根区不同灌溉方式对苹果幼苗水流阻力的影响

研究了滴灌条件下根区不同灌溉方式（交替滴灌ADI、固定滴灌FDI和常规滴灌CDI）和灌水量对苹果幼苗及各组成部分水流阻力、气孔导度和叶面积的影响.结果表明：根区灌溉方式和灌水量对苹果幼苗水流阻力（R）的影响显著; 在相同的根区灌溉方式下，苹果幼苗根系阻力（R_r）随着灌水量的减少而增大，冠层阻力（R_s）随着灌水量的减少而减小.在相同灌水量下，与常规滴灌相比，交替滴灌和固定滴灌均提高了苹果幼苗叶片和叶柄阻力（R_l+p），降低了幼苗全株阻力（R_t）、R_r、R_s以及侧枝和主杆阻力（R_lb+mr）.在20 mm和30 mm灌水定额下，交替滴灌的R_l+p分别比常规滴灌高1.06%和0.63%.在平均节水达33%的前提下，交替滴灌和固定滴灌的平均R_l+p分别比常规滴灌高19.65%和24.34%，但交替滴灌和固定滴灌的平均R_lb+mr分别降低了4.83%和14.97%.交替滴灌和固定滴灌等局部根区不同灌溉方式通过有效减小苹果气孔导度和叶面积，提高了R_l+p，从而减少了叶片的蒸腾失水，提高了苹果幼苗的水分利用效率，通过降低R_r和R_lb+mr提高了苹果幼苗调控水分的能力和抗干旱能力.

Effects of different root zone irrigation modes on apple seedlings hydraulic resistance.

This paper studied the effects of different root zone irrigation modes (alternate partial drip irrigation, ADI; fixed partial drip irrigation, FDI; and conventional drip irrigation, CDI) and their watering amount on the whole-plant and its components hydraulic resistance and the stomata conductance and leaf area of apple seedlings. The results showed that both the irrigation mode and the watering amount had significant effects on the apple seedlings hydraulic resistance (R). Under the same irrigation modes, the root resistance (Rr) of apple seedlings was increased, but the shoot resistance (Rs) was decreased with decreasing watering amount; and under the same watering amounts, ADI and FDI increased the leaf and petiole resistance (Rl+p), but decreased the whole-plant resistance (Rt), Rr, Rs, and lateral branch and master rod resistance (Rlb+mr), compared with CDI. Under the irrigation quota of 20 mm and 30 mm, the Rl+p of ADI was 106% and 063% higher than that of CDI, respectively; and with the prerequisite of saving 33% of irrigation water, the average Rl+p of ADI and FDI was increased by 1965% and 2434%, while the average Rlb+mr was decreased by 483% and 1497%, respectively, compared with those of CDI. ADI and FDI effectively decreased stomata conductance and leaf area and increased Rl+p, and thus, decreased leaf blade luxurious transpiration dehydration while increased plant water use efficiency. By decreasing Rr and Rlb+mr, the ADI and FDI improved apple seedlings water regulation function and drought-resistant capability.