Effect of Integrated Soil Fertility Management on Some Quantitative and Qualitative Characteristics and Nutritional Balance of Thompson Seedless Grape

In order to evaluate the effect of integrated soil fertility management (ISFM) on growth and nutritional balance of Thompson Seedless grape (Vitis vinifera L.), an experiment was conducted in a randomized complete block design including four treatments with three replications in five private vineyards located at Urmia, Iran, during 2020 and 2021seasons. Treatments included T1= check (no fertilization), T2= farmers’ conventional fertilization, T3=optimum fertilization of mineral nutrients and T4 integrated soil fertility management. Results indicated no significant difference among the study sites in terms of cluster weight, chlorophyll index, titratable acidity (TA) and total soluble solids (TSS) of fruits, but a significant difference was observed between macro- and micronutrients, except for iron (Fe). The cluster weight was increased in all fertilized treatments compared to the check (p≤0.05). Grapes increase in T3 and T4 compared to T2 was 2.27 and 4.04 kg/vine, respectively. A similar trend was observed in relation to the leaf chlorophyll index, which increased in T4 by 10.99% and 9.69%, respectively, compared to T2 and T3. TA and TSS concentration accumulation in berries were affected by T3 and T4 treatments. TA showed a significant decrease in T4 compared to T1 by 16.09% (p≤0.05). However, TSS accumulation showed the highest value in the T4 (p≤0.05). There was no significant difference between T3 and T4 in terms of these two qualitative Characteristics. Evaluation of nutritional status using compositional nutrient diagnosis (CND (norms in control treatments indicated that, on average, the order of nutritional requirements of macro- and micronutrients were K=Ca>Mg>N>P and Fe>Zn>Mn>Cu>B, respectively. The lowest nutrient balance index (9.02) was obtained in the T4 and the highest value was observed in T1 treatment (35.02). In general, it is concluded that due to the significant increase in quantitative and qualitative factors of grape yield with ISFM, this technology was the best for balanced fertilization program and optimum fruit production in vineyards.