Effect of salt, alkali and combined stresses on root system architecture and ion profiling in a diverse panel of oat (Avena spp.).

The co-occurrence of salinisation and alkalisation is quite frequent in problematic soils and poses an immediate threat to food, feed and nutritional security. In the present study, root system architectural traits (RSAs) and ion profiling were evaluated in 21 genotypes of Avena species to understand the effect of salinity-alkalinity stress. The oat genotypes were grown on germination paper and 5-day-old seedlings were transferred to a hydroponic system for up to 30days. These seedlings were subjected to seven treatments: T0 , treatment control (Hoagland solution); T1 , moderate salinity (50mM); T2 , high salinity (100mM); T3 , moderate alkalinity (15mM); T4 , high alkalinity (30mM); T5 , combined moderate salinity-alkalinity (50mM+15mM); and T6 , combined high salinity-alkalinity (100mM and 30mM) by using NaCl+Na2 SO4 (saline) and NaHCO3 +Na2 CO3 (alkaline) salts equivalently. The root traits, such as total root area (TRA), total root length (TRL), total root diameter (TRD), total root volume (TRV), root tips (RT), root segments (RS), root fork (RF) and root biomass (RB) were found to be statistically significant (P + and K+ content analysis in root and shoot tissues revealed the ion homeostasis capacity of different Avena accessions under stress treatments. Principal component analysis (PCA) covered almost 83.0% of genetic variation and revealed that the sharing of TRA, RT, RS and RF traits was significantly high. Biplot analysis showed a highly significant correlation matrix (P <0.01) between the pairs of RT and RS, TRL and RS, and RT and RF. Based on PCA ranking and relative value for stress tolerance, IG-20-1183, IG-20-894, IG-20-718 and IG-20-425 expressed tolerance to salinity (T2), IG-20-425 (alkalinity; T4) and IG-20-1183, IG-20-894 and IG-20-1004 were tolerant to salt-alkali treatment (T6). Multi-trait stability index (MTSI) analysis identified three stable oat genotypes (IG-20-714, IG-20-894 and IG-20-425) under multiple environments and these lines can be used in salinity-alkalinity affected areas after yield trials or as donor lines for combined stresses in future breeding programs.

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.