Volume of individual internodes of sugarcane stalks

Sugarcane (Saccharum spp.) is rather unusual among field crops in that it is not the seed that is of economic value, but rather the stalk. Sucrose is extracted from the large stalks that are produced by sugarcane plants. Considering their economic value, it is rather surprisingly that there is very little information concerning the development and size of the individual internodes over the length of sugarcane stalks. The objective of this study was to document internode volume over the sugarcane stalk of four cultivars and to observe changes in individual internode volume later in the growing season and in response to lodging. When harvested in August, the size of the internodes varied in a continuous manner along the stalk with the largest internode occurring at the bottom of the plant at approximately internode #15. One cultivar (CP80-1743) had much less of a decrease in internode volume below internode #15 than the other cultivars, indicating that growth was more concentrated in the lower internodes of this cultivar. Since the internode volume diminished as the apex was approached, much of the harvested material was concentrated in the bottom nodes. Comparison of a mid-season harvest (August) and a final harvest (January) indicated both that additional internodes were added to the stalk and that the size of all internodes increased. That is, plant growth was distributed all along the stalk and not focused on one particular zone. Similarly, the negative impact of plant lodging was uniformly distributed over the entire stalk, although there appeared to be differences in cultivars in the extent to which the growth of the stalk was decreased.