Seed priming to alleviate salinity stress in germinating seeds

Water scarcity is a major constraint limiting grain legume production particularly in the arid and semi-arid tropics. Different climate models have predicted changes in rainfall distribution and frequent drought spells for the future. Although drought impedes the productivity of grain legumes at all growth stages, its occurrence during reproductive and grain development stages (terminal drought) is more critical and usually results in significant loss in grain yield. However, the extent of yield loss depends on the duration and intensity of the stress. A reduction in the rate of net photosynthesis, and poor grain set and grain development are the principal reasons for terminal drought-induced loss in grain yield. Insight into the impact and resistance mechanism of terminal drought is required for effective crop improvement programmes aiming to improve resistance to terminal drought in grain legumes. In this article, the impact of terminal drought on leaf development and senescence, light harvesting and carbon fixation, and grain development and grain composition is discussed. The mechanisms of resistance, management options, and innovative breeding and functional genomics strategies to improve resistance to terminal drought in grain legumes are also discussed.

Drought Stress in Grain Legumes during Reproduction and Grain Filling

The present study investigates the roles of exogenous proline (Pro, 5 mM) and glycine betaine (GB, 5 mM) in improving salt stress tolerance in salt sensitive (BRRI dhan49) and salt tolerant (BRRI dhan54) rice (Oryza sativa L.) varieties. Salt stresses (150 and 300 mM NaCl for 48 h) significantly reduced leaf relative water (RWC) and chlorophyll (chl) content and increased endogenous Pro and increased lipid peroxidation and H2O2 levels. Ascorbate (AsA), glutathione (GSH) and GSH/GSSG, ascorbate peroxidae (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), catalase (CAT), and glyoxalase I (Gly I) activities were reduced in sensitive variety and these were increased in tolerant variety due to salt stress. The glyoxalase II (Gly II), glutathione S-transferase (GST), and superoxide dismutase (SOD) activities were increased in both cultivars by salt stress. Exogenous Pro and GB application with salt stress improved physiological parameters and reduced oxidative damage in both cultivars where BRRI dhan54 showed better tolerance. The result suggests that exogenous application of Pro and GB increased rice seedlings’ tolerance to salt-induced oxidative damage by upregulating their antioxidant defense system where these protectants rendered better performance to BRRI dhan54 and Pro can be considered as better protectant than GB.

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Exogenous Proline and Glycine Betaine Mediated Upregulation of Antioxidant Defense and Glyoxalase Systems Provides Better Protection against Salt-Induced Oxidative Stress in Two Rice (Oryza sativa L.) Varieties

Learning Expectations:
1.	Functions of water in crop plant
2.	Physical and chemical properties of water
3.	Thermodynamic description of water 
4.	Driving forces of water in SPAC
5.	Soil-Plant-Atmosphere Continuum (SPAC)
6.	Water deficit, water use strategy and crop yield

Crop Production I

Considering titanium dioxide nanoparticles (TiO2 NPs) role in plant growth and especially in plant tolerance against abiotic stress, a greenhouse experiment was carried out to evaluate TiO2 NPs effects (0, 50, 100 and 200 mg L−1) on agronomic traits of Moldavian balm (Dracocephalum moldavica L.) plants grown under different salinity levels (0, 50 and 100 mM NaCl). Results demonstrated that all agronomic traits were negatively affected under all salinity levels but application of 100 mg L−1 TiO2 NPs mitigated these negative effects. TiO2 NPs application on Moldavian balm grown under salt stress conditions improved all agronomic traits and increased antioxidant enzyme activity compared with plants grown under salinity without TiO2 NP treatment. The application of TiO2 NPs significantly lowered H2O2 concentration. In addition, highest essential oil content (1.19%) was obtained in 100 mg L−1 TiO2 NP-treated plants under control conditions. Comprehensive GC/MS analysis of essential oils showed that geranial, z-citral, geranyl acetate and geraniol were the dominant essential oil components. The highest amounts for geranial, geraniol and z-citral were obtained in 100 mg L−1 TiO2 NP-treated plants under control conditions. In conclusion, application of 100 mg L−1 TiO2 NPs could significantly ameliorate the salinity effects in Moldavian balm.

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Titanium dioxide nanoparticles (TiO 2 NPs) promote growth and ameliorate salinity stress effects on essential oil profile and biochemical attributes of Dracocephalum moldavica

An experiment was conducted to investigate the effects of zinc application and salinity stress (0, 33, 66 and 99 mM NaCl) on some morphological and physiological parameters of soybean ('Glycine max' L., var. Williams). Results showed that zinc application improved shoot length, root fresh and dry weight and shoot fresh and dry weight under all salinity treatments. The catalase (CAT), ascorbate peroxidase (APX), polyphenoloxidase (PPO) and peroxidase activity (POD) and also proline content increased as a result of salinity stress. Lipid peroxidation and hydrogen peroxide concentration under the highest salinity were significantly greater than those under other treatments. However, lipid peroxidation and hydrogen peroxide concentration under salinity treatments significantly reduced as a result of zinc application. Zinc may act as a scavenger of ROS for mitigating the injury on biomembranes under salt stress. Adequate zinc also prevents uptake and accumulation of Na in shoot, by increasing membrane integrity of root cells.

