The chloroplast and PS Ⅱ particles isolated from spinach leaves was treated with sulfite. The results showed that the strength of florescence by PS Ⅱ particle was decreased with increase of both the sulfite concentration and the treatment timer; that the damage was more serious when pH 7.3; that sulfite did not damage young chloroplast but it did so to the aged chloroplast; in which decomposition rate of chlorophyll was slower than that of photoreduction of DCIP; that Ca2+ protected chloroplast from sulfite damage and accelerated the damage of PSⅡ particles; and that the reqular pattern can be described by of Logistic equation.

In this paper, We studied soil microoganism and biochemical activities of Chinese-fir plantation on the four different ecological area of Longshen county, Yishan county, Cenxi county and Tianlin county in Guangxi. The results of the studies indicate. 1. In terms of the amount of microbe and the quantity of groups, the forest areas of the Lilou in Longshen county and the Laoshan in Tianlin county appear to be the greatest, and the Qiping of Cenxi county the scond, and the Qingyuan of the Yishan county the least. 2. The soil boichemical activities (the stransformable intensity of soil nitrogen, the stransformable intensity of carbon in soil, soil enzymes activities, soil respiration intensity) were the highest on the Lilou and Laoshan, and the Qiping were the second, and the Qingyuan were the lowest. 3. In the four different Chinese-fir plantation areas, the stand growing is the best in Lilou and Laoshan, and the Qiping is the second, and the Qingyuan is the poorest. This′s also the order of the amount distribution of soil microbe and the biochemical activities in these areas.

The concept of membership degree of the fuzzy set theory is well suited for the analysis of plant communities,where both abrupt and smoothly continuous distribution variations of plants and environmental quantities are often found. This work is an application of ISODATA based on fuzzy set theory to the classification problem of the grassland community in Songlun Plane,Northeast China. The result shows that the technique is objectively correct and is manipulative compared to the classical methods. In addition,the classification guided by the Minimum Description Length Principle proved that the principle is suitable for this type of classification problems.

This paper made a comparative study on the water use of the artificial alfalfa grassland and the natural Stipa bungeana grassland with the method of rapid weighing cut leaves or shoots improved by author in Ningxia Yanchi in 1988. The results showed that the productivity in the very arid alfalfa grassland was very high, but that in the Stipa bungeana grassland with a better soil water content it was very low. The ratio of water consumption by transpiration and by evapotranspiration in the alfalfa grassland was 86.0%,but in the Stipa bungeana grassland it was 40.7%.The water use intensity of the alfalfa grassland was 137.32%, but in the Stipa bungeana grassland it was 88.72%. And there were signs to show that the depth of water use in the alfalfa grassland was deeper than 180cm, but in the Stipa bungeana grassland it did not go over 180cm. The transpiration efficiencies in both the grasslands were basically identical, but the evapotranspiration efficiency in the alfalfa grassland was much higher than in the Stipa bungeana grassland (0.82‰ and 0.54‰ respectively) . After the growth phase, the water deficit in the alfalfa grassland reached -101.8mm, but in the Stipa bungeana grassland it was only -17.6mm.

Experiments were carried out to study the effects of different fertilization levels on water use efficiency (WUE) of winter wheat (Triticum aestivum cv. Shaanhe No.6) grown in the field under dryland conditions at Luojiawa, Chengcheng, Shaanxi in 1987—1988 to explore the physiological mechanism of“regulating water using fertilizer”. The results showed that: (1)Fertilization on dryland raised not only soil water content, but also soil water potential, thus increased water use. (2) Fertilization on dryland increased leaf area of winter wheat, delayed leaf senescence, thus reduced soil evaporation, increased the potential of water-use by transpiration and the potential of photosynthesis. However, the net assimilation rate was apparantly not significantly affected. (3) Fertilization increased total water use (ET) and water-use by transpiration (T) of winter wheat under dryland conditions, increased above ground biomass yield and grain yield, so that WUE of winter wheat was improved. (4) Fertilization has the effect of regulation to winter wheat underrdryland conditions, making the plants more efficient in water economy, and hence more adaptable to drought enviroment.

