Date of Award

1982

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Ratoon decline of sugarcane, Saccharum spp., is a significant worldwide problem especially in temperate zone areas such as Louisiana. This study was begun with the object in mind to examine in detail the ratooning behavior within a sugarcane progeny of the type used in the Louisiana breeding programs since the 1930's. The cross examined was L 65-69 x CP 65-357. Data were taken in plant cane, first ratoon and second ratoon crops on 210 clones established randomly from individual seedlings of this cross. Data included number of stalks per plot, mean weight of stalk, mean length of stalk, mean diameter of stalk, and sucrose percent of expressed juice. Yield was estimated as the product of number of stalks per plot x mean weight per stalk. The ratooning ability of the progeny was examined in comparison to the parents' behavior for each trait individually and in combinations. There was a high incidence of clones with good ratooning ability for each of the individual yield components; however, only approximately 5% of the clones showed ratooning abilities of yield which equalled those of the parents. The severe second ratoon decline in yield of the progeny and parents was due to declines in all of the yield components studied. Certain negative interrelationships among traits, notably that of stalk diameter and stalk population (r = -0.33), appeared to be important factors in reducing the number of segregants showing good ratooning ability within the cross. Although yield and its components showed high repeatability between the plant crop and ratoon crops, the correlations were not perfect, and all clones with acceptable plant cane behavior showed some yield loss in the second ratoon crop. Furthermore, the severity of second ratoon yield decline in clones could not be predicted from first ratoon data. Thus, the data indicated that second ratoon information on clones obtained at early stages of selection would be a useful adjunct to data normally taken at these stages.

Pages

160

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