| The exact role of peroxidase in plants is not yet clear but it has been
shown to be involved in growth and devopment by inactivating auxin (GALSTON
et al. 1953). Accumulation of peroxidase in slow growing tissues
and dwarf plants suggests a growth inhibitory activity of growth regulating
enzyme, auxin. Single gene dwarf mutant when treated with gibberellin have
shown a decrease in peroxidase activity and an increase in growth (MCCUNE
& GALSTON, 1959). Conversely, marked increase in peroxidase activity in
normal plants with the application of compounds which prevent gibberellin
biosynthesis has also been observed (GASPER & LACOPPE 1968). RAO et al.
(1976) had also observed a positive correlation between peroxidase activity
and degree of grain shrivelling in triticale. Peroxidase activity in coleoptile
showed a negative relationship with plant height and kernal weight (SINGHAL
et al. 1979) and plant height has been found to have relationship
with kernel weight (EPHRAT 1974), further the present study extends the
negative effects of peroxidase on dry matter accumulation at different stages
of kernel development. An important question arises that how the development
of a semi-dwarf wheat plant with higher kernel weight is possible. Our previous
study (SINGHAL et al. 1979) showed considerable variation in the
amount of peroxidase activity among the semi-dwarf wheats and a deviation
from negative relationship and possibility of developing a dwarf plant type
with well filled grain do exist. The critical examination of data from the
present study showed that the triple dwarf variety HD 1944 had higher kernel
weight at maturity and lower peroxidase activity than the double dwarf variety
Kalyansona. Upto day 24 after anthesis, avarage kernel weight accumulation
and peroxidase activity did not differ much between Kalyansona and HD 1944.
The variety HD 1944 showed a substantial decrease in peroxidase activity
from day 24 to day 31 at a period when substantial increase in its kernel
weight (1.78 g/100 kernels) occurred. On the other hand in variety Kalyansona
peroxidase activity did not change in this period, therefore, the increase
in kernel weight was relatively low (0.587 g/100 kernels). At maturity HD
1944, possessed relatively lower peroxidase activity, higher grain weight
and short plant height than variety Kalyansona. The present study indicates
that a genotype with relatively higher peroxidase activity during early
stages of plant growth would result in the dwarf plant type and decrease
in peroxidase activity at later stages of kernel development as has been
noticed in HD 1944, would result in the greater accumulation of grain weight.
References EPHRAT, J. 1974. Z. Pflanzenziichtg 72 : 39-45. GALSTON, A.W., J. BORNER, & R.S. BAKER. 1953. Arch. Biochem Biophys. 42 : 456-470. GASPER, J. & J. LACOPPE. 1968. Physiol. Plant. 21 : 1104-1109. MCCUNE, D.C. & A.W. GALSTON 1959. Plant Physiol. 34 : 417-418. RAO, V.R., S.L. MEHTA & M.G. JOSHI 1976. Phytochemistry 15 : 893-895. SHANNON, L.M., E. KAY & J.Y. LEW. 1966. J.B. Biol. Chem. 241 : 2166. SINGHAL, N.C., S.L. MEHTA & M.P. SINGH 1979. Theor. Appl. Genet. 55 : 87-92. |
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