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Unexpected bioaccumulation and biomagnification of heavy metal(loid)s (HMs) in the environment have become a predicament for all living organisms, including plants. The presence of these HMs in the plant system raised the level of reactive oxygen species (ROS) and remodeled several vital cellular biomolecules. These lead to several morphological, physiological, metabolic, and molecular aberrations in plants ranging from chlorosis of leaves to the lipid peroxidation of membranes, and degradation of proteins and nucleic acid including the modulation of the enzymatic system, which ultimately affects the plant growth and productivity. Plants are equipped with several mechanisms to counteract the HMs toxicity. Among them, seed priming (SP) technology has been widely tested with the use of several inorganic chemicals, plant growth regulators (PGRs), gasotransmitters, nanoparticles, living organisms, and plant leaf extracts. The use of these compounds has the potential to alleviate the HMs toxicity through the strengthening of the antioxidant defense system, generation of low molecular weight metallothionein's (MTs), and phytochelatins (PCs), and improving seedling vigor during early growth stages. This review presents an account of the sources, uptake and transport, and phytotoxic effects of HMs with special attention to different mechanism/s, occurring to mitigate the HMs toxicity in plants employing SP technology. Novelty statement: To the best of our knowledge, this review has delineated the consequences of HMs on the crucial plant processes, which ultimately affect plant growth and development. This review also compiled the up to dated information on phytotoxicity of HMs through the use of SP technology, this review discussed how different types of SP approaches help in diminishing the concentration HMs in plant systems. Also, we depicted mechanisms, represent how HMs transport and their actions on cellular levels, and emphasized, how diverse SP technology effectiveness in the mitigation of plants' phytotoxicity in unique ways. [ABSTRACT FROM AUTHOR]

Salicylic acid is involved in the regulation of metabolic activity and defense mechanism in plants under various stress conditions. Present study was conducted to determine the effects of salicylic acid (10 to 500 μM) on seedling growth, development and nitrogen use efficiency in cucumber (Cucumis sativus L.) plants with or without nitrogen nutrient. Salicylic acid increased contents of chlorophyll, total non-structural carbohydrate and total nitrogen, as well as nitrate assimilation through the induction of nitrate reductase (EC 1.6.6.1) activity in isolated cucumber cotyledons. Accumulation of salicylic acid was two-fold higher in cotyledons without nitrate supply in comparison to that with nitrate supply. Further 50 μM of SA induced enhancement in seed germination and growth characteristics. However higher salicylic acid concentrations inhibited above physiological characteristics. Results show that, field application of salicylic acid need optimum physiological concentration (e.g., 50 μM) to increase nitrogen use efficiency particularly during germination and seedling growth.

The present review article is dealing with the potentiality of micronutrients in terms of seed priming treatment and its effect within the plant system is considered. Since last 3 to 4 decades various scientists are working with different planting methods and introduced several seed invigoration techniques, one of them is seed priming. Seed priming is basically a restricted hydration treatment with appropriate timing, in which seeds are treated with various types of organic and inorganic compounds. Whereas in this review, we have discussed the potential of different micronutrients in seed priming treatments for escalating crop growth, development and grain yield. Micronutrient priming has several beneficial effects in the morpho-physiological, biochemical and molecular aspects of the plants. In most cases, micronutrient application through seed treatment has astonishingly performed better than other application methods. Being an easy and cost effective method of micronutrient application, seed priming offer an attractive option for resource-poor farmers. [ABSTRACT FROM AUTHOR]

The present piece of work was conducted in the Seed Physiology Laboratory of Institute of Agricultural Sciences, Banaras Hindu University in the year 2011-12, where the rice seeds variety MTU 7029 were primed with different combinations of kinetin (in ppm) and magnesium nitrate (in mM) (2.5 ppm+2 mM, 2.5 ppm+4 mM, 2.5 ppm+6 mM, 2.5 ppm+8 mM, 5 ppm+2 mM, 5 ppm+4 mM, 5 ppm+6 mM, 5 ppm+8 mM kinetin and magnesium nitrate respectively) whereas; seeds without any treatment referred as control (non-primed). Various physiomorphological (shoot and root lengths (in cm), root number, fresh and dry weights (in g)) and biochemical (proline content (mg g-1 dry weight of seedlings), total chlorophyll content (mg g-1) and superoxide dismutase activity (unit×102 g-1 min-1 fresh weight of leaf; at 20 days after sowing)) parameters were studied in the seedlings, obtained from 10, 15 and 20 DAS old primed and non-primed plants. All the primed seeds were found to perform better as compared to non primed control one. However, treatment 2.5 ppm kinetin+4 mM magnesium nitrate performed best among all the treatments and all the studied parameters such as shoot and root lengths, root number, fresh and dry weights, proline content, total chlorophyll content and superoxide dismutase activity in 10, 15 and 20 days after sowing. [ABSTRACT FROM AUTHOR]

