Usually, pomegranate fruit in humid areas is under attack from fungal diseases. In addition to skin damage to the fruit, fungal diseases also reduce qualities and visual charactristics. Fruit cracking is another physiological disorder that causes a lot of damages to the crop and causes irreparable damage to the gardeners. Control of these diseases is very difficult, and the use of recommended treatments also has yielded different outcomes. Finding the appropriate solution based on nutritional and chemical products is necessary to overcome this problem.
Materials and Methods
This research was conducted in a commercial orchard located in Sorak city, 10 km from Sari city with a longitude of 53 degrees and 17 minutes and a latitude of 36 degrees and 61 minutes, and a height of 9 meters from the sea level in summer of 2017. The research was carried out as a factorial test in randomized complete block design with the aim of investigating the effects of Copper, Silicon, Vermiwash and Rovral TS on the quality of pomegranate fruit of Shavar cultivar. Experimental factors consisted mineral nutrition (in four levels of control, Copper nano-chelate, Silicon, and Copper+Silicon) and Fungicide (in two levels of vermiwash and Rovral TS). Foliar application was performed 4 times at intervals of 15 days and fungicidal treatments were carried
out at 3 times intervals of 20 days. Then morpho-physiological studies were carried out.
Results and Discussion
The results of this experiment showed that the highest amount of flower conversion to fruit and the highest amount of dry weight (49.78 g) were obtained in Vermiwash and Silicon treatments. The least amount of infected fruit was observed in the application of Rovral TS+copper, Rovral TS+Silicon and Vermiwash+Si+Cu, and. Simultaneous treatment of Silicon and Copper significantly increased fruit size. The treatments of Silicon+Copper and Silicon alone led to a decrease in the number of cracked fruits compared to the control. The highest amount of anthocyanin pigment was observed in Vermiwash alongside with Silicon+Copper treatments. The percentage of free radical scavenger in all treatments was higher than the control. Overall, the results of this experiment showed that Vermiwash, Copper and Silicon alone improved the traits studied. Silicon is naturally present as a compound of the cell wall and hardly bonds with the cell wall mass, thereby elicits resistance against cracking. Silicon also has a fungicidal effect, as has been reported in plants such as rice and cucumbers that can delay the development of pathogens such as Rhizoctonia solani and Pythium ultimum after treatment with Silicon. It has also been reported that the use of Vermiwash in various plants did affect control up to 93% of the diseases.
Vermiwash alongside with Si+Cu caused the lowest fungal infection, highest anthocyanin and appropriate fruit set, so this treatment can be strongly recommended. Besides, the results indicated that adding Si and Cu to chemical fungicide can boost its efficiency and decrease cracking significantly.