Drought is one of the major constraints for sustainable crop production worldwide, especially in arid and semiarid regions. The global warming and climate change scenario has worsened the dilemma of water scarcity, creating an immediate threat to food security. Conserving water resources and exploiting various strategies that enable plants to withstand water deficits need to be urgently addressed. Drought adversely affects plant growth by modulating a range of physio-chemical, metabolic, and molecular processes inside the plant body, which ultimately reduces crop productivity. Besides developing drought-tolerant cultivars, better nutrient management could be a promising strategy to enhance drought tolerance in crop plants. Silicon, a quasi-essential element, is known to play a vital role in improving crop performance under a range of biotic and abiotic stresses. This review discusses the potential of Si application in attenuating the adverse effects of water-deficit stress. Silicon enhances plant growth by improving seed germination, cell membrane stability, carbon assimilation, plant–water relations and osmotic adjustment (by accumulating soluble sugars, proline and glycine betaine). It triggers the activity of antioxidants, promotes the biosynthesis of phytohormones, enhances nutrient acquisition and regulates the activity of vital enzymes in plants under drought stress. Silicon also induces anatomical changes in the plant cell wall through the deposition of polymerized amorphous silica (SiO₂-nH₂O), thereby improving stem and leaf erectness and reducing lodging. Further, Si-mediated physiological, biochemical and molecular mechanisms associated with drought tolerance in plants and future research prospects have been elucidated.

Genome-wide association study (GWAS) was performed for stomata- and yield-related attributes with high-density Illumina 90 K Infinium SNP (single nucleotide polymorphism) array in bread wheat to determine genetic potential of germplasm for scarce water resources with sustainable yield potential. Major yield and stomata attributes were phenotyped on a panel of Pakistani and foreign accessions grown in non-stressed and water shortage environments during two seasons. Highly significant variations were shown among accessions in both conditions for examined characteristics. Water shortage conditions reduced the overall wheat yield and strong positive correlation existed among stomatal frequency, leaf venation and grain yield per plant. Population structure analyses based on 90,000 SNP data classified the accessions into four sub-populations which indicated the presence of genetic variability. Marker-trait association (MTA) analyses revealed that 422 significant SNPs at p ≤ 10⁻³, after crossing the false discovery rate (FDR) <0.05 threshold, were linked with examined attributes. Pleiotropic loci (wsnp_Ex_c8913_14881924 and Tdurum_contig10598_304) were associated with flag leaf area (FLA), stomata size (SS), stomata frequency (SF), leaf venation (LV), number of grain per spike (NGS) and grain yield per plant (GYP), which were located on chromosome 4B and 6B at the positions 173.63cM and 229.64cM, respectively, under water shortage conditions. Pleotropic loci wsnp_Ex_c24167_33416760, wsnp_Ex_c5412_9564046 and Tdurum_contig81797_369 on chromosomes 7A, 2A and 4B at the positions 148.26cM, 261.05cM and 173.63cM, respectively, were significantly linked with stomata and yield indices such as FLA, SS, SF, LV, NGS and GYP under normal and water shortage conditions. The current experiment not only validated several MTAs for studied indices reported in other studies but also discovered novel MTAs significant under water shortage environments. Associated and significant SNPs will be useful in discovering novel genes underpinning water shortage tolerance in bread wheat for producing high-yielding and drought tolerant wheat varieties to fulfill the wheat demand for growing populations.

Coating materials generally a provide physical barrier to control instant dissolution of the urea fertilizer thereby delaying its consequent reactions in soil. The use of zinc salt as coating material causes slow dissolution of urea due to physical impact and hence minimizes immediate urea hydrolysis, ammonia (NH3) volatilization and enhances N utilization in crop production. The current investigation studied the impact of Bioactive Zincated urea on NH3 losses, yield parameters and quality traits of maize and rice crops grown under field conditions. Treatments included Bioactive zincated urea (ZU) was applied at 100%, 90% and 80% of recommended N rates (RNR) (125 and 160 kg N ha-1 for rice and maize, respectively) having a control (zero N application), conventional urea at RNR (CU100) without Zn and along with Zn (CU+Zn) treatments. The NH3 losses were recorded at 2, 4, 7 and 14 days after application of each split application of N treatments. The results indicated 117 and 6% increase in maize grain and 167 and 2.7% in total paddy yield as compared to control (no Zn) and CU+Zn, respectively while the corresponding increase in grain Zn concentration was 37 and 15% in maize and 25 and 14% in rice, respectively. Similarly, the corresponding grain N increases were 16 and 22%. Furthermore, ZU100 application markedly decreased NH3 volatilization (5 to 14% in maize and 2 to 24% in rice field) as compared to CU100. The studies clearly elucidates the effectiveness of Bioactive zincated urea in increasing yield and quality of crops (rice and maize); the lower N application (up to 80% of RNR) is possible without imminent impact on crop yield as well as on environment owing to lower N losses.