Effects of organic, biological and chemical N-fertilizers on some quantity and quality ‎characteristics of Thompson seedless grape

To evaluate the possibility of replacing urea with organic and bio-fertilizers, a study carried out on 14 years old Thompson Seedless grapevines (Vitis vinifera</em> L.) in a calcareous soil. The results showed that treatments affect cluster yield, chlorophyll index, total soluble solids and total acidity of fruit and N, Fe, Mn and Zn concentrations in leaves, significantly. Maximum fruit yield resulted in liquid inoculum of N-fixing bacteria+animal manure and solid inoculum of N-fixing bacteria with 11.73 and 11.83 kg/vine, respectively. All treatments showed relatively similar increase in soluble solids content and decrease in fruit acidity compared to the control. The Highest chlorophyll index and concentration of N, Fe, Mn and Zn in leaf have been reported in liquid inoculum of N-fixing bacteria+animal manure and solid inoculum of N-fixing bacteria+animal manure treatments. The nutrient balance indices were 160 and 145 in treatments without N or urea application, but the amount was decreased to about 107 and 108 in N-fixing liquid inoculum+animal manure and solid N-fixing inoculum+animal manure treatments respectively, which shows the improvement in nutritional balance status under these treatments. The results indicated that application of N bio-inoculations with animal manure more than N chemical fertilizer source improved the nutritional balance of grape and produced the highest yield, but their effect on fruit quality was similar to urea.