ISHS Acta Horticulturae 726: IV International Symposium on Pistachios and Almonds
EFFECTS OF FOLIAR APPLICATIONS OF NITROGEN, BORON AND ZINC ON FRUIT SETTING AND QUALITY OF ALMONDS |
| Authors: | A. Bybordi, M.J. Malakouti |
| Keywords: | nitrogen, boron, zinc, initial fruit set, final fruit set. |
| Abstract:
Almond (Prunus amygdalus) fruit drop is one of the many problems that fruit growers face, a problem that is often related to nitrogen, zinc and boron nutrition in particular. Nitrogen rates (applied as urea) of 0 and 5000 mg/kg made factor one, boron applied as boric acid at three rates of 0, 2000, and 4000 mg/kg was used as a second factor and zinc applied as zinc sulfate at three rates of 0, 2000 and 4000 mg/kg was the third experimental factor tested. The analysis of variance shows that the main effect of rates of nitrogen, boron, and zinc on the rates of initial fruit setting was found to be significant at P<0.01. The highest percentage of initial fruit set was obtained at the highest rate of boron application (4000 mg/kg), and likewise at the highest rate of zinc application (4000 mg/kg). The main effect of rates of nitrogen on the rates of final fruit sets was also found to be significant. The highest rate of final fruit set was obtained at the highest and the second rate of application of boric acid. The main effects of nitrogen, boron and zinc applications, on the weight of a single almond nut was found to be significant at P<0.01; the interaction between nitrogen and boron fertilizers also significantly (P<0.05) affected the weight of a single nut. The heaviest single almond nut was obtained with the combined application of urea (5000 mg/kg) and boric acid (4000 mg/kg). The main effect of rates of nitrogen and boron on the weight of a single nut was found to be significant at P<0.01. Likewise, the main effect of rates of nitrogen and boron on percent in nuts was found to be statistically significant. The highest percentage of nuts was obtained with the highest rates of boron application. The main effects of boron rates on the length of almond nuts were found to be significant at P<0.01. The longest almond fruit (4.4 cm) was obtained with the highest rate of boron application. Similarly, the main effects of the rates of nitrogen and boron on the width of almond nuts was found to be significant at P<0.01. The widest almond fruit was obtained at the highest and the second rate of application of boric acid. The main effects of the rates of nitrogen and zinc application on the oil content of almond nuts was found to be significant at P<0.05. The highest oil content was obtained at the highest rate of zinc application without nitrogen treatment. Effect of nitrogen rates, and of boron rates, and of interaction between nitrogen and boron on percentage of hard-shells were found to be significant at P<0.01, and P<0.01, and P<0.05, respectively. The highest percentage in nutshells resulted from the foliar applications of combinations of nitrogen at the second rate along with the highest and the second rates of boric acid. Main effects of nitrogen and boron, and the effect of interaction of nitrogen and boron on the protein content of almond nuts were found to be similarly significant at P<0.01. The highest protein content was obtained with the combined foliar sprays of urea and the highest rate of boric acid. Main effects of nitrogen on percentage of green shells was found to be significant at P<0.01. Neither the single effect of year or location nor the interaction between year and location were found to be statistically significant with any of the fertilizer treatments. | |
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