In order to enlarge the extent of soya hybridization, to increase the range of variations and to create the new cultivar of high photosynthetic rate, of good quality and of high yield by means of somatic cell hybridization, we have used the cotyledon, leaf, stem and hypocotyl of soya as the material for tissue culture, have obtained the plantlets derived from callus for the first time and have harvested the seeds therefrom. This is the preparatory work for cell hybridization in further experiments.

This experiment is dealing with the high temperature injury from milky stage to ripening stage of early rice, and is in the phytotron under natural light. The main purpose is to study the effect of the different temperatures and their duration on fruiting during from milky to ripening stage. The early milky stage (6–10 days after heading) is more sensitive to the influence of high temperature on the percentage of ripened grain. The late milky stage (11–15 days after heading) is more sensitive to the influence of high temperature on the weight of kilograin. The cause of the decrease of output effected by 35 ℃ is mainly due to the decrease of weight of kilograin and the percentage of ripened grain from milky to ripening stages, but little influence on the percentage of empty seeds. The main cause of the decrease of kilograin weight and percentage of ripened grain is due to too early decrease of food accumulation, but not to sharp decrease of the assimilates.

The haploid breeding method of using anthers was successfully applied in the experiment of breeding new rice varieties, resulted in obtaining several dominant lines. From the second generation of the pollen plants, we made a series of cultivation test and observations for three years. We found that the main genetical characters and viguor between generations of the progenies were stable and even. The coefficient of variation (c. v) was below 5%, and could be maintained. Demonstration of cultiva- tion and productive assessment have confirmed its value and named it late ken type rice "Sin Sieu". This proves that after selection of partents and combination of crosses were made, anthers of the hybrid could be artifically cultured, through which pollen plants could be obtained. Among them , good lines could be selected. After testing their productive ability, followed by propagastion, new variety could be obtained. This is a fast and efficient approach in crop breeding.

callus and its differentiation into plantlets. In our work, by using N3 and N6 medium devoid of hormones, pollen embryo and plant were obtained derived from anther in rice and wheat. Thus, not only the procedure was simplified but also the very expensive plant hormones were omitted. This will benefit haploid breeding work in the masses. The microscopical observation indicats that the development of pollen embryo of rice and wheat are basically conformable with zygotic embryo. With regard to the development of pollen embryo of wheat there are two ways: (1) originate directly from uninucleate pollen; (2) uninucleate pollen divides into vegetative cell and generative cell and then the vegetative cell develops into pollen embryo, but the generative cell degenerates gradually. In the present article we also suggest some opinions to raise the frequency in inducing pollen embryo in order to improve the method further.

This is a preliminary report on potato stem tip culture since 1974. It also presents how to carry out the socialist cooperation and a suggestion of prevention from potato degeneration by means of seed-potato production. Excised stem tips with 1–2 leaf primordia (usually less than 0.5 mm long) were cultured in vitro. The improved basic culture medium contained Muller's macro-nutrients plus micro-nutrients and onganic substances of "AES" A (Japanese Agricultural Experiment Station, Medium A) plus sucrose (20 g/l) and agar (7 g/l). The pH of the medium was adjusted to 5.7–5.8. GA3 (0.1 ppm), 6-BAP (0.05 ppm) and NAA (0.01–0.1 ppm) were added to the medium at the first cultural stage. Two weeks later, they were transfered to a basic medium minus plant growth regulators. The cul- tures were grown under a temperature between 20–30 ℃ and a light intensity of 1,000–3,000 Lux. Four types of developmental growth patterns were obtained. By using different methods for different growth patterns, better results could be achieved. Seedlings usually developed in three months. The rate of seedling formation was about 50% and sometimes even as high as 70%–80% in some varieties. By way of repeated systematic virus assays, including host plant test and serological test, eight varieties of virus-free potato plants are now available. After cutting the seedlings into segments (each segment bearing one leaf) and culturing them in the basic medium, the production of daughter plants was found to increase exponentially. The Production rate was 7–8 times per month. When 10 ppm B9 was added to the medium, the seedlings were found to be more healthy and much greener than those of the controls. This is beneficial for successive transplantation. The viability of the seedling was above 90%. Over ten thousands of virus-free seedlings and tubers have already distributed to several initial stook farm bases used as the basic stock.