improved nutrient use efficiency and cotton yield. [Conclusion] We conclude that application of ammonium sulfate plus superphosphate as seeding fertilizer combining with applying ammonium sulfate at flowering and boll stage can improve phosphate fertilizer efficiency and yield in saline soil.
[Objective] The aim of this research is to explore the possibility of rapid identification of aphid damage to cotton leaves by identifying the hyperspectral image about healthy and aphid damage cotton leaves. [Method] Taking Xinluzao 45 as material, hyperspectral images of healthy and damaged cotton leaves by aphids were obtained, and hyperspectral image information was extracted from interested regions of different cotton samples. Then three descending dimension methods were used to extract hyperspectral feature, and Gray-Level Co-occurrence Matrix to extract image texture feature. Finally a cotton aphids damage diagnostic model was built up. [Result] The prediction accuracy based on all textural samples input Random frog-partial least-square-linear discriminant Function (RF-PLS-LDA) model was 91.49%. The prediction accuracy based on energy data input principal component analysis-loading partial least-square-linear discriminant function (PCA-Loading-PLS-LDA) model was 92.55%. [Conclusion] The second-order statistics (energy) of gray co-occurrence matrix can be used to simplify the model, reduce the computation and improve the stability of prediction. Based on the texture feature vector, the identification of aphid cotton leaves can be realized effectively, which provides a method for the rapid identification of insect pests.
[Objective] The aim of this study is to clarify the competition of the absorption and accumulation of nutrients in cotton by the Bolboschoenus planiculmis (F. Schmidt) T. V. Egorova. [Method] In this experiment, the population densities of B. planiculmis were set at 0, 20, 40, 60, 80, 100 plant·m-2. The contents of phosphorus, potassium, nitrate nitrogen, soluble sugar and soluble protein in cotton seedling stage, bud stage and flowering and boll stage were detected to study the effect of population density of B. planiculmis on the nutrient absorption and accumulation of cotton. [Result] At the cotton seedling stage, when the population density of B. planiculmis was 20 plants·m-2, the soluble protein content of cotton leaves increased significiantly (P<0.05) compared with the CK, but there was no significant difference in other indicators. However, the higher population density of B. planiculmis could reduce the soluble protein content of cotton leaves and increase the soluble sugar content of cotton leaves. At the cotton bud stage, when the population density of B. planiculmis was lower than 40 plants·m-2, the phosphorus content in cotton leaves increased significantly. At the cotton boll stage, the population density of all B. planiculmis populations could reduce the content of potassium and soluble sugar in cotton leaves. When the population density of B. planiculmis was 20 plants·m-2, no significant effects were found on cotton yield. But under other population densities, the cotton yield was significantly reduced. [Conclusion] When the population density of B. planiculmis was higher than 20 plants·m-2, significant effects were found on the absorption and accumulation of cotton nutrients and cotton yield.
[Objective] This study aims to explore the difference of imidacloprid resistance between Aphid gossypii and Aphid craccivora in intercropping field of cotton and peanut, and the mechanism of imidacloprid resistance to A. craccivora, so as to scientifically control these pests and to effectively avoid the rapid development of the resistance to imidacloprid. [Method] Two A. gossypii field populations and two A. craccivora field populations were collected from intercropping field of cotton and peanut in Juye and Linqing county of Shandong province, China. The bioassay experiment with two A. gossypii field populations, the bioassay and synergism experiment in two A. craccivora field populations were performed by the leaf dipping method. In addition, the activities of carboxylesterase (CarE), glutathione S-transferase (GST) and cytochrome P450 monooxygenase (P450) were assayed in the susceptible strain and two field populations of A. craccivora. [Result] Two A. gossypii field populations from Linqing and Juye exhibited moderate levels of resistance to imidacloprid, with the resistance ratios of 43.2- and 54.6-fold, while two A. craccivora field populations from Linqing and Juye showed susceptible and low level of resistance to imidacloprid, with the resistance ratio of 3.7- and 8.3-fold, respectively. According to the synergistic experiments, PBO and DEM significantly synergized imidacloprid in A. gossypii field population of Juye with the synergistic ratio of 3.63- and 1.95-fold, respectively, and TPP had no effect on imidacloprid toxicity. In A. craccivora field population of Linqing, PBO significantly synergized imidacloprid with the synergistic ratio of 3.05-fold, and DEM and TPP had no effect on imidacloprid. Further enzyme activity tests revealed that the activities of P450 and GST in Juye A. craccivora population were significantly higher than susceptible strain, and the activity of CarE had no significant difference between Juye A. craccivora population and susceptible strain. However, the activity of P450 in Linqing A. craccivora population was higher than susceptible strain, and the activities of CarE and GST had no significant differences. [Conclusion] Sensitivity of the two aphids in intercropping field of cotton and peanut to imidacloprid were greatly different, and P450 and GST may play an important role in resistance of A. craccivora to imidacloprid. The results are valuable for reasonable use of pesticides to delay the development of pesticide resistance of two aphids.
Diploid cotton species provide parental (ancestral) species for tetraploid cultivars and are the key germplasm resources for cotton genetic improvement. In addition, diploid cotton species supply excellent materials for mutant library construction and functional genomics. Diploid cotton species originated from Asia- Africa, America, Oceania regions with rich genetic diversity. The tissue culture research mainly involves regeneration of plant organs and cell culture, protoplast culture, somatic culture and fusion. The regenerated plants have been obtained in Gossypium klotzschianum, G. gossypioides, G. arboreum, G. davidsonii, G. raimondii, G. stocksii, G. nelsonii, G. bickii, etc. Among them, regenerated plants in shoot tip culture were only obtained in G. arboreum, G. bickii. Regenerated plantlets in protoplast culture were obtained in G. klotzschianum, G. davidsonii. Interspecific hybrids between G. hirsutum and diploid cotton of G. klotzschianum, G. stocksii and G. bickii were obtained, respectively. The tissue culture systems of diploid cotton were different from each other, and the strategy is similar to that in woody plants. This paper summarized the progresses in related researches and discussed the future research.
Chemical defoliation and ripening is the important premise of machine-harvested cotton, and also the key of agronomic measures technology of machine-harvested cotton. Appropriate and safe harvest aids will improve timing and facilitate harvest of cotton. However, there are only few types of the cotton harvest aids active ingredients, and with serious formulation homogeneity as well as the backward equipments and technologies of cotton harvest aids spraying lead to high impurity content of seed cotton and seriously affects the quality of cotton. In this paper, the research status of harvest aids and its scientific application were reviewed, and the existing problems and solutions of cotton harvest aids were summarized. The prospect and research direction of reducing application efficiency of cotton harvest aids in the future were prospected.
