Nitrogen use efficiency in cotton: Challenges and opportunities against environmental constraints.

Nitrogen is a vital nutrient for agricultural, and a defieciency of it causes stagnate cotton growth and yield penalty. Farmers rely heavily on N over-application to boost cotton output, which can result in decreased lint yield, quality, and N use efficiency (NUE). Therefore, improving NUE in cotton is most crucial for reducing environmental nitrate pollution and increasing farm profitability. Well-defined management practices, such as the type of sources, N-rate, application time, application method, crop growth stages, and genotypes, have a notable impact on NUE. Different N formulations, such as slow and controlled released fertilizers, have been shown to improve N uptake and, NUE. Increasing N rates are said to boost cotton yield, although high rates may potentially impair the yield depending on the soil and environmental conditions. This study comprehensively reviews various factors including agronomic and environmental constraints that influence N uptake, transport, accumulation, and ultimately NUE in cotton. Furthermore, we explore several agronomic and molecular approaches to enhance efficiency for better N uptake and utilization in cotton. Finally, this objective of this review to highlight a comprehensive view on enhancement of NUE in cotton and could be useful for understanding the physiological, biochemical and molecular mechanism of N in cotton.

Recent Advances in Agronomic and Physio-Molecular Approaches for Improving Nitrogen Use Efficiency in Crop Plants.

The efficiency with which plants use nutrients to create biomass and/or grain is determined by the interaction of environmental and plant intrinsic factors. The major macronutrients, especially nitrogen (N), limit plant growth and development (1.5-2% of dry biomass) and have a direct impact on global food supply, fertilizer demand, and concern with environmental health. In the present time, the global consumption of N fertilizer is nearly 120 MT (million tons), and the N efficiency ranges from 25 to 50% of applied N. The dynamic range of ideal internal N concentrations is extremely large, necessitating stringent management to ensure that its requirements are met across various categories of developmental and environmental situations. Furthermore, approximately 60 percent of arable land is mineral deficient and/or mineral toxic around the world. The use of chemical fertilizers adds to the cost of production for the farmers and also increases environmental pollution. Therefore, the present study focused on the advancement in fertilizer approaches, comprising the use of biochar, zeolite, and customized nano and bio-fertilizers which had shown to be effective in improving nitrogen use efficiency (NUE) with lower soil degradation. Consequently, adopting precision farming, crop modeling, and the use of remote sensing technologies such as chlorophyll meters, leaf color charts, etc. assist in reducing the application of N fertilizer. This study also discussed the role of crucial plant attributes such as root structure architecture in improving the uptake and transport of N efficiency. The crosstalk of N with other soil nutrients plays a crucial role in nutrient homeostasis, which is also discussed thoroughly in this analysis. At the end, this review highlights the more efficient and accurate molecular strategies and techniques such as N transporters, transgenes, and omics, which are opening up intriguing possibilities for the detailed investigation of the molecular components that contribute to nitrogen utilization efficiency, thus expanding our knowledge of plant nutrition for future global food security.

Alterations of Oxidative Stress Indicators, Antioxidant Enzymes, Soluble Sugars, and Amino Acids in Mustard [Brassica juncea (L.) Czern and Coss.] in Response to Varying Sowing Time, and Field Temperature.

