Nadeem Hashmi

Salicylic acid-induced physiological and biochemical changes in lemongrass varieties under water stress

Abstract Salicylic acid (SA) treatment reduces the damaging action by water deficit on growth and accelerates a restoration of growth processes. The aim of the present work was to study the physiological and biochemical alteration induced by SA in lemongrass plants under stress conditions. Therefore, a pot culture experiment was conducted to test whether SA application at concentration of (10−5 M) through foliar spray could protect lemongrass (Cymbopogon flexuosus Steud. Wats.) varieties (Neema and Krishna), subjected to drought stress on the basis of growth parameters and biochemical constituents, proline metabolism and quality attributes including citral content. The treatments were as follows: (i) 100% FC + 0 SA; (ii) 75% FC + 0 SA; (iii) 50% FC + 0 SA; (iv) 75% FC + 10−5 M SA; and (v) 50% FC + 10−5 M SA. The growth parameters were significantly reduced under the applied water stress levels; however, foliar application of salicylic acid (10−5 M) improved the growth parameters in stress-affected plants. The plants under water stress exhibited a significant increase in activities of nitrate reductase and carbonic anhydrase, and electrolyte leakage, proline content, free amino acid and in PEP carboxylase activity. Content and yield of essential oil also significantly decreased in plants that faced water stress. Thus, it was concluded that variety Neema is the more tolerant variety as compared to Krishna on the basis of content and oil yield and well adapted to drought stress conditions.

Methyl jasmonate counteracts boron toxicity by preventing oxidative stress and regulating antioxidant enzyme activities and artemisinin biosynthesis in Artemisia annua L.

Boron is an essential plant micronutrient, but it is phytotoxic if present in excessive amounts in soil for certain plants such as Artemisia annua L. that contains artemisinin (an important antimalarial drug) in its areal parts. Artemisinin is a sesquiterpene lactone with an endoperoxide bridge. It is quite expensive compound because the only commercial source available is A. annua and the compound present in the plant is in very low concentration. Since A. annua is a major source of the antimalarial drug and B stress is a deadly threat to its cultivation, the present research was conducted to determine whether the exogenous application of methyl jasmonate (MeJA) could combat the ill effects of excessive B present in the soil. According to the results obtained, the B toxicity induced oxidative stress and reduced the stem height as well as fresh and dry masses of the plant remarkably. The excessive amounts of soil B also lowered the net photosynthetic rate, stomatal conductance, internal CO2 concentration and total chlorophyll content in the leaves. In contrast, the foliar application of MeJA enhanced the growth and photosynthetic efficiency both in the stressed and non-stressed plants. The excessive B levels also increased the activities of antioxidant enzymes, such as catalase, peroxidase and superoxide dismutase. Endogenous H2O2 and O2− levels were also high in the stressed plants. However, the MeJA application to the stressed plants reduced the amount of lipid peroxidation and stimulated the synthesis of antioxidant enzymes, enhancing the content and yield of artemisinin as well. Thus, it was concluded that MeJA might be utilized in mitigating the B toxicity and improving the content and yield of artemisinin in A. annua plant.

Utilizing the γ-Irradiated Sodium Alginate as a Plant Growth Promoter for Enhancing the Growth, Physiological Activities, and Alkaloids Production in Catharanthus roseus L.

Abstract Sodium alginate is a polysaccharide that is largely obtained from the brown algae (Sargassum sp.). It has been used as a wonderful growth promoting substance in its depolymerized form for various plants. The aim of this study was to find out the effects of various concentrations of γ-irradiated sodium alginate (ISA), viz., deionized water (control, T0), 20 (T1), 40 (T2), 60 (T3), 80 (T4), and 100 ppm (T5) on the agricultural performance of Catharanthus roseus L. (Rosea) in terms of growth attributes, photosynthesis, physiological activities, and alkaloid production. The present work revealed that ISA applied as leaf-sprays at concentrations from 20 to 100 ppm might improve growth, photosynthesis, physiological activities, and alkaloid production in C. roseus L. significantly. Of the various ISA concentrations, 80 ppm proved to be the best one compared to other concentrations applied.

