This paper presents about pollen morphology of the plants from Xisha Qundao (China’s islands in the South China sea). 39 species in 37 genera are belonging to 25 families described and photomicrographically illustrated. These are: Sesuvium portulacastrum L., Alternanthera sessilis (L.) DC., Amaranthus viridis L., Celosia argentea L., Gomphrena celosioides Mart., Cordia subcordata Lam., Messerschmidia argentea (L.f.) Johnston, Cleome viscosa L., Casuarina equisetifolia L., Chenopodium acuminatum Willd. subsp, virgatum (Thunb.) Kitam., Terminalia catappa L., Conyza bonariensis (L.) Cronq., Tridax procumbens L., Vernonia patula (Dry.) Merr., Wedelia biflora (L.) DC., Ipomoea pes-caprae (L.) Sweet, Ⅰ. tuba (Schlecht.) G. Don, Euphorbia atoto Forst. f., Scaevola sericea Vahl, Eragrostis ciliata (Roxb.) Nees, Calo- phyllum inophyllum L., Pemphis acidula J. S. & Forst., Mimosa pudica L., Bogenhardia crispa (L.) Kearney, Sida parvifolia DC., Mollugo oppositifolia L., Boerhavia diffusa L., B. erecta L., Pisonia grandis R. Br., Canavalia maritima (Aubl.) Thou., Crotalaria mucronata Desv., Guettarda speciosa L., Morinda citrifolia L., Solanum nigrum L. var. pauciflorum Liou, Suriana maritima L., Lippia nodiflora (L.) Rich., Waltheria americana L., Clerodendron inerme (L.) Gaertn., Tribulus cistoides.

Crop plants irrigated with waste water contained low concentration (under 1mg/l) of arsenic may normally grow and develop, and the arsenic contents accumulated in soils and crop plants are similar to those irrigated with clean water. As the concentration of arsenic rises up to 5 and 20 mg/l, however, the yields of wheat and rice are decreased respectively. Arsenic accumulation in rice increases evidently with irrigated concentration 5 mg/1 of arsenic. It is suggested that approximately 5 mg/l of arsenic may be the critical concentration for the crop plants irrigated with the waste water. A certaim amount of FeSO4 added to the soil may reduce the uptake of arsenic by rice.

The pollen plants were successfully grown from the embryoids and calli induced from pollen in anther culture. By doubling chromosomes, more homozygous diploids were obtained. The effect of Laser on induction of the embryoid from the pollen was also studied and the preliminary effective measures of shoot formation from embryoid were made to decrease mixoploid phenomena. No reduction of the pollen plant in vitality from embryoid and callus has been detected.

This is a study on the pollen abortion in five backcross generations of "Red-awned wild rice × Liao-tan-zao". Various abnormalities were observed in the whole period of microsporogenesis. Pollen development was usually arrested before the binucleate stage, resulting in abortion of pullen grains finally. Pollen abortion took place mainly at the late uni-nucleate stage. On the whole, various abnormalities in pollen abortion were found in all the five backcross generations.

1. The vegetation of the Xizang plateau is different from the general vegetation of "horizontal zones" and it is also different from that of "vertical zones” in mountainous country. It belongs to the vegetation of vertical zones of the "peneplain pattern”. Therefore, it may be called the vegetation of "plateau zones". 2. The zonation of vegetations in Xizang changes from the southeast to the northwest as follows: forest–meadow–steppe–desert. The formation of these plateau zones is determined mainly by the elevating of the plateau to such a great extent that the particular regime of air circulation was obtained. The wet'southwest monsoon is the fundemental factor for the development of the tropical and subtropical mountain forests in southeast part of Xizang. The plane of the plateau is under the control of the westerly wind circulation and "Qinghai-Xizang" high pressure. Under the in-fluence of such continental climatic conditions on the plateau, the high-cold meadow, steppe and desert vegetations are formed.

The pollen plants developed directly from wheat pollen grains by two ways: (1) The uninucleate pollen divided many times and developed into mature pollen embryos, which then grew into plantlets; (2) The globular embryo grew further and formed irregular small callus which in turn differentiated rapidly into plantlets on the same medium without any transplanting. 2. Of all basal mediums N6 medium is considered to be the best one. 3. If the spike of wheat is treated with the centrifuge at 2000 rev./min, for 20 minutes before placing on the medium, the frequency of plantlets developed directly from pollen grains is, greatly increased. 4. The extraneous hormone was found to be beneficial to the embryogenesis of the wheat pollen embryos. The best result was obtained from the anthers cultured continuously at 7–10 ℃ for 120 hours on medium added with 2:6 mg/l IAA and kinetin after inoculation. Under these conditions the frequency of induction increased to 6.2%.

