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

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

Light and simplified cultivation of cotton, an approach of global relevance?

A paper recently published about China

In a recent visit to Shadong Cotton Research Institute, I was introduced to the approach of carrying out new cultivation techniques destined to adapt to the current context of labor scarcity and high production costs for cotton production in China. This approach is being elaborated in a recent paper by the research team led by Prof. Dong HeZhong who is also a member of the Executive Committee of our Association.

The paper titled ‘Technologies and theoretical basis of light and simplified cotton cultivation in China’ is available here. The paper is not in open access, if needed, the corresponding author can be contacted (donghezhong@163.com ).

To me, the paper is interesting at least for two reasons. One, it gives a good view on how cotton is being cultivated in China, through an intensive way, in terms of production chemicals and knowledge.

Machine to sow single seed of cotton after garlic
Machine to sow single seed of cotton after garlic

Second, it provides scientific basis to sustain why some techniques, already finalized along the approach followed, work.

Plantlet obtained from single seed sowing are shorter, stronger and have a more rooting system
Plantlet obtained from single seed sowing are shorter, stronger and have a more developed rooting system
Industrial nursery can prevent farmers from producing plantlets by themselves
Industrial nursery can prevent farmers from producing plantlets by themselves

Semi-mechanized transplanting

Semi-mechanized transplanting

Potential relevance to other contexts?

The issue of producing cotton in a competitive way, notably against alternative crops in a same country, is common to many producing countries. The concern to decrease costs is global however cotton cultivation is intensive in capital and/or in chemical use. The concern to reduce labor cost is particularly felt in countries with production which is little mechanized, if not manual.

China is probably producing cotton by farms of the smallest size in the world, with average farm size of less than one hectare in traditional production regions of Yellow River and Yangtze River valleys. The way China has succeeded to conceive adapted mechanization, although there are still many challenges ahead, is worth consideration in many developing countries where farmers grow cotton on a few hectares each.

Where cotton is grown under irrigation in large areas, the various techniques China has been developing if not adopting in its North-western region is worth of consideration as well. The combination of sowing, fertilizing and posing mulching film is an example.

Machine for several operations in one time
Machine for several operations in one time

Environmental considerations worth being more explicitly highlighted as well?

Nowadays, there is a worldwide consensus on reducing at most the potential negative impacts in agricultural production in general, not only in cotton cultivation. To capture furthermore the attention on the Light and Simplified Cultivation approach, probably the potential environmental impacts that could result, either positive or negative, should be addressed too.

Seventh ‘Asian Cotton Research and Development Network’ Meeting, 15-17 Sept 2017, Nagpur India.

The Seventh Meeting of the Asian Cotton Research and Development Network was held at Nagpur during 15-17 September 2017. The Indian Society for Cotton Improvement (ISCI), Mumbai hosted the meeting together with the ICAR-CICR (Central Institute for Cotton Research), Nagpur and ICAR-CIRCOT (Central Institute for Research on Cotton Technologies). The main theme of the meeting was PRODUCING QUALITY FIBRE & DOUBLING COTTON FARMERS INCOME. Cotton researchers from public and the private sector participated. Dr. C. D. Mayee, President, Indian Society for Cotton Improvement, was the chairman, of the organizing Committee. The meeting elected Dr. Prashant G. Patil as Chairman of the Network until the next meeting. Eminent cotton experts i.e., Dr. Timorthy Dennehy, Dr Judith Brown, Dr Albert Santos from US; Dr Derek Russell from Australia, Dr Negm from Egypt and several senior research leaders from India and Bangladesh attended the meeting. The proceedings, recommendations, presentations and abstracts of the meeting can be accessed here.

Seventh Meeting of the ACRDN

Proceedings are available

The Seventh Meeting of the Asian Cotton Research and Development Network was held at Nagpur, India during 15-17 September 2017. The Indian Society for Cotton Improvement (ISCI), Mumbai hosted the meeting together with the ICAR-CICR (Central Institute for Cotton Research), Nagpur and ICAR-CIRCOT (Central Institute for Research on Cotton Technologies).

