The effects of photoperiod and temperature on floral initiation, growth, and peroxidase activity of milo maturity genotypes of Sorghum bicolor (L.) Moench.
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1983.
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| Subjects: | |
| Online Access: | Link to ProQuest Copy Link to OAKTrust copy |
| Abstract: | Photoperiods of 8, 10, 12 and 14 h and temperature cycles out of phase with the photoperiod were used to study floral initiation in 11 genotypes of milo group of Sorghum bicolor (L.) Moench. Peroxidases were studied in order to characterize their role in floral induction. Genotypes 38M, 44M, and 58M initiated floral buds earlier than the other milos under 8, 10 and 12 h photoperiods. Even under 14 h photoperiod, the ma(,3)('R) genotypes achieved floral initiation quite early while other milos remained vegetative until the end of the experiment (110 days). Under 12 h photoperiod, the time of floral initiation ranged from 22 to 66 days and plants segregated into 7 groups by Duncan's test. Under 10 h photoperiod, floral initiation occurred 34 days earlier in 90M and 100M but only 4 to 5 days earlier in SM80 and SM90 compared with 12 h photoperiod. Differences in time to floral initiation between 10 h and 12 h photoperiods were not observed in SM60, SM100, 60M and 80M. Floral initiation could also be enhanced by phase shift treatment in which a 12 h thermoperiod was shifted in time 2.5 h forward out of phase with the 12 h photoperiod. In ma(,3)('R) genotypes, time to floral initiation was not affected by the phase shift treatment. The sensitivity to phase shift treatment was different among the genotypes with Ma(,3) or ma(,3) alleles. The presence of the ma(,3)('R) gene in 38M, 44M and 58M reduces leaf area, increases the length of leaf blade and leaf sheath and accelerates internode elongation. The ma(,3)('R) allele makes plants develop morphologically like a GA surplus mutant. A close correlation of peroxidase peak activity with the time of floral initiation was observed for the ionically bound peroxidases extracted from genotype 100M grown under 10 h photoperiod as well as 38M grown under 10 h and 14 h photoperiods. Genotype 100M remained vegetative under the 14 h photoperiod and showed a different pattern of peroxidase activity. Peroxidases in the soluble and covalently bound fractions were separated by polyacrylamide gel electrophoresis. Predominant changes were observed in cationic isozyme components during the transition to reproductive stage which implicate an important role of this enzyme in cellular differentiation. The involvement of peroxidases in cessation of leaf initiation, lignin synthesis and cell elongation is discussed. |
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| Item Description: | "Major subject: Plant Physiology." Typescript (photocopy). Vita. |
| Physical Description: | xxiii, 242 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 208-218). |