Response of Siddek and Kiett mango trees to gibberellic acid and urea foliar spraying at flower bud induction period a. floral aspects

الملخص EN

During ٢٠١٤ / ٢٠١٥ and ٢٠١٥ / ٢٠١٦ seasons, a field experiment was conducted on ٤٥ trees of each of Siddek and Kiett mango cvs.

The trees were ٨-year-old, grafted on Succari rootstock, similar in growth vigour as possible and grown at ٤ × ٣ m in sandy soil under drip irrigation system in a private mango orchard at Belbies District, Sharkia Governorate, Egypt.

The experimental trees were foliar sprayed with GA٣ at ٠, ٥٠ or ١٠٠ ppm and urea at ١.٥ % either alone or in combination with GA٣ at ١٠٠ ppm.

The trees were sprayed at ٣ dates at fortnightly intervals (١st Dec., mid Dec.

and ١st Jan.).

The obtained results showed that sex ratio, fruit set and flower drop percentages were higher on Siddek trees than those of Kiett ones.

The trees were sprayed at mid Dec.

induced the highest sex ratio and fruit set percentages.

The trees were sprayed at early Dec.

showed the highest flower drop percentage than those sprayed at the other two dates.

Fruit retention percentage was significantly affected by either variety or spraying date in both seasons.

Mango trees sprayed with GA٣ at ١٠٠ ppm or urea at ١.٥ % either alone or combined exhibited the highest values of sex ratio, fruit set and fruit retention percentages in most cases.

Whereas, unsprayed trees (control) and those sprayed with GA٣ at ٥٠ ppm induced the highest flower drop percentage.

It is quite evident from the previous trends that spraying Siddek and Kiett mango trees with GA٣ at ١٠٠ ppm or urea at ١.٥ % either alone or in combination at early or mid Dec., was more effective in increasing fruit set and fruit retention percentages than unsprayed trees (control) which gained the least percentages in most cases and the highest flower drop percentage.

Accordingly and from the economic view, we can suggest to spray Siddek and Kiett mango trees with urea at ١.٥ % at early or mid Dec.

for increasing fruit set and fruit retention percentages and consequently increasing fruit yield/tree.