The main theme of the meeting was  “PRODUCING QUALITY FIBRE & DOUBLING COTTON FARMERS INCOME.” Cotton researchers from public and the private sector participated. Dr. C.D. Mayee, President, Indian Society for Cotton Improvement, was the Chairman of the Organizing Committee. The meeting elected Dr. Prashant G. Patil as Chairman of the Network until the next meeting. Eminent cotton experts like Dr. Timorthy Dennehy, Dr Judith Brown, Dr Albert Santos from US; Dr Derek Russell from Australia; Dr Negm from Egypt and several senior research leaders from India and Bangladesh attended the meeting.

The proceedings, recommendations, presentations and abstracts of the meeting are now available at the ICAC website.

SCREENING OF SOMATIC MUTANTS FOR RESISTANCE TO VERTICILLIUM WILT IN GOSSYPIUM HIRSUTUM L.

Abstract                                                                         Back to Table of contents

Growth and phytotoxin-producing conditions of the Tianman isolate of V. dahliae were studied showing that filtrates of the pathogen cultures were able to make cotton seedlings wilt or die.  Furthermore, the filtrates decreased seed germination rate, increased penetrability of leaf discs and reduced the survival rate of callus.  Large differences existed between resistant and susceptible varieties in the above aspects.

Callus formed from mutated explants was used to select tolerant mutants using toxic filtrates as the screening factor.  Some tolerant cell lines and tolerant plants were obtained.

Thirty two plantlets were obtained from all the tolerant cell lines, and their resistance was tested.  On the medium with toxic filtrates, the tolerant plantlets showed low symptoms of the disease.

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INHERITANCE AND GENETIC EFFECT OF CLEISTOGAMY IN UPLAND COTTON

Abstract                                                                         Back to Table of contents

Generally Gossypium hirsutum and G. barbadense flowers are chasmogamous. A true-breeding, cleistogamous line was derived from the F2 population of an interspecific cross between G. hirsutum and G. barbadense.  The inheritance of cleistogamy was studied in F1 and F2 generations of two crosses.  Cleistogamy is a variable character that changes with genotypic background and environmental factors or time of flowering.  The results suggest that cleistogamy is governed by a single recessive gene in the G. hirsutum upland background with indications that modifying factors influence the expression of cleistogamy.  A preliminary test showed no apparent deleterious effect due to the cleistogamous trait on agronomic performance in upland cotton.

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IDENTIFICATION OF THE KARYOTYPE OF GOSSYPIUM BICKII PROKH.*

Introduction                                                                Back to Table of contents

Chromosome spreads from the root tips of Gossypium bickii Prokh. were analysed to establish an accurate karyotype.  Of 122 cells with clear chromosomes, about 60% (73) did not show any satellites.  Nine exhibited four visible satellites, one small pair associated with the homologues of chromosome four and a larger pair with those of chromosome 13…

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DEVELOPMENT OF MAR COTTON GERMPLASM WITH MORPHOLOGICAL MUTANT TRAITS

Abstract                                                                         Back to Table of contents

Higher levels of resistance to insects, plant pathogens, and abiotic stresses are needed in cotton cultivars to maintain plant health and increase yield.  The multi-adversity resistance (MAR) program has been successful in transferring and developing cotton germplasm with morphological mutant traits known to impart host resistance to pests.  Thirteen experiments were conducted over three growing seasons (1990-92) in Texas to quantify yield, earliness, and fiber quality traits of nine MAR strains with the mutant traits frego bract, nectariless, okra-shaped leaf, and red plant color.  Tests included the MAR mutant strains, advanced MAR-6 strains and cultivars representing the MAR-1 to MAR-6 gene pools.  Performance of most mutant strains was similar for all measured traits in either glabrous or hairy backgrounds.  Yields of the frego bract and nectariless strains were similar to those of non-mutant MAR-6 strains, while the okra leaf and red plant strains produced lower yields.  Nectariless and okra-shaped leaf strains were earlier in maturity, and the red plant strains matured later than MAR-6 strains.  Okra leaf strains produced a longer fiber than the other mutant strains and non-mutant cultivars.  The frego bract, okra leaf and red plant strains produced a stronger fiber compared to the Tamcot cultivars. Mutant strains generally were similar in fiber uniformity, elongation, and micronaire, but the red plant strains produced a higher micronaire value.  The MAR mutant strains have simultaneous genetic gains for many traits, and will provide new sources of host-plant resistance to cotton insects and plant pathogens.

