الفهرس 
Potential utilization of boron and nano-calcium fertilizers to improve mango (cv. Zebda) fruit productivity and quality using 15n-tracer technique
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Abstract
This study was undertaken to investigate the effect of nano-calcium and boron fertilizers on Zebda mango productivity and fruit quality. A field experiment was conducted using 15 years old productive mango (Mangifera indica) trees (cv. Zebda). The trees were grown at AlMalak Valley Farm, El-Sharkeya Governorate-Egypt. Trees were grown in sandy soil under drip irrigation system using the Nile water. Treatments included 3 concentrations of boron (foliar at 0.00, 150, 250 mg.L-1), 3 concentrations of foliar nano-Ca ( 25%, 50%, 100% of the recommended rate) and convention calcium (foliar and soil application at 100% of the recommended rate). Trees was arranged in a Completely Randomized Block Design with 3 replicates. Another objective of this study is to evaluate the effect of nano-Ca relative to convention-Ca fertilizer on nitrogen uptake and nitrogen use efficiency using the N-15 tracer technique as (15NH4)2SO4. In both experiments boron was applied as boric acid (H3BO3) and calcium as calcium oxide (CaO) for both the convention and the nano forms.
Results demonstrated that mango trees treated with foliar (250 mg.L-1 B + 50% nano-Ca) achieved the highest flower percentage, initial and final fruit set, fruit retention, fruit quality and yield. This was demonstrated by fruits being firmer, higher in TSS, lower in acidity, higher in vitamin C, higher in total flavonoids, total carotenoids and vitamin C but lower in total phenols than the control. Leaf and fruit boron and calcium concentrations were higher under nano-calcium than under convention calcium fertilization. Results of the N-15 study revealed that in all growth cycles, the 15N translocation was higher under foliar nano-Ca than under convention Ca. In the fall growth cycle, fertilizer nitrogen use efficiency was 64.9%, 81.8%, 51.2% for 25%, 50%, 100% nano-Ca rates, respectively. Calcium concentrations in the shoot and root were higher under nano-Ca than convention calcium in all growth cycles. The summer growth cycle recorded the highest plant biomass and the highest %15N recovery compared with the fall or spring growth cycles. Allocation of biomass to the shoot was higher under nano-Ca foliar application than that of soil application in all cycles. The best treatment is the foliar spray of (50% nano-Ca) as it resulted in the highest N-15 uptake, translocation and nitrogen use efficiency by mango seedlings in all cycles. Nano calcium proves to be more efficient as a fertilizer than convention calcium