The effect of foliar application of urea, boric acid and zinc sulfate on yield and quantity and quality characteristics of date palm (c.v Sayer)

Date palm is considered as a strategic crop in Iran. It is planted in south area that its soils are calcareous with high pH. The high soil pH causes reduction of nutrient elements absorption and yield. The results of researches in Iran and other countries show that foliar application of nutrient elements especially Nitrogen, boron and zinc with improvement pollination status are increasing yield and fruit set. There are little researches about effect of foliar application of nutrient elements on date palm. In order to evaluate the effect of foliar application of urea, boric acid and zinc sulfate on yield and quantity and quality characteristics of date palm (c.v Sayer), an experiment was carried out in randomized complete block design (RCBD) with eight treatments (each treatment consisted of two date palm) and three replications on 48 date palm (c.v Sayer) during 2004- 2006 in Arvand Kenar (Khuzestan Province). The treatments were: T1= Control (application of animal manure and chemical fertilizer based on soil testing for each date palm) T2= T1 + foliar application of urea T3= T1 + foliar application of zinc sulfate 15 T4= T1 + foliar application of boric acid T5= T1 + foliar application urea and boric acid T6= T1 + foliar application of urea and zinc sulfate T7= T1 + foliar application zinc sulfate and boric acid T8= T1 + foliar application of urea, zinc sulfate and boric acid Concentration of urea, zinc sulfate and boric acid was 5, 3 and 2 kg/1000L prospectively. In this experiment foliar application was carried out at four times: immediately after fruit harvesting time, 15 days after it, pollination time and 15 days after it. Agro- management was used for all of treatments as same. Animal manure was applied with macronutrient chemical fertilizers including (1500 gr ammonium sulfate, 1500 gr triple super phosphate and 1000 gr potassium sulfate based on soil testing) and micronutrient chemical fertilizers based on general recommendation for each tree at in winter. 1500 gr ammonium sulfate was applied in April, too for each tree. For leaf sampling it was sampled, the number of 20-25 leaflets from middle leaf of second row, every year. They were analysised mineral nutrients. At fruit harvesting time, the yield in each date palm (replication) measured and also the quantity characteristics such as: weight, length, diameter and volume of fruit fresh, weight of seed and pulp to seed ratio of 20 fruit dates, quality characteristics such as: pH, brix, reducing sugar, total sugar and fruit moisture and after pollination time fruit set were determined and used for statistical analysis. Data were analysised with MSTATC statistical program and means of data were compared with Duncan&rsquos Multiple rang test. The results showed that treatments had significant difference on yield, fruit set and some quantity characteristics such as: weight and diameter of fresh fruit and some quality characteristics such as: pH and reducing sugar as compared with the control treatment (T1). Treatment No.6 was the best of treatment (T6) due to the highest effect on yield, fruit set and quantity and quality characteristics of date palm. Therefore foliar application of Urea and Zinc sulfate with concentration 5, 3 kg/1000L prospectively at four times: immediately after fruit harvesting time, 15 days after it, pollination time and 15 days after it, is recommended by date growers.