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Changes in antioxidant enzymes activity and plant performance by salinity stress and zinc application in soybean ( Glycine max L.)

Atmospheric nitrogen fixation probably contributes at most about 10% of the total annual yield of fixed nitrogen. The most important source of fixed nitrogen derives from the activity of certain soil bacteria that absorb atmospheric N2 gas and convert it into ammonium. The process of biological nitrogen fixation offers an economical attractive and ecological advantage by of reducing external nitrogen input and improving the quality and quantity of internal resources. Mineral nutrients may influence N2 fixation in legumes and nonlegumes at various stages of the symbiotic process: infection and nodule development, nodule function, and host plant growth. Here, review the basic concepts of mineral nutrition, as well as the importance of mineral nutrients specifically for biological nitrogen fixation in the legume-rhizobia symbiosis. For healthy and vigorous growth, intact plants need to take up from the soil: relatively large amounts of some inorganic elements: ions of nitrogen (N), potassium (K), calcium (Ca), phosphorus (P) and sulphur (S); and, small quantities of other elements: iron (Fe), nickel (Ni), chlorine (Cl), manganese (Mn), zinc (Zn), boron (B), copper (Cu), and molybdenum (Mo). The enhancing effect of low levels of combined nitrogen on N2 fixation in legumes is related to the lag phase between root infection and the onset of N2 fixation. Phosphorus (P) is second only to nitrogen as an essential mineral fertilizer for crop production. At any given time, a substantial component of soil P is in the form of poorly soluble mineral phosphates. A high phosphorus supply is needed for nodulation. When legumes dependent on symbiotic nitrogen receive an inadequate supply of phosphorus, they may therefore also suffer from nitrogen deficiency. Potassium and sulphur are not usually limiting nutrients for nodulated legumes, although a K+ supplement for osmoadaptation has to be considered for growth in saline soils. Among mineral nutrients, B and Ca are undoubtedly the nutrients with a major effect on legume symbiosis. Both nodulation and nitrogen fixation depend on B and Ca2+, with calcium more necessary for early symbiotic events and B for nodule maturation.

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Role of Some of Mineral Nutrients in Biological Nitrogen Fixation

Multifunctional coating composed of Eryngium campestre L. essential oil encapsulated in nano-chitosan to prolong the shelf-life of fresh cherry fruits

The purpose of the present work was to evaluate effects of zinc application on growth and uptake and distribution of mineral nutrients under salinity stress [0, 33, 66, and 99 mM sodium chloride (NaCl)] in soybean plants. Results showed that, salinity levels caused a significant decrease in shoot dry and fresh weight in non-zinc application plants. Whereas, zinc application on plants exposed to salinity stress improved the shoot dry and fresh weight. Potassium (K) concentration, K/sodium (Na) and calcium (Ca)/Na ratios significantly decreased, while sodium (Na) concentration increased in root, shoot, and seed as soil salinity increased. Phosphorus (P) concentration significantly decreased in shoot under salinity stress. Moreover, calcium (Ca) significantly decreased in root, but increased in seed with increased salinization. Iron (Fe) concentration significantly decreased in all organs of plant (root, shoot, and seed) in response to salinity levels. Zinc (Zn) concentration of plant was not significantly a...

Effects of Zinc Application on Growth, Absorption and Distribution of Mineral Nutrients Under Salinity Stress in Soybean (Glycine Max L.)

A greenhouse research was conducted to evaluate the ameliorative effects of zinc application on soybean photosynthetic parameters, leaf relative water content (RWC), relative electrolytic leakage (REL), chlorophyll contents (Chl), and leaves and roots lipid peroxidation rate under salinity stress (0, 33, 66 and 99 mM NaCl). The results revealed that zinc application on plants exposed to salinity stress caused a noticeable enhancement of photosynthesis ( Pn ) by 110%, water use efficiency (WUE) by 54%, mesophyll efficiency (ME) by 98% and quantum yield ( �) by 102% compared with plants exposed to salinity stress alone. The chlorophylls a, b and total chlorophyll content and relative water content were significantly reduced with increasing NaCl salinity. The highest REL and lipid peroxidation were occurred at the highest salinity level.

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Weria Weisany

Papers

Changes in antioxidant enzymes activity and plant performance by salinity stress and zinc application in soybean ( Glycine max L.)

Role of Some of Mineral Nutrients in Biological Nitrogen Fixation

Multifunctional coating composed of Eryngium campestre L. essential oil encapsulated in nano-chitosan to prolong the shelf-life of fresh cherry fruits

Effects of Zinc Application on Growth, Absorption and Distribution of Mineral Nutrients Under Salinity Stress in Soybean (Glycine Max L.)

Physiological responses of soybean (Glycine max L.) to zinc application under salinity stress.