Gibberellin Studies with Sugarcane. III. Effects of Rate and Frequency of Gibberellic Acid Applications on Stalk Length and Fresh Weight
1980
Moore, Paul H. | Ginoza, Harold
Sugarcane (Saccharum spp. hybrids) stalk length, fresh weight, dry weight, and sucrose content, normally reduced when plants are grown under reduced sunlight (250 Langleys/day) and cool temperatures (mean daily temperature 23 C), can be increased with foliar applications of gibberellic acid (GA₃). Maximum increases in lengths and fresh weights of seven Hawaiian commercial cultivars were a function of cultivar treated, the amount of GA₃ applied, the number of applications, and the interval between applications. Lowland cultivars produced the largest gains in response to the largest quantities of GA₃; highland cultivars produced smaller gains. The effects of two applications of 1.0 mg GA₃ per stalk depended on the interval between applications. Least growth gains occurred when the intervals were 0 and 45 days; greatest growth gains occurred when the interval between applications was 15 days. The effect of a 30-day interval was nearly equal to the 15-day interval, but the 30-day interval did not result in as great a loss of stalks as occurred at the 15-day interval. Three and four applications of 0.5 mg GA₃ per stalk at 15-day intervals were less effective in increasing stalk length and fresh weight than were three and four applications of 0.5 mg GA₃ per stalk at 30-day intervals. Greatest gains in fresh weight in response to 2.0 mg GA~ per stalk were in response to the greatest number of applications, four, if they were at 30-day intervals.
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