By the year 2050, the world’s population is predicted to have grown to around 9–10 billion people. The food demand in many countries continues to increase with population growth. Various abiotic stresses such as temperature, soil salinity and moisture all have an impact on plant growth and development at all levels of plant growth, including the overall plant, tissue cell, and even sub-cellular level. These abiotic stresses directly harm plants by causing protein denaturation and aggregation as well as increased fluidity of membrane lipids. In addition to direct effects, indirect damage also includes protein synthesis inhibition, protein breakdown, and membranous loss in chloroplasts and mitochondria. Abiotic stress during the reproductive stage results in flower drop, pollen sterility, pollen tube deformation, ovule abortion, and reduced yield. Plant nutrition is one of the most effective ways of reducing abiotic stress in agricultural crops. In this paper, we have discussed the effectiveness of different nutrients for alleviating abiotic stress. The roles of primary nutrients (nitrogen, phosphorous and potassium), secondary nutrients (calcium, magnesium and sulphur), micronutrients (zinc, boron, iron and copper), and beneficial nutrients (cobalt, selenium and silicon) in alleviating abiotic stress in crop plants are discussed.

One of the biggest challenges to be addressed in world agriculture is low nitrogen (N) use efficiency (<40%). To address this issue, researchers have repeatedly underlined the need for greater emphasis on the development and promotion of energy efficient, and environmentally sound novel fertilizers, in addition to improved agronomic management to augment nutrient use efficiency for restoring soil fertility and increasing farm profit. Hence, a fixed plot field experiment was conducted to assess the economic and environmental competency of conventional fertilizers with and without nano-urea (novel fertilizer) in two predominant cropping systemsviz., maize-wheat and pearl millet-mustard under semi-arid regions of India. Result indicates that the supply of 75% recommended N with conventional fertilizer along with nano-urea spray (N₇₅PK+nano-urea) reduced the energy requirement by ~8–11% and increased energy use efficiency by ~6–9% over 100% nitrogen through prilled urea fertilizer (business as usual). Furthermore, the application of N₇₅PK+ nano-urea exhibited ~14% higher economic yields in all the crops compared with N₅₀PK+ nano-urea. Application of N₇₅PK+nano-urea registered comparable soil N and dehydrogenase activities (35.8 μg TPF g^-124 hrs^-1across all crops) over the conventional fertilization (N₁₀₀PK). This indicates that application of foliar spray of nano-urea with 75% N is a soil supportive production approach. More interestingly, two foliar sprays of nano-urea curtailed nitrogen load by 25% without any yield penalty, besides reducing the greenhouse gases (GHG) emission from 164.2 to 416.5 kg CO₂-eq ha^-1under different crops. Therefore, the application of nano-urea along with 75% N through prilled urea is an energy efficient, environmentally robust and economically feasible nutrient management approach for sustainable crop production.

Appropriate land configuration and assured nutrient supply are prerequisites for quality organic baby corn (Zea maysL.) production in high rainfall areas of the delicate Eastern Himalayan Region of India. A long term (5-year) study was conducted during 2012–2016 on a sandy loam soil in the mid attitude of Sikkim, Eastern Himalayan Region of India to evaluate the productivity, produce quality, the profitability of baby corn, and soil properties under different land configurations comprising flatbed, ridge and furrow, and broad bed and furrow, and organic nutrient management practices comprising un-amended control, farmyard manure 12 t ha⁻¹, vermicompost 4 t ha⁻¹and farmyard manure 6 t ha⁻¹ + vermicompost 2 t ha⁻¹. The baby corn sown on broad bed and furrow had the tallest plant (149.25 cm), maximum dry matter (64.33 g plant⁻¹), highest leaf area index (3.5), maximum cob length (8.10 cm), cob girth (6.13 cm) and cob weight (8.14 g) leading to significantly higher fresh baby corn yield (1.89 t ha⁻¹), and net returns (US$ 906.1 ha⁻¹) than those of other treatments. Mineral composition (phosphorus, potassium, iron, and zinc), protein, and ascorbic acid content were also the highest in baby corn grown under the broad bed and furrow system. The soil of broad bed and furrow had a higher pH, organic carbon content, organic carbon pools, microbial biomass carbon, and enzymatic activities (dehydrogenase, fluorescein diacetate, and acid phosphatase) compared to soils of other land configurations. A combined application of farmyard manure (6 t ha⁻¹) + vermicompost (2 t ha⁻¹) improved the crop growth and produced 117.8% higher fresh baby corn and 99.7% higher fodder yield over control (0.9 t fresh corn and 13.02 t fodder yield ha⁻¹), respectively. This treatment also registered significantly higher gross return (US$ 1746.9 ha⁻¹), net return (US$ 935.8 ha⁻¹), and benefit–cost ratio (2.15) than other nutrient management practices. Fresh cob quality in terms of protein (22.91%) and ascorbic acid content (101.6 mg 100 g⁻¹) was observed to be significantly superior under combined application of farmyard manure (6 t ha⁻¹) + vermicompost (2 t ha⁻¹) than those of other nutrient management systems. However, fresh baby corn cobs produced with vermicompost 4 t ha⁻¹had the highest concentration of phosphorus, potassium, iron, and zinc. Application of farmyard manure 12 t ha⁻¹registered the maximum increment in soil organic carbon content (1.52%), its pool (40.6 t ha⁻¹) and carbon sequestration rate (0.74 t ha⁻¹ year⁻¹) followed by integrated application of farmyard manure (6 t ha⁻¹) and vermicompost (2 t ha⁻¹). The maximum soil microbial biomass carbon and enzymatic activities [dehydrogenase (22.1 µg TPF g⁻¹soil h⁻¹) and fluorescein diacetate (67.1 µg FDA g⁻¹soil h⁻¹)] were noted with the combined use of farmyard manure (6 t ha⁻¹) + vermicompost (2 t ha⁻¹). Thus, the study suggests that the broad bed and furrow land configuration along with the combined application of farmyard manure + vermicompost could be an economically feasible practice for quality organic baby corn production and soil health improvement in the Eastern Himalaya and other similar eco-regions elsewhere.

