2种雀稗属牧草对低磷胁迫的生长、生理应激响应

为比较宽叶雀稗(Paspalum wettsteinii)和巴哈雀稗(Paspalum notatum)适应低磷胁迫的能力,揭示其对低磷胁迫的形态及生理响应机理,试验以石英砂为基质,定期浇灌200 μmol·L^-1(常磷)、20 μmol·L^-1、 2 μmol·L^-1的Hoagland营养液模拟低磷胁迫处理,分别在磷处理10、20、30 d时测定供试材料的幼苗形态及生理特性。结果表明,低磷处理30 d时,2种雀稗属牧草地上部生物量、株高、叶面积、叶长呈降低趋势,根干重、根冠比、总根长、根尖数、根毛数量较常磷处理增加,超氧化物歧化酶(SOD)(除巴哈雀稗)、过氧化物酶(POD)、过氧化氢酶(CAT)、酸性磷酸酶(ACP)活性较常磷处理显著增加(P<0.05),根部电导率、叶片电导率较常磷处理显著提高(P<0.05)。当磷水平降低至2 μmol·L^-1时,宽叶雀稗地上部生物量降幅最大,为41.67%,根冠比、SOD活性增幅最大,分别为86.36%、113.19%;巴哈雀稗叶长降幅最大,为90.43%,根冠比、根毛数量增幅最大,分别为108.47%和74.91%。综上,低磷胁迫抑制了2种雀稗属牧草地上部的生长,促进了地下部的生长,提高了保护酶活性,且宽叶雀稗的低磷适应能力高于巴哈雀稗。本研究为2种雀稗属牧草在低磷环境下的栽培提供了理论依据。

Growth and Physiological Responses of Two Species of Paspalum Forage to Low Phosphorus Stress

In order to compare the tolerance of Paspalum wettsteinii and Paspalum notatum to low phosphorus stress, and reveal their morphological and physiological mechanisms under low phosphorus stress, modified Hoagland nutrient solution 200 μmol·L^-1 (normal-phosphorus), 20 μmol·L^-1 and 2 μmol·L^-1, which were regularly irrigated in a bucket were used to simulate low phosphorus stress treatment with quartz sand as the substrate. The morphology and physiological characteristics of seedlings were measured at 10, 20 and 30d. The results showed that the above-ground biomass, plant height, leaf area, and leaf length of the two Paspalum grass decreased while root dry weight, root shoot ratio, total root length, number of root tips, number of root hairs increased under low-phosphorus treatment for 30 days. The activities of superoxide dismutase (SOD) (except P. notatum), peroxidase (POD), catalase (CAT) and acid phosphatase (ACP) significantly increased compared with normal-phosphorus treatment (P<0.05), and the electrical conductivity of roots and leaves significantly increased (P<0.05) compared with normal-phosphorus treatment. When the phosphorus level was reduced to 2 μmol·L^-1, the above-ground biomass of P. wettsteinii had the largest increase of 41.67%, the root shoot ratio and SOD activity had the largest increase of 86.36% and 113.19%, respectively. The leaf length of P. notatum had the largest decrease of 90.43%, the root shoot ratio and the number of root hair had the largest increase of 108.47% and 74.91%, respectively. In summary, low phosphorus stress inhibited the growth of the upper part of two Paspalum species, promoted the growth of the underground part, and improved the activity of protective enzymes. The P. wettsteinii had better adaptability to phosphorus starvation. The results provide a theoretical basis for the cultivation of two species of Paspalum grasses under low-phosphorus environment.