Spinach chloroplasts treated by incubation with Naja naja venom, or with phospho- lipase A purified from it, lost their activity in the reduction of NADP, ferricyanide, MV, and DCPIP and the concomitant evolution of O2. But if benzoquinone or thymoquinone was added as electron acceptor, O2-evolving capacity of such chloroplasts could still be shown. On the other hand, when DCPIPH2 or TMPDH2 was added as electron donor, NADP- or MV-reducing activity could be demonstrated. These results suggest that the site of inhibition of the Hill reaction by venom is located between Photosystem Ⅰand Photosystem Ⅱ. Plastoquinone is probably the point of disjunction of the electron transport chain. The incubated chloroplasts were examined under electron microscope. It was found that the lamellar membranes of grana were swollen up and disintegrated to varying extents depending on the duration of incubation.

The changes in peroxidase isozymes of different varieties of Cotton seedlings after inoculation by Fusarium oxysporum f. sp. vasinfectum was studied with polyacrylamide gel electrophoresis. After inoculation, the activities of peroxidase isozymes in cotyledons were intensified and new bands appeared. The enzyme activities of susceptible varities (4 varieties) were higher than those of the resistant ones (8 varieties). The susceptible varieties invariably had one or two more isozyme bands than the resistant ones. The changes in intensity of the peroxidase isozymes of cotton seedlings after infection is coincident with the appearance of morphological symptom of the disease. The number of isozymes increased with the severity of the disease, so that the changes in the number of isozymes in the infected plant can be taken as the intrinsic "bioche- mical symptom" of the plant. There were distinct differences among the three species of cotton plants in their peroxidase isozymes. The number of isozymes is greatest in Island cotton, which is highly susceptible to fusarial wilt disease, followed by the susceptible varieties of Continent cotton and its resistant varieties, while the least is the Chinese cotton which is immune to the disease. It is suggested that the appearauce of more new isozymes in the susceptible varieties upon inoculation may be used as a criterion for screening the resistant varieties of cotton plants from those susceptible to fusarial wilt disease.

In a previous report it was shown that the activity of coupling factors isolated from chloroplasts of other plant species was higher than those obtained from chloroplasts of the same species for restoring the cyclic photophosphorylation activity of the deficient particles. However, the coupling factors then used were crude extracts or extracts after partial purification only. Verification of the results with purified preparation was highly desirable. To this end several methods of extraction and purification of chloroplast coupling factors were compared. It was found that the coupling factors extracted with dilute EDTA solution from the chloroplasts after the removal of heterogeuous proteins showed a single band on polyacrylamide gel electrophoresis. When deficient particles from spinach chloroplasts were incubated with coupling factors purified in this way from broad bean (Vicia faba L.) or barley (Hordeum vulgare L.), the restored photo- phosphorylation activity was still higher than that incubated with coupling factors prepared from spinach chloroplasts and purified in the same way. Thus it can be concluded that the enhancement effect of coupling factors from different species was due to the coupling factors per se and not to any substance(s) contaminated in the crude extracts.

The isolation technique, culture medium and cultural conditions of rice protoplasts were modified and a great amount of calli regenerated from individual protoplasts was obtained successfully. The main conditions which are necessary for obtaining repro- duceable result are discussed.

Three alkaloids: harringtonine, cephalotaxine and schelhammera alkaloid B were isolated from Cephalotaxus oliveri Mast. which is distributed in Guangdong Sheng. The inhibiting effect of harringtonine for sarcoma 180 in mice was 42.3% at a dosage of 1 mg/kg. It showed high activity against the acute nonlymphoblastic leukemia in clinical experiments. A pretty high yield of 1.3/10000 antileukemic ingredient harring- tonine was extracted from the plant and the resources of C. oliveri Mast. in China are abundant, so that this plant is a good material to produce harringtonine.

This paper presents the chemical constituents of the essential oil from the leaves of Rhododendron thymifolium. 10 components have been separated and identified e.i. germacrone, juniper camphor, nonaldehyde, myrcene, limonene, humulene, camphene, farnesene, α-pinene and β-pinene. Their contents have been determined also.