Exploration of physiological and biochemical processes of canola with exogenously applied fertilizers and plant growth regulators under drought stress

Environmental stresses may alter the nutritional profile and economic value of crops. Chemical fertilizers and phytohormones are major sources which can enhance the canola production under stressful conditions. Physio-biochemical responses of canola altered remarkably with the use of nitrogen/phosphorus/potassium (N/P/K) fertilizers and plant growth regulators (PGRs) under drought stress. The major aim of current study was to evaluate nutritional quality and physio-biochemical modulation in canola (Brassica napus L.) from early growth to seed stage with NPK and PGRs in different water regimes. To monitor biochemical and physiological processes in canola, two season field experiment was conducted as spilt plot under randomized complete block design (RCBD) with four treatments (Control, Chemical fertilizers [N (90 kg/ha), P and K (45 kg ha-1)], PGRs; indole acetic acid (IAA) 15g ha-1, gibberellic acid (GA3) 15g ha-1 and the combination of NPK and PGRs] under different irrigations regimes (60, 100, 120, 150 mm evaporations). Water stress enhanced peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), polyphenol oxidase (PPO), soluble sugar, malondialdehyde (MDA), proline contents as well as leaf temperature while substantially reduced leaf water contents (21%), stomatal conductance (50%), chlorophyll contents (10–67%), membrane stability index (24%) and grain yield (30%) of canola. However, the combined application of NPK and PGR further increased the enzymatic antioxidant pool, soluble sugars, along with recovery of leaf water contents, chlorophyll contents, stomatal conductance and membrane stability index but decreased the proline contents and leaf temperature at different rate of evaporation. There is positive interaction of applied elicitors to the water stress in canola except leaf area. The outcomes depicted that the combination of NPK with PGRs improved the various morpho-physiological as well as biochemical parameters and reduced the pressure of chemical fertilizers cost about 60%. It had also reduced the deleterious effect of water limitation on the physiology and grain yield and oil contents of canola in field experiments.

Effect of Water Stress on Grain Yield and Physiological Characters of Quinoa Genotypes

Climate change scenarios predict that an extended period of drought is a real threat to food security, emphasizing the need for new crops that tolerate these conditions. Quinoa is the best option because it has the potential to grow under water deficit conditions. There is considerable variation in drought tolerance in quinoa genotypes, and the selection of drought-tolerant quinoa germplasms is of great interest. The main goal of this work is to evaluate the crop yield and characterize the physiology of 20 quinoa genotypes grown under water deficit in a wirehouse. The experiment was a complete randomized design (CRD) factorial with three replications. Seedling growth, i.e., fresh weight (FW), dry weight (DW), root length (RL), shoot length (SL), relative growth rate of root length (RGR-RL), shoot length (RGR-SL), and physiological performance, i.e., chlorophyll content (a and b), carotenoid, leaf phenolic content, leaf proline content, membrane stability index (MSI), and leaf K+ accumulation were evaluated in a hydroponic culture under different water-deficit levels developed by PEG 6000 doses (w/v) of 0% (control), 0.3%, and 0.6%. Yield attributes were evaluated in a pot at three different soil moisture levels, as determined by soil gravimetric water holding capacity (WHC) of 100 (control), 50% WHC (50 % drought stress) and 25% WHC (75% stress). In both experiments, under the water stress condition, the growth (hydroponic study) and yield traits (pot study) were significantly reduced compared to control treatments. On the drought tolerance index (DTI) based on seed yield, genotype 16 followed by 10, 1, 4, 5, 7, and 12 could be considered drought-tolerant genotypes that produced maximum grain yield and improved physiological characteristics under severe water stress conditions in hydroponic culture. In both studies, genotypes 3, 8, 13, and 20 performed poorly and were considered drought-sensitive genotypes with the lowest DTI values under water-stressed conditions. All the studied agronomic traits (grain yield, root and shoot length, shoot fresh and dry weights) and physiological traits (leaf phenolic, proline content, carotenoid, K+ accumulation, membrane stability index, and relative water content) were firmly inter-correlated and strongly correlated with DTI. They can be regarded as screening criteria, employing a large set of quinoa genotypes in a breeding program.

