The foliar application of 'crimson seedless' grapes grown under black net with abscisic acid and potassium phosphate and improvement of its coloration and yield

الملخص EN

This investigation was carried out during the two successive seasons of both 2016 and 2017 on seven years old 'Crimson Seedless' grape trees (Vitis vinifera L.).

Trees were planted in sandy soil conditions in a private orchard located at El-Nobaria, El-Beheira, Governorate, Egypt.

The trees were spaced at 1.5 x 3 m apart and irrigated by drip irrigation system and received similar cultural practices adopted in the orchard.

The present investigation aimed at improving coloration, earliness and yield of 'Crimson Seedless' grape grown under black net by foliar application of abscisic acid and potassium phosphate.

This experimentation comprise fourteen treatments arranged in a spilt plot design with four replicates per treatment and one vine for each replicate.

The first independent variable (i.e.

open field and black net) was arranged in the main plot, and the second independent variable, i.e.

pre-harvest treatments abscisic acid at 100, 150 and 200 mg / l and potassium phosphate at 2.5, 5 and 7.5 g / l was arranged in the sub plot.

The obtained results revealed that black net; gave rise to the highest mean values of physical characters (i.e.

berry length, berry diameter, weight of 100 berry, volume of 100 berry and fruit firmness).

Also, all yield and yield components (i.e., cluster length, cluster diameter, cluster weight, yield / vine and yield / fed.) recorded the maximum mean values under black net and all chemical compositions (i.e., total sugars, reducing sugars, nonreducing sugars, total carbohydrates and anthocyanin content), which recorded the significant increased mean values under black net, but vitamin C recoded the best results under open field treatments.

On the other side, potassium phosphate at 7.5 g / l; gave rise to the highest mean values of berry length, berry diameter, weight of 100 berry, fruit firmness, total sugars, nonreducing sugars and total carbohydrates, while abscisic acid at 200 mg / l recorded the maximum values of volume of 100 berry, cluster length, cluster diameter, cluster weight, yield / vine, yield / fed., reducing sugars, anthocyanin content and vitamin C content as compared with the control treatment, which recorded the lowest mean values of the studied characters during both seasons.