Genotypic variance in 13C-photosynthate partitioning and within-plant boll distribution in cotton

[Background] Photosynthate partitioning and within-plant boll distribution play an important role in yield formation of cotton; however, if and how they interact to mediate yield remains unclear. The objective of this study was to investigate the genotypic variance in photosynthate partitioning and within-plant boll distribution, with a focus on their interactions with regard to yield and yield components. A field experiment was conducted in the Yellow River region in China in 2017 and 2018 using a randomized complete block design with three replicates. Photosynthate partitioning of three commercial cultivars (DP 99B, Lumianyan 21 and Jimian 169), varying in yield potential, to different organs (including bolls) at early flowering, peak flowering, and peak boll-setting stages, as well as within-plant boll distribution at harvest, and their effects on yield formation were examined.

[Results] Lint yield of Jimian 169 was the highest, followed by Lumianyan 21 and DP 99B. Similar differences were observed in the number of inner bolls and boll weight among the three cultivars. J169 partitioned significantly more photosynthate to the fruit and fiber than Lumianyan 21 and DP 99B and allocated over 80% of assimilates to the inner bolls. Additionally, Lumianyan 21 allocated a higher proportion of photosynthate to bolls and fiber, with 12.5%–17.6% more assimilates observed in the inner bolls, than DP 99B.

[Conclusions] Genotypic variance in lint yield can be attributed to differences in the number of inner bolls and boll weight, which are affected by photosynthate partitioning. Therefore, the partitioning of photosynthate to fiber and inner bolls can be used as an important reference for cotton breeding and cultivation.

[Title] Genotypic variance in 13C-photosynthate partitioning and within-plant boll distribution in cotton

[Authors] NIE Junjun, QIN Dulin, MAO Lili, LIU Yanhui, DONG Hezhong, SONG Xianliang and SUN Xuezhen

Journal of Cotton Research 3, Article number: 15 (2020)

https://doi.org/10.1186/s42397-020-00055-3

Abstracts of “3rd Sino-Pak ICICBB” Changji, China 4-9 September 2019

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Effect of heat stress on cotton (gossypium hirsutuml.) fruit development and seed physical traits

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Authors

muhammad iqbal*, Sami Ul-Allah

Department of Plant Breeding and Genetics, UCA&ES, The Islamia University of Bahawalpur-PAKISTAN

Abstract

Cotton (G. hirsutum) is a crop of tropical and subtropical regions but despite of this, it is highly sensitive to heat stress. Heat stress during flowering and boll growth period cause shedding of flowers and bolls which cause a significant loss in yield. There is only a little information is available which describes the effect of high temperature on development of fruiting parts in cotton. Therefore an experiment was conducted to assess the effect of heat stress on development of reproductive parts. A two year experiment was laid out in randomized complete block design with four replications and three factors during 2013-15. The factors included four sowing dates (1 April, 1 May, 30 May and 30 June) and three cotton cultivars (IUB-222, IUB-13 and IUB-63). Flowering in early sowing (1 April and 1 May) initiated during high temperatures of June and July and these are taken as heat stressed whereas flowering in late sown (30 May and 30 June) initiated during optimum temperatures of august and September and these were taken as non-stressed. Data was collected for daily mean temperature, days taken to initiation of square development, days taken from square to flower, days taken from flower to boll open, boll retention, boll size, seed weight, seed volume, seed density and seed surface area. The  analysis of variance revealed  that significant (P≥0.05) genotypic and sowing date differences existed for all studied traits and genotype × sowing date interaction was also significant (P≥0.05). The results revealed that heat stress decreased the days taken for initiation of square development, days taken from square to flower and flower to boll open, boll retention, and boll size. Due to reduction in boll retention and boll size there was reduction in the yield. All seed traits seed weight, seed volume, seed density and seed surface area reduced with heat Correlation analysis revealed that mean daily temperature had significant (P≥0.05) negative correlation with all the traits studied. The genotype IUB-63 performed best and was least affected by the heat stress, so proved as heat tolerant genotype. It is conclude from the results that fruit development traits and seed physical traits can be an effective selection criteria for heat stress breeding.