Depolymerized carrageenan ameliorates growth, physiological attributes, essential oil yield and active constituents of Foeniculum vulgare Mill.

Irradiated carrageenan (IC) elicits an array of plant defense responses and biological activities in plants. An experiment was carried out in the naturally illuminated conditions of net house in order to assess the effects of foliar spray of IC on agricultural performance of fennel (Foeniculum vulgare Mill.), which is a high-value essential oil bearing medicinal crop used in pharmaceutical, food and cosmetic industries. There were applied four IC concentrations (40, 60, 80 and 100 mg L(-1)) as foliar sprays. Application of IC significantly improved the growth attributes, physiological and biochemical parameters, essential oil yield and the contents of main components of essential oil of fennel. IC applied at 80 mg L(-1) enhanced these parameters maximally. Unirradiated carrageenan and deionized water had no effect on the attributes studied. Moreover, GLC analysis revealed a significant increase in the components of essential oil, viz. fenchone (4.48-7.82%) and anethole (78.38-86.08%) compared to the control.

Use of N and P biofertilizers reduces inorganic phosphorus application and increases nutrient uptake, yield, and seed quality of chickpea

Leguminous crops suffer severely in soils poor in phosphorus. A 2-factor factorial experiment was conducted in a net-house to explore the effect of graded levels of P fertilizer (0, 30, and 60 kg P ha-1 or P0, P30, and P60, respectively) together with rhizobium (biological nitrogen fertilizer (BNF)) and/or phosphate-solubilizing bacteria (biological phosphorus fertilizer (BPF)) in terms of nutrient uptake, yield, and quality of chickpea (Cicer arietinum L.). Phosphorus was applied as basal dose, while seeds were treated with respective biofertilizer(s) before sowing according to the treatments [BF0 (control), BNF, BPF, and BNF+BPF]. Concerning the main effects, P60 proved superior or equivalent to P30, while among the biofertilizer treatments, BNF+BPF gave the greatest values for nutrient uptake as well as for yield and quality parameters. The interaction between P levels and biofertilizer treatments was generally significant. 30 kg P ha-1 applied with N and P biofertilizers (P30 × BNF+BPF) was the most profitable interaction for N uptake as well as for yield and quality characteristics. Compared to P60 applied alone (P60 × BF0), P30 × BNF+BPF resulted in greater N uptake (27.3%), seed yield (21.1%), and the content of seed protein (2.9%) and carbohydrate (5.6%). Furthermore, P30 × BNF+BPF was statistically equal to P60 × BNF+BPF with regard to N uptake, seed yield, and protein content as well as for most yield components. Thus, P30 × BNF+BPF saved 30 kg P ha-1 of the costly inorganic P fertilizer to achieve the greatest crop yield and quality.

Radiolytically depolymerized sodium alginate improves physiological activities, yield attributes and composition of essential oil of Eucalyptus citriodora Hook

Eucalyptus citriodora Hook. is highly valued for its citronellal-rich essential oil (EO) extracted from its leaves. Hence, escalated EO production of eucalyptus is the need of hour. Marine polysaccharides (sodium alginate) are processed through gamma radiation of particular intensity, to obtain the irradiated sodium alginate (ISA). A pot experiment was conducted to study the effect of foliar application of ISA on growth, biochemical, physiological, EO yield and composition of E. citriodora. The treatments were applied as: foliar spray of deionized water only (control), seed soaked with ISA (90 mg L(-1)) and foliar spray of ISA with 30, 60, 120 and 240 mg L(-1). The treatment 6 (spray of ISA at 120 mg L(-1)) showed the highest value for most of the parameters studied. It also enhanced the EO content (33.3%), EO yield (86.7%), citronellal content (63.4%) and citronellal yield (205.5%) as compared to the control.