In the present piece of work the effects of seed priming with KNO3 on late sown sesame crop (Sesamum indicum) var. T-4 (V1), T-12 (V2) and Shekhar (V3) in respect of germination, physiomorphological, biochemical and yield parameters were observed. The treatments comprised of KNO3 [10 mM (T1), 15 mM (T2)] and distilled water (DW) primed sets (T0). The results showed that the KNO3 treatment promoted germination percentage, root and shoot length, fresh and dry weights of seedling, catalase, peroxidase and proline content as well as yield attributes like number of capsules plant-1, number of seeds capsule-1, test weight (1000 seed weight in g) and yield plant-1 (g). After 80 h, the highest germination percentage was recorded in 15 mM KNO3 (T2) primed seeds of Sesamum indicum var. T-4, T-12 and Shekhar. The average of root length, shoot length, fresh weight, and dry weight was recorded highest in treatment T2 in comparison to distilled water primed seeds (control) at 25 DAS in all varieties i.e., T-4, T-12 and Shekhar respectively. Yield attributes like number of capsules plant-1, number of seeds capsule-1, test weight and yield plant-1 were also highest in treatment T2 in all varieties V1, V2 and V3 respectively. Variety V1 and treatment T2 recorded the highest values of catalase, peroxidase and proline content followed by variety V3 and V2and treatment T1 and T0 at 45 DAS respectively. It had been found that seed priming with KNO3 ameliorate the effect of late sowing. [ABSTRACT FROM AUTHOR]

Due to anthropogenic as well as by natural factors the climate of earth is predicted to be warm by an average of 2-4 °C, at the end of the 21st Century. Emission of green house gases (GHG) from agricultural system is one of the major contributing factor in global warming. Heat stress is one of the major abiotic stresses threatening plant growth worldwide. Agricultural crops suffer in presenting their optimum yield potential due to heat stress. Heat stress causes enormous alterations in various processes within the plant system; most of them are well understood from various physiological, biochemical and molecular studies. Heat stress not only affects the morphological and phenological parameters but also the physiological and biochemical parameters like plant water relationship, photosynthesis, assimilate partitioning, hormonal changes, cell membrane stability, production of secondary plant metabolites, antioxidative metabolism, synthesis of heat shock proteins, cell signalling etc. In the advent of climate change and subsequent global warming there is an urgent need for understanding the physiological and biochemical basis of heat stress tolerance in crop plants. There has been a lot of effort worldwide in this regard to develop high temperature tolerant genotypes through transgenic intervention and genetic engineering. This paper reviews the literature supporting evidence for the morphological, phenological, physiological and biochemical effects of heat stress on several plants and different molecular approaches to develop transgenics tolerant to high temperature stress. A plethora of these kinds of plant responses are finally regulated by the genes. Hence, more biotechnological and molecular studies including genomics, proteomics, metaboliomics and the cryptomics are necessary to elucidate the processes further. [ABSTRACT FROM AUTHOR]

The aim of the study is to establish a routine procedure for high frequency plant regeneration from in vitro raised embryogenic callus of indica rice var. MTU 7029. In the present piece of work, various concentrations of surfactants [sodium hypochlorite (10 to 30%) and mercuric chloride (0.01 to 1%)] were tested and best concentration of surfactants was chosen according to the parameters like callus induction percentage and its growth as well as status of contamination. On the basis of available data of the said parameters, 0.1% mercuric chloride has shown best performance in all the aspect for surface sterilization of mature rice seeds for 5 minutes and the percentage of the contamination was also very less. The effect of synthetic auxin [2,4-D (0 to 4 mg L-1)], cytokinin [kinetin (0 to 1 mg L-1)], sucrose (0 to 50 g L-1), agar (6-16 g L-1) and growth medium (MS, N6 and LS) on callus induction were optimized to achieve high frequency plant regeneration from fresh embryogenic callus without further subculture. Results suggests that 2 mg L-1 2, 4-D, 30 g L-1 sucrose, 8 g L-1 agar and MS basal medium were best for embryogenic callus induction. From the present piece of work an efficient protocol was developed for in vitro embryogenic callus formation. [ABSTRACT FROM AUTHOR]

