Combined application of methyl salicylate and L-arginine alleviates chilling injury, potentiates antioxidant system and maintains quality of sweet pepper (Capsicum Annum L.) fruits cv. ‘Winner’

Chilling injury is the critical issue in sweet pepper fruit under low temperature storage. Present work was aimed to evaluate the effect of different concentration of methyl salicylate (MS) and L-arginine (Arg) on chilling injury and overall quality of sweet pepper fruits cv. ‘Winner’. The treatments were T1 = Control, T2 = 0.01mM MS, T3 = 0.05 mM MS, T4 = 1mM Arg, T5 = 1.5mM Arg and T6 = 0.01mM MS+1.5mM Arg. After respective treatment (for 10 min) fruits were kept at 5 ± 1 ◦C with 85-90 % RH for 28+2 days of storage. Physical, biochemical, and phytochemical parameters were studied at 7 days interval followed by two days of reconditioning at ambient conditions (25 ± 2 °C). On last removal (28+2days), sweet pepper fruits treated with combined MS and Arg treatment (T6) showed highly significant results in lower fruit weight loss (8.3%), maintained fruit colour (0.3 score) and firmness (13.4N), and reduced wrinkling (2 score), disease incidence (0.4 score), ion leakage (45.4%), alleviated chilling injury (1.7 score), retained total antioxidants (49.1%) and total phenolic content (74.4 mg 100 g-1 GAE FW) as compared to control. In addition, the ascorbic acid content was observed higher in all treatments in comparison with untreated control fruits. In conclusion, MS and Arg combine treatment improved storage potential with reduced chilling injury by maintaining higher total phenolic concentrations, ascorbic acid content and total antioxidants in terms of DPPH radical scavenging activities, and markedly maintained overall quality of sweet pepper under cold storage condition at 5 °C for 28 days.

Foliar application of micronutrients enhances growth, flowering, minerals absorption and postharvest life of tuberose (Polianthes tuberosa L.) in calcareous soil

Micronutrients applications are effective for better crop production in calcareous soils because these soils are usually deficit in iron (Fe), zinc (Zn) and boron (B). In Pakistan, most of soils are calcareous in nature. When tuberose is grown in such soils as a cut flower, its production is negatively affected. Therefore, a study was aimed to evaluate the effects of micronutrients as foliar sprays on cut tuberose production in calcareous soil. Micronutrients (Fe, Zn and B) alone and in combinations were sprayed on the plants after 60, 90 and 120 days of planting. The mixture of all these three micronutrients increased the plant height (95.77 cm), chlorophyll content (38.13 SPAD), number of leaves (79.63), leaf length (44.73 cm), fresh (111.64 g) and dry (16.16 g) plant weights, root length (15.13 cm), number of stalks (3.73), stalk length (79.03 cm), spike length (22 cm), number of florets (51.67), floret fresh weight (11.85 g), leaf Zn concentration (53.6 mg/g) and vase life (8.4 days). Fe + Zn enhanced the number of leaves (76.60), leaf length (45.83 cm), root length (15.05 cm), spike length (22.33 cm), and leaf Fe (128.18 mg/g) and Zn concentrations (55.02 mg/g). The Fe spray increased the leaf length (44.10 cm), days to flower initiation (142.47 days) and leaf Fe concentration (130.75 mg/g) in tuberose plants. Application of Zn improved the leaf length (45.87 cm) and diameter (1.32 cm), root (15.03 cm), spike (21.77 cm) and floret lengths (4.74 cm), floret dry weight (1.49 g) and leaf Zn concentration (57.5 mg/g). Foliar spray of B increased the B concentration (21.1 mg/g) in tuberose leaves. It is concluded that foliar application of micronutrients alone and in combinations improved the plant growth, flowering, leaf minerals concentrations and vase life of tuberose spikes. However, mixture of Fe, Zn and B was more effective as compared to other treatments. Moreover, current study encourages the foliar application of micronutrients in tuberose when grown in calcareous soils.

Evaluation of Capsicum annum L. genotypes against salinity induced by NaCl

Soil salinity harmfully effect bell pepper production being salt sensitive crop. The aim of this study was to compare capsicum (bell-pepper) cultivars for their ability to tolerate salt stress. Electrical conductivity of different levels i.e., control (no sodium chloride), 1.5, 3.0, 4.5, and 6.0 dS m-1, was developed by using NaCl, after 30 days of seedling emergence of six cultivars (Yolo Wonder, California Wonder, Cop-amber Hybrid, F1 Pangs No. 206, Sweet Pepper F1, Kaka F1). These cultivars were evaluated based on morphological (shoot and root length, plant fresh and dry biomass), physiological (chlorophyll content) and biochemical attributes (nitrogen concentration, and protein contents). Minimum chlorophyll contents (SPAD units) in Kaka F1 (16.77 SPAD units) at 1.5 dSm-1. However, maximum value of chlorophyll contents was observed in Sweet Pepper F1 (49.23 SPAD units) at control followed by “Yolo Wonder” (41.53 SPAD units) at control. Maximum dry biomass was found in California Wonder (0.468 g) at 1.5 dSm-1, while minimum value of dry biomass (g) was observed in Kaka F1 (0.095 g) at 4.5 dSm-1. Six cultivars of capsicum were categorized into three groups. Salt tolerant cultivars included “California Wonder” followed by “Yolo Wonder”. “Kaka F1” was proved most salt sensitive and all others were moderately salt tolerant.

