Kenefick Donald G, Koepke James A, Sutton Fedora
Abiotic Stress Laboratory, Plant Science Department, College of Agriculture and Biological Sciences, South Dakota State University, Brookings, SD, USA.
BMC Plant Biol. 2002 Sep 26;2:8. doi: 10.1186/1471-2229-2-8.
Hard red winter wheat (HRWW; Triticum aestivm L.) plants from genotypes selected in the Northern Great Plains of the U.S. have less tissue water after exposure to cool autumn temperatures than plants from the Southern Great Plains. It is generally assumed that the reduced tissue water content of northern compared to southern cultivars is due to an impedance to water uptake by northern plants as a result of the low autumn temperatures. We hypothesize that if low temperature impedes water uptake then less soil water would be removed by northern than by southern-selected cultivars. This hypothesis was tested by comparing plant water uptake of a northern (FR) and a southern (FS) cultivar in relation to their foliage water content at 2 degrees C.
At 2 degrees C foliage water content of FR plants decreased more rapidly than that of FS plants, similar to field results in the fall. During 6 wk, foliage water content of FR plants decreased 20 to 25% of the pre-treatment value, compared to only 5 to 10% by FS plants. Plant water uptake was about 60 g H2Og FDW(-1) by FS plants, while FR plants maintained plant water uptake in excess of 100 g H2Og FDW(-1) during the 6 wk period at 2 degrees C. When four other northern genotypes of equal freeze resistance were studied, foliage water content and plant water uptake change were similar to FR plants.
In these northern-selected HRWW cultivars foliage water content reduction resulting from cold acclimation is not due to impedance to plant water uptake.
在美国大平原北部选择的基因型的硬红冬小麦（HRWW；Triticum aestivm L.）植株，在经历凉爽的秋季温度后，其组织含水量比大平原南部的植株少。一般认为，与南部品种相比，北部品种组织含水量降低是由于秋季低温导致北部植株对水分吸收的阻碍。我们假设，如果低温阻碍水分吸收，那么北部选择的品种比南部选择的品种去除的土壤水分会更少。通过比较北部（FR）和南部（FS）品种在2摄氏度时的植物水分吸收与其叶片含水量，对这一假设进行了检验。
在2摄氏度时，FR植株的叶片含水量比FS植株下降得更快，这与秋季的田间结果相似。在6周内，FR植株的叶片含水量下降了预处理值的20%至25%，而FS植株仅下降了5%至10%。FS植株的植物水分吸收约为60 g H2Og FDW(-1)，而FR植株在2摄氏度的6周期间保持植物水分吸收超过100 g H2Og FDW(-1)。当研究其他四个具有相同抗冻性的北部基因型时，叶片含水量和植物水分吸收变化与FR植株相似。
在这些北部选择的HRWW品种中，冷驯化导致的叶片含水量降低不是由于对植物水分吸收的阻碍。
