جستجوی مقالات مرتبط با کلیدواژه « سفتی » در نشریات گروه « منابع طبیعی »

Bell pepper is a popular agricultural product, not only for its economic value but also for the nutritional value of its fruits, which are enriched source of natural colors and antioxidant compounds. During developmental stages, the pepper fruit serves as a significant carbon sink, exerting a notable influence on the growth and carbon levels of adjacent organs including buds, flowers, and immature fruits. The occurrence of abortion and the abscission of flowers and immature fruits can lead to substantial alterations in crop output during the growth cycle. The fruiting patterns are influenced by both environmental conditions and the quantity of fruits. When specific fruits attain ripeness, their rate of sink power decelerates. Consequently, a novel fruit set initiates its growth, thereby initiating a fresh cycle of fruit production. Consequently, the presence of unpruned plants leads to flash fruiting, characterized by periodic variations in fruit output, thereby constituting a significant challenge in greenhouse cultivation of bell pepper. The purpose of the current experiment was to investigate the effect of fruit pruning and harvest sequence on the yield and qualitative characteristics of two common bell pepper cultivars grown under greenhouse condition.

This study was conducted in a greenhouse located in the east of Isfahan during 2019. A factorial experiment was carried out based on completely randomized design with four replications. The experiment factors included a) fruit pruning at four levels: Non-pruning (control), and 10%, 20% and 30% pruning, b) pepper cultivar at two levels: Lumos yellow cultivar (from Syngenta company) and Lorka red cultivar (from Seminis company) and c) harvest sequence at four levels: first, second, third and fourth. Seeds sowing was done on October 23, 2019. Seeds were sown in transplant trays filled with a mixture of peat moss and perlite. Subsequently, on December 1, 2019, seedlings were transferred to the primary substrate, when they had developed four to six true leaves. The individuals were relocated to the greenhouse. During this period, the pepper plants were pruned and secured to the taut wires of the trellis. Furthermore, the greenhouse temperature was adjusted on 26-28 °C as day temperature and 16-18 °C as night temperature. Irrigation was implemented in a strip-wise manner. During this research, the effect of fruit pruning and cultivar on morpho-physiological traits and also, the effect of fruit pruning and harvest sequence on performance characteristics of pepper plant were investigated.

Results indicated that pruning 10 % led to an increase in seed weight, flesh thickness and L* color index of yellow cultivar. The effect of pruning on fruit weight of yellow cultivar during successive harvests revealed that unpruned plants had relatively acceptable fruit weight on first harvest, but the weight of the fruits decreased over the time during subsequent harvests, indicating when fruit pruning is not done the number of fruits increases, and as a result, the weight of each fruit decreases. While, pruning 30% was able to maintain the fruit weight from the first harvest to the fourth harvest. Maintaining the fruit weight during successive harvests is highly important for pepper farmers. Reduction of fruit number through the pruning leads to prevention of fruit weight loss during successive harvests followed by higher fruits marketability. The effect of pruning on fruit weight of red cultivar during different harvests revealed that unpruned and pruned plants at 10 % level did not produce any fruits at first harvest, and fruit production initiated at second harvest leading to lower yield performance. The highest fruit diameter of yellow cultivar during successive harvests was recorded at pruning 30 %. Also, the highest fruit length of red cultivar was measured at first harvest and pruning 30 %. All pruning levels increased the total weight of first grade fruits of red cultivar, so that the lowest value of this trait was recorded in unpruned plants.  

Fruit pruning appears to improve the source/sink relationship in pepper by increasing fruit yield and weight as well as fruit qualitative characteristics so that the red cultivar outperformed the yellow cultivar in most growth and qualitative traits, and pruning 10 and 20 % were more positively effective on fruit firmness and size (diameter and length) comparing to other levels. Based on results, it is recommendable to conduct pruning at levels of 10 and 20 % on two bell pepper cultivars, namely yellow (Lumos) and red (Lorka), in order to enhance the fruit yield and qualitative characteristics.

Plant growth regulators has been recently attracted considerable attention as a one of the main important methods to induce natural resistance of agricultural crops. In this study, the effect of foliar application with methyl jasmonate at four levels (0, 1, 10 and 100 μM) with three replications on some quantitative and qualitative characteristics of Physalis fruit was investigated. Fruits length and diameter, fresh and dry weight of fruits, fruits firmness, pH of fruit extract, total soluble solid, titratable acidity, fruits flavor and total phenol and flavonoids were evaluated. The results showed that foliar application of methyl jasmonate had a significant effect on the evaluated parameters. The highest total phenol and flavonoids content were recorded in 100 μM methyl jasmonate treatment, while lower concentrations of methyl jasmonate had a greater effect on soluble solids, fruit flavor and titratable acidity. Also, application of different concentrations of methyl jasmonate had a significant positive effect on fruit length and diameter compared to the control, but different concentrations of methyl jasmonate did not show significant differences on fruit length and diameter. Based on the results of the present study, it was found that methyl jasmonate treatment can be used as a healthy and safe treatment in the production of Physalis peruviana fruit in greenhouse conditions by affecting phenolic compounds and improving quantitative and qualitative properties.

The shelf life of Indian coastal fruits is relatively short. Therefore, in this study, the effect of different concentrations of salicylic acid (SA) (0, 0.5, 1 and 2 mM) on storage life and post-harvest quality of stored fruits at 4 ± 1° C with 85-90% RH in a factorial completely randomized design was studied. Postharvest quality and biochemical properties of the fruit were measured during 30 days of storage in intervals of 10 days. The results showed that with increase in shelf life, fruit tissue firmness, total acidity (TA), ascorbic acid and total phenolics content were decreased in treated and control fruits, but the rate of weight loss, decay extension rate, and decrease in soluble solids (TSS) content, TSS ratio and TA was decreased in SA treated fruit. Also, the level of total antioxidant activity and the activity of SOD and CAT enzymes in fruits treated with SA were significantly higher than the control fruits. In general, 1 and 2 mM SA were the best concentrations of SA in maintaining the quality indices and biochemical properties of harvested Indian kunar during storage. Overall, the results showed that SA treatment can be used as an effective and efficient method in post-harvest technology of Indian kangaroo fruit.