[Objective] The aim of this study was to analyze the genetic diversity of morphological traits, yield, and fiber quality characteristics in introduced upland cotton resources so as to provide references for the exploration and utilization of superior germplasm. [Methods] A total of 213 Gossypium hirsutum accessions introduced from Central Asia were planted in Aksu, Xinjiang, from 2023 to 2024. Twenty-six traits were measured. Through analysis of the coefficient of variation and genetic diversity index, correlation analysis, cluster analysis, principal component analysis, and comprehensive evaluation, superior germplasms were identified and screened. [Results] The genetic diversity indices of 13 traits (plant type, stem color, main stem hardness, stem hair number, leaf color, corolla color, anther color, style length, fruiting branch type, boll arrangement, boll type, ease of boll opening, and color of short fiber) ranged from 0.09 to 1.04. For the other 13 traits (growth period, plant height, first fruiting branches node, number of fruiting branches per plant, number of bolls per plant, boll weight, lint percentage, seed index, upper half mean length, uniformity index, breaking tenacity, breaking elongation, and micronaire), the coefficients of variation ranged from 1.37% to 19.20%, and the genetic diversity indices ranged from 1.85 to 2.11. Among them, the genetic diversity indices of 12 traits were greater than 2. Plant height showed highly significant or significant positive correlations with the number of fruiting branches per plant and lint percentage. Boll weight was significantly positively correlated with seed index, upper half mean length, and uniformity index. Cluster analysis classified the materials into six major groups at a Euclidean distance of 9.5. Groups Ⅱ and Ⅵ exhibited superior overall performance. From these two groups, 31 materials met the Type Ⅲ fiber quality standard, and one material met the Type Ⅱ standard. Group Ⅱ contained the highest number of resources with high boll weight (≥ 7 g). Principal component analysis extracted five principal components, with a cumulative contribution rate of 73.522%. The top ten materials based on comprehensive evaluation scores were 13TJ272 selected line, 13TJ186 selected line, Jimian 5, 13TJ111 selected line, 12TJ11 selected line, 17W1-17, 12TJ15 selected line 1, 13TJ229 selected line, 17W1-3, and 13TJ207. [Conclusion] The 213 introduced upland cotton resources exhibit relatively rich genetic diversity. Ten materials with high comprehensive scores were screened, which can serve as genetic improvement materials for breeding new upland cotton varieties.
[Objective] This study aimed to explore the application potential of cotton-soybean intercropping in addressing prominent issues such as the intense conflict between grain and cotton for land, as well as soil degradation, in the cotton-growing areas of the Yellow River Basin. [Methods] The experiments were conducted in Binzhou City, Shandong Province, from 2023 to 2024. Different treatments were set up, including cotton monocropping (CK1), soybean monocropping (CK2), and five row ratio configurations of cotton-soybean intercropping (2 rows of cotton intercropped with 2 rows of soybean, 2 rows of cotton intercropped with 3 rows of soybean, 2 rows of cotton intercropped with 4 rows of soybean, 4 rows of cotton intercropped with 4 rows of soybean, and 4 rows of cotton intercropped with 6 rows of soybean, denoted as 2||2, 2||3, 2||4, 4||4, and 4||6). The effects of these intercropping patterns on soil nutrient content, crop agronomic traits and yield, fiber quality, land equivalent ratio (LER), and comprehensive economic benefits were studied. [Results] Compared with monocropping, the intercropping system increased the contents of alkali-hydrolyzable nitrogen and available phosphorus in the 0-20 cm soil layer between cotton rows. The 4||6 intercropping pattern was beneficial for increasing the soil organic matter content and total humus content in the 0-20 cm and 20-40 cm soil layers between cotton rows and soybean rows. At the boll-opening stage, the number of mature bolls per plant under the five intercropping treatments was significantly lower than that under CK1. At the maturity stage, compared with monocropping, the number of nodes and effective branches per plant of intercropped soybeans decreased. Compared with CK1, the intercropping patterns led to a reduction in the number of bolls per plant and boll weight; however, the seed cotton yield increased due to the higher harvest density. In 2023, the 4||6 treatment achieved the highest seed cotton yield, which was significantly 19.34% higher than that of CK1. In 2024, the 2||3 treatment had the highest seed cotton yield, showing a significant increase of 15.20% compared with CK1. There were no significant differences in cotton fiber quality indicators among different treatments. Compared with CK2, the soybean yield under the 4||4 and 4||6 patterns increased by 1.58% and 12.00%, respectively in 2023. In 2024, the soybean yield under the 2||3, 4||6, and 4||4 treatments increased by 17.76%-26.18%. In 2023, the 4||6 treatment had the highest LER (1.15) and the highest net income. In 2024, the 2||3 treatment achieved the highest LER (1.19) and the highest net income. [Conclusion] Cotton-soybean intercropping was beneficial for increasing seed cotton yield, land use efficiency, and net income. Among the tested intercropping patterns, the 4||6 and 2||3 patterns showed greater promotion potential in the cotton-growing areas of the Yellow River Basin.