Effect of oxalic acid on vase life and antioxidative activities of ‘Mero Star’ cut lily flowers

Lily (Lilium L. hybrids) is sub-tropical cut flower that can be grown in open place or in green house and has consumer demand in local as well as in offshore markets. Short vase life, postharvest decay of flowering petals, activities of oxidative enzymes, malondialdehyde contents, electrolyte leakage and low water ratio are the main problems in marketing of cut lilies. This study was carried out to investigate the effect of oxalic acid (OA) treatments on vase life (12 days) and postharvest quality of ‘Mero Star’ cut lily flowers. The flowering stems were placed in 2, 4 and 6% aqueous solution of OA for 12 days at 20±2 °C with 70±5% relative humidity. Flowers placed in 6% OA solution exhibited longest vase life and flower diameter with higher relative water content and increased fresh weight and reduced flower decay. Reduced malondialdehyde contents and electrolyte leakage with higher activities of catalase, superoxide dismutase and peroxidase enzymes were also noted in 6% OA-treated flowers. In conclusion, exogenous postharvest application of 6% OA extended vase life and maintained postharvest quality of cut flowers by reducing electrolyte leakage and malondialdehyde contents with higher antioxidative enzymes activities.

Pre-Harvest Oxalic Acid Application Improves Fruit Size at Harvest, Physico-Chemical and Sensory Attributes of ‘Red Flesh’ Apricot During Fruit Ripening

Apricot is a highly nutritive stone fruit which ripens quickly after harvest and exhibits rapid fruit quality deterioration at ambient conditions. The current research work was executed to evaluate the effect of pre-harvest application of oxalic acid (OA); (0, 0.5, 1, and 2mM) on fruit quality of ‘Red Flesh’ apricot during fruit ripening at shelf under ambient conditions (25±1 °C; 60-65% RH). Fruit size, average fruit weight, fruit juice percentage was determined at harvest. While, fruit weight loss, fruit colour, fruit firmness, titratable acidity (TA), soluble solid contents (SSC), ratio of SSC to TA, ascorbic acid, total phenolics content (TPC), anti-oxidative scavenging activity (ASA), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) enzymes activity were determined during fruit ripening. Fruit sensory attributes (fruit pulp colour, fruit taste, fruit flavour and overall acceptability were determined at fruit ripening. Pre-harvest application of 2mM-OA was found the most effective in improving fruit size, average fruit weight, juice percentage at harvest, about 5%, 6% and 15% higher than control, respectively. Additionally, pre-harvest application of 2mM-OA retained higher fruit firmness, ascorbic acid, TPC, ASA and activities of POD, CAT enzymes in apricot fruit during fruit ripening at ambient conditions. On day-5 of fruit ripening 2mM-OA-treated apricot fruit exhibited about 28%, 20%, 17%, 7%, 9% and 23% higher fruit firmness, ascorbic acid, TPC, ASA and activities of POD, CAT enzymes, respectively as compared to control. Moreover, significant lower fruit weight loss (35%), SSC (20%) and SSC:TA ratio (30%) were exhibited by the apricot fruit treated with 2mM-OA than unsprayed apricot fruit. However, fruit treated with 1 mM-OA exhibited better fruit sensory attributes compared to other treatments at fruit ripening. Conclusively, pre-harvest application of 2 mM-OA improved the fruit size, delayed fruit ripening, and retained higher fruit antioxidants of apricot at ambient conditions.

Physiology of tuber dormancy and its mechanism of release in potato

The tuber dormancy is an important aspect of tuber’s physiological age and begins with tuber initiation. It is largely dependent on genotype, environmental conditions, and tuber age. The group Phureja among diploid potatoes, has a very short or no tuber dormancy while the tubers of Solanum jamesii, a wild potato species, may remain dormant for more than eight years and have the tendency to sprout in favourable conditions. The dormancy breakage in potato is accompanied by many physiological changes such as changes in the ratios of abscisic acid (ABA)/ cytokinin and ABA/ gibberellic acid (GA3), catalase inhibition and accumulation of soluble sugars. These all changes are interlinked and occur in the same time frame. The dormant buds have 77% of their nuclei in the growth phase (G1), compared to only 13% in the preparation phase for mitosis (G2), resulting in slower development of active buds. This paper reviews various factors involved in natural and forced dormancy breakage of potato tuber in relation to their use as seed potatoes immediately after harvesting and implementation of different exogenous dormancy breaking methods like cold pre-treatment, growth regulators, electric current and irradiation to induce sprouting in potatoes.

