Sweet pepper was cultivated, for 129 days after germination, in plastic growth pages containing sandy soil incorporated with or without a hydrogel polymer (9: 1 v/ v). Plants were irrigated, to 80% field capacity, with full-strength Hoagland nutrient solution and the physiological response of the plant to the growth-retardant cycocel (CCC) and/ or hydrogel polymer was investigated. Generally, all morphological, anatomical and physiological criteria were enhanced by increasing the plant age as well as by soil incorporating with hydrogel polymer. Cycocel retarded shoot elongation and leaf expansion, but increased leaf thickness. Leaf anatomy revealed that the cell-wall area of palisade and spongy cells were enlarged under CCC application. Such enlargement was associated with increasing the photosynthetic and respiratory activities. Leaf contents of N, P, and Mg were increased by CCC application, while the reverse was true in case of K. Chlorophyll contents (a & b) of the 6th leaves were improved by CCC treatment, especially in presence of the polymer. Whereas, post-illumination CO2 outburst-1 & -2 [PIB-1 & PIB-2] as well as dark respiration were declined under the same treatment. Carbohydrate and protein contents - in the 6th leaves of plants- treated with CCC - were higher than those of the control whether in the presence or absence of hydrogel polymer, but the response was more evident in presence of the polymer. It was also observed that CCC-treated plants produced flowers better than untreated ones. This observation was ascribed to the higher metabolite accumulation in CCC-treated plants compared with the untreated ones.
Key words: Capsicum annuum L., chlorophyll, hydrogel polymers, minerals, post-illumination CO2, proteins, outburst-1 & 2 [pib-1 & pib-2], respiration, sugars
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