[Objective] This research aimed to study the effects of different amounts of carbon-containing organic fertilizer on cotton biomass, nutrient accumulation, yield, and soil nutrient content to provide a reference for local cotton production. [Methods] From 2022 to 2023, field experiments were conducted in Wusu City, Tacheng Prefecture, Xinjiang. Six treatments were set up: no fertilization (CK), no application of carbon-containing organic fertilizer (C0), and application of carbon-containing organic fertilizer at 400 kg·hm-2, 800 kg·hm-2, 1 200 kg·hm-2, and 1 600 kg·hm-2 throughout the cotton growth period (referred to as C400, C800, C1200, C1600, respectively). The effects of different amounts of carbon-containing organic fertilizer on the aboveground dry matter mass; accumulation and distribution of nitrogen, phosphorus, and potassium of cotton; yield; and soil nutrient content were analyzed. [Results] From 2022 to 2023, the dry matter mass, the accumulation of nitrogen, phosphorus, and potassium of cotton straw, fiber, cottonseed, and aboveground parts; and seed cotton yield all showed an overall upward trend with the increase of carbon-containing organic fertilizer application. The proportion of dry matter mass in fiber under C1600 treatment was higher than that in the other treatments. CK treatment exhibited the lowest proportion of nitrogen accumulation in straw and fiber but the highest proportion of nitrogen accumulation in cottonseed. Compared with C0 treatment, the application of carbon-containing organic fertilizer showed no obvious effect on the proportion of phosphorus and potassium accumulation in various aboveground parts of cotton. The seed cotton yield under C1600 treatment was highest, significantly increasing by 53.79%-83.34% and 8.95%-11.77%, respectively, compared with CK and C0 treatments. After harvesting cotton in 2023, the contents of organic carbon, nitrate nitrogen, ammonium nitrogen, available phosphorus, and available potassium in the 0-20 cm soil layer, as well as the content of available potassium in the 20-40 cm soil layer, all showed an upward trend with the increasing application rate of carbon-containing organic fertilizer. [Conclusion] Under the conditions of this experiment, the application of 1 600 kg·hm-2 carbon-containing organic fertilizer is beneficial for increasing soil nutrient content, promoting cotton's uptake of nitrogen, phosphorus, and potassium; increasing cotton aboveground dry matter mass; and achieving the highest seed cotton yield.
