SEED PRIMING AND EXOGENOUS APPLICATION OF SALICYLIC ACID ENHANCE GROWTH AND PRODUCTIVITY OF OKRA (Abelmoschus esculentus L.) BY REGULATING PHOTOSYNTHETIC ATTRIBUTES

Low and uneven germination is a serious problem for the successful production of okra seedlings. Priming of seeds as well as supplementation of different plant growth regulators exhibited better response in successful seedling production which eventually results in higher yield. Therefore, the present study was conducted to evaluate the effects of seed priming and exogenous application of salicylic acid (SA) on okra seed germination and plant development. The okra seeds were primed by 1 mM and 2 mM of SA for 60 minutes whereas the seeds were washed several times with distilled water for the control treatment. Similar doses of SA have been exogenously sprayed to the 12 days okra seedlings for 4 days. The results of the study revealed that seed priming with SA enhanced germination percentage (GP), increased coleoptile length and weight, shoot and root length, and seed vigor index (SVI). Similarly, exogenous application of 1 mM SA increased relative water content (RWC), contents of chlorophyll a, chlorophyll b, total chlorophyll while a higher dose of SA (2 mM) degraded the leaf pigments. Supplementation of SA altered photosynthetic attributes, net photosynthetic (Pn) and transpiration rate (Tr), stomatal conductance (Gs), and water use efficiency (WUE). Moreover, SA treatment reduced the time duration of flower bud initiation and days to first flowering and enhanced the yield per plant. The results of this study indicated that seed priming and exogenous application of SA enhanced germination and okra productivity by regulating RWC and photosynthetic attributes where 1 mM SA is more effective compared to 2 mM SA.

Ameliorative Effects of Exogenous Proline on Photosynthetic Attributes, Nutrients Uptake, and Oxidative Stresses under Cadmium in Pigeon Pea (Cajanus cajan L.)

Proline plays a significant role in the plant response to stress conditions. However, its role in alleviating metal-induced stresses remains elusive. We conducted an experiment to evaluate the ameliorative role of exogenous proline on cadmium-induced inhibitory effects in pigeon pea subjected to different Cd treatments (4 and 8 mg/mL). Cadmium treatments reduced photosynthetic attributes, decreased chlorophyll contents, disturbed nutrient uptake, and affected growth traits. The elevated activity of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), in association with relatively high contents of hydrogen peroxide, thiobarbituric acid reactive substances, electrolyte leakage, and endogenous proline, was measured. Exogenous proline application (3 and 6 mM) alleviated cadmium-induced oxidative damage. Exogenous proline increased antioxidant enzyme activities and improved photosynthetic attributes, nutrient uptake (Mg2+, Ca2+, K+), and growth parameters in cadmium-stressed pigeon pea plants. Our results reveal that proline supplementation can comprehensively alleviate the harmful effects of cadmium on pigeon pea plants.

Exceeding Potassium and Zinc Application Rate above Farmers Practiced Rate Improves Dry Matter Partitioning, Photosynthetic Attributes, Yield and Quality of Maize (Zea mays L.) under Dryland Condition

Aims: This field experiment was conducted to compare the combined application of different rates of potassium and zinc application against the standard farmers practised application rate based on dry matter distribution, net photosynthesis, transpiration rate, sub stomatal C02 concentration, stomatal conductance, grain yield and quality attributes (protein and carbohydrate content and yield). Place and Duration of Study: This short-term field trial was conducted on the Agronomy Research Farm of Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India on the Kharif (Post monsoon) season of 2016. Methodology: The experiment was conducted in Factorial Randomized Block Design (FRBD) with two factors i.e., potassium and zinc, each having three levels. The experiment was replicated thrice. The three potassium levels were 30, 60 and 90 kg K2O ha-1 while the zinc was applied 20, 30 and 40 kg ZnSO4.7H2O ha-1 as three distinctive levels. A short duration dwarf maize cultivar Ravi-81 was used for the experiment. Results: Perusal of experiment results confirmed that potassium and zinc have positive interaction even in short duration crop under dryland condition. The higher dry matter accumulation, crop growth rate, photosynthetic attributes, yield, protein content, protein yield, and carbohydrate yield has been recorded with the application of potassium at a rate of 60 kg K2O ha-1 along with zinc application of 30 kg ZnSO4.7H2O ha-1 which has been found to be statistically superior over farmers adopted practice (30 kg K2O ha-1 along with zinc application of 20 kg ZnSO4.7H2O ha-1). Conclusion: Combined application of potassium and zinc has positive interaction on each other, and the increased rate is needed to meet the demand for short duration high yielding maize crop for enhanced growth, yield and quality attributes.

Exogenous application of potassium improves the drought tolerance in chickpea

Drought is one of the major agricultural problems which cause losses to crop productivity. It is a worldwide problem and prevails in many parts of the world as a major threat to agriculture. Potassium (K) is considered to be an essential nutrient that plays an important role in growth, development and defense response in the plant under stressful conditions. This work investigated the effects of K in drought tolerance of chickpea seedlings by examining growth, photosynthetic performance, total osmo-regulation substance contents and antioxidative enzymes subjected to drought stress. The drought stress impaired the growth (root and shoot dry weight, root: shoot ratio, seedlings biomass), water relations, photosynthetic attributes, transpiration rate and chlorophyll contents and anti-oxidants activity of chickpea seedlings. Nonetheless, the foliar application K improved the growth, water relations, photosynthetic attributes, transpiration rate, chlorophyll contents and anti-oxidative activity of chickpea under drought conditions. Moreover, an increase in antioxidant enzyme activity and accumulation of osmoprotectants (proline, soluble protein and soluble sugar) was noted under stressed conditions, which was more pronounced in chickpea which experienced of K application. To conclude that, foliar application of K mitigated the adverse effect of drought, K was proved to be even more effective in alleviating the adverse effect of drought stress on chickpea.

Response of Potato (Solanum Tuberosum L.) Plants to Spraying by Hydrogen Peroxide

The biocidal properties of hydrogen peroxide (H2O2) could be used in plant protection. However, the effects of H2O2 foliar spraying on the performance of the potato photosynthetic apparatus are still unclear. A pot experiment was conducted to investigate the effect of foliar spraying, which was done twice, with various H2O2 concentrations (1, 3, 6, 12, and 18%) on the potato photosynthetic apparatus efficiency and antioxidant capacity. The measurements were taken four times: on the first and seventh day after each application. Foliar spraying with 1% H2O2 concentration was the most stimulating for the course of physiological processes in leaves. Further increased doses of H2O2 enhanced stress in plants which is manifested by a decrease in pigment levels, photosynthetic attributes, antioxidant capacity in leaves, and fresh mass above-ground parts of potato plants. The intensive effect of spraying was particularly observed on the first day after application, while later, the activity of the photosynthetic apparatus and antioxidant capacity increased. The study provides information that foliar spraying with 1% H2O2 can be taken into account in further research on the development of a potato plant protection methods.