菹草石芽萌发及幼苗生长对光、温因子的响应

Responses of Potamogeton crispus to Light and Temperature in Turion Germination and Seedling Growth

试验分冬夏2季进行。冬季采用盆栽试验方法,研究了菹草石芽在弱光环境下的萌发和幼苗生长以及弱光对菹草叶片光合效率的影响。冬季试验共设6个光照处理,即:2×104～5×104(对照,晴天中午最大[光]照度)、350～450、160～260、60～80、30～50、0～30lx,试验时间为67d。夏季试验在光照培养箱内进行,研究高温条件下石芽萌发的[光]照度阈值。夏季试验设6个光照处理,即:1400、970、660、450、160、120lx。结果表明:(1)冬季试验,栽培45d时菹草石芽全部萌发,光照对石芽萌发无显著影响;夏季水温(32±1)℃条件下,石芽萌发的[光]照度阈值为120～160lx,[光]照度达到1400lx,石芽就能够达到自然萌发率。(2)菹草幼苗生长前期,5个弱光处理菹草株高生长速率(约1.20cm.d-1)快于光照较充足的对照(0.92cm.d-1);幼苗生长后期,对照菹草生长速率(3.15cm.d-1)快于5个弱光处理菹草生长速率(1.09cm.d-1),且各处理叶片数并未随株高的增加而增加。(3)冬季试验,菹草石芽萌发后的第39天,对照及各处理菹草幼苗的PSⅡ最大光化学效率(Fv/Fm)、PSⅡ光量子产量(ΦPSⅡ)、光化学淬灭系数(qp)随着[光]照度的减弱而下降,弱光对菹草幼苗光系统Ⅱ(PSⅡ)产生显著影响;非光化学淬灭系数(qn)随[光]照度的减弱而增加,对菹草幼苗叶片PSⅡ有一定的保护作用。(4)从快速光响应曲线可以看出,长期光照不足导致菹草植株的光响应能力显著降低。

Responses of Potamogeton crispus in turion germination,seedling growth and leaf photosynthesis efficiency were studied in 2 pot culture experiments. The winter experiment had six treatments with controlled light,i, e. 2 × 10^4-5 × 10^4 （ CK, maximum light intensity at noon） ,350-450,160-260,60-80,30-50, and 0-30 lx, and lasted 67 days from January 20th to March 28th of 2007. And the summer experiment was carried out in a light incubator, also with six treatments, various in light intensity, that is, 1 400,970,660,450,160 and 120 lx ,to study light threshold of turion germination under high water temperature in summer was studied. Results show that （ 1 ） light intensity had no significant effects on turion germination, which completed on D45 in the winter experiment, while in the summer experiment, light intensity threshold was found to be in the range of 120 -160 lx, and over 90% of the turion germinated under the light intensity of 1 400 lx;（2） at the early growth stage, the P. crispus seedlings displayed a higher growth rate（ about 1.20 cm . d^-1 ）in the 5 treatments than in CK（0.92 cm . d^-1） ,and a reverse trend at the late growth stage,that is,about 1.09 cm . d^-1 in the treatments and 3.15 cm . d^-1 in CK,and moreovcr,the number of leaves of the seedlings in the treatments did not increase with the growth of P. crispus in plant height ; （ 3 ） in the winter experiment, beginning on the 39th day after the germinalion, maximal photochemical efficiency of PS Ⅱ （ Fv/Fm ） ,quantum yield of PS Ⅱ （ ФPS Ⅱ ） and photochemical quenching（qp ） of the plants declined with decreasing light intensity, and the effect of dim light on PS Ⅱ of P. crispus was significant,whereas, non-photoc, hemical quenching（pn ）increased, protecting PS Ⅱ of P. crispus leaves;and （4）hmg-term exposure to dim light seriously affected the light corresponding capacity of the seedlings.