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Impact of potassium application on plant biomass and yield of cotton under agro-climatic conditions of southern punjab, pakistan

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Authors

Dil Baugh Muhammad*, Muhammad Naveed Afzal*, Muhammad Tariq* and Zahid Iqbal Anjum**

*Agronomy Section, Central Cotton Research Institute, Multan, Pakistan

** Cytogenetic Section, Central Cotton Research Institute, Multan, Pakistan

Abstract

The transgenic cotton cultivars require higher potassium and its deficiency during peak bloom and boll setting period adversely affects the yield potential. The two years field experiments were conducted at Central Cotton Research Institute, Multan to investigate the potassium requirement of transgenic cotton. In experiment-I, three potassium doses

i.e. 0, 100 and 200 kg K2O ha-1  were applied at sowing and splitted into

two equal splits of 100 at pre-plant and 45 DAS and four equal splits of 200 at pre-plant, 30, 45 and 60 DAS were tested. While in experiment-II, the impact of four foliar sprays of 2% K2O was evaluated in combination with pre-plant application of 0, 100 and 200 K2O ha-1 for seed cotton yield and yield components. The results revealed that all the potassium levels produced higher seed cotton yield and plant biomass over control. However, split application of potassium irrespective of potassium level was most promising over full pre-plant application for plant height, total fruit production, no. of bolls, boll weight, seed cotton yield and plant biomass. Furthermore, it was also observed that pre-plant application of 200 kg K2O ha-1  along with four foliar sprays of 2% K2O produced the highest figures for plant structure, yield components and seed cotton yield over 0 and 100 kg K2O ha-1. Therefore, it is recommended  that cotton must be fertilized with four splits of 200 kg ha-1 over pre-plant application and four foliar sprays of 2%  K2O can  further increase  the profit margin from pre-plant potassium application.

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Evaluation of genetic diversity in short duration cotton (Gossypium hirsutum L.)

[Background] Cotton (Gossypium hirsutum L.) is an important fiber crop in Bangladesh. Genetic diversity among the genotypes of a germplasm has a great importance for cotton breeding. An experiment was carried out at the experimental field of Cotton Research, Training and Seed Multiplication Farm, Sreepur, Gazipur during the cropping season of 2015–2016 with 100 genotypes to evaluate genetic diversity of cotton genotypes for short duration using field performance.

[Results] The genotypes under study were grouped into ten clusters through multivariate analysis using GENSTAT-5. Cluster III contained maximum number of genotypes (16) while cluster X contained the least number of genotypes (7). The inter cluster distances were larger than intra cluster distances in all cases suggesting wider genetic diversity among the genotypes of different clusters. The maximum and minimum inter cluster distances were observed between clusters II and V (10.78) and clusters VIII and IX (3.30), respectively. The results indicated diverse and close relationship among the genotypes of those clusters. Earliness index, single boll weight and days to boll opening showed the higher contribution to the genetic divergence among 19 characters.

[Conclusion] Based on the results of genetic diversity and earliness index, the genotypes from cluster II could be used as parent in hybridization program for the development of short duration cotton variety.

Evaluation of genetic diversity in short duration cotton (Gossypium hirsutum L.)

AKTER T., ISLAM A. K. M. A., RASUL M. G., KUNDU S., KHALEQUZZAMAN and AHMED J. U.
Journal of Cotton Research. 2019; 2:1.
https://doi.org/10.1186/s42397-018-0018-6

Genetic diversity and population structure of Gossypium arboreum L. collected in China

[Background] Gossypium arboreum is a diploid species cultivated in the Old World. It possesses favorable characters that are valuable for developing superior cotton cultivars.

[Method] A set of 197 Gossypium arboreum accessions were genotyped using 80 genome-wide SSR markers to establish patterns of the genetic diversity and population structure. These accessions were collected from three major G. arboreum growing areas in China. A total of 255 alleles across 80 markers were identified in the genetic diversity analysis.

[Results] Three subgroups were found using the population structure analysis, corresponding to the Yangtze River Valley, North China, and Southwest China zones of G. arboreum growing areas in China. Average genetic distance and Polymorphic information content value of G. arboreum population were 0.34 and 0.47, respectively, indicating high genetic diversity in the G. arboreum germplasm pool. The Phylogenetic analysis results concurred with the subgroups identified by Structure analysis with a few exceptions. Variations among and within three groups were observed to be 13.61% and 86.39%, respectively.

