The Role of Roots in Different Depth on Water Absorption of Potato

以两个不同根重的马铃薯品种为试材，在灌溉和旱作条件下，研究了马铃薯生长过程中不同深度吸水率的变化，土壤水分状况对根系发育的影响，以及品种间根重差异与蒸腾速率、叶片生长和总干物质生产的关系。此外，本研究还对两个品种的四个嫁接组合进行了比较。在旱地，土壤水分从浅层向下逐步吸收，最后从150 cm处开始吸收。两个品种在20 cm以上深度的根长，旱地均大于水浇地。虽然两个小区根长的品种顺序是一致的，但灌溉小区0-20 cm土层的品种差异较大，而不灌溉小区的20-70 cm土层差异较大。在旱地，两个品种的叶片生长、蒸腾速率和光合速率都受到严重抑制。然而，根长较小的Konafubuki比根长较大的Norin 1的凹陷程度更大。土壤干旱对Konafubuki块茎产量的影响也大于Norin 1号。在嫁接植株中，砧木基因型主要影响两个地块的根系生长和旱地地上部和块茎生长的抑制程度。我们认为，两个品种之间根系生长的差异主要是由于根和块茎干物质分配的内在特性，并与耐旱性相对应。

Two potato varieties with different root mass were examined in the irrigated and unirrigated fields with rain shelters to investigate the changes in water absorption at different depth during the growth, the effect of soil water condition on root development, and the relationship of varietal difference in root mass with transpiration rate, leaf growth and total dry matter production. Additionally four combinations of grafting plants produced with the two varieties were also compared in the present study.At the unirrigated plot the soil water was absorbed stepwise from the shallow depth downward and finally from the depth of 150 cm. The root length in the depth deeper than 20 cm was greater at the unirrigated plot than at the irrigated plot in both varieties. Although the varietal order in root length was consistent at both plots, the varietal difference was larger in the depth of 0-20 cm at the irrigated plot, while in the depth of 20-70 cm at the unirrigated plot. The leaf growth, transpiration rate and photosynthetic rate were severely depressed at the unirrigated plot in both varieties. The extent of the depressions, however, was greater in Konafubuki of smaller root length than in Norin 1 of larger root length. The depression of dry tuber yield by soil dryness was also greater in Konafubuki than in Norin 1. In the grafting plants, the stock genotypes mainly influenced the root growth at both plots and the extent of depressions in shoot and tuber growth at the unirrigated plot.We concluded that the difference in root growth between the two varieties was mainly due to the inherent characteristic in the dry matter partition between root and tuber, and corresponded to the drought tolerance.