1. A study was made with the same method of previous suudy, of various oxygen concentrations . in the soil atmosphere affecting the growth of pear, persimmon and apple seedlings.
2. Normal top growth was made in the about 7% oxygen level and practically'there was no difference from check plots about 15-20% oxygen level. When the oxygen level decreased below 5%, the leaf color somewhat turned yellowish or dwarfish but not so remarkable as peach seedlings.
3. Below 5% oxygen, root development was also checked. Under the oxygen concentration 1% or more, the root development was made by these three kinds of trees used in contrast with the death -of fibrous roots of peach seedlings in such low oxygen level in previous study. Although furher experiments must be done with an-other method of experiment before the relative difference among the pear, persimmon and apple seedlings for lethal low oxygen level can be found with certainty, there would be not so much difference between them practically.

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Following after the previous I to III reports, several new polyploid flower plants induced by colchicine treatment in 1949 are described on the next page. We notice some different types of growing habits for many polyploid flower plants induced recently at our Farm. Most of them show distinctly vigorous growing, “Polyploid vigor” with larger flowers, thicker leaves and higher stems than normal diploids, as wallflower, stock, verbena and Lychnis charcedonica. On the contrary, however, some polyploids, for instance, double portulaca or Lychnis coronata, become much dwarf and shortened, and sometimes can not bear any seed at all as Four o'clock or double Impatiens. Although causes of this N polyploid feebleness is not cleared up why, a part of them possibly due to the genic over-action caused by a plenty of genes located on duplicated chro-mosomes.

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1. The investigations were carried out about the influences of the soil moisture and soil density on the germination of tubers and tuberous root of potato, taro, and Iseimo (one species of Chinese yam), and about the relation of the oxygen and carbon dioxide in the soil atmosphere to the germination of potatoes.
2. With the porous soil the suitable soil moisture for germination of tubers and tuberous roots is 60% of water capacity, but in the case of the dense soil it is 40%.
Increasing soil moisture over these optimum levels, the normal respiration of tubers and tuberous roots are more or less disturbed owing to the decrease of the air content and air permeability in the soil.
When the air content decreases below 30%, the velocity of the sprout growth of the tubers and tuberous roots declines.
3. A, sufficient quantity of oxygen must be supplied for the germination of tubers and tuberous roots.
As to potatoes, under low oxygen supply with in 4-12% of soil atmosphere, the bud and root growth and development do not reach 30% and root weight is only 13_??_14%, of those under sufficient oxygen supply, such as 16_??_18% of soil atmosphere.

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Experiments were carried out in order to clarify deficiency symptoms of nutrient elements on toma-toes, radishes, cabbages and onions in solution and sand cultures. The results are as follows:
Nitrogen deficiency : Plants were dwarfed, and had small, yellowish green leaves. In radishes andd cabbages, red color was intensified due to develop-ment of anthocyan pigments. Roots were white and healthy.
Phosphorus deficiency: Plants were dwarfed and rather thin. Leaves were small and dark green; anthocyan pigments had developed in cabbages ;pnd radishes. In tomatoes, petioles of young leaves attached to stem with narrow angles, and leaflets curved to under side. Roots were poor in growth, and reddish brown.
Potassium deficiency Early growth was not so affected, but in later stage, especially after the symptoms had appeared, growth was drastically checked. In cabbages and radishes, margin of older leaves had turned to grayish brown and dried out. Younger leaves were progressively affected and lower leaves had dropped off. In onion, interveinal area of outer leaves turned to brown color, longi-tudinally, and later, leaf tips withered and dried up. In tomatoes, potaiium deficient plants were small, but did not reveal any specific symptoms.
Calcium deficiency In tomatoes, stem tips were dead; elongation of stem had consequently ceased; lower leaves curled upwards. In other crops plants had been dwarfed, but no specific symptoms were observed.
Magnesium deficiency: Early growth 'of magne-sium deficiency plants were excellent as well as that of normal plants. In the later stage, yellow patches had developed between large veins of lower leaves. In tomatoes, petiole of lower leaves attached to stem with very wide angles. In cabbages, older leaves abscissed prematurely. In onions, no specific symptoms had developed, but plants feeled rather soft. After deficiency symptoms had developed, plant growth was seveereiy retarded.
Sulphur deficiency: Lower leaves turned to slightly lighter color. Red pigments had developed in veins of tomatoes. In onions, plants were dwaf-ed without any specific symptoms.
Iron deficiency: Interveinal portions of young leaves turned to yellow, while narrow portions along veins remained green. Later, young leaves turned to pale yellow; at first leaf size was not so affected, but later, growth had been severely che-cked.
Boron deficiency: Stem tips of tomatoes had died. In onions, growth was poor, but did not developed any specific` symptoms.
Deficiency symptoms of manganese, zinc, copper and molybdenum were not developed in this expe-riment which may be due to the impurities, contain-ed in sand, chemicals or water used. It seems that some specific treatments on them shall be necessary for the study of such minor elements.
Cabbage plants of different treatments were ana-lized for their inorganic constituents. Nitrogen, phosphorus, and sulphur contents of nitrogen, phosphorus' and sulphur, deficient plants respecti-vely were low, while potassium, magnesium and calcium contents of potassium, magnesium, and calcium deficient plants respectively were signifi-cantly low. The latter three elements may be not so much essential for plant growth as the former three elements. After the contents of the former dropped to'or below the critical levels, physiological functions may be distinctly affected.
Calcium, bofon, and iron dificiency symptoms had developed at the younger portion, while the ones of the other elements at the older portions. It seems that these elements may not be easily mobilized from older parts to younger parts as other elements.

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Three seasons' data on the flower-bud formation in turnip varieties may be summarized as follows: 1. It took about 50_??_60 days after sowing to reach to the period of the flower-bud formation in spring planting, and about 60_??_80 days `in autumn planting. The turnip required 20_??_30 days more than the Japanese radish to form flower-buds from sowing.
2. There were considerable differences in the periods of the flower-bud formation among varie-ties. When sown in April, early one reached the period after about 50 days, and late one did notform flower-buds even after 65 days. According to the longevity of the period, turnip varieties may be classified into 4 groups.
3. The flower-bud formation of the turnip is proved to be hastened by low temperatures as same as the Japanese radish, Chinese cabbage and others. Practically the bolting seems to fail if the seed were sown after May.
4. There seems no direct relation between the period of flower-bud formation and the occurrence of pithyness.

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1. In order to investigate the development of the fruit of walnuts, the weight and size of the fruit and the chemical composition in its kernel, were observed at the interval of two weeks, using Oni kurumi (Juglans Sieboldiana MAXIM.) and Teuchi-kurumi(J. regia var. orientalis KITAMURA).
2. The growth period in the size of fruits was chiefly found within six weeks after the flowering, while that in the weight was within nine to ten weeks after it.
3. Concerning the chemical composition in the kernel, the soluble non-nitrogen substances which were abundant at the earlier stage, decreased gradually with the fruit growth, but the fat increased rapidly after the fruit reached the maximum weight. Protein increased gradually till the end of the growth.

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