http://www.lifesciencesite.com ) 4 2012;9( Life Science Journal 1979 The Effects of Foliar Applications of Nitrogen, Boron, and Zinc on the Fruit Setting and the Quality of Almonds Mohammad Taher Nezami Department of Soil Science,Islamic Azad University, Karaj Branch,Karaj,Iran. *Corresponding author: Mohammad Taher Nezami E-mail: Taher.nezami@yahoo.com. Abstract: Fruit drop in orchards of almonds (prunus amygdalus L.) is one of the major problems encountered by producers of fruit in Iran. Nutritional elements, particularly nitrogen and boron, have an effective role in this issue. To study the effect of these elements, a factorial experiment was done based on randomized complete blocks with 18 applications and three repetitions – altogether, 108 8-year-old Azar trees were tested in the county of Shabestar during 2002 and 2003. The first factor was nitrogen supplied from a urea source in two levels (zero and 5000 ppm), the second factor was boron from a boric acid source in three levels (zero, 2000 ppm and 4000 ppm), and the third factor was zinc supplied by a source of zinc sulfate in three levels (zero, 2000 ppm and 4000 ppm). The highest percentage of fruit setting (24 percent) was measured at the third levels of boron and zinc. The highest final fruit setting percentage (15 percent) was obtained for second- and third-level boric acid. Also, the highest single kernel weight (2.4 grams) was measured for combined foliar application with 5000-ppm urea and 4000-ppm boric acid. The highest kernel percentage (14 percent), on the other hand, was achieved with third-level boron. The highest fruit length (4.4 centimeter) was also obtained for third-level boron. Furthermore, second- and third-levels of boric acid led to the highest fruit width (3.1 centimeter). The highest oil percentage measured (53 percent) was observed for third-level zinc without applying nitrogen. The highest hard shell percentage (22 percent) was obtained when combined foliar applications of second- level nitrogen and second- and third-level boric acid were used. On the other hand, the highest protein percentage (23 percent) was measured for the combined foliar application of urea and third-level boric acid. No significant simple or interactive year by location effects were obtained for any of the fertilization applications. [Mohammad Taher Nezami. The Effects of Foliar Applications of Nitrogen, Boron, and Zinc on the Fruit Setting and the Quality of Almonds. Life Sci J:9(4):1979-1989]. (ISSN: 1097-8135). http://www.lifesciencesite.com . 297 Keywords: nitrogen, boron, zinc, initial fruit setting, final fruit setting, almonds Introduction: Despite ranking fourth in the world in the production of almonds, Iran lacks in performance and quality in this field. Therefore, considering the role this product can have in increasing exports and bringing in foreign currencies, ways to enhance performance should be examined and determined. One of the factors leading to decreased performance is mismanagement particularly in the case of the lack of nutrients, a problem that crucially needs to be resolved. As Vezvaee and Ghaderi (1999) have reported in Karaj, autumn foliar applications of boric acid and zinc sulfate brought about an increase in fruit setting from 18.5 percent in the control application up to 39.5 percent in the combined application of boron and zinc. As reported for Italian plums by Hanson (1985), autumn foliar applications of boron led to 15 percent increases in fruit setting as well as lowered ovary lengths in trees without boron deficiency. Mahyoub et al. (1993) brought about considerable increases in apricot yields by means of combined foliar applications of boron along with nitrogen. Ahmad and Abddel (1995) reported that foliar applications of boron, nitrogen and zinc on oranges leads to higher product yield, fruit weight and diameter, extent of dissolved solid matter and total sugar content. As reported by Salem (1996), the application of iron, zinc and nitrogen raises the number and amount of tangerine yields. This researcher reported that autumn applications of 5000-ppm zinc sulfate and urea causes noticeably higher fruit settings. Nyomora et al. (1999) concluded that foliar applications of 1 percent boric acid in the autumn following harvest – when active green surfaces for sufficient boron intake existed – led to considerably higher amounts of boron in the almond plants’ internal organs as well as 22 percent increases in fruit setting and 15 percent raises in product yield. Furthermore, Nyomora et al. (1995 and 1997) concluded that autumn foliar applications of boron upon the flower leaves and stigmas led to 20 and 25 percent increases of the concentrations of this element respectively as compared to the control application. These researchers concluded that boron deficiency brings about slower growth and thus delayed flowering in almonds. When boron deficiencies occur, the stamen loses its spore tissue, and part of the plant’s reproductive organs is injured. In such circumstances, the stamens have lower capacities for producing pollen, and the size and the growth of the pollens is thus affected. Chaplin et al. (1977) presented a theory based upon which boron exists in the pollen tube along with callose compounds. With boron deficiencies, callose increases, and pollen tubes grow and evolve with difficulty. Furthermore, nitrogen and carbohydrates