Modulation of defence responses by improving photosynthetic activity, antioxidative metabolism, and vincristine and vinblastine accumulation in Catharanthus roseus (L.) G. Don through salicylic acid under water stress

A pot experiment was conducted to find out whether the foliar spray of salicylic acid (SA) could successfully ameliorate the adverse effects of water stress on periwinkle. Pots were irrigated with ground water regularly as a control and other treatments were given as 15 and 30 days interval drought (DID) at 30 DAS. Plants were uprooted randomly at 46 and 61 DAS, washed carefully and separated into root, stem and leaf for analyses. A uniform concentration (10−5 mol/l) of salicylic acid (SA) was applied as a foliar spray at the vegetative stage. Water stress significantly reduced the growth attributes including plant height, leaf-area index, shoot and root fresh weights, shoot and root dry weights. Long term water stress led to a gradual decrease in photosynthetic parameters and activities of nitrate reductase and carbonic anhydrase. Ascorbic acid, total alkaloids and antioxidant enzymes: superoxide dismutase, catalase and peroxidase increased in stress faced plants. Foliar application of SA (10−5 M) reduced the damaging effect of stress on plant growth and accelerated the restoration of growth processes. It not only improved the growth parameters but also partially reversed the effects of salinity. Total alkaloid content was improved by SA application both in unstressed and stressed plants. Foliar spray of SA not only overcame the adverse effect of stress but also improved the content of vincristine and vinblastine in stressed plants.

Cumulative effect of gibberellic acid and phosphorus on crop productivity, biochemical activities and trigonelline production in Trigonella foenum-graecum L.

Abstract Fenugreek (Trigonella foenum-graecum L.) is an antidiabetic plant. Its bioactive compound, trigonelline, is known to counter diabetes through insulin secretion, modulation of β cell regeneration and quick activity of glucose metabolism related enzymes. A pot experiment was conducted in the natural conditions of net house of the Department of Botany, Aligarh Muslim University, Aligarh (UP), India, to evaluate the effect of four concentrations of GA3 (0, 10−7 M, 10−6 M and 10−5 M), alone and in combination with phosphorus (40 kg P ha−1), on growth, biochemical and yield attributes of fenugreek. Compared to control, the combination of GA3 and phosphorus (P40 + 10−6 M GA3) significantly increased the activities of nitrate reductase (30.8%) and carbonic anhydrase (30.7%) enzymes; it also enhanced the seed yield (140.6%) and the content of total chlorophyll (28.5%) and carotenoids (26%). There was also significant increase (19.51%) in the content of seed trigonelline.

Recent Trends in Jasmonate Signaling Pathway

Jasmonates (JA) are a new class of plant hormones that has recently been worked out regulating the interweaving plant responses against invading microbes, herbivores, mechanical damage, and other environmental stresses. Their interactions are extensive working at the forefront of root or shoot tissues through volatile regulators, or they are regulated interdependently through the cross talk of other established growth regulators. Jasmonates, the product of octadecanoid pathway, have recently emerged as a versatile regulator of plant physiological and defense responses after salicylates. Most of the components of their signaling pathway have been identified through mutant studies. A progress towards the interaction of JA with other phytohormones is underway. Present review sheds the light on the recent progress made in identification and working mechanism of jasmonate receptor complex, its downstream signaling pathway, and the molecular interaction of its components with the signaling pathways of some other plant hormones.

Changes in growth, yield, photosynthetic characteristics, enzyme activities and essential oil production of fennel (Foeniculum vulgare Mill.) under growth regulator treatments

Fennel (Foeniculum vulgare Mill.) belongs to the Apiaceae family. It is a high value medicinal and essential oil bearing crop used in pharmaceutical, food and cosmetic industries. Keeping the medicinal as well as economic importance of this herb in mind, a pot experiment was carried out under the net house conditions of the Botanical Garden, Fort, AMU, Aligarh. The experiment was conducted using a randomized block design with four replications. This study was conducted to assess the effects of triacontanol (TRIA) alone and in combination with gibberellic acid (GA3) on growth characteristics, photosynthetic parameters, some other physiological and biochemical attributes, composition and yield of essential oil of fennel. At 30 days after sowing, the plants were sprayed with either TRIA or with different combination of TRIA and GA3. Among the treatments, foliar spray of 10−6 TRIA + 10−6 GA3 significantly promoted the values for most of the growth, physiological and biochemical attributes as well as for essential oil composition and yield attributes. It was concluded that a combined spray of TRIA and GA3 (10−6 TRIA + 10−6 GA3) might be highly effective for increased productivity and essential oil composition of fennel.