Abstract
The
root cortex is an important anatomical phenes, and
root cortical senescence (RCS) is
closely associated with root absorptive function. However,
characteristics and responses of
RCS to drought stress in cotton have received little attention. This
study subjected the drought-tolerant cotton variety ”Guoxin 02” and the
drought-sensitive variety ”Ji 228” to drought stress (8% PEF6000) and
no-stress (0% PEG6000) treatments to determine the characteristics and
responses of cotton RCS to drought stress.
The results showed that the RCS of
the two varieties was significantly promoted under drought stress.
The greater the distance from the
root tip, the more severe the RCS occurrence under drought stress
compared with non-stress treatment.
The occurrence of RCS in ”Guoxin
02” highered by 14.03%-20.18% compared to ”Ji 228” under drought
stress. Moreover, the RCS was significantly negatively correlated with
root respiration but significantly positively correlated with total root
length and leaf water potential (p < 0.05).
Indole-3-acetic acid (IAA) content increased, while abscisic acid (ABA)
content decreased as the RCS increased. In summary,
endogenous
hormones regulated the occurrence of RCS, which reduced the root
metabolic costs and seemingly achieved more resource redistribution to
new roots, thereby expanding the water absorption capacity of roots to
fully utilize deep water resources. Thus, the study demonstrates the
potential of RCS in improving the drought stress tolerance of cotton.
KEYWORDS:Root
cortical
senescence,
Cotton, Drought tolerant, Root metabolic costs