Influence of different levels and application method of diphenylamine on production and quality of flower spike of symphyotrichum novi- belgii l. cv. white casablanca

الملخص EN

The present study was carried out under field conditions at the Experimental Farm and the laboratory of Antoniades Research Branch, Horticulture Research Institute, A.

R.

C.

Alexandria, Egypt during the two successive seasons of (2017- 2018) and (2018-2019).

The aim of this work was to study the effects of different application levels of diphenylamine (DPA) at rates of (zero, 50, 100 and 200 ppm) by two application methods (soil drench and foliar spray) on vegetative growth, flowering characteristics, leaves photosynthetic pigments content and postharvest characteristics of Aster New York plants (Symphyotrichum novi-belgii cv.

white casablanca).

The plants were treated four times at 30, 60, 90 and 120 days from the final transplanting.

The results showed that there was no significant difference between DPA application method or their combinations with its different concentrations in most recorded data.

On the other hand, using different concentrations of DPA caused a significant effect on all studied characteristics.

The highest plant height, leaf area, number of shoots/plant, leaves dry weight, inflorescence stalk diameter and dry weight, root volume and dry weight and leaves content of chlorophyll a, chlorophyll b and total carbohydrate was obtained after using DPA at 100 ppm.

Also, this treatment caused the longest vase life, the highest final water uptake and floret opening percentage and the lowest loss of flower fresh weight percentage.