Correlation at Different Ages Between Nitrogen, Green- and Dry-Matter Contents of Leaves, and Yield of Sugarcane Grown in Sand Culture

Abstract

Sugarcane variety M. 336 was grown in sand cultures in 28 pits under cover to study the effect of increasing levels of nitrogen on crop yield and the correlation between the nitrogen, the green- or dry-matter contents, and crop yield. Seven increments of nitrogen, replicated four times, were studied with other nutrients and water at optimum levels. The yield in tons per acre varied as follows: Cane, 20.0 to 83.1; sugar, 2.1 to 11.0; trash, 5.8 to 19.0; roots, 4.0 to 8.4. The sugar in the cane varied from 10.3 to 13.7 percent when the crop was harvested at the age of 15 months. There were significant responses to nitrogen at the 1-percent level in the yields of cane, sugar, trash, and roots. The nitrogen content of the third, fourth, fifth, and sixth leaves varied from 0.95 to 3.10 percent when the cane was between 3 and 15 months old; the green weight of these four leaves varied from 100 to 315 gm. and their dry weight from 22 to 85 gm. Results indicate that nitrogen, and the green- or dry-matter contents of the cane leaves can be used to predict relative crop yields at specific crop ages. This is illustrated with three formulas derived from the data.