Conclusion

The performance of the MAR cotton strains with mutant morphological traits in comparison with the new MAR-6 advanced germplasm, and the Tamcot CAB-CS and Tamcot HQ95 cultivars is summarized in Table 7.  The MAR mutant strains have the high and broad levels of resistance to insects and plant pathogens, and improved drought tolerance, as the advanced MAR-6 germplasm (El-Zik and Thaxton, 1989; El-Zik et al., 1991; Thaxton et al., 1991).  The frego bract and nectariless strains produced similar yields, and the okra leaf and red plant strains lower yields than the MAR-6 strains.  The nectariless and okra leaf strains were earlier in maturity, and the red plant strains matured later than the MAR-6 strains.  Lint percentages were lower for the red plant, okra leaf, and frego bract strains than for the MAR-6 strains and for the nectariless strains.  The okra leaf strains had a longer fiber than the other mutant strains and MAR-6 strains.  All strains generally were similar in fiber uniformity, elongation and micronaire, but the red plant strains had a higher micronaire value.  The frego bract, okra leaf, and red plant strains produced a stronger fiber than CAB-CS and HQ95, and the nectariless strains had a similar fiber strength to the Tamcot cultivars.  MAR mutants in hairy and glabrous backgrounds performed similarly for all measured traits, indicating no interaction of mutant traits with plant pubescence.

Cotton management programs of the future will depend less on pesticides to control insects and  pathogens.  Cultivars having resistance to pests will continue to be the cornerstone of crop production.  Eight new MAR cotton strains with the mutant morphological traits frego bract (fg-Sm, fg-H), nectariless (ne-Sm), okra-shaped leaf (L-Sm, L-H), and red plant color (R-Sm, R-H) are being released from the MAR program.  These MAR mutant strains have shown simultaneous genetic gains for many traits and should be useful to breeders in genetic improvement programs.  This germplasm will provide new sources of host plant resistance to insects and plant pathogens and will benefit the cotton growers and industry.

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INTERSPECIFIC HYBRIDIZATION AND SYNTHESIS OF ALLOTETRAPLOID GENOTYPES IN COTTON

Abstract                                                                         Back to Table of contents

Cotton is an important commercial crop of the world.  It has four cultivated and 41 wild species.  The genes for resistance to various biotic and abiotic stresses along with desirable fibre quality traits exist in the wild species of cotton.  The introgression of useful genes to cultivated types can help to reduce the cost of cultivation, overcome the environmental hazards and improve the fibre quality traits.  In the present study, an embryo culture technique has been followed for hybridising diploid cultivated Gossypium arboreum cv G27 with wild diploid Gossypium thurberi to introgress genes for good fibre strength, and resistance to frost, wilt and bollworms from G. thurberi.  The in-vitro cultures of embryos excised 12 and 15 days after pollination (DAP) were employed to develop whole plants from sexually-mediated interspecific crosses.  The 15 DAP embryos produced more vigorous seedlings than 12 DAP embryos.  The embryo germination and seedling response observed was better on Murashige and Skoog’s medium supplemented with Ch (250 mg/1) + IAA (1.5 mg/1) + Kin (0.5 mg/1).  The plant regeneration increased considerably if the plants were kept in the dark for the first 15 days.  After the development of roots and two young leaves the embryo derived plants were transferred to the pots containing sterilised soil mixture.  The seedlings were treated with 0.25% colchicine solution for 12 hours with the help of a cotton plug.  Large seedling mortality was observed after the application of colchicine solution.  The synthesised allotetraploid plants obtained after colchicine treatment showed bigger leaves than diploids.  The allotetraploid possessed pigmented plant body and okra type leaves, whereas G27 has pigmented plant body with broad-lobed leaves and G. thurberi possesses green stem and okra type leaves.

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