Phosphorus (P) is a non-renewable resource which may be depleted within next few decades; hence high P use efficiency is need of time. Plants have evolved an array of adaptive mechanisms to enhance external P acquisition and reprioritize internal utilization under P deficiency. Tissue specific biomass and P allocation patterns may affect the P use efficiency in plants. six rice cultivars were grown in solution culture for 20 days and then were divided into two groups to receive either adequate P or no P that were harvested at 30, 40 and 50 days. Plants were dissected into various tissues/organs. Two rice cultivars viz Super Basmati (P-inefficient) and PS-2 (P-efficient) were grown in soil with no or 50 mg P kg⁻¹ soil till maturity. Rice cultivars PS-2 and Basmati-2000 had higher P uptake, utilization efficiency and internal remobilization than other tested cultivars after P omission. Young leaves and roots were the major sinks while stems and mature leaves were the sources of P during P omission. In conclusion, biomass allocation and P accumulation among various tissues and P remobilization were major factors responsible for P efficiency.

Zinc (Zn) deficiency is common on calcareous soils due to fixation with soil components and precipitation with other ions. ZnO nanoparticles (ZnO NPs) may serve a better source of Zn for improved growth and biofortification in maize grains. Pot and field experiments were conducted to evaluate the effect of ZnO nanoparticles in comparison with conventional Zn fertilizer (ZnSO₄) on growth and grain Zn contents of maize. In both experiments, Zn application improved growth and physiological parameters of plants; however, maximum improvement was observed in treatments receiving ZnSO₄ (soluble) or ZnO nanoparticles (insoluble source of Zn). Application of ZnO nanoparticles also improved Zn concentration in shoots as well as in grains in field experiment. In field experiment, Zn partitioning was also calculated and interestingly it is found that Zn concentration at maturity stages was reduced in stem and mature leaves. Maximum Zn concentration (~80 mg kg⁻¹) was observed in young leaves at vegetative growth stage in treatments receiving ZnO nanoparticles. Foliar applied ZnO NPs showed maximum increase in grain Zn concentration (82%). It is concluded that ZnO NPs improved maize growth, yield and grain Zn contents. Being cheaper and efficient source, it can be used for Zn biofortification.

Silicon is known to improve resistance against salinity stress in maize crop. This study was conducted to evaluate the influence of silicon application on growth and salt resistance in maize. Seeds of two maize genotypes (salt-sensitive ‘EV 1089’ and salt-tolerant ‘Syngenta 8441’) were grown in pots containing 0 and 2 mM Si with and without 50 mM NaCl. After detailed investigation of ion concentrations in different maize organs, both genotypes were further selected in hydroponic experiment on basis of their contrasting response to salinity stress. In the second experiment, pre-germinated seedlings were transplanted into nutrient solution with 0 and 60 mM NaCl with and without 2 mM Si. Both genotypes differed significantly in their response to salinity. Silicon addition alleviated both osmotic and oxidative stress in maize crop by improving the performance of defensive machinery under salinity stress. Silicon application also improved the water-use efficiency in both tested genotypes under both normal and salinity stress conditions. In conclusion, this study implies that the silicon-treated maize plants had better chance to survive under salinity conditions and their photosynthetic and biochemical apparatus was working far better than that of silicon-non-treated plants.

Production of phosphorus efficient crop cultivars can increase food productivity and decrease environmental pollution. Categorization of existing germplasm is a prerequisite to develop P efficient crop cultivars. For first experiment, 30 wheat genotypes were grown in hydroponics with two P levels (i.e., deficit, 20 μm KH₂PO₄ and adequate, 200 μm KH₂PO₄). Genotypes differed significantly for various P efficiency parameters. Two genotypes (Dirk and Bhakkar-02) showed < 25% decrease in growth at P deficiency. Genotype Seher-06 proved to be inefficient. Twelve selected genotypes based on the first experiment were sown in soil with two P levels (0 and 30 mg P kg^-1) till maturity. As expected, genotypes differed for grain yield at both P levels. The efficient cultivars selected on the basis of both absolute and relative dry matter production at both P levels such as Dirk. Genotypes were grouped into three, four and nine classes on the basis of various parameters for P efficiency as proposed by different researchers. Most genotypes behaved in a similar fashion by different categorization methods and also at different P supply. The method to categorize the genotypes into three classes and plotting them into 9 classes proposed by Gill and his coworkers, is the best to differentiate the minor differences in genotypes. At least three different parameters at both P regimes should be used. The parameters may vary as per objectives of the study and/or growth conditions.

Salinity is a devastating problem of arid and semi-arid climatic regions with uneven salt accumulation which hinders growth and development of crops. The deleterious effects of salinity mainly depend on level and source of salinity. We hypothesized that types of sodium salt (NaCl and Na2SO4) might cause variable toxicity in maize (Zea mays L.) plants. The objective of the present study was to compare the effect of different types of sodium salt (NaCl and Na2SO4), each at EC 5 and 10 dS m–1 on growth, physiology and nutrient contents of maize plant grown in earthen pots under wire house conditions. Results revealed toxic effects of salt stress on seed germination, root and shoot growth and biomass. Maize physiology in terms of sub-stomatal CO2 index, chlorophyll and relative water contents, photosynthetic and transpiration rate also reduced under salt stress. Among the types of salt and levels of salinity, NaCl applied at the rate of 10 dS m–1 caused the highest reduction in seed germination, growth and physiology due to high accumulation of Na and Cl ions whereas low in K ion in maize plant tissues. Based on the findings, we do conclude that NaCl applied at the rate of 10 dS m–1 has more negative impact on maize growth and nutrient acquisition than Na2SO4 at same level of salinity.