Efficiency of exogenous zinc sulfate application reduced fruit drop and improved antioxidant activity of ‘Kinnow’ mandarin fruit

‘ Kinnow’ mandarin (Citrus nobilis L.× Citrus deliciosa T.) is an important marketable fruit of the world. It is mainstay of citrus industry in Pakistan, having great export potential. But out of total production of the country only 10% of the produce meets the international quality standard for export. Pre-harvest fruit drop and poor fruit quality could be associated with various issues including the plant nutrition. Most of the farmers do not pay attention to the supply of micro nutrients which are already deficient in the soil. Furthermore, their mobility within plants is also a question. Zinc (Zn) is amongst those micronutrients which affect the quality and postharvest life of the fruit and its deficiency in Pakistani soils is already reported by many researchers. Therefore, this study was carried out to evaluate the influence of pre-harvest applications of zinc sulfate (ZnSO4; 0, 0.4%, 0.6% or 0.8%) on pre-harvest fruit drop, yield and fruit quality of ‘Kinnow’ mandarin at harvest. The treatments were applied during the month of October i.e. 4 months prior to harvest. The applied Zn sprays had significant effect on yield and quality of the “Kinnow” fruit. Amongst different foliar applications of ZnSO4applied four months before harvest, 0.6% ZnSO4 significantly reduced pre-harvest fruit drop (10.08%) as compared to untreated control trees (46.45%). Similarly, the maximum number of fruits harvested per tree (627), fruit weight (192.9 g), juice percentage (42.2%), total soluble solids (9.5 °Brix), ascorbic acid content (35.5 mg 100 g-1) and sugar contents (17.4) were also found significantly higher with 0.6% ZnSO4 treatment as compared to rest of treatments and control. Foliar application of 0.6% ZnSO4 also significantly improved total antioxidants (TAO) and total phenolic contents (TPC) in fruit. In conclusion, foliar spray of ZnSO4 (0.6%) four months prior to harvest reduced pre-harvest fruit drop, increase yield with improved quality of ‘Kinnow’ mandarin fruit.

Growth and gas exchange of soursop under salt stress and hydrogen peroxide application

ABSTRACT The cultivation of irrigated soursop in semiarid Northeastern Brazil highlights the need for information regarding its responses to the salinity of irrigation water and the use of techniques that allow its exploration, such as the use of hydrogen peroxide. Thus, the study aimed to evaluate the effect of soaking of seeds and foliar application of hydrogen peroxide on soursop plant growth and physiology under conditions of salt stress. The study was conducted in lysimeters in a greenhouse, and the treatments were distributed in a randomized block design and 4 × 4 factorial scheme, with four values of electrical conductivity of the irrigation water - ECw (0.7, 1.7, 2.7, and 3.7 dS m-1) and four concentrations of H2O2 (0, 25, 50, and 75 μM), with three replicates and one plant per plot. H2O2 concentrations were applied via seed imbibition and foliar spray. Irrigation with water from 0.7 dS m-1 impairs gas exchange and absolute growth rates of plant height and stem diameter and relative growth rate in height of soursop plants. Concentrations of 35, 33 and 23 µM of hydrogen peroxide favored the relative and absolute growth rates of plant height and transpiration, respectively. Compared to the aerial part, the root of soursop plants is more affected when irrigated with water from 1.6 dS m-1.

Nano Zinc-Oxide Enhanced Photosynthetic Apparatus and Photosystem Efficiency of Maize (Zea Mays L.) in Sandy-Acidic Soils

Conventional Zinc (Zn) fertilization (e.g., zinc sulfate) often leads to poor availability in soils. Zinc oxide nanoparticles (nano ZnO) can be a potential solution, but their effect on crop photosynthetic activity isn’t well documented. The effects of nano ZnO (50, 100, 150, 200 mg L-1) and application methods (seed-coating, soil-drench, and foliar-spray) in comparison with ZnSO4 recommended dose were evaluated for plant height, biomass, chlorophyll pigments and photosystem efficiency in a greenhouse pot experiment. 100 mg L-1 of nano ZnO significantly increased the chlorophyll (Chl.) a, b, a+b, carotenoids (x+c), a+b/x+c, SPAD, leaf Chl., total chlorophyll content plant-1, plant height and total biological yield (by 18-30%, 33-67%, 22-38%, 14-21%, 14-27%, 12-19%, 12-23% 58-99%, 6-11% and 16-20%, respectively) and reduced Chl. a/b (by 6-22%) over the other treatments (p<0.01) irrespective of application methods. Nano ZnO applied at 100 mg L-1 significantly increased photochemical quenching (qP) and efficiency of photosystem II (EPSII) compared to 150 and 200 mg L-1 regardless of application methods. The positive correlations between Chl. a and Chl. b (r2 0.90), Chl. a+b and x+c (r2=0.71), SPAD and Chl. a (r2=0.90), SPAD and Chl. b (r2=0.94) and SPAD and Chl. a+b (r2=0.93) indicates a uniform enhancement in chlorophyll pigments; SPAD value, qP, EPSII, and growth and yield parameters. This elucidates that the application of nano ZnO at 100 mg L-1 promotes corn biochemical health and photosynthesis, irrespective of the application method. These findings have a great propounding for improving plant growth through nano ZnO bio-fortification in acidic Spodosols.