[Objective] This study aims to increase cotton yield and water use efficiency in southern Xinjiang under limited water resources. [Methods] The experiment was conducted using the cotton variety Tahe 2. In 2023, three spring drip irrigation quotas were set: T1 (600 m3·hm-2), T2 (900 m3·hm-2), and T3 (1 200 m3·hm-2). In 2024, a conventional spring irrigation quota of 2 250 m3·hm-2 was added as the control(CK). The effects of different drip irrigation quotas on soil water-salt changes, cotton physiological growth, and yield were studied. [Results] In the two-year experiment, the soil water storage in the 0-60 cm layer under the T2 treatment was the highest at all cotton growth stages, increasing by 1.01%-14.88% compared to T1, and by 1.25%-15.26% compared to T3. In 2024, the soil water storage in the 0-80 cm layer for all treatments followed the order of T3 > CK > T2 > T1. In 2023, the electrical conductivity in the 0-60 cm layer under T2 and T3 was lower than that of T1 by 6.08%-19.26% and 19.86%-32.96%, respectively. In 2024, the electrical conductivity in the 0-80 cm layer under T2 and T3 was reduced by 3.33%-25.81% compared to T1. Compared with T1 and T2, the T3 treatment showed a 10.54-19.95 percentage points higher seedling emergence rate, a 9.23%-23.54% increase in plant height, an 11.11%-23.87% increase in leaf area index, and a 26.32%-59.11% increase in fresh weight at the flowering and boll stages. The boll weight under the T3 treatment was 2.86%-8.51% higher than that under T1 and T2, and the seed cotton yield increased by 2.39%-10.24%. In 2024, compared to CK, the seedling emergence rate under T3 was 1.21 percentage points higher, and plant height, leaf area index, and fresh weight at the flowering and boll stages increased by 3.67%, 6.69%, and 0.55%, respectively. Compared to CK, the seed cotton yield under T1 was significantly reduced by 8.55%, while the yields under T2 and T3 did not show any significant difference. The irrigation water use efficiency for T1, T2, and T3 was significantly higher than that of CK, increasing by 27.38%, 24.30%, and 22.87%, respectively. The TOPSIS comprehensive evaluation showed that the drip irrigation method performed better, with 1 200 m3·hm-2 being the optimal irrigation quota for cotton fields under drip irrigation. [Conclusion] It is recommended to adopt a 1 200 m3·hm-2 drip irrigation quota in spring in southern Xinjiang, as this irrigation amount is beneficial for increasing soil water storage, promoting cotton growth, and improving seed cotton yield.
[Objective] Gossypium aridum exhibits excellent stress tolerance. Plant homeodomain (PHD) proteins play a crucial role in regulating plant responses to abiotic stress. This study aimed to mine PHD genes in the whole genome of G. aridum, and analyze their expression patterns under abiotic stress. [Methods] G. aridum genome was mined for PHD using bioinformatics methods. The physicochemical properties, conserved domains and motifs, phylogenetic relationships of PHD proteins, cis-acting elements and transcription factor binding sites in the promoter region were predicted and analyzed. The expression levels of GarPHD genes under salt, drought, and low-temperature stresses were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR). [Results] A total of 38 GarPHD genes were identified in G. aridum. The PHD domain of GarPHD proteins contains the consistent sequence: X(0-1)-C-X(1-2)-C-X(8-13)-C-[DESANQ]-X(1-2)-C-X(4)-H-X(2)-C-X(9-16)-[WYF]-X-C-X(2)-C. PHD proteins of G. aridum, G. tomentosum, and G. barbadense were divided into 5 subgroups. The promoter regions of GarPHD contain cis-acting elements related to growth and development, plant hormones, and stress responses, as well as binding sites for 33 transcription factors. The qRT-PCR analysis revealed significant changes in the expression levels of certain GarPHD genes in response to salt, drought, and low-temperature stress. Specifically, GarPHD19 was found to respond to both low-temperature and drought stress, GarPHD31 responded to both salt and drought stress. [Conclusion] Thirty-eight PHD genes were identified in G. aridum. Some GarPHD responded to salt, drought, and low-temperature stress, which lays the foundation for further research on the function of GarPHD genes.
