根系分区交替供水对玉米养分吸收影响的机理与效应

【作者】 韩艳丽；

【导师】 康绍忠；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2001， 硕士

【摘要】 本文研究新型的节水灌溉技术—根系分区交替灌水对玉米养分吸收影响的机理与效应。以玉米为材料进行了两次试验，设计3种灌水方式：（1）常规灌水方式（对照），每次对盆内全部土壤均匀灌水；（2）固定灌水方式，每次固定1/2区域的土壤灌水；（3）交替灌水方式，每次交替1/2区域土壤灌水。第1次试验每次灌水量，常规灌水方式为w，而固定灌水方式与交替灌水方式则为w/2；第2次试验每次灌水量，常规、固定、交替灌水方式均为w。主要试验结果如下： （1）光合速率、气孔导度和蒸腾速率等结果表明，随着处理时间延长，交替方式的光合速率逐渐增加，而固定与常规灌水方式的光合速率呈减少趋势，到拔节后期，交替方式比其他两种方式增加65.0％和51.7％。交替灌水方式气孔导度比常规和固定方式低，到孕穗期，交替灌水气孔导度低于固定及常规方式51％和71％。交替灌水整个生育期叶片蒸腾速率都比固定、常规方式低，分别降低15％-110.7％和5.1％-78.4％，这表明交替方式可有效抑制蒸腾而使光合作用维持较高水平。固定方式受到水分胁迫相对严重，非气孔因素对光合限制占比例更大，导致光合器官的光合活性降低。 （2）交替灌水方式的总根长和根长密度均大于其它两种灌水方式。交替灌水两区域总根长、根密度差异不大，但固定灌水干湿两区域随处理时间延长，差异有增大趋势。苗期3个处理根条数基本相同；拔节后期交替处理比常规的根条数增加36.3％，比固定增加50％。交替灌水方式两个区域根条数相差2条，固定灌水方式相差了6条。交替处理经过干湿交替灌水，刺激了根系生长，促进根系下扎，两个区域根系分布比较均匀；而固定方式干燥区域抑制了根系生长，甚至后期由于水分胁迫严重导致部分根系死亡，不利于根系的生长。 （4）孕穗期交替方式叶面积比固定方式增加58.1％，比常规方式增加13.5％。交替方式新叶发生速率明显大于其它两种方式，而枯叶数目明显减少。各个生育时期交替灌水处理株高均比常规方式和固定方式高，平均高2.8-4.3cm。 （5）不同灌水方式改变了光合产物在根冠之间的分配。从拔节前期到孕穗期，交替方式根重增加67.0％，而冠重增加81.2％；固定方式根重增加57.9％，冠重增加74.6％；常规方式根重增加47.4％，冠重增加80.6％。表明交替方式有利于光合产物向地上部分的运输，而固定方式遭受水分胁迫，对根系生长造成伤害，导致根生长一直较弱，由此抑制了冠部生长。常规灌水方式下由于土壤板结对根系生长产生机械阻力，从而影响冠层生长。 （6）交替方式与固定方式湿润根区相比，根系活力稍高一些，两者相差不大；与固定方式干燥区域相比，根系活力明显增加，大约提高30％—98％。交替方式根系活力均比常规灌高，上述结果表明交替方式增加根系活力，有助于很系吸收衣分和养分。此外，交替方式根系传导度明显高于固定方式和充分灌水的常规方式。 （）交替处理与固定方式相比，1lljlt脯氨已含量降低 26．7％－38．1％，表明固定方式水分亏缺程度相对较重，而交替灌水使作物水分条件得到改善，能够维持作物的生长需求，有利于维持细胞膨压和细胞正常延伸生长。叶片硝酸还原酶在前月各处理间无差异，到抽雄期，交替方式叶片硝酸还原酶活性增加57．4％，而固定方式却降低15％，孕穗期交替方式分别高于固定、常规方式121刀％和23．5％，从而保持较高的硝酸还原酶活性，利于甫态氮转化和植株吸收。 （8）固定方式根系N、P吸收量比其‘占两种方式都低。第1次结果表明拔节前期交替方式地上部N吸收量比固定和常规方式高；地上部P吸收量在苗期表现出交替方式比常规方式低。第2次结果表明各生育时期交替方式地上部N吸收量比其它两种方式都高，拔节后期以后交替方式地上部P吸收量比固定方式、常规方式都高。 （9）第互次结果表明拔节前期交替方式N吸收总量比固定和常规方式高；交替方式P吸收总量均比其它两种方式高。第2次结果是拔节前期交替方式N吸收总量比固定方式高，和常规方式相差不大，而到生育后期比固定和常规方式都高：拔节后期以后交替方式P吸收总量比固定方式、常规方式都高。试验结果还表明，生育后‘田交替方式更有利于氮、磷向地上部分转移，固定方式氮素向地上部分转移相对减少，而常规方式磷素向地上部转移减少。 （10）3种灌水方式耗水量有明显的差异，交替灌水比常规灌水节水 10．26％－27．6％。交替方式在整个生育期叶片水分利用效率逐渐增加，拔节后期交替方式水分利用效率比同期固定与常规方式增加 41．3％和 29．7％。孕穗期交替方式水分利用效率比同期固定与常规方式增加 70．5％和 53．6％。交替灌水方式群体水分利用效率最高，卜匕常规灌水方式提高5．8％－20．l％。 （11）交替灌水方式比常规灌水方式的氮利用效率提高 4．76％－25．1％，磷利用效率提高4．79％一25．3％。更多还原

【Abstract】 The mechanism and effect of the new water-saving method梒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更多还原