EVALUATION OF DROUGHT TOLERANCE AND HETEROSISE OF SOME ROOT CHARACTERS IN RICE (Oryza sativa L.)

The present investigation was conducted at the Rice Research and
Training Center (RRTC),Sakha, Kafrelsheikh, Egypt, during 2014 and 2015
growing seasons to evaluate some root characters of some rice genotypes for
drought and well-watered conditions and determination of heterosis of some
root characters in rice (Oryza sativa, L.) in relation to drought tolerance.
Preliminary analysis of variance showed that genotypes were differently
influenced by sowing conditions. Growth rate (g day¯¹) differed significantly
among the genotypes studied. The genotype, Nerica4 had much greater
growth rate than other genotypes under study.
It was clear that drought stress reduced total root length for all five genotypes.
Root volume differentially decreased to a range from 24.53to 19.17 under
drought condition. Numbers of total roots were significantly different under the
two sowing conditions. Under well watered, the number of roots increased as
compared with drought condition. In addition, analysis of variance showed
that root dry weight was higher at the well watered compared to drought,
meantime root to shoot ratio decreased under drought. The highest values
were recorded under well watered condition.
The magnitude of heterosis manifested over mid parent and better
parents are presented. Highly significant estimates of heterosis as a deviation
from mid parent and better parent were exhibited in all studied crosses for
growth rate (g day¯¹) and root length (cm) under normal and drought
conditions crosses for growth rate (g day¯¹) and root length (cm) are desirable
for drought tolerance in rice.