The present study was conducted to examine the effects of storage humidity and germination temperature on the dormancy and viability of Brassica seeds. Three species of Brassica, i. e., B. japonica. B. cernua and B. napus, were used. Imnlediately after harvest, seeds were stored in five air-tight vessels in each of which relative humidity (RH) of air was settled to be O, 15, 34, 51 and 78% with the aid of varying concentrations of sulfuric acid (H₂S0₄) (Table 1). Germination tests were carried out at five different temperatures, i. e., 5, 15, 25, 35 and 45'C, at one or two week intervals during 8 months in B. japonica, 19 months in B. cernua and 11months in B. napus. Therefore, 25 combinations of storage humidity and germination temperature were made in each species as shown in Figs. 1-3. The optimum storage humidities for the removal of seed dormancy corresponded to 35-50% RH in B. japonica, 15-50% RH in B. cernua and 0-35% RH in B. napus. In these humidities dormancy could be completely removed in 4, 2 and one weeks, respectively, at their own optimum temperatures. In other humidities than the optimum ones, the removal of dormancy was more or less prevented. The preventing effects of desiccation or moistening continued at least until the end of the experiment. It is sometimes said that freshly harvested seeds can germinate only at a limited temperature. However, as the removal of dormancy proceeds, they soon widen the temperature range within which germination can occur. In the present study, seeds, began to germinate at 15'C, which was followed by 25, 35 and 5'C, and Linally at 45'C in every species. When dormancy was removed, seeds could germlnate at all the temperatures, or 45'C. Fig.4 presents one of the examples showing widening of germination temperature ranges.

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A series of experiments were conducted to promote chrysanthemum breeding for resistance to white rust (Puccinia horiana P. Hennings), For testing the resistance to white rust, three plants of each species and cultivar were incubated in a box kept at 17'C under 100% relative humidity and the inoculation was effected by hanging leaves with telia actively producing sporidia from the ceiling of the box. The inoculum concentration was restricted to ca. 70 sporidia per 1mm² leaf area. Reliable criteria for grading and rating inLection were established based principally on the extent of telium formation on the fully unfolded top leaves. White rust resistance of chrysanthernum cultivars could be evaluated by this testing method at an early stage of the plants, for their reactions to white rust at the young plant stage and the flowering stage were highly correlated. Variation in resistance depending on the fungal isolates was found in the tests of 40 cultivars inoculated with 6 typical isolates in Japan, suggesting physiological specialization in the pathogen. Among 6 isolates, some showed a wide range of pathogenicity and others medium and narrow ranges. Besids the existence of unstable cultivars showing various reactions to the fungal isolates, cultivars with stable resistance to all the isolates were also found.

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To give a solution of the problems in progamic phase of test-tube pollination, native behavior of pollen tubes in an ovary was examined. The observation was mainly performed on self-pollinated ovary of Nicotiana tabacum by scanning electron microscope. For finding easily pollen tube entrance into an ovule, a new method using dark field microscope was developed. The first group of pollen tubes penetrated into ovarian cavity about 32 hr after pollination, grew down directly on the surface of placenta and reached the bottom of placenta about 38 hr after pollination. The pollen tubes penetrated later grew down on the layer of pollen tubes which had already covered the surface of placenta and entered into ovules gradually from top to bottom of the placenta. The pollen tube entrance into an ovule began about 38 hr after pollination at the top and completed in 3 rd day at the bottom of placenta. Thus, ' it was cleared that a great deal of pollen tube more than all of ovules on a placenta and the order on behavior of pollen tubes are required for the pollen tube entrance into an ovule. These conditions in ile vivo progarnic phase may be important also in the case of test-tube pollination.

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To identify rice cultivars resistant to the brown planthopper, Nilaparvata lugens Stal., 2, 904 introductions of indigenous cultivars and breeding lines and 383 domestic, mostly old indigenous, cultivars were screened by the bulk seedling method with biotype I(wild type) of the insect. Except for the breeding lines most of the resistant indigenous cultivars were found to originate from Sri Lanka and southern India. While only a fer originated from northern India, Burma and Thailand. Tolerant but not resistant cultivars distributed rather widely within Asia, while almost no one was detected in Europe, Africa, America and Australia. Biotype groups II and III of the brown planthopper, selected through rearing on the resistant cultivars, were found to be effective folestimating the genotypes of resistant cultivars. A total of 120 cultivars were classified according to their pattern of biotype reactions. About 60 per cent of the Sri Lanka cultivars were found to possess the resistance gene bph 2, in contrast with only 10 per cent among the Indian cultivars.

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Since the principal injury of A1 on crop plants is an inhibition of root cell division, most of the methods for screening for A1 tolerance are based on measuring inhibition of root growth. This approach has some inconvenient procedures as a screening method for A1 tolerance, for example, it requires much time for the measurements and the complexity of maintaining the pH of the nutrient solution. It is known that crop species or varieties tolerant to A1 accumulate less A1 in their roots than susceptible ones (VOSE et al. 1962). It was recently reported that hematoxylin staining of A1 absorbed in wheat roots was of use for detecting A1 tolerance (POLLE et al. 1978). Therefore, ¥ve have conducted experiments to evaluate the hematoxylin staining method from the viewpoint of practical wheat breeding.

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Protoplasts from callus tissues of rlce, Oryza sativa L., and soybean, Glycilee max (L.) Merrill., were cultured in liquid media. Cell division occurred in protoplasts of both plants and resulted in the formation of calluses or cell colonies after one or two months. Protoplasts of both plants were Lused by using polyethyleneg'lycol (PEG)-high pH-high Ca++ technique. The percentages of hybrld protoplasts obtalned by fusron of rice and soybean were approximately 1-3 percent. The hybrid protoplasts gave rise to cell clusters after two weeks of successive culture. The cell clusters of hybrid cell lines could be distinguished by features of nucleus and cytoplasm frorn those originated from non-hybrid cells of rice and soybean.

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A wide range of Camellia species and hybrids have been surveyed for the presence of the eugenol glycoside, sasanquin, and two fluorescent flavonoid sulfates of unknown structure designated here, for convenience, camellin I and camellin II. Sasanquin is restricted to C. sasanqua Thunberg, C. hiemalis Nakai, C.verlealis (Makino) Makino, their hybrids and a very small number of C.japoleica L. cultivars. The camellins are found in all accessions of C. japonica L., C. Iutchuensis T. Ito, C.tralesleohoensis Hayata, most accessions of C. sasalequaThunberg and most hybrids involving these species. Cork-wart variation in some progenies of C.sasanqua Thunberg and C. hiemalis Nakai is also included. The evidence presented here supports the idea that occasional events of hy-bridization between C.japoleica L. and C.sasanqua Thunberg have produced hybrids that backcross to C.sasalequa Thunberg and have introgressed the cultivated forms of C. sasanqua Thunberg.

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This study was planned to know how the two-rowed barley varieties have been improved in Japan during about 100 years in various agronomic characters and malting quality, especially in their fortilizer response. The materials used in this study are as listed in Table 1, consisting of very old cultivars of foreigh origin, and old and newly crossbred cultivars thereaLter in Japan. Two six-rowed cultivars were also included in the materials for comparison. A comparative field test was made under four levels of fertilizer application according to split-plot design with three replications at Okayama University, and malt analysis was performed at Tochigi Branch, Tochigi Agricultural Experiment Station.

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