Effect of Tryptophan Application Method and Sorbitol Spray on Growth of Mandarian Transplants

Sorbitol (a non-cyclic polyol) and sugar are the major products of photosynthesis and the major components transported through the phloem in some economically important species in the Rosaceae family, especially in apple Malus pumila, pear Pyrus communis, almond Prunus dulcis, cherry Prunus spp., peach Prunuspersica L. and plum Prunus spp.

A field experiment was conducted in a private orchard in Diyala Governorate to reveal the effect of the tryptophan application method and sorbitol spray on the growth of 2-yrs old mandarin transplants. The study included two factors: tryptophan application method (control, spray 200, 400 mg.L^-1 and soil application at 500, 1000 mg.L^-1) and sorbitol spray (0, 20 and 40 g. L^-1).

Sorbitol spray at 20 g.L^-1 caused a significant increase in stem length and diameter, leaves number, leaf area and leaves P and K content. Tryptophan application at 1000 mg.L^-1 gave the best increase in stem length and the largest number of leaves per plant, furthermore, this treatment gave the highest carbohydrates, nitrogen and phosphorus content, whereas the largest increase in stem length and leaves chlorophyll content resulted from tryptophan spray at 400 mg. L^-1, On the other hand, the highest leaves potassium content in the leaves resulted from tryptophan application at 500 mg.L^-1 in soil.