Abstract:
The purpose of this study
was to evaluate the response of four maize
varieties to different simulated watering
regimes in term of proline, starch and
soluble sugar contents as well as relative
water content. Maize seeds were planted in
64 plastic pots of 20 litre capacity, arranged
in a factorial fitted in completely
randomized design (CRD), with four
replications in the screen house of the
Institute of Agricultural Research and
Training (I.A.R&T), Moor Plantation
Ibadan. The watering was done based on the
designated field capacities (FC) of 25, 50,
75 and 100%. Fresh leaf samples were
collected five weeks after planting and at
the end of each stress period. The proline,
soluble sugar, leaf starch and the relative
water contents in the leaves were estimated.
The results obtained showed that watering
regime significantly influenced the leaf
starch, soluble sugar, proline and relative
water contents. The varieties also differ
significantly in the proline, soluble sugar
content, leaf starch and the relative water
contents. Watering regime and variety
interaction was significant for soluble sugar,
starch, proline and the relative water
content. Highest soluble sugar of 1.28 mg/g
and proline of 35.70 μmol/g FW were
obtained when FC was 25% and lowest
when watering level was optimum. The
starch and relative water contents were
optimum under full watering (100% FC)
and lowest when field capacity was 25%.
Variations were observed with regards to
different maize varieties. ART98SW6-OB
accumulated the highest quantity of soluble
sugar and proline under 25 and 50% field
capacities alongside DTESYN, which is a
drought tolerant maize variety. It could be
concluded that water stress increased
production of soluble sugar and proline,
while water availability increases relative
water content and favors starch
accumulation. The consideration of these metabolites alongside other physiological
features is a very fast and reliable method
for drought tolerant plant selection even at
the plant seedling growth stage.
