In maize cultivation of East Java, Indonesia, stand irregularities and decreases of population may result from such causes as the damages of Java downy mildew and seedling fly.
In this report, data on the seasonal changes of infection of Java downy mildew and the seasonal damages by seedling fly were presented, and then the effects of nonuniformity of stand on maize yield were examined.
1) maize plants which were sown 2 to 3 weeks after the onset of rainy season showed the highest infection rate of downy mildew. In this period, Harapan variety was infeted more than 90%, while, on Kretek variety, about 50% of infection rate was obsered. However, infection rate decreased gradually according to the late sowing, and on maize plants sown at March, the increase of infection rate was observed again.
On the other hand, the highest damages by seedling fly was shown at period when infection of downy mildew showed the lowest rate, that is, at late January and early February. It was apparently observed that there was a time lage on the outbreak of both damages.
2) Uniformal stand plots and nonuniformal stand plots were set artificially by sowing the different number of seeds per hill, and grain yield, rate of steril plant and 100 grains weight were compared between both plots.
3) On the comarison of yield per unit area, uniformal 2 plants plot showed the highest yield, and the yield of uniformal 3 plants plot was slightly lower than that of uniformal 2 plants plot.
On the comparison among nonuniformal plots, although alternating 1 and 3 plants plot and 1, 2 and 3 plants plot are same as uniformal 2 plants plot on number of plants per unit area, both nonunif ormal plots showed the lower yield than uniformal 2 plants plot.
4) The difference on yield between uniformal plot and nonuniformal plot, as mentioned above, may be explained as follows.
(1) On nonuniformal plot, mutual compensation among each hill. (2) It was supposed that the serious drought at tasseling and silking stage arrested the mutual compensation among maize plant hill.
5) The rate of steril plant on 2 plants hill increased with the increase of number of plants on adjacent hill, and decreased on the contrary cases. While, on the cases 1 and 3 plants hill, no effect was obsrved about this character.
6) Grain weight per hill consisting of 1 and 2 plants decreased as number of plants on adjacent hill increased, and on grain weight per hill consisting of 3 and 2 plants, the contrary relation was noticed. The same tendencies were obseved on 100 grains weight.
7) Coefficient of variation for grain weight per plant within each plot was calculated.
The results showed that value which was obtained from the plot consisting of 3 plants per hill, was larger than that of the plots consisting 1 and 2 plants per hill.
From this fact, it is thought that mutual compensation among plants acts ordinary with-in a hill, in order to maintain the grain yield per hill to some level.

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Young leaves in Cinnamomum species were used as materials. Preparations for electro-microscopical observations were made as follows
1) fixation; osmic acid-phoshoric buffer mixture containing sugar at the rate of 2%
2) dehydration; ethyl alcohol and propylene oxide
3) imbedding; epon resin
4) electronic staining; aceticuranium and causticlead
The authors observed the microscopic structures of nucleus, nucleolus, nuclear membrane, cell wall, cell membrane, cytoplasm, mitochondria, endoplasmic reticulum, Golgi's apparatus and chloroplast. In particular, Golgi's apparatus were ob- served in the peripheral regions of the oil- vesicle cell.
Osmium-stainable granules in the chloroplast of Cinnamomum plants were considerably large as compared with granules of other aromatic plants (cf. YASUNAGA and YOSHIDA, 1973) . In sections most of these granules took a spherical shape, which suggests that they are liquid. Their electron density was not so high.
There were other kinds of osmium-stainable coherent masses in the cytoplasm. They were highly electron-dense, presumably viscous, irregular in shape, and pressent in a majority of cells.
The essential oil in the vesicle in fusible with ethyl alcohol and propylene oxide. There was found no complicated structure in any vesicle.
In conclusion, there are three kinds of oil-like substances in the plant, i. e., osminm-staihable granules in chloroplats, osmium-stainble coherent masses in the cytoplasm, and essential oil in vesicler. These substannces are supposed to be different in their chemica components from one another.

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This study was undertaken in order to find out the relationship between the productive structure and the light extinction coefficient (K) in sugarcane plant communities. Different Ks were obtained for communities of different varieties which had different productive struetures, having straight and erect leaves, or curved and drooping leaves.
A negative correlation (r=-0.7300) was found between Ks and leaf area indies (F) for different vavieties, thus larger Fs were realized in communities with smaller Ks.
A positive correlation was obtained between the ratio, (weight of dead leaves) / (weight of green leaves) in percent and K. Assuming that death of leaves in the lawer part of the community is caused by low illumination near or below the compensation point, the community with smaller K is expected to have a smaller percent of dead leaves, because of its advantage in receiving light effectively.
It was clear that the extinction coefficient was important as index of permeation of light into plant communities of sugarcane varieties, and that the value of this coefficient was dependent upon plant form, such as the angles of leaves in relation to the stem.

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The results in the previous paper in this series have shown that dormancy in rice seed is caused by the inhibitors contained in the hulled seed as well as those in the hull, and it is broken by the decrease of their quantities. In this study, the inhibitors contained in each of three organs ; embryo, endosperm, and hull, were examined by means of the biological and chemical determintions. And auxin was also determined with the same methods. The results obtained are summarized as follows:
1. Two inhibitors in the dormant rice seed existed in all organs, i. e. embryo, endosperm, and hull, with nearly equal biological activities. Consequently, if the activities of the inhibitors of each organ are calculated in term of one-seed, the almost equal quantities of the inhibitors are distributed in each organ, and it is noticeable that embryo contains, in spite of its relatively very small body, as much the inhibi tors as other organs.
On the basis of previous and this results, the breaking of dormancy by husking treatment seems to be brought about by not only the removal of the inhibitors in hull but also the inactivation of inhibitors in embryo and endosperm, which may be caused by the increasing of oxygen entrance into their their tissue. It further may be satisfactorily considered that the respective biological determination of the inhibitors contained in three organs which differ muturally in genetical constitution may become a effective means to clarify more the genetical analysis of dormancy in rice seed.
The chemical determination by means of thin layer chromatographies showed that the main inhibitor was nearly undoubtedly abscisic acid (ABA) .
2. Auxin in dormant seeds was recognized only in both embryo and endosperm, and not in hull. Activity of auxin in endosperm was stronger than that of embryo, then it was cleared that the most of auxin in seed was contained in endosperm unlike inhibitors.
The chemical determination by means of paper chromatography showed that auxin contained in rice seed was probably 3-indoleacetic acid (IAA) .

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Some experiments were conducted to find out causes of the growth retardation of pineapple by continuous cropping. Soil samples used in this experiment were (1) surface soils collected from continuous cropping of pineapple approximately 6 years, (2) subsoils of above mentioned surface soils collected from 50 cm depth, (3) surface soils of uncultivated fields located near the above mentioned samples.
The results obtained were as follows :
1. Vegetative growth, weight of fresh root and root length of pineapple planted on the surface soils callected from continuous cropping fields were smaller than those of subsoils and uncultivated surface soil.
2. Roots of pineapple planted on the surface soils of the continuous cropping fields became brownish in color and decayed awfully. However those symptoms were not observed when these surface soils were fumigated with Chloropicrine and EDB.
3. Eighty per cent of pineaplle roots was distributed in the surface soil of 20 cm depth in the fields.

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