אסיף מאגר המחקר החקלאי

Antagonistic effects of paclobutrazol and gibberellic acid on growth and some biochemical characteristics of pepper (Capsicum annuum) transplants

Year:

1987

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Volume :

33

Co-Authors:

Aloni, B., Agricultural Research Organization, Institute of Field and Garden Crops, Department of Vegetable Crops, P.O. Box 6, Bet Dagan, 50 250, Israel
Pashkar, T., Agricultural Research Organization, Institute of Field and Garden Crops, Department of Vegetable Crops, P.O. Box 6, Bet Dagan, 50 250, Israel

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Abstract:

Spraying pepper (Capsicum annuum L.) transplants (30 days old) with paclobutrazol (PP333) at concentrations higher than 1 mg l-1 inhibited their growth. At 0.5 and 1 mg l-1, seedling growth was slightly enhanced, whereas at 50 mg l-1 stem elongation was completely inhibited. At all PP333 concentrations tested (0.5-50 mg l-1), root development was stimulated and leaf chlorophyll was increased. Spraying 50-mg l-1 PP333-treated seedlings with gibberellic acid (GA3) after their growth had been inhibited caused a resumption of stem elongation, reduction in chlorophyll content of the newly developed leaves, reduced root weight gain, and concomitantly stimulated root exudation, which had been almost totally abolished in the PP333-treated seedlings. Fourteen days following application of PP333 (50 mg l-1) there was a slight increase in soluble sugars in both leaves and roots. However, most noticeably the free proline content was 3- and 4-fold higher in the roots and leaves, respectively, of treated plants than in untreated plants. The changes in the free amino acids level were small, suggesting that proline accumulation was unique. Four days following treatment of these transplants, treated transplants returned to the levels found in the untreated transplants. On the other hand, when given in solution to leaf discs prepared from PP333-treated plants, GA3 did not change proline content, nor did GA3 have any effect on proline levels of discs which were pre-loaded with exogenous proline or which accumulated proline during disc incubation in PEG solution. It is suggested that GA3 causes the disappearance of the accumulated proline and sugars in the PP333-treated seedlings by influencing the growth of the young sink leaves and not by an in situ effect on metabolization of the substrates. © 1987.

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