Impact of blanching and packaging materials on postharvest quality and storability of fresh spinach

Spinach is a widely consumed leafy green vegetable, but it exhibits short storage life due to quick loss in moisture contents during postharvest period. The present study was aimed to evaluate the effect of blanching treatment and different types of packaging on spinach quality under cold storage conditions. Fresh spinach after treatment [T0 = control, T1 = blanching, T2 = modified atmosphere packaging (MAP-1, Xtend®), T3 = MAP-2 (Bio-fresh®) and T4 = perforated polyethylene (PE)] application was stored at 4±1 °C and 90±5 % RH for 20 days. Samples were analyzed at the time of harvest (0 day) and then after 3 days interval during storage. MAP treatments performed well and had a positive effect on spinach by maintaining its freshness and quality. Decay, ion leakage and weight loss were observed lower in spinach packed in MAP-1(Xtend®) followed by MAP-2 (Bio-Fresh®) and perforated PE packaging. MA packaging maintained higher ascorbic acid content, chlorophyll, and total antioxidants of spinach during storage. Nevertheless, spinach packed in perforated PE also displayed better results in maintaining quality as compared to control and blanched samples. The maximum weight loss, poor quality, minimum ascorbic acid content with lower consumer acceptability was recorded in control samples. Overall, MAP-1(Xtend®) could be used as a promising technology to maintain the quality of spinach up to 20 days of cold storage.

Salinity affects the growth and quality of rose (Rosa damascena)

Soil salinity is an important abiotic factor that adversely affects plant growth. In present study, response of rose (Rosa damascena) was evaluated to various NaCl salinity levels developed by irrigating saline water. Plants were irrigated with different salinities, viz. 0 (control), 50, 100, 150, 200 and 250 mM NaCl. After treatments application, plants were sampled, and relative growth rate (RGR) was calculated. Growth rates were significantly reduced as recorded for flower diameter, number of leaves per plant, number of shoots per plant, number of flowers per plant, number of petals per flower, fresh and dry weight of flower and petals. Results depicted that plant growth and yield significantly reduced with increase in salt concentration particularly when >150 mM NaCl was applied. Therefore, it is suggested that Rosa damascena may be best grown when salinity level of ≤150 mM and should not be grown in areas where salt concentrations are greater than 150 mM.

Postharvest calcium chloride application maintains shelf life and quality of loquat (Eriobotrya japonica L.) fruit

Loquat (Eriobotrya japonica L.) is an important sub-tropical fruit with very limited postharvest life. Therefore, in the current study, we investigated the effect of calcium chloride (CaCl2) treatments on the shelf life and quality of loquat fruit. After harvest loquat fruit treated with different concentrations of CaCl2 viz. 2%, 4% and 6% for 2 min were kept at room temperature (30±2oC) for 5 and 10 days. Untreated fruit were kept as control. The results showed that fruit treated with 6% CaCl2 exhibited minimum fruit weight loss (9.1%), external browning (8.83%), and internal browning (9.1%) after 10 days shelf period in contrast with control fruit. Lowest total soluble solids contents (9.11%), highest titratable acidity (0.53%) and juice (28%) contents were found in fruit treated with 6% CalCl2 as compared to other treatments. In conclusion, among the tested treatments, application of highest level of CaCl2 (6%) effectively maintained the quality of loquat fruit a room temperature.

Soil application of fungicides affects nutrient dynamics in ‘Blood Red’ sweet orange

Infected and damaged root system of sweet oranges (Citrus sinensis Osbeck L.) budded on rough lemon (Citrus jambheri Lush.) in Punjab-Pakistan has been suspected to affect nutrient uptake due to rootstock susceptibility to soil born fungal diseases. The experiment was performed on 12-15 years old ‘Blood Red’ sweet orange ‘Blood Red’) trees of uniform size and vigour at the Fruit Garden Sq. 9, Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Punjab, Pakistan. This study was conducted for consecutive two years. The objective of the research was to introduce sweet oranges in the main streamline of the citrus industry by improving their root health through fungicides treatments ultimately enhancing mineral nutrient uptake from the soil. The experiment was laid out according to Randomized Complete Block Design (RCBD) replicated thrice, taking a single tree as a treatment unit. The fungicides used in the experiment were Metalaxyl Mencozeb (Ridomil Gold), Fosetyl-Al (Alliette) and copper sulphate (CuSO4), in different combinations. Nutritional status of tree leaf macronutrients (N, P and K) and micronutrients (Mg, Fe, Mn, Cu and Zn) during flowering and final fruit set was evaluated at fortnight intervals with respect to different treatments. The different treatments enhanced nutrient uptake through roots and improved health and vigour of trees. It was more evident from the improvement of fruit quality and yield of treated trees compared with control. Although fungal analysis could not be performed, the improvement in general health and vigour of trees lead to the conclusion that root health was improved substantially. It might be concluded from this study that best orchard management emphasizing improvement in the root health could enhance the yield and quality of sweet oranges.