1994 Volume 63 Issue 3 Pages 418-422
Effects of soil water stress on root development of winter wheat seedling was studied with special reference to elongation and branching of seminal roots. Japanese wheat variety Norin 61 was planted in acrylic tubes (diameter : 26 mm, length : 1 m) which were filled with gardening soil. Soil water content was adjusted to 30% for W plot and 20% for D plot at the beginning of the experiment, and irrigation was withheld afterward. Plants were grown under controlled conditions (day length: 14 hours, day temperature : 25°C, night temperature : 20°C, illumination : 10, 000 lux) and were sampled for 1 month at intervals. In D plot, the rate of leaf emergence was slower compared with W plot, whereas the root/shoot ratio was remarkably higher in D plot. The number of seminal roots was almost the same for both plots. Although W plot had more nodal roots, they were quite short. These facts suggested that the difference in root dry weight between the two plots was due to that of seminal root system development. Detailed examinations on the primary seminal root of the two plots showed that soil water stress first inhibited elongation of the main axis, then promoted the production of first-order lateral roots per main axis, and finally increased the average length of lateral roots. These sequential responses in root morphology to soil drying resulted in more-developed branching of primary seminal root in D plot.
