Effect of Water Deficit during Grain Filling on the Pattern of Maize Kernel Growth and Development1
- S. Ouattar,
- R. J. Jones and
- R. K. Crookston2
There are distinct phases of grain development in maize (Zea mays L.). Little has been reported on the relative effects of water deficits during the different phases of maize kernel development. Since endosperm cell number is important in determining sink capacity or strength, a water deficit during the lag phase may affect kernel development differently than one during the linear phase dominated by starch deposition. The objective of this research was to determine the effect of short- and long-term water deficit, imposed during different phases of grain filling, on the pattern of maize kernel growth. We conducted two separate experiments. In the first, a short-term (10 day) water deficit was imposed during endosperm cell division (the lag phase) or during the period of rapid starch deposition (the linear-filling phase). In the second, a water deficit was initiated during the same phases, but extended until maturity. Plants were grown outdoors in Rabat, Morocco, in large pots arranged to achieve a stand density of 50 000 plants/ha. Short-term water deficit during the lag phase resulted in a significant but transient delay in the accumulation of kernel dry mass. However, recovery from this delay was such that overall rate and duration of kernel growth were not affected. Similarly, short-term water deficit during the linear-filling phase had no effect on the rate or duration of kernel growth. When the long-term water deficit treatment was initiated during the lag phase, kernel growth rate was not affected for approximately 24 days. Grain filling then terminated prematurely, resulting in a significant decrease in the duration of the grain-filling period, and a 50% decrease in final kernel weight. When long-term stress was imposed during the linear-filling phase, kernel growth was not affected for 20 days, but then terminated abruptly, resulting in an 8-day decrease in the grain-filling period. Final kernel weight was not significantly decreased, however. Our results show that kernel growth is more sensitive to water deficits during endosperm cell division than during the period of rapid starch deposition. The higher sensitivity to water deficits during the lag phase was not a consequence of either a lack of carbohydrate availability to the grain, or an inhibition of starch synthesis, but was apparently due to an inhibition of endosperm cell division and the subsequent establishment of kernel sink capacity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © . .