局部水分胁迫对玉米根系生长的影响

采用分根法进行玉米水培试验, 研究局部水分胁迫对玉米根系生长的影响。设4个水分胁迫水平: CK, 0.2 MPa, 0.4 MPa, 0.6 MPa, 在整个根系经受一定的水分胁迫之后对部分根系复水处理, 测定局部供应后 0 h、6 h、12 h、1 d、3 d、5 d、7 d、9 d等不同时期各部分根系的面积、长度及干重。结果表明, 各胁迫程度均表现为, 与对照相比, 复水侧根区的根系面积、根长与根干重出现了明显增长, 且始终显著大于持续胁迫侧根区, 且随处理时间延长更加明显。不同胁迫程度下复水侧玉米根系的增长幅度不同。水分胁迫预处理后, 0.2 MPa水平下, 复水侧根区根系的面积、长度与干重以及整个根区总根长、总面积均可以达到甚至高于对照水平, 其他处理均显著低于对照。轻度胁迫后复水的根区根系产生明显的补偿效应。适度胁迫后复水有利于作物根系总面积增长, 但对总根长、根干重无显著影响。根系补偿效应与胁迫强度及复水的时间有关。

Effect of partial root-zone drought stress on root growth of maize

The effects of partial root-zone drought stress on root growth in maize were studied in split-root and solution culture experiments. Sub-root samples were scanned for root length and area using CI-400 computer image analysis system (CID Ltd, USA). Maize plants were subjected to water stress by regulating the osmotic potential of the solution using polyethylene glycol (PEG-6000) in the experiment. Water was supplied at four levels - CK (sufficient water supply), 0.2 MPa (low water stress), 0.4 MPa (medium water stress) and 0.6 MPa (high water stress) for 6 days. After that, the roots were divided into two parts, one part was re-watered, and the other part was imposed continuously four water supply levels - over eight time periods - 0 h, 6 h, 12 h, 1 d, 3 d, 5 d, 7 d and 9 d. Compared with CK, growth of the re-watered roots part significantly increased after drought stress. While the re-watered half was larger than the stressed half of the root, the total root length was not significantly different under different water stress treatments. The increasing strength of the re-watered half of the root at the four different levels was different. The order of strength for the treatments was CK > 0.2 MPa > 0.4 MPa > 0.6 MPa. After preprocessing stage of total root osmotic stress, both sides of the root showed signs of water stress. Root length, area and dry weight in the re-watered root-zone and total root length and area of plant in the 0.2 MPa treatment were either close to or higher than the control treatment. Water absorption of the root system was influenced by re-watering after root-zone drought stress, which was compensated for root growth. Appropriate drought stress increased root area, but did not significantly increase total root length and dry root weight. Under the experimental conditions, the compensation effects of maize root system were related to the degree and time of drought stress.