摘要:
通过盆栽控水试验,采用Li-6400 便携式光合仪测定光合速率、蒸腾速率,采用称重法测定耗水量,同步测定
气象因子,对比研究了不同土壤水分梯度对油茶苗木气体交换及耗水规律的影响。结果表明:W1(田间持水量
(FC)的95%~100%)、W2(FC 的80% ~ 85%)、W3(FC 的65% ~ 70%)梯度下,试验期间晴天苗木的光合速率
(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、耗水量(Wc)日变化都呈单峰曲线,Pn和Gs的峰值出现在10:0012:00 间,大
小排序为W2 W1 W3,而Tr和Wc的峰值出现在12:0014:00 间,大小排序为W1 W2 W3;W4(FC 的45% ~
55%)的Pn、Tr、Gs、Wc大幅降低且日变化较平缓,土壤水分限制其正常生长;苗木潜在水分利用效率在W4 条件下
显著降低。不同土壤水分条件下,W2 为适宜油茶生长的水分条件,而W3 条件下苗木的生产力已有下降;在水分
充足条件下苗木的最大耗水速率为153.7 g/(m2h),日平均耗水速率85.3 g/(m2h);苗木的耗水受天气条件和土
壤含水量共同影响,土壤含水量从高到低渐变中,苗木的气体交换、耗水指标并没有均匀降低,应是受到土壤水分
有效性降低或生长阻滞湿度拐点的影响。
关键词:
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油茶
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水分梯度
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蒸腾速率
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光合速率
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耗水量
Abstract:
The effects of soil water availability on gas exchange characteristics and water consumption of
seedlings of Camellia oleifera were analyzed, including the influence of different soil moisture gradients
and weather conditions. Photosynthetic characteristics, water consumption and environmental factors
related to the growth of seedlings were measured in the field with a Li-6400 portable photosynthesis
system, an electronic balance and a Hobo Weather Station in Hunan Province of southern China. Four
soil water gradients were analyzed, i. e. W1 (soil moisture content was set at 95% - 100% of field
capacity (FC)), W2 (80% -85% of FC), W3 (65% -70% of FC) and W4 (45% -55% of FC);
for each of these four treatments, we measured the diurnal courses of stomatal conductance (Gs ), net
photosynthetic rate (Pn ), and transpiration (Tr ). Gs, Pn and Tr were graphed and showed unimodal
curves. Pn and Gs peaked in 10:00 to 12:00, and Tr and water consumption peaked in 12:00 to 14:00.
During the study period, Pn and Gs for each treatment were W2 W1 W3 W4. Under the W4
treatment, Pn, Gs, and water consumption reduced greatly, the peaks of above were lower than observed
in the other treatments with more soil moisture, and low soil moisture in W4 prevented the natural growth
of seedlings. Intrinsic water use efficiency decreased significantly during the W4 treatment. Our results
indicated that the W2 treatment was more suitable for seedling growth because seedling productivity was
greater under W2 than under W3 conditions. The maximum water consumption rate of seedling leaves was
153.7 g/(m2hour) and their average daily water consumption rate was 85.3 g/(m2hour) with adequate
water. Weather conditions and soil moisture had a combined effect on the water consumption of seedlings.
When soil moisture changed from high to low, water consumption of unit leaf area decreased unevenly,
and its diurnal course became flat, which may be a result of the reduction of soil water availability or
existence of a critical moisture point, which limits the seedling growth.
百度学术
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