不同滴灌方式和NaCl处理对苹果幼树生长和水分传导的影响

为了探讨不同滴灌方式和土壤盐分对苹果(Malus pumila)幼树生长和水分传导(简称水分传导K)的影响。采用3种滴灌方式(交替滴灌(ADI, 根区两侧交替灌水)、固定滴灌(FDI, 根区固定一侧灌水)和常规滴灌(CDI, 根区两侧均灌水))和4个NaCl浓度梯度(0 (CK)、0.2% (S₁)、0.3% (S₂)、0.4% (S₃))。结果表明: 滴灌方式和NaCl浓度对苹果幼树生长和水分传导有显著影响。在相同的滴灌处理下, 随着NaCl浓度的增大, 苹果幼树的干物质、叶面积和净生长量及水分传导均显著地下降。根系水分传导(K_r)与总根干重间, 冠层水分传导(K_sh)与冠层干重间均呈显著的线性相关关系。在相同的NaCl处理下, 与CDI处理相比, ADI处理节水达50%, 平均根系干重、冠层干重、总干重、叶面积、净生长量和K_r仅分别下降了8.7%、19.24%、13.47%、11.87%、32.96%和10.72%; 这说明ADI处理对果树的生长和K_r具有明显的促进作用。在高盐分S₂和S₃处理下, ADI处理的叶水分传导(K_l+p)分别降低了33.56%和44.26%, 但ADI处理的K_r反而高出了CDI达1.13%和10.91%, 说明ADI处理增强了苹果幼树根源水力信号的传输效率和调控苹果幼树体内水分平衡的能力及抗盐分胁迫能力。ADI处理的生长状况和K_r均高于FDI。采用ADI处理进行灌溉不仅提高了节水调控能力, 而且也增强了抗盐分胁迫能力。

EFFECTS OF DRIP IRRIGATION MODE AND NaCl CONCENTRATION ON GROWTH AND HYDRAULIC CONDUCTANCE OF APPLE SEEDLINGS

Aims Hydraulic conductance, which is characterized by root water uptake and xylem water transport efficiency, is a physiological response of plants to different environmental factors, such as salt-stress and water deficit. However, there is little research on relationships between different drip irrigation modes and hydraulic conductance. Our objectives were to determine 1) the impact on growth and hydraulic conductance of different drip irrigation modes and salinity treatments and 2) the relationship between apple seedling growth and hydraulic conductance. Methods The experiment used a NaCl concentration gradient of 0 (CK), 0.2% (S1), 0.3% (S2) and 0.4% (S3) and three drip irrigation modes: alternate partial root zone drip irrigation (ADI, alternate watering on both sides of the root zone), fixed partial root zone drip irrigation (FDI, fixed watering on one side of the root zone) and conventional drip irrigation (CDI, simultaneous watering on both sides of the root-zone). Important findings Drip irrigation modes and NaCl concentration significantly affect apple seedling growth and hydraulic conductance. Dry matter, leaf area, net growth and hydraulic conductance of apple seedlings were significantly inversely related to NaCl concentration under the same drip irrigation treatment. Root hydraulic conductance (K_r) was significantly linearly correlated with total root dry weight, shoot hydraulic conductance (K_sh) and shoot dry weight. Under the same NaCl concentration treatment and compared with CDI, ADI had a water savings of up to 50%, but average root dry weight, shoot dry weight, total dry weight, leaf area, plant net growth and root hydraulic conductance of ADI only decreased by 8.7%, 19.24%, 13.47%, 11.87%, 32.96% and 10.72%, respectively, showing that ADI has an obvious promoting effect on apple seedling growth and hydraulic conductance. Compared with CDI, high NaCl concentrations S2 and S3 led to decreases in K_l+p of ADI of 33.56% and 44.26%, respectively, while the K_r of ADI treatment increased by 1.13% and 10.91%, respectively, indicating that the root hydraulic signal transmission efficiency of ADI treated seedlings, the ability of seedlings to regulate water balance and resistance stability to salt-stress could be enhanced. The growth and hydraulic conductance of ADI were all higher than FDI. Use of ADI not only improved water-saving regulation ability, but also strengthened resistance stability to salt-stress.