Growth and Development of Cranberry (Veccinium macrocarpon) As Influenced by Application of Nitrogen, Gebberellic Acid and Succinic Acid 2,2 Dimethyl Hydrazide

Abstract

An experiment no the ‘Early Black' variety of cranberry was conducted in the greenhouse to investigate the effects of exognously applied N, GA, and SADH upon the numbers and lengths of upright and vines, the numbers of flowers and berries, the percentage fruit set and the size and weight of berries. Two levels of N, GA and SADH were applied to the plants in a factorial combination with three replications. High N increased the length and the number of vines of vines but affected neither the production nor the number of uprights. High N decreased the number of flowers in the second growing season. GA had no effect on the number of vines but increased the length of vines. GA increased the length of uprights but reduced the number of uprights produced. The fruits of the GA-treated plants were smaller and lighter and possessed fewer seeds than did those of the untreated plants. The stimulated vegetative growth and the reduction in flowering associated with both N and GA treatments suggest that some metabolite imbalance in the plant may be responsible for the loss in flowering. SADH effected no change in the number of vines produced but did decrease the length of vines and the production of uprights in the presence of low N. SADH reduced the growth stimulating effect of GA in the plant. SADH also decreased the number of uprights in the plants receiving a low level to N in 1971 and at both N levels in 1972. Plants receiving the combination treatment of SADH and high N produced the greatest number of flowers. The increase in flowering may be related to the reduced vegetative growth and therefore a reduced competition between vegetative growth and flower buds for available photosynthesis, or SADH may have in some way altered the hormonal balance in the plant so as to have favored flowering. The combination of GA and SADH increased fruit set, but this effect was reduced with the application of high N. The failure of berries to size in GA-treated plants is probably related to the low seed count. This suggests that the developing embryo is necessary in the cranberry plant to serve as a sink for metabolites or as the source of some hormone essential for the normal enlargement of the fruit. The lower N content, associated with GA in the presence of SADH and resulting in little growth stimulation, suggests some antagonistic effect of GA upon N utilization and assimilation in the plants. The combination of high N and exogenously applied GA reduced the number of buds on each vine. This combination may have combination may have contributed to GA levels that exceeded some critical level for bud formation to occur. When compare with solvent extraction method, the centrifuge extraction method for gibberellins was found to be simpler and more effective. Approximately 50% GA3 was lost during the purification stage was not appreciable. The barley endosperm bioassay and the lettuce hypocotyl bioassay were used to test the extracts for the level of endogenous gibberellin-like substances in the shoot tissue of the cranberry , the barley endosperm bioassay was found to be a more sensitive method for measuring the level of these substances than the lettuce hypocotyl bioassay