Foliar application of potassium and soil moisture stress were evaluated
through two successive field experiments during growing seasons of 2001 and 2002
at Giza Agricultural Research Station. A. R. C. To verify this objective. maize ( Zea
mays) • single cross ( S.C.10) cultivar was grown and treated with potassium fertilizer
at concentrations of 0 . 2 and 3 % KzO as foliar application under three conditions of
soil moisture content expressed as depletion in available soil moisture namely wet
(35- 40 %). medium (55 - 60 %) and dry (75 - 80 %), depletion in AS. M. Results of
the combined analysis could be summarized as follows: 1· Plant height and stem diameter of the plant were Significantly increased under wet
treatment followed by those under medium and dry ones. The same parameters
showed gradual and significant increase with raising the concentration of K20 from
o to 3 % . However; the interaction between the two factors was insignificant as
wetl. 2- AU growth parameters i.e, leaf area index (lAl). net assimilation rate (NAR) and
crop growth rate (CGR) at all growth stages were Significantly higher under wet
treatment than those under the other soil moisture stress levets. 3- LAI at all growth stages and NAR at the last period of growth (80-90 days after
sowing, DAS) were significantly increased with the gradual increase of K20 up to
3%. while vice versa was observed at 35·50 DAS. At the period of 65·80 DAS,
NAR was the highest and significant with 2% K20. CGR at all growth stages was
significantly increased with increasmq K20 level. 4· The significant effect of the interaction between moisture stress and K spray was
pronounced for NAR. CGR and LAI at 50-65 and 80·90 and 35-50 DAS periods,
respectively. 5- All yield attributes of maize plant were significantly and gradually increased as a
result of raising the availability of soil moisture content and the level of K20 up to
3%. The exception is shelling% Which didn't affect with spraying K20. However, no
significant effect could be noteced due to the interaction between the two factors
under study on all yield parameters. s-There was gradual and significant increase of maize productivity as a result of the
reduction in soil moisture depletion. The same response was observed for raising
K-Ievel. However. the interaction caused inSignificant effect on grain and stover
yields .. 7- Higher protein content of maize grains was gained under condition or severe in soil
moisture content. Spraying maize plants with water (0% K20) caused the highest
protein content and the interaction between the above two treatments was the
best. Total carbohydrates content of the grains showed a reverse trend for main
and the interaction effects. 9· The highest mean values of water consumptive use during growing season were
recorded when maize plants sprayed with the highest level of K20 (3%) under wet
treatment. Whereas, water use efficiency (kg/m3) reached its highest value at
medium soil moisture stress with potassium nutrition.