Rashad Mukhtar Balal

Exogenous 24-Epibrassinolide Elevates the Salt Tolerance Potential of Pea (Pisum sativum L.) by Improving Osmotic Adjustment Capacity and Leaf Water Relations

Salinity, as a wide spread problem around the globe, can drastically limits the crop growth and productivity. Therefore, there is a growing need to mitigate the drastic effects of this abiotic stress through the use some sustaiable short-term or long term approaches. An investigation was carried out to assess the potential role of 24-epibrassinolide (EBL) in mitigating the drastic effects of salt stress on growth, water relations, osmolytes, and ions accumulation of salt-tolerant and salt-sensitive pea genotypes. EBL treatment significantly altered the leaf water status and accumulation of osmolytes and various ions in salt-stressed [with sodium chloride (+NaCl)] plants. The plants of both salt-tolerant and salt-sensitive genotypes, subjected to +NaCl conditions had a significant reduction in plant fresh and dry weights, internodal distance, leaf area (LA), leaf water potential (w), leaf osmotic potential (o), leaf turgor potential (t), relative water content (RWC), number of seeds pod−1, seed weight, root/leaf inorganic osmolytes (Ca2+, K+ and Mg2+), while increased the levels of root/leaf proline, glycinebetaine, total free amino acids, total soluble sugars, sodium (Na+), and chloride (Cl−). There was non-significant effect of EBL on number of pods plant−1 both under saline and non-saline conditions. However, the foliar application of EBL significantly alleviated the deleterious effects of salinity by improving the plant biomass, water relations and concentration of organic/inorganic osmolytes and yield attributes. However, EBL minimized the drastic effects of salt stress by limiting the root/leaf Na+ and Cl− contents. It can be concluded that EBL efficiently alleviated the salinity-induced drastic effects by improving the water status of plant tissues, which led to salt dilution within plant tissues, thus minimized the ion-toxicity, ultimately elevated the plant growth by minimizing the toxic action of Na+ and Cl−. Secondly, EBL augmented the salt-tolerance capacity of tested pea genotypes by enhancing their osmotic adjustment potential, in terms of high accumulation of organic and inorganic osmolytes within leaf and root tissues.

Tritrophic interactions between parasitoids and cereal aphids are mediated by nitrogen fertilizer

Host plant nutritional quality can directly and indirectly affect the third trophic levels. The aphid–parasitoid relationship provides an ideal system to investigate tritrophic interactions (as the parasitoids are completely dependent for their development upon their hosts) and assess the bottom up forces operating at different concentrations of nitrogen applications. The effects of varying nitrogen fertilizer on the performance of Aphidius colemani (V.) reared on Sitobion avenae (F.) and Aphidius rhopalosiphi (D.) reared on Rhopalosiphum padi (L.) were measured. Parasitism and percent emergence of parasitoids were positively affected by nitrogen fertilizer treatments while developmental duration (egg, larval, and pupal stages) was not affected by increasing nitrogen inputs. In males and females of both parasitoid species, adult longevity increased with the increasing nitrogen fertilizer. Hind tibia length and mummy weight of both parasitoid species increased with nitrogen fertilizer concentrations, as a result of larger aphids. This study showed that nitrogen application to the soil can have important consequences for aboveground multitrophic interactions.

Foliar treatment with Lolium perenne (Poaceae) leaf extract alleviates salinity and nickel-induced growth inhibition in pea

Abstract The plants of pea (Pisum sativum L.) were grown under NaCl and/or NiCl2 stress, to comparatively evaluate stress-mitigating effects of pure proline and naturally proline-enriched Lolium perenne (L.) aqueous leaf extract. Both stress factors (salinity and nickel) significantly reduced plant biomass, chlorophyll content, photosynthetic activity, stomatal conductance, intercellular carbon dioxide (CO2) level, number of stomata, stomatal size, water-use efficiency, relative water content (RWC), and the membrane stability index (MSI). However, the proline and glycinebetaine contents, lipid peroxidation, electrolyte leakage, and activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, guaiacol peroxidase, and glutathione reductase) were significantly increased. Exogenously applied proline and Lolium perenne (LP) leaf extracts significantly overcame the nickel and/or salinity-induced toxic effects on growth, RWC, and various photosynthetic attributes. However, follow-up treatment with proline and LP-leaf-extract detoxified the stress caused by NiCl2 and/or NaCl, by suppressing lipid peroxidation and electrolyte leakage, accelerating the antioxidant enzyme activities, and improving the MSI, leaf/root proline, and glycinebetaine contents. LP-leaf-extract proved to be better than pure proline for improving growth, gas exchange parameters, osmolytes, RWC, and antioxidant enzyme activities. As LP-leaf-extract was enriched with a substantial amount of proline along with many other essential osmoprotectants, it was found to be as effective as pure proline in ameliorating growth, some major physiological attributes, and non-enzymatic and enzymatic antioxidant activities in the pea, under nickel and/or salinity stress. Thus, it could be used as an alternative inexpensive source of proline, to be used as a mitigating agent for protecting plants against the deleterious effects of nickel and/or salinity stress.