Date of Award

1983

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Some growth and metabolic responses of different clones of Saccharum in relation to their flood-tolerance were examined. Clones grown in soil subjected to flooding demonstrated their ability to produce water roots as a means of morphological adaptation to flooding. Significant differences were observed among the clones with respect to the quantities of water roots produced, but all the clones were visually tolerant to flooding. Clones representing Saccharum spontaneum followed by the commercial hybrid produced the maximum quantities of water root under the flooded condition. The clones of Saccharum barberi and Saccharum robustum produced the least quantities of water root. Artificially imposed anoxia under nutrient culture provided a basic screening technique for the tolerant and intolerant clones. The tolerant clones suffered only a minimal reduction in root growth ((LESSTHEQ) 40%) and stalk elongation (41-53%) whereas the intolerant clones suffered greater reductions in root growth (> 50%) and stalk elongation (80-98%) under anoxia. Intolerant clones tended to cease stalk elongation and root growth beyond 20 days of anoxic treatment while the tolerant clones continued to grow throughout the experimental period. Both inter- and intraspecific differences in growth parameters were observed with the clones tested. Among the metabolic parameters, the activity of the enzyme alcohol dehydrogenase (ADH) appeared to hold some merit for identifying the intolerant clones. Although two different trends of responses were obtained with the tolerant clones viz., Coimbatore, CP 65-357, and NG 77-59, this enzyme showed a consistently high level of activity in the intolerant clones viz., NG 77-160, Cavengerie and D-74. The activity of the enzymes, malate dehydrogenase, lactate dehydrogenase and peroxidase did not show any metabolic significance in relation to flooding tolerance of the clones tested. A low level of pyruvate decarboxylase activity was detected only at 3 days of anoxia. Of the metabolites, the concentration of ethanol appeared to complement the response characteristics due to ADH. Other metabolites viz., malate, sucrose, glucose and fructose, did not show any consistent changes that could be correlated with tolerance or intolerance of the different clones tested; however, there were consistently higher levels of ethanol, malate and sugars under anoxic conditions.

Pages

115

Share

COinS