| The mechanism and effect of the new water-saving methodę¢'ontolled roots-divided alternative irrigation on maize nutrient uptake were studied in this paper. The treatments consist of controlled fixed irrigation for half part of root zone (CFI), controlled alternate irrigation for half part of root zone (CAl) and conventional irrigation for whole root zone (Cl) . Two experiments were carried out in pots containing soil. In the first experiment, CI was irrigated for total amount of water (w), but CAl and CFI only half amount of water (w/2); but in the second experiment, the irrigation amount was w for three treatments during the period of irrigation experiment. Main experiment results were shown as followed: With the developing of maize, the photosynthetic rate (P11) of CAl was increased, but that of CFI and Cl tended to decrease. At the later jointing stage. P,, in CAl treatment was increased by 65.0% and 5 1.7% compare with CFI and Cl. Leaf stomata! conductance (Cs) of CAl was lower than that of CFI and CI. At ear pregnant stage, stomata! conductance (C5) of CAl was reduced by 51% and 71% compared with CFI and CI. During whole experiment, transpiration rate (TR) of CAl was lower than that of CFI and CI, reduced by 15%-I 10.7% and 5.1%-78.4% compared with CFI and Cl, respectively. The above-mentioned results were shown that CAl inhibited TR effectively and stimulated photosynthesis. Because of corn in CFI treatment under water stress condition, P,, limitation was mainly controlled by non-stomatal factors, thus reduced photosynthetic activity. Root length and density of CAT was higher than CFI and CI. Root length and density of two root zones of CAl did not show any difference, but that of two root zones of CFI tended to show significant difference as maize growing. At the later jointing stage, compared with CFI and CI, root numbers of CAl were increased by 36.3% and 50%. Thus, by alternate irrigation for root zone, root growth was stimulated and root was distributed evenly in both root zones in CAl. While in CFI treatment, root growth was inhibited by water stress in drying root zone, even part of root dead in the end of development, therefore CFI method is unfavorable to root growth. At ear pregnant period, plant leaf area of CAl was greater than that of CI and CFI, the relative increment were 58.1% and 13.5%, respectively. In CAl treatment, leaf growth rate was far greater, but dead leaves are lower compared with CFI and Cl treatments. Plant height of CAl was higher than that of CFI and CI. The distribution of photosynthetic products between roots and shoots was changed by water method treatments. From jointing stage to ear pregnant stage, root biomass and shoot biomass in CAT, CFI and CI were increased by 67.0% and 81.2%, 57.9% and 74.6%, 47.4% and 80.6%, respectively. The above-mentioned result suggested the photosynthetic product of CAl be transported to shoot more than roots compared with other treatments. Since root growth in CFI was under stress condition, shoot growth was limited. In CI treatment because hardened soil had effect on root growth, therefore, the photosynthetic product transported to shoot was reduced. Root activity of CAl was significantly higher than that of dry root zones of CFI and CI. And root hydraulic conductance of CAl increased more than that of CFI and CI, thus, CAL treatment is beneficial to water and nutrient absorption. Leaf proline content in CAl was less than in CFI, with reduction of 26.7%-38.I%, which suggest corn suffer stronger water stress in CFI treatment than in CAl. There... |
PDF Full Text Request