Effects of Zinc rates and application methods,on orange tree (Citrus sinensis) yield and fruit quality

In citrus tree Zinc is routinely supplied by foliar/soil method to combat Zn deficiency. The effect of Zn application on the yield, fruit quality and leaf micronutrient of orange tree (citrus sinensis) was studied in Dezful Agric. Experiment. Stat. (South West of Iran) during 1999-2001 growing season in Shah-Abad silty clay loam (Ustic Hyperthermic). The climate is semi-tropical, with long hot summer seasons and mild winter. The experiment was arranged in RCBD with 3 replicates, and 9 Zn treatments (TRT). The Zn TRT superimposed on a basic fertilizer dose using either surface (SA) or localized (LA) application methods. In T1, T2, T3 and T4, treat 0, 100, 200 and 300gr ZnSO4+LA, in T5 and T6 200 and 300gr ZnSO4,+ SA, T7 and T8 two times (mid- May and late- September) foliar application of 2 and 4 gr ZnSO4/litter, respectively + LA, were used. In T1 TRT the leaves were sprayed by water. The T4 and T5 TRT increased yield and number of harvested fruit per tree, by 54% and 34% compared with control 81 and 70.7 vs. 52.7 kg tree-1, respectively. The T8 and T9 TRT significantly increased leaf Zn, compare with T1 TRT. The effect of treatments on ascorbic acid, brix index, percent citric acid, percent peel+rind, percent juice and percent refuse were not significant. Therefore, T4 TRT is a feasible method to achieve a high yield and good quality orange fruits.

Keywords:

Zn , foliar and soil application , Citrus Sinensis , fruit yield and quality