The impact of elevated temperature at the reproductive stage of a crop is one of the critical limitations that influence crop growth and productivity globally. This study was aimed to reveal how sowing time and changing field temperature influence on the regulation of oxidative stress indicators, antioxidant enzymes activity, soluble sugars (SS), and amino acids (AA) in Indian Mustard. The current study was carried out during the rabi 2017-2018 and 2018-2019 where, five varieties of mustard viz. Pusa Mustard 25 (PM-25) (V1), PM-26 (V2), BPR-541-4 (V3), RH-406 (V4), and Urvashi (V5) were grown under the field conditions on October 30 (normal sowing; S1), November 18 (late sowing; S2) and November 30 (very late sowing; S3) situations. The S1 and S3 plants, at mid-flowering stage, showed a significant variation in accumulation of SS (8.5 and 17.3%), free AA (235.4 and 224.6%), and proline content (118.1 and 133%), respectively, and played a crucial role in the osmotic adjustment under stress. The results showed that S3 sowing, exhibited a significant induction of the hydrogen peroxide (H2O2) (110.2 and 86.6%) and malondialdehyde (23.5 and 47.5%) concentrations, respectively, which indicated the sign of oxidative stress in plants. Interestingly, the polyphenol oxidase, peroxidase, superoxide dismutase, and catalase enzyme activities were also significantly increased in S3 plants compared to S1 plants, indicating their significant roles in ameliorating the oxidative stress. Furthermore, the concentration of fatty acid levels such as palmitic, stearic, oleic, and linoleic acids level also significantly increased in S3 plants, which influenced the seed and oil quality. The study suggests that the late sowing significantly impaired the biochemical mechanisms in Indian mustard. Further, the mustard variety V4 (RH-406) was found to be effective for cultivation as well as environmental stress adoption in Indian soils, and it could be highly useful in breeding for developing heat-tolerant genotypes for ensuring the food security.

Gamma-rays and EMS induced resistance to mungbean yellow mosaic India virus in mungbean [Vigna radiata (L.) R. Wilczek] and its validation using linked molecular markers.

PURPOSE: Mungbean yellow mosaic India virus (MYMIV) is a serious constraint in the mungbean which is a potential source of easily digestible high-quality proteins, fibers, minerals, and vitamins in Asian countries. Developing resistant cultivars is the most cost-effective, eco-friendly, and sustainable approach to protect mungbean from MYMIV damage. Mutation breeding provides a quick and cost-effective way of developing resistance as lack of genetic variability is the biggest bottleneck for other traditional breeding tools. MATERIALS AND METHODS: Outstanding but MYMIV-sensitive varieties of mungbean, viz., MH 2-15 and MH 318 were mutagenized through various individual and combined doses of gamma-rays and Ethyl methanesulfonate (EMS) and evaluated in M2 and M3 generations for the appearance of resistance reactions. This was subsequently validated through marker-assisted genotyping using previously reported Yellow Mosaic Disease (YMD) linked markers. RESULTS: The phenotyping in M3 generation yielded 64 MYMIV resistant mutants whereas, marker-assisted genotyping identified the 22 mutants with true resistance. Markers YR4, CYR1, and CEDG180 were found associated with MYMIV resistance whereas, DMB-SSR158 did not show any amplification. Among identified resistant mutants, ten lines exhibited at par and two revealed a little higher seed yield over controls. CONCLUSIONS: The mutagenesis created significant variability in MYMIV resistance as well as seed yield per plant. YR4, CYR1, and CEDG180 are found to be linked with the MYMIV loci in the mungbean and could be utilized for MYMIV resistance breeding. Mutant M-37 from MH 2-15 and M-104 from MH 318 exhibited more seed yield along with MYMIV resistance which upon further validation can be released as a variety. The induced mutagenesis integrated with powerful emerging molecular and next-generation sequencing (NGS) tools would be highly helpful in breeding mungbean for durable resistance against threatening MYMIV.

Molecular diversity of Annona species and proximate fruit composition of selected genotypes.

Understanding the genetic variation in germplasm is of utmost importance for crop improvement. Therefore, efforts were made to analyse the molecular marker based genetic diversity of 20 Annona genotypes from five different species of family Annonaceae. During analysis, a set of 11 RAPD primers yielded a total of 152 bands with 80.01 % polymorphism and PIC for RAPD ranged from 0.86 to 0.92 with a mean of 0.89. With 93.05 % polymorphism, 12 SSR primers produced 39 amplicons. The PIC for SSRs ranged from 0.169 to 0.694 with of average of 0.339. The dendrogram produced from pooled molecular data of 11 RAPD and 12 SSR primers showed seven clusters at a cutoff value of 0.78. The dendrogram discriminated all the Annona genotypes suggesting that significant genetic diversity was present among the genotypes. Proximate fruit composition study of nine fruiting genotypes of Annona revealed that A. squamosa possessed significantly higher amount of most of studies biochemical which gives an opportunity to fruit breeders to improve the other Annona species. Likewise, A. muricata being rich in seed oil content can be exploited in oil industries.