RESPONSE OF Conocarpus erectus L. PLANTS TO DIFFERENT IRRIGATION INTERVALS AND CYTOKININ SPRAY APPLICATION

Abstract

This study was conducted at the nursey of the Local Unit of Somosta, Bani-Sweif Governorate, Egypt during the two seasons of 2008/2009 and 2009/2010, with the aim of evaluating the effects of different irrigation intervals (2, 3, 4 or 5 days) and cytokinin treatments [spray application of benzyladenine (BA) and kinetin (Kin) at concentrations of 0 (control), 50, 100 or 150 ppm] on the vegetative growth and chemical composition of Conocarpus erectus L. plants. C. erectus transplants (10-15 cm /tall) were planted individually in polyethylene bags (30 cm diameter) filled with a sandy soil plus sheep manure (100 g/1). The recorded results indicated that irrigation intervals had significant effects on plant vegetative growth. Irrigation every two days gave the tallest plants, the highest number of branches and leaves, as well as the highest fresh and dry weights of the stems, leaves and roots (in both seasons). In both seasons, the different Kin and BA treatments resulted in better growth, compared to the control. BA was most effective when applied at concentrations of 50 or 100 ppm, while Kin was most effective at 100 ppm. These treatments gave the tallest plants, the highest number of branches and leaves, as well as the highest fresh and dry weights of stems, leaves and roots (in both seasons). Irrigation every 2 days increased chlorophyll and carotenoids in the leaves. In most cases, the different BA and Kin decreased the leaf chlorophyll content. The carotenoids content was increased by BA, but was decreased by the Kin treatments. The highest total carbohydrate percentages in the leaves, stems and roots were obtained with irrigation every 2 days, 4 days, and 5 days, respectively. BA at 150 ppm or Kin 100 ppm gave the highest total carbhydrate percentages in the leaves, stems and roots. In most cases, irrigation every 4 days gave the highest N % in leaves, while irrigation every 2 days gave the highest N % in stems and roots. Using the different Kin treatments increased the N % in the leaves, stems and roots, whereas BA treatments increased the N % in the leaves and stems, but decreased it in the roots. Irrigation every 2 days increased the P % in the leaves and roots, while prolonging the irrigtion intervals increased the P % in the stems. Also, BA and Kin at concentrations of 100-150 ppm increased P in the leaves, stems and roots. Irrigation every 4 days gave the highest K % in the leaves and roots, while irrigation every 2 days gave the highest K % in the stems. BA increased the K % in the leaves, stems (especially at 100 ppm) and roots (especially at 50 ppm). Kin increased the K % in the leaves (especially at 100 ppm) and stems (especially at 50 ppm).