[Photosynthesis and transpiration characteristics of female and male Trichosanthes kirilowii Maxim individuals].

A field research was conducted on the photosynthesis and transpiration characteristics of dioecious Trichosanthes kirilowii individuals at four key development stages. At vegetative growth stage, the photosynthesis rate, transpiration rate, stomatal conductance, and water use efficiency of male individuals were higher than those of female individuals, and hence, male individuals entered into reproductive growth stage 22 days earlier than female individuals. After entering into reproductive growth stage, male individuals had higher photosynthesis rate, transpiration rate, and stomatal conductance, but slightly lower water use efficiency than female individuals. As the female individuals started to reproductive growth, their photosynthesis rate and water use efficiency were significantly lower, while the transpiration rate and stomatal conductance were higher than those of the male individuals. The effects of climate factors on the growth and development of T. kirilowii mainly occurred at its vegetative growth and early reproductive growth stages, and weakened at later reproductive growth stages. Higher temperature and lower relative humidity benefited the growth and development of T. kirilowii, and illumination could enhance the photosynthesis rate of T. kirilowii, especially its male individuals. After entering into reproductive growth stage, the photosynthesis rate of male individuals increased significantly with increasing illumination, but that of female individuals only had a slight increase, and the transpiration rate of male individuals as well as the photosynthesis rate of female individuals all increased significantly with increasing temperature.

[Clonal plasticity of Iris japonica under different soil and canopy conditions in subtropocal evergreen broad-leaved forest].

An investigation was made on the growth indices of Iris japonica growing on the yellow soil and Karst soil within a subtropical evergreen broad-leaved forest and in the forest gaps, aimed to approach the clonal plasticity of I. japonica in heterogeneous habitats. The results showed that the ramet height and diameter and the rhizome diameter of I. japonica were significantly higher in yellow soil habitat than in Karst soil habitat, while the individual density was in adverse. Light had significant effects on rhizome diameter, but soil condition had lesser effects under the same light environment. Within the forest of Karst soil habitat, the bud number and flower number of I. japonica were zero, possibly due to the double pressure from soil quality and light environment for the balance between resources uptake and energy assignment and for the sustaining of growth. In a certain extent, I. japonica in yellow soil habitat tended to K strategy via decreasing the individual number for improving competition to adapt environment, while I. japonica in Karst soil habitat tended to r strategy via increasing individual number for sustaining competition capability.

[Effects of drought stress and re-watering on the active oxygen scavenging system of Cupressus funebris seedlings in Karst area].

This paper studied the active oxygen scavenging system of Cupressus funebris seedlings under drought condition and the recovery capability of the system after re-watering, aimed to understand the adaptation mechanisms of C. funebris to the 'drought and re-watering' environment in Karst area. With the increasing time of drought stress, the seedling's relative water content (RWC) decreased, soluble protein concentration increased first and decreased then, and malondialdehyde (MDA) content increased consistently. The MDA content recovered to the level of the control (CK) when re-watering was implemented within 2 weeks of drought, but could not when the re-watering was made after 4 and 6 weeks of drought. Under drought stress, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased consistently. After rewatering, the SOD activity had somewhat decrease but still remained at a higher level than the CK, and the POD and CAT activities decreased to the CK level when suffered mild stress but had less decrement when suffered severe stress. It was concluded that C. funebris seedlings could resist mild drought stress via increasing their soluble protein concentration and inhibiting membrane lipid peroxidation, but could not resist severe drought stress because of the irreversible damage of their membrane structure.

[Species diversity of AMF community colonized in herbages roots in calcareous soil and purple soil].

A total of 17 herbages belonging to 12 families were selected as the host plants of arbuscular mycorrhizal fungi (AMF). They were grown on calcareous soil and purple soil, respectively, and sampled on the 120th day after seedling emergence. The DNA of AMF in the herbages roots was extracted by CTAB method, the partial rDNA sequence encoding ribosomal 28S big unit was amplified with special primers U1/U2 for fungi, and the PCR products were analyzed with PAGE silver staining method. In calcareous soil, 29 AMF bands were found in the roots of the 17 host plant species, and each host plant was colonized by 8.29 AMF bands; while in purple soil, only twenty-four AMF bands were found, with 9.47 bands in each host plant. All the AMF bands included unique bands and common bands. Cluster analysis showed that the AMF colonization in host plant roots was family-specific, and affected by soil factors. The feasibility of applying AMF in ecological restoration of limestone area was also discussed in this paper.

[Growth response of Broussonetia papyrifera seedlings to VA mycorrhizal fungi inoculation].

In an experiment with single inoculation (SI) and co-inoculation (CI) of three VA mycorrhizal fungi, i. e., Glomus mosseea (GM), Glomus versiforme (GV) and Glomus diaphanum (GD), the growth response of Broussonetia papyrifera seedlings in limestone area was studied. The results showed that after 3 months of growth, the aboveground-, underground-, and total biomass were increased significantly by the inoculation, being 2.49-8.19 times as much as the control. Treatment CI had the highest biomass, but the leaf number had little difference with the control. In SI, GD inoculation had the greatest effect; and CI was more effective than SI. The ground diameter, height, and total leaf area in CI were 1.5, 2.2, and 6.0 times as much as those in CK, respectively, and the root/shoot ratio in CI was the highest (0.446). There existed an interactive selection between host plants and VA mycorrhizal fungi.