A comparative study was made on the characteristics of water relation (e.g. transpiration rate, transpiration efficiency, water potential etc.) of 9 Masson pine provenances from July 1988 to January 1989. The results indicate that the characteristics of water relations have definite cor-relationship with the growth and have a relatively higher genetic stability. It is shown that the mechanism of drought-resistance Of Masson pine may be attributed to its good drought-avoidance and drought-tolerance besides its strong water-absorbing ability. Owing to the above differences, the different provenances of Masson pine have the dissimilar drought-resistance. It was further observed that good provenances Of Masson pine(e.g. the provenances in southern zone) were characterized by lower transpiration rate and water saturation deficit, higher transpiration efficiency and critical w.s.d, and higher drought-resistance, which result a less influence of water stress on the growth and a higher increment. Consequently, the 9 provenances may be classified into 3 types and 5 sub-types on the bases of the characters of water relations, using the method of cluster analysis

Echinochloa spp., which was a annual weed belonging to Gramineae and had strong adaptibility and wide distribution, was one of the staple noxious weeds in rice, wheat and soybean fields. The author studied the biological characteristics of Echinochloa crusgalli and its controlling methods in rice fields since 1975. It has been shown that the initial temperature for its germination and the optimal temperature for its growth were found to be 12℃, and 30—35℃ respectively. The emergence peak of Echiochloa cursgalli would be predicted by two indices i.e. accumulated temperature biological zero = 10℃ and leaf age. The former was 33.8—49.5℃ when the soil moisture was sufficient and the latter was oneleaf age of Echinoloa crusgalli after puddling. The experiment results also pointed out that the control of Echinochloa crusgalli in rice field should begin with the control in nursery bed and the key to success was to make the effective stage of herbicides coincide with the emergence peak (sensitive stage) of weeds: The chemical control by herbicides such as butachlor, thiobencarb, molinate, oxidizon, dimethametyn (piperophos), pretilachlor and quinclorac combined with agricultural practice such as cleaning up seeds and water management, etc. may result in optional weed control.

The root system of the Chinese-fir stands on the repeated plantation woodland in Sanmin, Fujian was studied. The results showed that: the biomass, the constituent, the morphology, and the distribution of the root system of the Chinese-fir stands in replanting woodland vary significantly with the number of successive cultivation, The root biomass per tree in the first cultivation is 24.93% higher than that in the second, and 41.69% higher than that in the third. The sum of the root biomass of all stands in the first cultivation is 31.93% higher than that in the second, 55.52% higher than that in the third cultivation. The constituent, the morphology and distribution of root system in the first cultivation were more advantageous for the trees to enlarge their nutrient-absorption space and growth.

This Paper presents the contents of foliar nutrients and their seasonal variations for 9 major tree species in northeast China during a growing season.Using the Principal Component Analysis and Cluster Analysis,this paper demonstrated that N, P and Ca are importantly critical elements for plants, and Fe and Mn highly accumulated in the soil. Moreover, N, P and Ca, taken by plants are highly dependent on the soil contents of the elements, while uptake of Fe and Mn, is independent of the soil contents and is selective. From the nutrient utilization point of view, Pinus Koraiensis + Juglans mandshurica,Larix gmelini + Fraxinus mandshurica,hard broad-leaved tree + soft broad-leaved tree, conifer + broadleaf tree, and Betula platyphylla + other tree species are the rational mixed types in the establishment of mixed forests.

Ecological experiments of wheats was arranged in Lasa during 1982—1985. Liaochun 6 is a typical spring wheat, on the other hand, Taishan 4 is a winter variety. Heading and maturation were postponed, so were the growth periods and periods from sowing to maturation for wheats in Lasa. The low temperature was an important influential factor. Plant height of wheats was higher in Lasa, because growth periods was longer. The difference of temperature between day and night was bigger, the night temperature was lower, and the radiation of sun was stronger than most places in China, this contributes to the bigger weight of the seed.