Journal of Horticulture and Postharvest Research

Abstract Purpose: The experiment aimed to evaluate the effect and optimal dose of paclobutrazol, and appropriacy of bunch covering materials on productivity and quality of banana. Research method: This study was laid out following a randomized complete block design with four replications. The experiment consisted of two factors namely Factor A: Different doses of paclobutrazol i.e. no paclobutrazol, 1 g/L paclobutrazol and 2 g/L palobutrazol and Factor B: bunch covering i.e. control (no polythene covering), white polythene covering and blue polythene covering. Paclobutrazol was sprayed 2 times; firstly, at fruit set stage and secondly, one month after 1st spray. Findings: The treatments showed significant effect on the yield as well as qualitative traits of banana. Paclobutrazol sprayed plants performed better than non-paclobutrazol treated plants. Application of paclobutrazol (2 g/L) and blue bunch covering banana contained higher amount of sugar. However, blue and white polythene had no significant effect on color measurement of banana peel. Paclobutrazol (1g/L) and white polythene treated bunch produced the highest bunch weight (24.91 kg), pulp:peel ratio (3.57), fibre content (4.20%) while no polythene treated with no paclobutrazol produced the lowest bunch weight (16.77 kg), pulp:peel ratio (1.89), fibre content (2.60%) of banana. These results generally prove that paclobutrazol application could potentially be used to improve crop productivity and their quality value. Research limitations: There were no limitations identified. Originality/Value: Paclobutrazol (1mg/L) with white polythene as bunch covering resulted in the maximum banana production and quality when compared to other treatment combinations, without compromising of human health and environmental sustainability.

Abstract Purpose: Lime (Citrus aurantifolia) is a lucrative crop with a year-round demand. However, seasonality in fruiting causes market glut. Therefore, potential of gibberellic acid (GAs), brassinolide (BL) and salicylic acid (SA) as preharvest foliar sprays on widening narrow harvest window alongside improved fruit quality were studied. Research Method: Experiments were performed on five-year-old 30 lime trees of cv. Monaragala Local. Trees were treated with aqueous solutions of GA (12.5, 25.0, 37.5 mg L^-1), BL (0.5, 1.0, 1.5 mg L^-1) and SA (1, 2 and 3 mmol L^-1) at 4-5 mm and 12-15 mm diameter stages of fruit growth. Findings: Two higher doses of GA (25.0 and 37.5 mg L^-1) delayed lime fruit maturity by ≈25 - 40 days while the highest dose of BL (1.5 mg L^-1) and the lowest dose of SA (1.0 mmol L^-1) advanced fruit maturity by ≈75-80 days significantly (p<0.05). Treatment with PGRs resulted in improved fruit weight, size, shape, firmness, and peel colour compared to the control. Research limitations: High cost of plant growth regulators specially BL hampered its commercial applicability. Originality/Value: preharvest foliar application of 37.5 mg L^-1 GA which delayed the fruit maturity by ≈40 days and 1.0 mmol L^-1 SA which hastened the maturity by ≈80 days could be recommended to expand the existing acute harvest window along with improved fruit quality

Abstract Purpose: The efficiency of callus induction as source of bioactive compound is a critical step in the cell suspension culture for commercial production of important secondary metabolites. One of the main factors affecting callus efficiency is the developmental stage of explants. On the other hands, it has been declared that the optimization of medium composition has a significant influence on callogenesis and increment of biomass.  Research method: The aim of this study was the evaluation of different developmental stages of saffron corms as a source of explant preparation (immature and mature corms), plant growth regulators (PGRs) combinations (1-Naphthaleneacetic acid (NAA); 2, 4-dichlorophenoxyacetic acid (2,4-D); 6-Benzyladenine (BA) and kinetin (Kin)) and type of medium (Gamborg (B₅) medium and Murashige and Skoog (MS) medium) in callus induction in saffron corms to increase cell biomass. The media were supplemented with different combinations of 1-Naphthaleneacetic acid or 2, 4-dichlorophenoxyacetic acid (2, 4, 8 mgL^-1) as auxins and 6-Benzyladenine or kinetin (1, 4, 8 mgL^-1) as cytokinin. Findings: The results showed that mature corms harvested in May had the best developmental stage for callogenesis. The maximum callus formation was recorded in B₅ medium supplemented with 2,4-dichlorophenoxyacetic acid (4 mgL^-1) and kinetin (1 mgL^-1) with 2.61 g fresh weight. Limitations: No limitations to report. Originality/Value: This protocol for sampling explant and callus formation was found to make suitable sources of plant material for further study in production of bioactive compounds via cell suspension cultures.

Abstract Purpose: Saffron (Crocus sativus L.) is a valuable medicinal plant with a short flowering period. Its flowering management can be useful for the production of saffron in a farm or controlled condition. The objective of this study was to determine the effect of plant growth regulators (PGRs) on saffron corms sprouting. Research method: For this purpose, corms were treated with different PGRs including α-naphthaleneacetic acid (NAA) (0, 100, 200, 300 ppm), chlorocholine chloride (CCC) (0, 100, 200, 300 ppm) and gibberellic acid (GA₃) (0, 5, 10, 20 ppm) for two hours and incubated at 20-22 °C for eight weeks. Findings: The results revealed that the effect of PGRs on corms sprouting was significant. It has been shown that treatment of corms with auxin at all concentrations reduced sprouting compared to the control. To prolong dormancy for five weeks, NAA at 200 mg L^-1 was the best choice. While for the fifth week onwards, the most effective treatment was NAA at 100 ppm. Treatment with GA₃ (20 ppm) has shown a stimulatory effect on corm sprouting. Research limitations: No limitations were founded. Originality/Value: Sprouting acceleration can keep flowering away from early autumn frosting in farm conditions, while prolongation of corms dormancy provides the possibility of harvesting saffron flowers in several times in a hydroponic system. The results of this study suggested two kinds of chemical for different purposes, inhibition and stimulation of sprouting of saffron corms that can be applicable for saffron hydroponic or farm production, respectively.

Abstract Purpose: The study of effects of 1-Methylcyclopropene (1-MCP) on ripening of bananas is still an important issue for commercial application of 1-MCP on bananas. Research Method: Mature green bananas were treated with ethylene only (100 µL L^-1 for two consecutive days) and ethylene the same treatment followed by 1-MCP (300 nL L^-1) for 24 h to evaluate the ethylene and 1-MCP effects on ethylene biosynthesis enzyme activities. Ethylene production of whole banana fruit, ACC synthase (ACS) and ACC oxidase (ACO) activities in the pulp and peel of samples were measured. Findings: The result showed that ethylene production rate by the control fruit was significantly greater than the ethylene production rate by the 1-MCP-treated fruit at days 4, 8 and 10. However, changes in ethylene production were similar in both control and 1-MCP-treated bananas. The banana peel and pulp show different patterns of ethylene production during ripening. At the onset of ripening pulp tissues showed higher levels of ACS, and lower levels of ACO activity than peel. Assays of ACO and ACS activities in ethylene-treated fruit showed that the peel had higher levels of ACO activity than the pulp. The ACO and ethylene production were inhibited by 1-MCP treatment whereas ACS increased following 1-MCP application. Research limitations:  Evaluation of ACS and ACO activities during different seasons. Originality/value: Pulp and the peel of bananas respond differently to ethylene and 1-MCP treatment with a greater impact on peel than the pulp. The findings of this study allow 1-MCP to be used in a more commercially reliable manner.