RESUMO
The use of fixed emission factors (EFs), combined with insufficient temporal distribution, leads to substantial uncertainties in current emission inventories for India, the world's second-largest producer and consumer of synthetic N-fertilizers. Our study aimed to improve the NH3 and N2O emission estimates by utilizing crop-specific district-level activity data and refined EFs tailored to Indian conditions. In this study, a comprehensive NH3 and N2O emission inventory (EI) is methodically developed at 0.1° * 0.1° spatial and monthly temporal resolution for the year 2018-19 considering 52 crops. The data for developing this inventory is aggregated through detailed field surveys, conducted across 102 districts of 14 states, and relevant government databases. EFs have been adjusted for the Indian context by refining them to reflect local conditions through consideration of ambient temperature, application rate, and other factors. Further, upon preparing an EI for FA, a spectrum of mitigation strategies are evaluated to assess their effectiveness in reducing emissions. Yearly total NH3 and N2O emissions amount to 3.15 Tg and 138.53 Gg, with urea fertilizer as the dominant contributor accounting for 93.85% and 96.44% of emissions, respectively. Key crops such as rice, wheat, maize, sugarcane, and cotton collectively represent approximately 82% of the total N consumption. The state of Uttar Pradesh emerges as the largest emitter, contributing 706.5 Gg and 25.31 Gg of NH3 and N2O emissions, respectively. Conversely, PB and HR exhibit the highest NH3 emissions per capita. Temporally, NH3 emissions peak in August, while N2O emissions peak in July, with both pollutants reaching their nadir in February. Among the array of mitigation strategies assessed in this study, 'adhering to recommended fertilizer doses' and 'incorporating urease inhibitors' demonstrated substantial potential for reducing emissions. The current study aids policymaking to mitigate the environmental and health impacts of atmospheric emissions from synthetic N-fertilizers. Future researchers can adopt this study as a benchmark to improve Indian FA emission estimates, which helps in promoting sustainable agricultural practices and contributes to climate change mitigation efforts.
RESUMO
Boron (B) is an essential micronutrient, crucial for the growth and development of crop plants. However, the essential to a toxic range of B in the plant is exceptionally narrow, and symptoms develop with a slight change in its concentration in soil. The morphological and anatomical response, such as leaf chlorosis, stunted growth, and impairment in the xylem and phloem development occurs under B-toxicity. The transport of B in the plant occurs via transpiration stream with the involvement of B-channels and transporter in the roots. The higher accumulation of B in source and sink tissue tends to have lower photosynthetic, chlorophyll content, infertility, failure of pollen tube formation and germination, impairment of cell wall formation, and disruption of membrane systems. Excess B in the plant hinders the uptake of other micronutrients, hormone transport, and metabolite partitioning. B-mediated reactive oxygen species production leads to the synthesis of antioxidant enzymes which help to scavenge these molecules and prevent the plant from further oxidative damage. This review highlights morpho-anatomical, physiological, biochemical, and molecular responses of the plant under B toxicity and thereby might help the researchers to understand the related mechanism and design strategies to develop B tolerant cultivars.
The physio-biochemical and molecular responses and mechanism of B uptake under its toxic condition have been illustrated. The spatial distribution of boron under its toxic condition and its accumulation in the plant might be regulated with sugar alcohols (polyols). This review throws light on the elevated level of B in the soil-plant system and provides management strategies for alleviating B toxicity in the plant.
