火龙果对干旱胁迫的适应性研究

干旱胁迫是影响植物生长和发育的一个重要因子,当植物受到干旱胁迫后,其自身也会作出一些适应性变化。本研究以贵州地区广泛种植的火龙果（Hylocereus undatus）品种‘紫红龙’为试验对象,通过对其茎和根系生长量、茎含水量、气孔运动、叶温变化及叶绿素合成等方面进行研究,并对其抗旱适应性进行评价。结果表明：干旱处理16周,土壤含水量下降到15%（严重缺水）时,火龙果茎中含水量仍有80%（轻度失水）;干旱限制茎伸长和增粗生长,而促进根系萌发和伸长生长;干旱下,气孔开放率、气孔开放度、气孔密度和气孔大小均降低;火龙果新茎比老茎对于气温的升高或者降低更加敏感,而干旱处理的火龙果茎表温度比对照高;随着干旱程度的加深,光合色素显著降低,叶绿素荧光参数发生变化。火龙果茎具有很强的保水能力和耐干旱胁迫能力;干旱下,火龙果的水分优先提供根系促进根生长,维持茎伸长生长,而增粗生长受抑制;在轻度和中度水分胁迫下,火龙果茎光合能力不会明显下降,在重度水分胁迫时才会显著影响其光合效率。

Drought Adaptability of Hylocereus undatus

Drought stress is an important factor affecting plant growth and development. When plants are in drought stress, they also make some changes to adapt to the environment. This study used ‘Zihonglong’ as the experimental material, a variety of pitaya widely planted in guizhou. In order to lay a theoretical foundation for the physiological research of pitaya, the adaptability of pitaya to drought was evaluated by studying its stem and root growth, stem water content, stomatal movement, leaf temperature change and chlorophyll synthesis. The relative water content in the stem of pitaya was slightly decreased (80%) in drought treatment lasted 16 weeks in soil moisture content 15%. The drought treatment significantly promoted the growth and elongation of new roots, but limited stem elongation and crosswise. Under drought treatment, the stomatal open frequency, stomatal apertura, stomatal size, and stomatal density were lower than those in the control. New stems of pitaya were more sensitive to temperature increase or decrease than mature stems, and the stem surface temperature of drought treatment was higher than that of the control. With the degree of drought, the photosynthetic pigments decreased significantly, and the chlorophyll fluorescence parameters changed. The pitaya stem had strong water retention capacity and was highly resistant to drought. Under drought, the water of pitaya fruit was preferred to providing to the root system to promoting root growth, maintaining stem elongation and growth, while crosswise was inhibited. Under mild and moderate water stress, the photosynthetic capacity of the stem of pitaya did not decrease significantly, while under severe water stress, the photosynthetic efficiency was significantly affected.