Z. Plaut, SENSITIVITY OF CROP PLANTS TO WATER-STRESS AT SPECIFIC DEVELOPMENTAL STAGES - REEVALUATION OF EXPERIMENTAL FINDINGS, Israel journal of plant sciences, 43(2), 1995, pp. 99-111
It has been suggested that in many crops differences in sensitivity to
water stress occur at different growth stages. Since identical amount
s of water may be applied, irrespective of whether a crop is exposed t
o relatively severe and short periods of stress or to extended periods
of mild stress, the responses to such differing conditions should be
compared. Unfortunately, such a comparison has not been conducted in m
ost studies on sensitivity to water stress at different growth stages.
In the present study, based on three field experiments conducted for
different purposes, such a comparison was made for three crops: corn,
sunflower, and tomato. In corn, distinct responses of ear and kernel y
ields to the timing of water stress were found. Withdrawal of irrigati
on water during flowering and cob formation resulted in greater yield
losses than during other stages, indicating that this is a critical gr
owth stage. However, slight and uniform reduction of water during the
entire growth period resulted in significantly less damage to kernel o
r ear production, although the total amount of water applied was simil
ar to that under staged withdrawal. In sunflowers, the withdrawal of i
rrigation water even at noncritical growth stages caused a more marked
reduction in grain yield than did a uniform reduction throughout the
entire season. In tomatoes, on the other hand, the withdrawal of irrig
ation water during specific growth stages caused minimal damage to fru
it and total soluble solids yield as compared with fully irrigated con
trol; reduction of irrigation water throughout the season brought abou
t a significant decrease in yield. The difference between these crops
is interpreted on the basis of the determinance of their floral merist
ems.