Effect of different constant soil moisture levels on foliage development in maize

The effects of constant soil moisture levels of 90, 60 and 40% of the maximum capillary capacity, applied beginning from the planting of the germinated kernels, on the dynamics of the foliage development of maize was studied in relation to ontogenical changes in leaf area of individual leaves. There were two maxima in the growth of total leaf area (characterized by leaf area duration and loaf area relative growth rate) unrelated to the soil mositure. The first maximum which was less marked, appeared in the phase of 5–8 leaves, the second and main increase being observed before flowering in the phase of 10–12 leaves. The effects of continued decrease in soil moisture were a correspondingly progressive reduction in leaf area and delayed development of the whole plants. Plants with 60% soil moisture attained the same leaf area as those with 90% but only after the end of the vegetative phase. The greatest differences in rate of development between watering treatments appeared at the time of greatest increase in leaf area of control plants. Continued decrease in soil moisture markedly affected the development of the leaves at different insertion levels (especially in elder leaves). Clear-cut prolongation of ontogenesis took place under dry conditions. In conditions of higher soil moisture growth was rather limited or stopped after reaching a certain maximum.