Foliar Nourishment with Different Zinc-Containing Forms Effectively Sustains Carrot Performance in Zinc-Deficient Soil

Among the essential micronutrients, zinc (Zn) affects vital functions in crop plants. The influences of foliar nourishing with certain Zn-containing forms on the growth, productivity, and physiology of carrot plants (cv. Fire wedge F1) and their nutritional contents when grown in Zn-deficient soil were examined in both 2019/2020 and 2020/2021 field trials. Two doses of zinc oxide nanoparticles (ZnO-NPs(1) = 20 and ZnO-NPs(2) = 40 mg L−1), zinc–EDTA (Zn–EDTA(1) = 1 and Zn–EDTA(2) = 2 g L−1), or bulk zinc oxide (ZnO-B(1) = 200 and ZnO-B(2) = 400 mg L−1) were applied three times. The data outputted indicated, in general, that ZnO-NPs(2) were the best treatment that conferred more acceptable plant growth (measured as shoot length and fresh and dry weights), physiology (measured as cell membrane stability index, SPAD readings, and nutrient uptake), and nutritional homeostasis (e.g., P, Ca, Fe, Mn, Zn, and Cu contents). All these positive attributes were reflected in the highest yield, which was measured as fresh weight, dry matter, length, diameter, volume, and total yield of carrot roots. However, there were some exceptions, including the highest membrane stability index in both seasons, the highest Cu uptake and Mn content in the first season, and root fresh weight in both seasons obtained with ZnO-NPs(1). Moreover, the maximum P uptake and root dry matter were obtained with ZnO-B(1) and the highest content of root P was obtained by ZnO-B(2). Based on the above data, foliar nourishing with ZnO-NPs(2) can be recommended for the sustainability of carrot cultivation in Zn-deficient soils.

Growth, physiological, and biochemical responses of thyme (Thymus vulgaris L.) to the application of arbuscular mycorrhizal fungi under cadmium stress conditions

Thyme (Thymus vulgaris L.) is one of the most important medicinal plants used in various pharmaceutical, osmotic, health, and food industries. Arbuscular mycorrhizal fungi (AMF) symbiosis is viewed as one of the several methods to improve growth under heavy metals stress. To investigate the effects of cadmium (Cd) and AMF bio-fertilizers on the growth and morpho-physiological characteristics of thyme, a greenhouse experiment was performed in three replications. Experimental treatments included Cd at three levels 0, 75, and 150 mg/kg of soil and AMF at three levels without inoculation, inoculation with Funneliformis etunicatum, and Funneliformis mosseae. Cadmium stressed plant showed reduced plant height, number of leaves, stem fresh and dry weight, and root fresh and dry weight while AMF inoculation enhanced the increased means of these traits considerably. Inoculation with F. mosseae also ameliorated the Cd stress (150 mg/kg) induced reduction in plant height, number of leaves, and stem and root dry weight by 13.41%, 8.42%, 30.3%, and 22.2%, respectively. Cadmium stress reduced membrane stability index while AMF inoculation enhanced membrane stability index considerably. An increase in soluble carbohydrate and proline content was observed due to Cd stress and AMF inoculation caused a further increase in these two metabolite contents ensuring better growth under Cd stressed conditions. Results indicated that F. mosseae had a higher efficiency in increasing morphological traits and improving physiological characteristics than F. etunicatum. Overall, AMF inoculation, especially F. mosseae significant ameliorative potential for Cd toxicity in thyme plants.

6-Benzylamino purine outperforms Kinetin and Thidiazuron in ameliorating flower longevity in Calendula officinalis L. by orchestrating physiological and biochemical responses

In view of extending the relatively brief postharvest life of flowers by a range of technologies, the present study elucidates the implication of 6-benzylamino purine (BAP), kinetin (KN) and thidiazuron (TDZ) on postharvest performance and flower longevity of isolated flowers of Calendula officinalis. BAP and KN belong to adenine group cytokinins while as TDZ is a diphenyl urea compound having cytokinin like activity. The harvested flowers were supplemented with BAP, KN and TDZ at various concentrations viz., 25, 50, 75 and 100 µM at one day before anthesis (cup shaped) stage. The control was designated by a distinct set of flowers held in distilled water (DW). Our findings revealed substantial enhancement in flower longevity by application of various growth regulators as compared to the control. Vase solutions containing BAP and KN at 50 µM and TDZ at 75 µM (individually) were most effective in improving the longevity of cut Calendula flowers. Improvement in flower longevity was primarily associated with high membrane stability index (MSI), upregulated activities of various antioxidant enzymes viz., catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX), besides an attenuated lipoxygenase (LOX) activity in the petals. As compared to control, the treated flowers exhibited higher values of soluble proteins, total phenols and total sugars, besides lower α-amino acid content in the petal tissues. However, BAP outplayed TDZ and KN in improving the flower longevity of Calendula officinalis by maintaining higher physiological and biochemical stability in petals.

Application of Silica Gel on Growth and Yield of Camelina sativa L.

