| dc.description.abstract | Five rice varieties of diverse Phenotypes, F; and F2 population of the crosses Zirasail
x Nerica-4, Hobigonj-6 x Nerica-4, Pariza X Nerica-4, BRRI Dhan -28 x Nerica -4
were grown in the field research field of Hajee Mohammad Danesh Science and
Technology University, Dinajpur-5200. To study the maximum growth occurrence of
root xylem vessel number, to investigate the gene systems of root and shoot
characteristics related to drought avoidance mechanism.The varietal differences for
root xylem vessel number was observed at 20 days after sowing and the maximum
growth occurred at 40 days after sowing. The root and shoot characters were generally
controlled by polymeric genes with additive and/or dominance effects. The additive
gene affects was important in the expression of root xylem vessel number. Dominant
alleles controlled root dry weight, Shoot dry weight, Root length, and Tiller no. and
plant height. Dominant alleles controlled shallow roots of Pariza, Zirasail and
hobigonj -6. Additive and dominant gene effects were important in the inheritance of
root xylem vessel number, root thickness and root- shoot ratio. Heterosis and
heterobeltiosis were observed for most traits. heterobeltiosis was positive for the trait
root dry weight, root length and tiller number. Heterobeltiosis was positive for the
trait root length, root thickness, root-shoot ration, tiller number and plant height. The
broad sense heritability estimates were relatively high for root xylem vassel number,
root-shoot ratio, root thickness, root dry weight and low to moderately high for root
length, shoot dry weight, plant height and tiller number. Results indicated that the root
characteristics such as thick and long root with high xylem vessel number and area
can be studied efficiently in early segregating generations. Above ground plant
characters like height, tiller number and shoot weight appear to be good indicators of
a
the extent of the development of a root system. The Parents obviously differed greatly
in their genetic make ups. Refined studies are needed to assess the genotype
environment interactions. Root length was positively associated with root-shoot ratio
and plant height. Root thickness was positively and significantly correlated with root
dry weight, shoot dry weight, tiller number. Root dry weight positively correlated
with shoot dry weight, Root —shoot ratio, plant height and tiller number. Shoot dry
weight was positively correlated with root-shoot ratio, tiller number and plant height.
Root —shoot ratio was positively correlated with tiller number and plant height. Plant
height was positively correlated with tiller number. On the other hand, Root xylem
vessel number was negatively and significantly correlated with root length, root dry
weight, shoot dry weight, root-shoot ratio, plant height and tiller number. Root length
was negatively and significantly correlated with root thickness, shoot dry weight and
tiller number. Root thickness was negatively and significantly correlated with rootshoot ratio and plant height. | en_US |