[Objective] The study aims at investigating the optimal transformation system to enhance genetic transformation efficiency of cotton shoot tips. [Methods] The shoot tips of Baimian 1 seeds were used as the explant. Different concentrations of ethylenediaminetetra-acetic acid(EDTA), various water bath treatment times, and different concentrations of bacterial suspension were set during the infection stage. During the co-culture stage, six exogenous additives (lanthanum chloride, EDTA, salicylic acid, thidiazuron, zeatin, and silver nitrate) at varying concentrations were introduced. During the screening stage, the concentrations of spectinomycin and ratios of various plant growth regulators (kinetin, naphthalene acetic acid, 6-benzylaminopurine, indole butyric acid, and 2,4-dichlorophenoxyacetic acid) were adjusted. The effects of these treatments on the transient transformation efficiency, germination rate, seedling survival rate, and positive rate of cotton shoot tips were analyzed. [Results] During the infection stage, adjusting the OD600 of bacterial suspension to 0.7 and pre-treating shoot tips with 100 μmol·L-1 EDTA in a water bath for 15 min can significantly improve the transient transformation efficiency (28.09%). During the co-culture phase, adding 1.5 mg·L-1 thidiazuron obtained the highest transient transformation efficiency (41.47%) and a relatively high germination rate (32.79%). In the screening phase, adding 200 mg·L-1 spectinomycin resulted in a higher seedling survival rate (32.44%) and the highest positive rate (19.97%); 1 mg·L-1 6-benzylaminopurine + 0.1 mg·L-1 naphthalene acetic acid treatment yielded a significantly higher germination rate (34.73%) than other plant growth regulator combinations. Under the optimized conditions described above, the transformation efficiency of cotton shoot tips reached 7.62%, with a positive rate of 18.52%. [Conclusion] The cotton genetic transformation system has been optimized, providing a reference for further improving the transformation efficiency of cotton shoot tips.
[Objective] This research aimed to investigate the effects of different pruning methods on the content of storage substances in upland cottonseed. [Methods] A field trial was conducted in Kashgar Prefecture, Xinjiang, in 2023, using a split-plot design. The main plots consisted of two cotton varieties (J8031 and Yuanmian 8), while the subplots involved different pruning treatments: retaining 3, 5, 7, or 9 bolls per plant from the flowering and boll-setting stage to harvest (T1, T2, T3, and T4 treatments); removing vegetative branches during the budding stage(T5); removing axillary buds during the flowering and boll-setting stage (T6); removing vegetative branches from the initial flowering stage to the flowering and boll-setting stage (T7); removing empty branches during the late flowering stage and early boll-opening stage (T8); and topping during the full flowering stage to boll opening stage (T9). No pruning was used as the control treatment (CK). The contents of total protein, 19 amino acids, total fat, 25 fatty acids, and gossypol in cottonseeds were measured under different treatments. [Results] Under T1 to T9 treatments, the total protein and total fat contents in cottonseed of J8031 and Yuanmian 8 showed no significant difference compared with CK. Compared with CK, T5 treatment significantly increased the contents of phenylalanine, arginine, tyrosine, proline, and glycine in J8031, as well as the contents of methionine, phenylalanine, arginine, tyrosine, proline, cysteine, and hydroxyproline in Yuanmian 8, significantly reduced the content of methionine in J8031. T6 treatment significantly increased arginine, tyrosine, and serine contents in J8031, as well as phenylalanine, tyrosine, and hydroxyproline contents in Yuanmian 8, significantly reduced methionine content in J8031. Compared with CK, the contents of stearic acid, heneicosanoic acid, and linoleic acid in J8031, and the contents of palmitic acid and eicosadienoic acid in Yuanmian 8 all significantly increased under T2 treatment. The contents of myristic acid, arachidic acid, eicosapentaenoic acid, and oleic acid in J8031 under T7 and T9 treatments significantly decreased. Under T1 treatment, the contents of palmitic acid, hexanoic acid, eicosapentaenoic acid, and eicosenoic acid significantly increased in Yuanmian 8; while the oleic acid content in J8031 and Yuanmian 8 significantly decreased. Under T7 and T8 treatments, the contents of heneicosanoic acid, linoleic acid, palmitoleic acid, oleic acid, and eicosenoic acid in Yuanmian 8 significantly decreased. Under T3, T5, T7, T8, and T9 treatments, both total (-)/(+)-gossypol and free (-)/(+)-gossypol contents in J8031 were significantly higher than that in CK. Compared with CK, total (-)/(+)-gossypol content in Yuanmian 8 significantly increased under T8 treatment, while free (-)/(+)-gossypol content significantly decreased under the nine treatments from T1 to T9. [Conclusion] Compared with CK, pruning treatment had no significant effect on the total protein and total fat contents in cottonseed of J8031 and Yuanmian 8, but significantly influenced the contents of certain amino acids, certain fatty acids, and gossypol.