The present study was designed to evaluate the effect of different concentrations of Silica gel on the growth and yield of Camelina sativa. A pot experiment was laid out in Completely Randomized Design (CRD) with three replications at Nanotechnology Laboratory, Department of Agronomy, PMAS Arid Agriculture University Rawalpindi. The experiment consisted of 4 levels (0.15 mg/g, 0.30 mg/g, 0.45 mg/g and 0.60 mg/g) of each mentioned nutrient along with control. The data were recorded and analyzed according to recommended procedure for following parameters viz., germination %, root and shoot length (cm), root and shoot biomass (g), relative water content of leaf and leaf membrane stability index. It was observed that 0.60 mg/g silica gel application increased the seed germination (80%), root length (6.67) cm, shoot length (35.33) cm, root biomass (1.7) g, shoot biomass (5.57) g, relative water content of leaf (0.69) and leaf membrane stability index (0.07). The study concluded that significant effect of silica gel application is crucial and important to improve vegetative attributes of false flax.

Differential modulation of heat inducible genes across diverse genotypes and molecular cloning of a sHSP from Pearl millet [Pennisetum glaucum (L.) R. Br.]

Environmental stresses negatively influence survival, biomass and grain yield of most crops. Towards functionally clarifying the role of heat responsive genes in Pearl millet under high temperature stress, the present study were carried out using semi quantitative RT- PCR for transcript expression profiling of hsf and hsps in 8 different inbred lines at seedling stage, which was earlier identified as thermo tolerant/susceptible lines through initial screening for thermo tolerance using membrane stability index among 38 elite genotypes. Transcript expression pattern suggested existence of differential response among different genotypes in response to heat stress in the form of accumulation of heat shock responsive gene transcripts. Genotypes WGI 126, TT-1 and MS 841B responded positively towards high temperature stress for transcript accumulation for both Pgcp 70 and Pghsf and also had better growth under heat stress, whereas PPMI 69 showed the least responsiveness to transcript induction supporting the membrane stability index data for scoring thermotolerance, suggesting the efficacy of transcript expression profiling as a molecular based screening technique for identification of thermotolerant genes and genotypes at particular crop growth stages. As to demonstrate this, a full length cDNA of Pghsp 16.97 was cloned from the thermotolerant cultivar, WGI 126 and characterized for thermotolerance. The results of demonstration set forth the transcript profiling for heat tolerant genes can be a very useful technique for high throughput screening of tolerant genotypes at molecular level from large cultivar collections at seedling stage.

Mitigation of Salinity Stress Effects on Growth, Physio-Chemical Parameters and Yield of Snapbean (Phaseolus vulgaris L.) by Exogenous Application of Glycine Betaine

Pots experiment was carried out during season 2017 at greenhouse of the Agric. Bot. Dep., Fac. of Agric., Zagazig Univ., Egypt to evaluate the effect of glycine betaine (GB) application under salinity stress (50 and100 mM NaCl) on growth, physio-chemical analysis and yield of snap bean cv. Bronco. A complete randomized blocks design was used in this search with three replications. Growth parameters, chlorophyll content and green pod yield were significantly decreased with subjecting plants to NaCl. However foliar application of GB detoxified the stress generated by NaCl and significantly improved the above mention parameters. Salinity stress increased the electrolyte leakage (EL) and decreased membrane stability index (MSI) and relative water content (RWC). While foliar application of GB was improved MSI and RWC and minimized EL. Proline content and antioxidant enzymes significantly increased in the response to NaCl stress as well as GB application.

Effect of Ethylene Antagonist Silver Thiosulphate on the Flower Longevity of Clarkia pulchella Pursh.

An experiment was conducted to study the effect of different concentrations of silver thiosulphate (STS) on flower longevity of Clarkia pulchella Pursh. The buds were subjected to 0.1, 0.25, 0.5, 0.75 and 1 mM of STS for 1 h pulse treatment. A separate set of flowers kept in distilled water was designated the control group. STS treatment resulted in improved flower longevity besides maintaining higher fresh and dry mass, water content and floral diameter. Conversely, total phenols, lipid peroxidation and lipoxygenase (LOX) activity decreased. The flowers treated with STS showed a significant increase in the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Amongst various grades used, 0.5 mM STS was found to be most effective in enhancing the flower longevity by 1.5 days. The present study reveals that STS maintains lower LOX activity, thereby increased membrane stability index by improving the activity of antioxidant enzymes.

Effects of Corm Dipping in Salicylic Acid or Potassium Nitrate on Growth, Flowering, and Quality of Saffron

The present research was conducted to find influence of salicylic acid (SA) at 0.5, 1, and 2 mM and potassium nitrate (KNO3) at 250, 500, and 1 000 ppm on reproductive and vegetative parameters, and color characteristics of saffron under field condition. The results indicated the highest a, L, and chroma and the lowest b at 2 mM SA treatment. The highest flowering appearance rate and membrane stability index and the lowest electrolyte leakage were observed at 2 mM SA and to lesser extent at 1000 ppm KNO3. The highest flower number, corolla dry weight, and stigma dry weight was shown in plants treated with SA. Chlorophyll a content and Fv/Fm value increased with the application of 2 mM SA. The data indicated the effectiveness of SA on the growth of saffron.