The Effects of Plant-growth Substances on Sugarcane

Sugarcane Sower initiation is dependent on day length, temperature, age, moisture, and variety, and can be prevented by chemical applications at, or very close to, the date of floral initiation. The effective chemicals have been of two types (a) photosynthetic inhibitors, such as 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), or (b) leaf-burning, contact chemicals. The very effective bipyridylium herbicides 6,7-dihydrodipyrido[l,2-a 2, r-c]pyrazidinium dibromide (diquat) and 1, l -dimethyl-4,4 -bipyridinium bis (methyl sulfate) (paraquat) combine the two properties, although the 

The bipyridylium compounds have also been Used experimentally to desiccate sugarcane leaves, and are more effective for this purpose than substituted phenols, oils, and chlorates. The yield of treated cane remained more or less constant for several weeks, and then increased again as new leaves formed. The yield of sucrose decreased as a result of treatment, partly because of the temporary reduction of photosynthesis, and partly as a result of increased stalk-moisture.800 

Indian work has tended to support the claims of increased sugar production, approximating 0.5% of sucrose on cane tonnage, from applications of (2,4-dichlorophenoxy) acetic acid of from 0.025 lb. per acre to 3 lb. or more per acre, on different varieties, autumn- and spring-planted cane, 

It is difficult to arrive at a definite conclusion from this work. The major criticism which has been made of this and similar testing is that at least 15 samples are required in order to provide statistical significance at 0.5 % sucrose based on cane yield. Variations in the yield from field blocks are commonly as high as 10%, and often more. 

Some of the demonstrated increases in the percentage of sucrose in the sugarcane have been accompanied by overall decreases in sugarcane yield per unit area. Other experiments have shown no effects on yield. 

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