[Conclusion] The information regarding genetic diversity and population structure from this study is useful for genetic and genomic analysis and systematic utilization of economically important traits in G. arboreum.

Genetic diversity and population structure of Gossypium arboreum L. collected in China
JIA Yinhua, PAN Zhaoe, HE Shoupu, GONG Wenfang, GENG Xiaoli, PANG Baoyin, WANG Liru and DU Xiongming
Journal of Cotton Research. 2018; 1:11.
https://doi.org/10.1186/s42397-018-0011-0

Map-based cloning of a recessive gene v1 for virescent leaf expression in cotton (Gossypium spp.)

[Background] Virescence, as a recognizable phenotype in the early development stage of cotton, is not only available for research on chloroplast development and photosynthesis but also for heterosis exploitation in cotton.

[Methods] In current study, for fine mapping of virescent-1 (v1) in cotton, three populations with a total of 5 678 individuals were constructed using T582 which has the virescent trait. Tobacco rattle virus, TRV1 and TRV2 (pYL156), were used as vectors for the virus-induced gene silencing (VIGS) assay.

[Results] The v1 gene was fine-mapped to a 20 kb interval on chromosome 20 of tetraploid cotton. We identified only one candidate gene with four single nucleotide polymorphisms between parents, among which the single nucleotide polymorphism at the position of 1 082 base pair caused the change of amino acid residue from Arg (3–79) to Lys (T582). The relative expression of the candidate gene in virescent plants was extensively lower than that in normal plants. Nullification of the gene by VIGS significantly turned the green leaf of normal cotton plants into yellow. We named this candidate gene as GhRVL.

[Conclusions] This study will facilitate the further research on virescent formation, and will be useful for breeding of hybrid cottons.

Map-based cloning of a recessive gene v1 for virescent leaf expression in cotton (Gossypium spp.)
ZHANG Youping, WANG Qiaolian, ZUO Dongyun, CHENG Hailiang, LIU Ke, ASHRAF Javaria, LI Simin, FENG Xiaoxu, YU John Z. and SONG Guoli
Journal of Cotton Research. 2018; 1:10.
https://doi.org/10.1186/s42397-018-0009-7

Identification and screening of nitrogen-efficient cotton genotypes under low and normal nitrogen environments at the seedling stage

[Background] Large quantities of nitrogen (N) fertilizer applied to cotton cropping systems support high yields but cause adverse environmental impacts such as N2O emission and water eutrophication. The development of cotton cultivars with higher N use efficiencies suitable for low-N conditions is therefore important for sustainable production. In this study, we evaluated 100 cotton genotypes in 2016 for N use efficiency and related traits at the seedling stage.

[Methods] Sand culture experiment was conducted with low N levels (0.01 g·kg−1) or normal N levels (0.1 g·kg−1). We investigated plant height, SPAD value (soil plant analysis development chlorophyll meter), dry weight, N accumulation, N utilization efficiency, and N uptake efficiency. Through descriptive statistics, principal component analysis and heatmap clustering analysis, we confirmed the evaluation index system of N-efficient genotypes and the classification of N-efficient genotypes.

[Results] Significant differences were observed among N levels and genotypes for all agronomic traits and N levels. Coefficients of variation varied greatly and ranged from 6.7~28.8 and 7.4~20.8 under low-N and normal-N treatment, respectively. All traits showed highly significant positive correlations with each other, except SPAD value. The principal components under both N levels were similar, showing that total dry weight, aboveground dry weight, total N accumulation, and N uptake efficiency were important components. We confirmed these four traits as suitable screening indexes for low N tolerance. Based on the results of heatmap clustering and scatter diagram analysis of N efficiency value, 10 genotypes were found low-N tolerant, in which five varieties were inefficient under both low and normal N conditions, while four varieties were found efficient under low-N conditions but inefficient under normal-N conditions. Only one variety was efficient under both low and normal-N conditions. Meanwhile, 20 genotypes were identified as low-N sensitive ones, in which 19 genotypes were inefficient under low-N conditions but efficient under normal-N conditions, one variety was inefficient under both low and normal-N conditions.

[Conclusion] We preliminarily identified Kashi as a low-N tolerant and N-efficient cotton genotype, and CCRI 64 as a low-N sensitive and N-inefficient cotton genotype. Further studies should be carried out to verify the yield and heritability effect of specific genotypes in the field.

