Effect of sink removal, kinetin and cppu on monocarpic senescence of sunflower plant

الملخص EN

Pot experiments were carried out in the green house, Faculty of Agric.

Ain Shams University during the two successive seasons of 2005 and 2006.

Treatments included head buds removal at 45 days after sowing.

As well as, foliar spry of intact plants with kinetin (Kin) at 50, 100 ppm, CPPU (N-(2- chloro-4-pyridyl)-N- phenylurea) at 10, 20 ppm and distilled water as control.

Plants received 3 foliar sprays started at 4 weeks after sowing with one week interval.

Head removal treatment induced significant reduction in plant height and an increase in leaf area in both seasons.

Furthermore, head removal showed an increase in shoot dry weight, this effect reached the levels of significant in the 2nd season.

Application of Kin at 50 and 100 ppm showed marked increase in shoot dry weight.

Insignificant differences were found between both Kin concentrations on leaf area and shoot dry weight.

Pronounced increase in heads weight was recorded by CPPU at 10 ppm followed by Kin treatments, while, CPPU at 20 ppm showed insignificant effect.

Application of CPPU at 10 ppm improved seeds weight/head and 100 seeds weight in both seasons.

Head removal treatment developmed lateral heads with few large seeds on the upper 5-6 nodes.

Meanwhile, CPPU at 20 ppm resulted in visible inflorescence buds or tiny heads in leaf axils.

All treatments showed an increase in total soluble proteins, chlorophylls and carbohydrates.

The highest values were recorded by Kin at 50 ppm.

The alternation in sunflower senescence by head removal and cytokinin treatments and correlated changes in biochemical constituents was discussed.

Key words: Sunflower- Monocarpic senescence- Head removal-Kinetin- CPPU- Growth- plant yield.