It is widely accepted that deficiency of macro (nitrogen) and micronutrients (zinc, copper etc.) affects the plant growth and development which cause a significant threat to crop production and food security. The Indian Farmers Fertilizer Cooperative (IFFCO) developed nano-urea (nano-N), nano-zinc (nano-Zn), and nano-copper (nano-Cu) liquid fertilizer formulations to enhance the crop yields, simultaneously addressing the nutrient deficiency, without causing toxicity. Therefore, this study was formulated to evaluate the effectiveness of nano-N (nano-urea), nano-Zn, and nano-Cu at varying N levels [0, 50, 75, and 100% of the recommended rates of nitrogen (RRN)] on maize-wheat and pearl millet-mustard systems during 2019–20 and 2020–21. The results exhibited that the application of nano-N + nano-Zn with 100% RRN exhibited significantly higher grain yields in maize (66.2–68.8%), wheat (62.6–61.9%), pearl millet (57.1–65.4%), and mustard (47.2–69.0%), respectively, over absolute control plots and combinations of three nano-fertilizers like nano-N + nano-Zn + nano-Cu applied plots. This was mainly attributed to the higher N and Zn uptake by the crops. However, 75% RRN with nano-N + nano-Zn also produced comparable yields. Thus, applying nano-N and nano-Zn via foliar applications, in conjunction with conventional urea, has the potential to reduce the required nitrogen fertilizer amount by up to 25%, while simultaneously maintaining equivalent yield levels. Similarly, 100% RRN and 75% RRN + nano-N + nano-Zn registered comparable profitability, soil mineral N, dehydrogenase activity (DHA), and soil microbial biomass carbon (SMBC), during both the study years. However, further research and field trials on nano fertilizers alone or in combination with conventional fertilizers are essential to fully unlock its benefits and ascertain its long-term effects which may offer a pathway to more efficient and eco-friendly crop nourishment.

The growing popularity of nano-fertilization around the world for enhancing yield and nutrient use efficiency has been realized, however its influence on soil microbial structure is not fully understood. The purpose of carrying out this study was to assess the combined effect of nano and conventional fertilizers on the soil biological indicators and crop yield in a wheat–maize system. The results indicate that the at par grain yield of wheat and maize was obtained with application of 75% of recommended nitrogen (N) with full dose of phosphorus (P) and potassium (K) through conventional fertilizers along with nano-N (nano-urea) or nano-N plus nano-Zn sprays and N₁₀₀PK i.e. business as usual (recommended dose of fertilizer). Important soil microbial property like microbial biomass carbon was found statistically similar with nano fertilizer-based management (N₇₅PK + nano-N, and N₇₅PK + nano-N + nano-Zn) and conventional management (N₁₀₀PK), during both wheat and maize seasons. The experimental data indicated that the application of foliar spray of nano-fertilizers along with 75% N as basal is a sustainable nutrient management approach with respect to growth, yield and rhizosphere biological activity. Furthermore, two foliar sprays of nano-N or nano-N + nano-Zn curtailed N requirement by 25%, furthermore enhanced soil microbial diversity and the microbial community structure. The specific microbial groups, including Actinobacteria, Bacteroidia, and Proteobacteria, were present in abundance and were positively correlated with wheat and maize yield and soil microbial biomass carbon. Thus, one of the best nutrient management approaches for sustaining productivity and maintaining sound microbial diversity in wheat–maize rotation is the combined use of nano-fertilizers and conventional fertilizers.

Heat and Water Deficit Stress (WDS) tend to impede and restrict the efficiency of photosynthesis, chlorophyll fluorescence, and maximum photochemical quantum yield in plants based on their characteristic ability to interfere with the electron transport system in photosystem II. Dissection of the electron transport pathway in Photosystem II (PSII) under water deficit and Heat Stress (HS) can be insightful in gaining knowledge on the various attributes of the photosynthetic performance of a plant. We attempt a high-resolution dissection of electron transport in PSII with studies on chlorophyll a fast fluorescence kinetics and non-photochemical quenching (NPQ) as a response to and recovery from these stresses in pearl millet [Pennisetum glaucum (L.) R. Br.] in isolation and combination. In this study, we bring out the mechanisms by which both heat and water stress, in isolation and in combination, affect the photosynthetic electron transport in Photosystem II. Our results indicate that oxygen evolution complex (OEC) damage is the primary effect of heat stress and is not seen with the same intensity in the water-stressed plants. Low exciton absorption flux in heat stress and combined stress was seen due to OEC damage, and this caused an electron transport traffic jam in the donor side of PS II. Both the specific energy flux model and the phenomenological flux model developed from the derived values in our study show that water deficit stress in combination with heat stress has a much stronger effect than the stresses in isolation on the overall electron transport pathway of the PS II in pearl millet plants.