Identification and screening of nitrogen-efficient cotton genotypes under low and normal nitrogen environments at the seedling stage
ZHANG Hengheng†, FU Xiaoqiong†, WANG Xiangru, GUI Huiping, DONG Qiang, PANG Nianchang, WANG Zhun, ZHANG Xiling and SONG Meizhen
†Contributed equally
Journal of Cotton Research. 2018; 1:6.
https://jcottonres.biomedcentral.com/articles/10.1186/s42397-018-0006-x

Analysis of short fruiting branch gene and Marker-assisted selection with SNP linked to its trait in upland cotton

[Background] With the rapid development of genomics, many functional genes have been targeted. Molecular marker assisted selection can accelerate the breeding process by linking selection to functional genes.

[Methods] In a study of upland cotton (Gossypium hirsutum L.), the F2 segregated population was constructed by crossing X1570 (short branches) with Ekangmian-13 (long branches) to identify the short fruiting branch gene and marker-assisted selection with SNP(Single Nucleotide Polymorphisms, SNP) linked to its trait.

[Result] The result demonstrated that linked SSR marker BNL3232 was screened by BSA(Bulked segregant analysis, BSA) method; one SNP locus was found, which was totally separated from the fruiting branches trait in upland cotton.

[Conclusion] It was verified that this SNP marker could be used for molecular assisted selection of cotton architecture.

Analysis of short fruiting branch gene and Marker-assisted selection with SNP linked to its trait in upland cotton
ZHANG Youchang, FENG Changhui, BIE Shu, WANG Xiaogang, ZHANG Jiaohai, XIA Songbo and QIN Hongde
Journal of Cotton Research. 2018; 1:5.
https://doi.org/10.1186/s42397-018-0001-2

Hypoxia tolerance studies for yield, fiber and physiological traits in cotton (Gossypium hirsutum L.)

[Background] Hypoxia tolerance studies in cotton are very rare in Pakistan. Unpredicted and excessive rainfalls result in severe losses to cotton crop in many regions of the country due to lack of hypoxia tolerance in current cotton varieties. The genotypes that can tolerate flooding are not reported earlier. The studies were conducted to explore hypoxia tolerance in local germplasm which will help to develop hypoxia tolerant cotton varieties.

[Method] An experiment with randomized complete blocks was designed to study the hypoxia tolerance in different cotton varieties. The genotypes were given two treatments i.e., water logged and non-water logged conditions.

[Results] The genotypes showed significant variability for yield, fiber and physiological traits. The hypoxia studies revealed that there is significant reduction for plant height in water sensitive genotype LRA-5166. The genotype MNH-786 showed better yield and MNH-556 showed superior ginning outturn percentage under water logged conditions. Staple length, strength and micronaire values also decreased under hypoxia. Similar pattern of negative effects were observed for Chlorophyll a, b contents and chl a/b ratio. Two hypoxia tolerant cultivars CIM-573 and MNH-564 had significantly higher chlorophyll a (1.664, 1.551) than other cultivars under both normal and waterlogged conditions. There was a significant decrease in total free amino acids in all genotypes/cultivars due to waterlogging. Free amino acid contents were significantly higher in two waterlogging sensitive cultivars, CEDIX and N-KRISHMA, than other cultivars under both non-waterlogged and waterlogged conditions. Waterlogging caused a significant reduction in shoot soluble proteins and increase in shoot proline. The genotype LRA-5166 was the highest in shoot soluble proteins content and showed significant decrease in shoot proline.

[Conclusions] With respect to yield MNH-786 showed better results and regarding ginning outturn percentage MNH-556 exhibited superior performance. The genotypes CIM-573 and MNH-564 showed higher chlorophyll a values. The above said genotypes may be exploited for further studies related to hypoxia tolerance.

Hypoxia tolerance studies for yield, fiber and physiological traits in cotton (Gossypium hirsutum L.)
HUSSAIN Altaf, FAROOQ Jehanzeb, AHMAD Saghir, MAHMOOD Abid, SADIQ M. Attiq, ZAFAR Ullah Zafar and ATHAR Habib-Ur-Rehman

Journal of Cotton Research. 2018; 1:8.
https://doi.org/10.1186/s42397-018-0008-8