黄河故道不同灌水方式刺槐人工林幼树水分利用效率和生长特性

干旱一直是限制黄河故道沙区树木生长的重要因素之一,而刺槐(Robinia pseudoacacia)以其较强的耐旱性、较高的成活率在造林时备受重视。适宜的灌水方式不但可以提高当地水资源的高效利用,而且可以促进刺槐迅速生长,改善当地环境生态。因此,在2011至2012年间,对黄河故道沙地进行刺槐人工林的建设与培育,开展滴灌(DI)、沟灌(FI)和软管喷灌(HSI)3种灌水方式对刺槐人工林幼树水分利用效率(WUE)和生长特性影响的研究。结果表明,在不同的水文年份,滴灌刺槐的净光合速率(Pn)、蒸腾速率(Tr)高于软管喷灌,软管喷灌高于沟灌。水分利用效率受年份影响较大,但均表现为前期下降,8月份前后降到最低值,随后缓慢回升。不同灌水方式叶绿素含量(CC)差异显著,滴灌条件下刺槐叶绿素含量最高,其次为软管喷灌,沟灌最低。不同树龄,不同灌水方式刺槐株高、地径和胸径差异显著。一年生林,滴灌刺槐的株高、地径和胸径分别比软管喷灌高出23.4、0.27 cm和0.14 cm;二年生林,滴灌刺槐的株高、地径和胸径分别比软管喷灌高53.7 cm、0.61 cm和0.54 cm。滴灌刺槐的株高、地径和胸径的年度生长量分别为软管喷灌的112.1%、107.1%和111.8%,同时分别为沟灌的121.8%、191.8%和343.6%。不同灌水方式刺槐幼树水分利用效率受年际间气象因素影响较大,滴灌可以显著地改善刺槐幼树的光合生理特性,促进其快速生长。

Water use efficiency and growth characteristics of young trees of Robinia pseudoacacia plantation forest under different irrigation methods in old course of Yellow river area

Drought is one of the important factors that limits the growth of trees in the sand of old course of Yellow river area, so the black locust (Robinia pseudoacacia) has been getting attention in the last several years, for its stronger drought resistance and higher survival rate in forestation. Appropriate irrigation methods not only can promote the efficient utilization of local water resource and the growth of plants quickly, but also improve the local ecological environment. This project was held in 2012 and 2013 years, in order to find the optimal irrigation method for black locust young trees. Plants were subjected to three irrigation methods: drip irrigation (DI), furrow irrigation (FI) and hose sprinkler irrigation (HSI). The plot area of each treatment was 1334 m², and the plant spacing was 3 m×4 m. The results showed that in different hydrological years, the net photosynthetic rate (Pn) and transpiration rate (Tr) of plants under DI both higher than that under HSI, as well as that under HSI than FI. Water use efficiency (WUE) was greatly influenced by the different hydrological years, characterized by early fall, down to the lowest in August and then slowly rose again. There were significant differences in the chlorophyll content (CC) of young trees between different treatments. The CC of plants under DI was highest, followed by which under HSI, and which under FI was minimal. For different ages, there were significant differences in plant height, ground diameter and diameter breast height of young trees between different irrigation methods. In 2011, the plant height, ground diameter and diameter breast height of young trees under DI were 23.4 cm, 0.27 cm and 0.14 cm higher than that under HSI, respectively. In 2012, the plant height, ground diameter and diameter breast height of young trees under DI were 53.7 cm, 0.61 cm and 0.54 cm separately higher than that under HSI. The annual growth of plant height, ground diameter and diameter breast height of young trees under DI were 112.1%, 107.1% and 111.8% of that under HSI, at the same time were 121.8%, 191.8% and 343.6% of that under FI, respectively. The WUE of young trees under different irrigation methods was greatly influenced by the meteorological factors of different years. DI can significantly improve photosynthetic physiological characteristics of black locust sapling, and promote the rapid growth of them.