Sulfur is a growth-limiting and secondary macronutrient as well as an indispensable component for several cellular components of crop plants. Over the years various scientists have conducted several experiments on sulfur metabolism based on different aspects of plants. Sulfur metabolism in seeds has immense importance in terms of the different sulfur-containing seed storage proteins, the significance of transporters in seeds, the role of sulfur during the time of seed germination, etc. The present review article is based on an overview of sulfur metabolism in seeds, in respect to source to sink relationships, S transporters present in the seeds, S-regulated seed storage proteins and the importance of sulfur at the time of seed germination. Sulfur is an essential component and a decidable factor for seed yield and the quality of seeds in terms of oil content in oilseeds, storage of qualitative proteins in legumes and has a significant role in carbohydrate metabolism in cereals. In conclusion, a few future perspectives towards a more comprehensive knowledge on S metabolism/mechanism during seed development, storage and germination have also been stated. [ABSTRACT FROM AUTHOR]

An experiment was conducted in both laboratory (germinative attributes) and field conditions (growth attributes) with completely randomized design (CRD) and randomized block design, respectively, to view the responses of different priming treatments in two wheat varieties: HUW-234 (V1) and BHU-3(V2). In the present study, seeds were primed with water (hydro; T2), Mg (NO3)2 (T3), ZnSO4 (T4), and a combination of both salts (T5). Their carry over effects were observed on the germinative and vegetative phases of growth. All treatments were compared with the performance of nonprimed control seeds (T1). Maximum germination percentage (98.33, 100%) was noted with T3, whereas length of shoot (8.83, 10.23 cm) and root (9.47, 10.73 cm) and their fresh (0.34, 0.45 g) and dry weights (0.05, 0.07 g) were recorded maximum in T5 for both varieties; however, the vigor index I and II showed varietal difference, but primed sets were found always superior with respect to nonprimed control. Study of plant height, leaf number and area, fresh and dry weights of total leaves and stem showed the best performance under combined use of both salts, i.e., Mg (NO3)2 and ZnSO4 as priming agents, followed by ZnSO4, Mg (NO3)2, hydro, and the nonprimed one. The study of biochemical parameters such as protein content and nitrate reductase activity of leaves showed the highest increment in combined priming treatment and increased 63.77, 90.37, 37.44% and 12.81, 5.61, 7.75%, respectively, after 35, 45, and 60 days after sowing. It is likely that chlorophyll, nitrogen, iron, and zinc content also followed a similar pattern and were enhanced in combined priming treatments as compared to nonpriming treatment. Therefore, the result suggests that priming seeds with Mg (NO3)2 and ZnSO4 worked synergistically at varietal level and improved growth attributes at field conditions. [ABSTRACT FROM AUTHOR]

• Heat stress in plants causes several morphological, physiological and molecular changes affecting growth and yield attributes. • Seed priming is an eco-friendly technology to induce uniform and rapid emergence of seed that leads to better stand establishment and improvement in yield, under both optimal and adverse environments. • Nitrate priming of seeds improves seed germination, crop growth, nitrogen metabolism and increases nitrate reductase activity, enabling reversal of heat stress induced responses in plants, maintaining the yield potential of the plants. Exhaustion of natural sources due to expanding usage leads to an increase in global temperature. Heat stress and rising CO 2 severely impact crop growth and catastrophic loss of agriculture ecosystem, productivity and quality. The physiological and metabolic processes of plants are affected by heat stress due to denatured proteins, lipid structure, alteration in membrane integrity and inactivation of enzymes incurred at various growth stages. To diminish heat stress losses in plants, many techniques such as conventional breeding, genetic engineering, molecular breeding were used by the agriculturists, which helped develop tolerant varieties of crops with increased quality and production. Recent advancement in seed priming has many fold impacts such as mitigation of stress via improving tolerance mechanisms in plants, reduction in soil and water pollution, improved production and food quality of important agriculture crops. It is one of the low-cost, reliable and profitable crop improvement techniques. Nitrates have several roles in modulating the plant processes. Priming with nitrate salts improves nitrate reductase and amylase activity, nitrogen, amino acid and chlorophyll content in leaves, causes increase in proline, sugar content, antioxidant metabolism, grain yield, protein and nutrient content in various crops. Despite positive responses of nitrate seed priming, this technology has been less applied in the area of crop production in the field condition. Considering these facts, this review depicts responses of the plants under heat stress and their management through nitrate seed priming. [ABSTRACT FROM AUTHOR]