莱州海涂海水灌溉下菊芋生理生态特性研究

PHYSIOLOGICAL CHARACTERISTICS OF HELIANTHUS TUBEROSUS IRRIGATED BY SEAWATER, LAIZHOU COAST, SHANDONG PROVINCE

在山东莱州对菊芋(Helianthustuberosus)进行了海水灌溉浓度及其灌溉次数的田间试验,结果表明:1)灌溉1次的处理中,全淡水同海淡水比例为1∶9、1∶4、1∶3的3种处理的菊芋块茎产量(鲜重)没有显著差异;菊芋生长中灌溉2次,以海淡水比例为1∶3处理的菊芋块茎产量最高,但各处理间菊芋块茎产量差异没有达到显著水平;无论何种比例海淡水灌溉,在莱州湾,灌溉两次菊芋块茎产量显著高于灌溉1次;2 )灌溉处理后连续5天内,菊芋光合速率与土壤表层盐分动态变化趋势一致:第一、二天,1∶9比例海淡水灌溉菊芋光合速率显著高于其它处理,而1∶4、1∶3比例海淡水处理在前二、三天光合速率同全淡水灌溉处理基本没有差异,第五天时,海淡水比例为1∶3的处理,菊芋光合速率显著低于其它处理;在灌溉后盐分变化达到平稳的较长时间内,土壤水分含量成为影响菊芋光合速率的主导因子,1∶3处理因土壤表层土壤水吸力较低而菊芋光合速率显著高于其它处理;3)第一次灌溉6 0d后,以全淡水灌溉处理菊芋的叶面积指数显著高于其它处理,1∶3处理显著低于其它处理,1∶9、1∶4两处理间没有差异。

Salt stress to plants results from both osmotic stress, due to low water potentials, and direct salt-ion injury. Salt-tolerant mechanisms of plants are mainly ion compartmentalization, osmoregulation and metabolic changes. In the past, Sigle-salt experiments were usually conducted to study salt-tolerance in plants; however, experimental results were often contradicted to field observations. To better simulate actual field conditions, we conducted a laboratory experiment to study the physiological characteristics of salt-tolerance in Helianthus tuberosus using natural seawater. Potted plants of H. tuberosus were irrigated with seawater taken from the Laizhou coast, Shandong Province, China in 2000, and diluted with freshwater at the following ratios: 0∶1 (Pure freshwater), 1∶9, 1∶4 and 1∶3. The results showed that at the end of the growing period, the yield of fresh tuber in all treatments was the same following one irrigation treatment period. However, following two irrigation treatment periods, the tuber yield in the 1∶3 treatment was much higher than in the other treatments whereas the other treatments were similar. When H. tuberosus was treated with two irrigation treatment periods, the tuber yield was greater in all saltwater treatments than in the single irrigation treatment. The photosynthetic rate of H. tuberosus was consistent with changes in the salt concentration of the surface soil. On the first or second day after irrigation, the photosynthetic rate of H. tuberosus in the controls was much higher than other treatments while there was nearly no difference in rates among treatments except for the 1∶3 treatment that had lower photosynthetic rate. After sixty days of irrigation, the greatest leaf area index (LAI) was achieved in plants irrigated with pure freshwater, LAI was the lowest in plants in the most saline treatment (1∶3 seawater:freshwater), and similar in the other two treatments.