Impact of Foliar Spray of NPK and Zn on Soybean for Growth, Yield, Quality, Energetics and Carbon Footprint under Dryland Condition at Indore

Background: Dryland is characterised by drought/dry spell (s) of 10 to 15 days and is the main reason for decline in soybean production. The aim of this study was to develop a strategy of drought amelioration by using foliar sprays and enhancement of yield, quality, energetics and carbon footprint. Methods: A field experiment was carried out at Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya, College of Agriculture, Indore, (M.P.) during 2017-18 under spilt-plot design having two main plot treatments viz., foliar application at dry spell (F1), foliar application after dry spell (F2) and seven sub plot treatments i.e. different variants of foliar sprays (DVFS). Different growth, yield, quality, energetic and carbon footprint traits were recorded. The data were analyzed using standard statistical procedures. Result: The highest growth, yield, quality and energetic parameters were recorded for F1 as compared to F2. In case of DVFS, foliar application of water soluble complex fertilizer 19:19:19 (NPK) @ 0.5% + 0.5% ZnSO4 (T4) produced maximum values for growth, energetics, carbon footprint, oil (22.5%) and protein (43.1%) content as well as produced maximum yield.

Influence of Phosphorous and Foliar Nitrogen on the Growth, Quality and Yield of Kasuri Methi (Trigonella corniculata L.)

Background: Nitrogen and phosphorus are amongst fundamental macronutrients, which are crucial for the growth and development of plant. Soils of dry land of central Rajasthan are deficit in nitrogen and phosphorus content which leads to lower productivity of kasuri methi. Therefore, adequate supply of nitrogen (foliar spray) and phosphorus could enhance productivity of kasuri methi. Methods: The experiment consisted of sixteen treatment combinations including four levels of phosphorus (control, 20, 40 and 60 kg/ha) and four levels of foliar application of nitrogen (control, 1.0, 1.5 and 2.0%). They were under taken in FRBD with three replications. Result: Growth parameters and yield of fresh and dried leaves of the crop increased almost linearly with increasing levels of phosphorus and foliar application of nitrogen. The result indicated that application of phosphorus 60 kg/ha and foliar nitrogen @ 2.0% to the kasuri methi crop significantly increased the plant height (cm) and leaf area per plant (cm2) at each harvest, number of nodules per plant (58.17 and 53.33, respectively) and chlorophyll content (2.32 and 2.39 mg/100 g, respectively), fresh leaves yield (139.1 and 141.66 q/ha, respectively), dry leaves yield (20.01 and 22.38 q/ha, respectively), protein content in leaves (5.28 and 5.75%, respectively) and ascorbic acid in leaves (218.15 and 222.42 mg/100 g, respectively).

Melatonin Promotes SGT1-Involved Signals to Ameliorate Drought Stress Adaption in Rice

Drought has become one of the environmental threats to agriculture and food security. Applications of melatonin (MT) serve as an effective way to alleviate drought stress, but the underlying mechanism remains poorly understood. Here, we found that foliar spray of 100-µM MT greatly mitigated the severe drought stress-induced damages in rice seedlings, including improved survival rates, enhanced antioxidant system, and adjusted osmotic balance. However, mutation of the suppressor of the G2 allele of skp1 (OsSGT1) and ABSCISIC ACID INSENSITIVE 5 (OsABI5) abolished the effects of MT. Furthermore, the upregulated expression of OsABI5 was detected in wild type (WT) under drought stress, irrespective of MT treatment, whereas OsABI5 was significantly downregulated in sgt1 and sgt1abi5 mutants. In contrast, no change of the OsSGT1 expression level was detected in abi5. Moreover, mutation of OsSGT1 and OsABI5 significantly suppressed the expression of genes associated with the antioxidant system. These results suggested that the functions of OsSGT1 in the MT-mediated alleviation of drought stress were associated with the ABI5-mediated signals. Collectively, we demonstrated that OsSGT1 was involved in the drought response of rice and that melatonin promoted SGT1-involved signals to ameliorate drought stress adaption.

Use of Biostimulants: Towards Sustainable Approach to Enhance Durum Wheat Performances

The use of biostimulant (BS) holds a promising and environmental-friendly innovation to address current needs of sustainable agriculture. The aim of the present study is twofold: (i) assess the potential of durum wheat seed coating with microbial BS (‘Panoramix’, Koppert), a mix of Bacillus spp., Trichoderma spp., and endomycorrhiza, compared to two chemical products (‘Spectro’ and ‘Mycoseeds’) through germination bioassay, pot and field trials under semi-arid conditions, and (ii) identify the most effective method of BS supply (‘seed coating’, ‘foliar spray’, and ‘seed coating + foliar spray’) under field conditions. For this purpose, three modern durum wheat cultivars were tested. ‘Panoramix’ was the most efficient treatment and enhanced all germination (germination rate, and coleoptile and radicle length), physiological (relative water content, chlorophyll content, and leaf area), and agro-morphological (plant height, biomass, seed number per spike, thousand kernel weight, and grain yield) attributes. Unexpectedly, the individual application of ‘Panoramix’ showed better performance than the combined treatment ‘Panoramix + Spectro’. Considering the physiological and agro-morphological traits, the combined method ‘seed coating + foliar spray’ displayed the best results. Principal component analysis confirmed the superiority of ‘Panoramix’ treatment or ‘seed coating + foliar spray’ method. Among tested durum wheat cultivars, ‘Salim’ performed better especially under ‘Panoramix’ treatment, but in some case ‘Karim’ valorized better this BS showing the highest increase rates. Based on these study outcomes, ‘Panoramix’ might be used as promising sustainable approach to stimulate durum wheat performance.