Impact of salinity stress on cotton and opportunities for improvement through conventional and biotechnological approaches

Excess salinity can affect the growth and development of all plants. Salinization jeopardizes agroecosystems, induces oxidative reactions in most cultivated plants and reduces biomass which affects crop yield. Some plants are affected more than others, depending upon their ability to endure the effects of salt stress. Cotton is moderately tolerant to salt stress among cultivated crops. The fundamental tenet of plant breeding is genetic heterogeneity in available germplasm for acquired characteristics. Variation for salinity tolerance enhancing parameters (morphological, physiological and biochemical) is a pre-requisite for the development of salt tolerant cotton germplasm followed by indirect selection or hybridization programs. There has been a limited success in the development of salt tolerant genotypes because this trait depends on several factors, and these factors as well as their interactions are not completely understood. However, advances in biochemical and molecular techniques have made it possible to explore the complexity of salt tolerance through transcriptomic profiling. The focus of this article is to discuss the issue of salt stress in crop plants, how it alters the physiology and morphology of the cotton crop, and breeding strategies for the development of salinity tolerance in cotton germplasm.

Exploitation of various physio-morphological and biochemical traits for the identification of drought tolerant genotypes in cotton

BACKGROUND

Drought is one of the limiting factors for quality and quantity of cotton lint in tropical and sub-tropical regions. Therefore, development of drought tolerant cotton genotypes have become indispensable. The identification of drought tolerant genotypes is pre-requisite to develop high yielding cultivars suitable for drought affected areas.

METHODS

Forty upland cotton accessions were selected on the basis of their adaptability and yield. The collected germplasm accessions were evaluated at seedling stage on the basis of morphological, physiological and biochemical parameters. The experiment was conducted under controlled conditions in greenhouse where these genotypes were sown under different levels of drought stress by following factorial under completely randomized design. The data were collected at seedling stages for root and shoot lengths, relative leaf water content, excised leaf water losses, peroxidase content and hydrogen peroxide concentrations in leaf tissues.

RESULTS

The biometrical analysis revealed that germplasm is significantly varied for recorded parameters, likewise interaction of genotypes and water stress was also significantly varied. The cotton germplasm was categorized in eight clusters based on response to water stress. The genotype Cyto-124 exhibited lowest H2O2 content under drought conditions, minimum excised leaf water loss under stress environment was exhibited by genotypes Ali Akber-802 and CEMB-33. Overall, on the basis of morphological and biochemical traits, SL-516 and Cyto-305 were found to be drought tolerant. Genotypes 1852 - 511, Stoneville 15-17 and Delta Pine-55 showed low values for root length, peroxidase activity and higher value for H2O2 contents. On the basis of these finding, these genotypes were declared as drought susceptible.

CONCLUSION

The categorization of cotton germplasm indicating the differential response of various parameters under the control and drought stress conditions. The recorded parameters particularly relative leaf water contents and biochemical assays could be utilized to screen large number of germplasm of cotton for water deficit conditions. Besides, the drought tolerant genotypes identified in this research can be utilized in cotton breeding programs for the development of improved cultivars.

Development and in-vitro Evaluation of Once Daily Tablet Dosage Form of Loxoprofen Sodium

Purpose: To formulate and characterize once daily controlled release tablet of loxoprofen sodium.Methods: Eudragit RS-100, hydroxylpropyl methylcellulose (HPMC) and pectin were used as release retarding polymers. All the formulations were prepared by direct compression method. Various precompression studies were carried out to determine Hausner’s ratio, Carr’s index, angle of repose, bulk density and tapped density Differential scanning calorimetry (DSC) studies and also post-compression studies to evaluate hardness, friability, weight variation, drug content, in-vitro drug release were conducted on the tablets. The drug release data were subjected to kinetic models, including zero order, first order, Hixon Crowell, Higuchi and Korsmeyer-Peppas.Results: Compressibility index (7.6 ± 1.32 - 12.5 ± 1.43%), Hausner’s ratio (1.08 ± 0.04 - 1.14 ± 0.03), angle of repose (27.78 ± 0.47 - 30.49 ± 0.46°), hardness (6.25 ± 0.27 - 7.21±0.21 kg/cm2), friability (0.14 ± 0.06 - 0.28 ± 0.0 %), weight variation (249.5 ± 2.09 - 251.35 ± 2.41 mg) and drug content  (97.30 ± 0.28 - 103.70 ± 0.31 %) were within generally accepted limits for the pre-and post-compression formulations, respectively. The tablets having the maximum amount of among the three polymers tested as matrix materials, HPMC, represented by F3 tablets, exerted better sustained release properties after 12 h. Release pattern was more of Fickian diffusion followed by Higuchi mechanism.Conclusion: The release of the loxoprofen sodium was optimized up to 12 h.Keywords: Loxoprofen, Sustained release, hydroxypropyl methylcelluose, Pectin, Eudragit, Matrix tablets

Ion accumulation in lucerne plants regenerated from salt-adapted suspension cultures compared with recultured cells from these plants

Lucerne (Medicago media cv. Rambler) plants, regenerated from cell suspension cultures adapted to 200 mM NaCl, and cell cultures derived from the leaflets of regenerated plants showed enhanced Na⁺ exclusion compared with the unselected plants and cell cultures. There was a decrease in the K⁺ concentration in response to NaCl treatment but the selected plants and cell cultures maintained a significantly higher K⁺ concentration and showed much lower Na⁺/K⁺ ratios than unselected plants and cell cultures. The proline concentration increased in the shoots and cell cultures in response to NaCl stress but the selected plants and cell cultures showed a significantly higher proline concentration than unselected plants and cell cultures.