عنوان مقاله [English]
Zinc and iron deficiency in Sistan soils, no use of micro- nutrients fertilizers by gardeners, and low yield are problems facing yaghoti grape production as an earliest- ripening grape cultivar in Iran.
This experiment was carried out in the form of factorial based on a randomized complete block design with three replications. The first experimental factor was fertilizing methods included: 1- control (Fm1), 2- foliar spraying of zinc and iron (Fm2), 3- localized placement method of zinc and iron (Fm3) and 4- localized placement method of zinc and iron + foliar spraying of zinc and iron (Fm4) and the second factor was fertilizing stages included 1- bud swelling (Fs1), 2- emergence of bunch (Fs2), 3- verasion (Fs3) and 4- leaf fall (Fs4). The concentration of iron and zinc elements in the fruit in Fm4×Fs3 condition increased by 21.3 and 30.7%, respectively, compared to the control. In the Fm4×Fs2 treatment, bunch length and width, and berry diameter increased by 19, 16.3 and 23% compared to the control, respectively. Also, berry weight, number of berries per bunch, bunch weight, bunchs/vine and fruit yield in the Fm4×Fs1 treatment were increased by 15.7, 18.5, 19.5 and 19%, compared to the control, respectively. The traits measured in this experiment increased each year compared to the previous year. Considering the positive role of zinc and iron elements in improving fruit characteristics and yield, fertilizing Yaghouti grape trees by a combination of localized placement and foliar application methods, with a 19% increase in yield, is recommended.
Yaghouti grape, the dominant variety of Sistan vineyards, is one of the seedless, early ripening grapes adapted to the storms of the Sistan region and suitable for table grapes. All plants require a sufficient amount of nutrients and micronutrients, which improve the physiological and biochemical reactions of the plant. The important factor that determines the yield and quality of the fruit is the utilization of nutrients in the adequate amount and at the appropriate time, which will increase the efficiency of fertilizer application.
Zinc plays a key role in the structural composition of a wide range of enzymes, different proteins, metabolisms of carbohydrates, proteins, auxins and many other important biochemical pathways in plants. Iron is the most abundant micronutrient in grape tissues, and has crucial roles in carbohydrate metabolism and fruit quality. The soil of the Sistan region is poor in terms of organic matter and nutrients, particularly the amount of trace elements. In this region, there are more than 1100 hectares of Yaghouti grapes, and due to the lack of micronutrients, the average yield of most vineyards in this region is five tons per hectare. The aim of this research was to determine the best method and time for the application of iron and zinc elements in order to improve the quantitative and qualitative traits of the Yaghouti grape.
Material and methods
This research was conducted in the Zahak agricultural research station with a latitude of 30'38'53'', longitude of 49'40'61'' and an altitude of 495 meters above sea level during the years 2018 to 2021. Zahk city has cold and dry winters with warm and dry summers. This experiment was carried out in the form of factorial based on a randomized complete block design with three replications. The first experimental factor was fertilizing methods included: 1- control, 2- foliar spraying of zinc and iron, 3- localizeed placement method of zinc and iron and 4- localized placement method of zinc and iron + foliar spraying of zinc and iron and the second factor was fertilizing stages included 1- bud swelling, 2- emergence of bunch, 3- verasion and 4- leaf fall.
The effects of year, fertilizing method, fertilizing stage, as well as the interaction of fertilization method and fertilization stage on the characteristics of bunch length, bunch width, bunch number, bunch weight, berry number of the bunch, berry weight, berry diameter and grape fruit yield were significant. The concentration of iron and zinc elements was increased in the fruit by using the localized placement method in combination with the foliar spraying method of zinc and iron elements at the stage of verasion by 21.3 and 30.7%, respectively, compared to the control. Meanwhile, in comparison to control, this treatment increased the bunch length and width and berry diameter by 19, 16.3 and 23 percent at the stage of bunch appearance, respectively, and the berry weight, number of berries per bunch, bunch weight, bunches/vine and fruit yield at the bud swelling stage by 15.7, 18.5, 19.5 and 19 percent, respectively.
The bud swelling stage in mid-March was the most productive period for Yaghouti across all fertilization methods. During this stage, nutrients from other plant parts migrate to the buds. Foliar spraying was crucial at this stage because the buds require a lot of nutrients for rapid initial growth at this time, but the roots can not absorb enough elements from the soil. However, the root system became active for nutrient uptake one to two weeks after the bud swelling stage. Therefore, the grapevine's own nutrient reserve was the key factor in this sensitive and essential stage. The higher the nutrient reserve, the better the flowering and fruiting processes, as well as the product quality and performance.
Fertilization is one of the most important management techniques in the vineyard, and has a significant effect on the amount of production and the final quality of the grapes. Unbalanced use of chemical fertilizers, high acidity and lack of organic matter in the soil cause signs of deficiency of elements, including low-use elements such as iron and zinc, in vineyards. At the beginning of the growing season, the aerial part of the tree, including vegetative and reproductive buds, begins its activity with rapid growth, while the active roots have not yet begun to grow and absorb the nutrients from the soil enough to meet the tree's nutritional needs. Therefore, the best time to apply the fertilizers used in this study was the swelling stage of the buds and the best method of fertilizer application was localized placement along with foliar spraying, which was more effective than the single application of each of them.