Effects of maleic hydrazide spraying on vegtable crops. I

Abstract

Studies were carried out in order to clarify the optimum concentration and time of spraying of maleic hydrazide (MH) as sprouting inhibitor of onions for storage. The results obtained were as follows: 1. Experiment on the concentration: 0.05_??_0.8% solutions of MH (as sodium and diethanolamine salts) were sprayed on onion plants nineteen or seven days before harvesting. Onions were har-vested when about 70% of leaf stalks have failed down. At the harvesting time, there found no significant difference in growth and yield of bulbs among the plots sprayed with various concentrati-ons of MH, and no chemical injury was observed on all the plots. After storage (in December), onions sprayed with higher concentrations of both salts (0.1% or more) were inhibited their sprouting, and onions sprayed with 0.8% of sodium salt and with 0.2%. or more of diethanolamine salt showed little sprouting. But higher concentrations tended to result more rot of onions in storage. Therefore percentage of bulbs with commercial value were higher in the plots sprayed with 0. 4%o of sodium salt and 0. 1% of more of diethanolamine salt. From the above mentioned results, the optimum concentration of MH may practically be 0.4% of sodium salt and 0.2% of diethanolamine salt, when 70_??_90 liters of solution was sprayed per acre. 2. Experiments on the time of spraying: At various times since 43 days before harvesting, 0.1 and 0.5% solutions of MH were sprayed on onion plants. Earlier spraying (30 days or more before harvesting) induced chemical injuries on leaves and bulbs of the plants, and reduced the yields of bulbs, and moreover increased percentage of rotted bulbs. From the results obtained, the optimum time of spraying of MH may practically be 1_??_3 weeks before harvesting.