A field experiment was conducted in sandy soil under drip irrigation at Aly
Mubarak Res. Farm, Nubaria during 2000 and 2001 growing seasons to study the
effect of two water irrigation treatments, i.e. 100 and 50% of the evaporated water
column from the evaporation pan on yield and yield components, growth characters,
relative water content (RWC), and leaf proline content (LPC) of four maize hybrids,
i.e. SC.122 (W), SC.129 (W), SC.155 (Y), and SC.161 (Y). The two water treatments
represent well watered (non-stressed) and water stressed environments. Results
cleared significant differences between the two stress levels for all studied traits
except for ear diameter, No. of rows/ear, and RWC in 2000 growing season, and for
No. of days to mid silking and LPC in 2001 season. Also, significant differences were
found among the four hybrids for all studied traits except for grain yield (both years),
no. of ears/100 plants and RWC in 2001 season. Water stress resulted in 30.3-43.2%
reduction in grain yield in 2000 season, and 11.6-20.0% in 2001 growing season.
Reductions due to water stress in No. of ears/1 00 plants, ear length and diameter,
No. of rows/ear, No. of kernels/row, 100-kernel weight, and plant height were 8.1-
20.8%, 9.1-14.3%, 0.7-4.5%, 1.4-3.7%, 13.1-23.6%, 6.4-12.8%, and 0.2-10.1%,
respectively. RWC of plant leaves was lower under water stress than under normal
irrigation by 5.5, 6.8, and 2.2% at 52, 62, and 90 days growth stage, as an average of
the two years. Considerable changes in LPG occurred in plants under stress at the
three plant growth stages especially at 62 days (flowering stage). LPG increased by
10.7, 41.1, and 19.9% at 52, 62, and 90 days as compared to values under normal
irrigation. RWG and LPG at critical period of plant growth (flowering) may be used as
indicators of drought stress of maize plants, but more investigations are
recommended.