Farenaz Parniyanifard
Adjusting the source-sink relationship in bell peppers and study the changes in nutrient movement pattern, yield and fruit quality in the low light greenhouse
Capsicum is one of the most important vegetables in the world, which is economically and nutritiously crucial for humans. This study was performed on the bell peppers of Lumos yellow cultivar to evaluate the yield and quality of the fruit and its changes with 4 pruning treatments without pruning, pruning with three fruits, pruning with five fruits and pruning with preservation. Seven fruits were placed in two greenhouses with different light in the form of a complete random block design. In control Greenhouse, normal light was reduced by an average of about 14,000 lux per square meter, and in a dimly lit greenhouse, it was reduced to about 6,000 lux per square meter by Sheed with a 60% mesh. At the end of the experiment, the weight, length, diameter, and volume of the fruit, chlorophyll, and carotenoids of leaves and fruit, soluble solids, hardness and relative moisture content of the fruit, fruit seed weight, calcium, and root nitrogen, shoots and fruits, antioxidants, phenol, carbohydrates, starch, leaf and fruit flavonoids, organic acids and vitamin C and L * a * b * color indicators were measured and analyzed by SAS program. The results showed that low light greenhouse and pruning treatment had the highest chlorophyll b, carotenoid; 3 fruit pruning had the highest chlorophyll a and total leaf chlorophyll; 5 fruit pruned had the highest volume, total chlorophyll, firmness, relative water content and root calcium and pruning. 7 fruit plants had the highest levels of leaf nitrogen. In the greenhouse with normal light in fruitless pruning treatment, the highest fruit volume, seed weight, fruit carotenoids, and L * a * b *, antioxidants and leaf phenol, starch, organic acids, and fruit flavonoids were observed. In 3 fruits- pruning highest weight, diameter, and starch of leaves were observed. In 5 fruits-pruning, the highest amount of chlorophyll a, calcium, and organic acids of fruit, total carbohydrates, and leaf flavonoids was seen. In 7 fruits-pruning, the highest hardness, chlorophyll b, antioxidants, phenol and, carbohydrate and leaf calcium and root nitrogen was observed. Also, artificial neural network (ANN) method for providing predictive models of quality parameters of bell pepper product (including antioxidants, carbohydrates, flavonoids, firmness, starch, and vitamin C) based on parameters of different levels of pruning and exposure as well as fruit characteristics including weight, content Relative (RWC), diameter, length, and volume were used. For this purpose, three-layer perceptron networks, including an input layer, a hidden layer, and an output layer, were used for modeling, and an independent ANN model was created for each of the 6 target variables. The results showed that pruning has the most significant effect on the quality and nutritional value of pepper, including the total soluble solids, hardness, antioxidants, carbohydrates, starch andvitamin C in the fruit,and these values can be pridicted withcoeffiction R2 (0/98-0/56) and greenhouse light has a lower effect. According to the results of this study, in low light conditions, pruning is recommended by maintaining 5 fruits, and in normal light conditions, pruning is recommended by keeping 7 or 5 fruits
