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Responses of the strawberry to maleic hydrazide and gibberellic acid Gubbels, Gerard Hubert


Greenhouse and field experiments were conducted with maleic hydrazide and gibberellic acid on the British Sovereign variety of strawberry at the University of British Columbia. Treatment with maleic hydrazide resulted in an increase in number of leaves and crowns per plant and an increase in mother plant vigour over control plants which were allowed to runner freely. In these respects the maleic hydrazide-treated plants responded similarly to those which had had their runners removed by hand. Length of runners and number of runner plants were effectively reduced. Top-root ratio on a fresh weight basis was decreased as a result of suppression of total top growth but there was no effect on root growth. Chemical analysis of plant tops 16 days after treatment with maleic hydrazide indicated increases in the percentages of dry weight, ash, sugar, starch (fresh weight) and in the carbohydrate-nitrogen ratio; and a decrease in the percentage of total nitrogen (dry weight). No change in total dry weight of tops was recorded. Field applications of 10 ounces of maleic hydrazide (active ingredient) per acre did not give adequate results with four applications at three-week intervals. Three applications at 25 ounces per acre at three-week intervals gave excellent runner control and mother plant vigour was equal to that of plants receiving hand runner removal. Two applications at 40 ounces per acre gave very good runner control hut mother plants were not as vigorous as those receiving three applications at the 25-ounce per acre rate. No effect of gibberellic acid application was noted on numbers of leaves, crowns, runners or flowers. Increase in fresh weight of tops, no change in roots and increase in top-root ratio were recorded 16 days after treatment, while total dry weight of tops was not affected. Two months after treatment, no effects were observed on fresh weight of tops, roots or top-root ratio. Flower truss emergence and flowering were hastened but did not result in earlier maturation of fruit. The percentage of fruit-set was reduced resulting in a reduction of weight of crop. Size of berry was also reduced. Other effects of gibberellic acid were an increase in sugar content of fruit when it was applied shortly before berry maturity and increases in length of peduncle and petiole if applied when these structures were making active growth. Chemical analysis of plant tops 16 days after treatment indicated decreases in the percentage of dry matter, sugar, starch (fresh weight) and in carbohydrate-nitrogen ratio. There was no change in the percentage of ash and nitrogen (dry weight) in plant tops.

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