1. The soil properties, top growth and root disribution of young peach seedlings were compared at Hiratsuka on triplicated plots under six treatments-clean cultivation, straw mulch and cover crop with and without fertilizing respectively-in 1950 and on triplicated plots under three treatments-clean cultivation, straw mulch, and cover crop without fertilizing-in the field with better subsoil in 1951. 2. Soil temperature of limiting the root development is about 35°C and optimum temperature is 24°C, and it is about 10% soil moisture that the top lineal growth of peach trees is ceased and optimum soil moisture for peach trees is 20-40% on dry basis. It was found that in the experiments in 1950 straw mulch was effective in maintaining the soil temperature in optimum range. The lowest soil moisture of the soil surface was found in the clean cultivation plots. In the soil between 5 to 10cm deep, however, the cover crop plots had the lowest soil moisture, which was less than 10%, compared with other treatments. From the experiment in 1951, the same effects of soil management upon soil moisture and soil temperature were found in 10cm depth of surface soil. Soil temperature 10cm deep in clean cultivation plots was 35°C on August 10, 1951, but in mulched plots it was lower than 35°C even on soil surface. Soil temperature in cultivation plots was about 24°C in 5cm depth before May 1 and also in 20cm depth on July 3, which was the optimum temperature for tree growth. On the contrary, temperature on soil surface of mulched plots just rised to 24°C on June 1 for the first time. Differences of soil moisture contents among treatments were greater in hotter and drier soil condition, and then soil moisture content in 5-10cm depth was 10-14% in cover crop plots, 16-18% in clean cultivation plots, and in mulched plots it was about 20% unrelated with soil depth. 3. It seems to be principally due to the effect of higher soil temperature in early season in 1951 that the peach seedlings showed the better top growth in clean plots than in mulch plots until early July. Subsequent rapid top growth of seedlings was made in mulched plots, growing as large as in clean cultivation plots in late August. This rapid growth was perhaps owing to the more developments of fibre roots of peach seedlings in surface mulched soil 0-10cm deep than in clean cultivation plots. In 1950 experiment, the most root development in 5cm deep was found in mulched plots. In 5-20cm soil layer root development of mulch plus fertilizing was best, and that of clean cultivation plus fertilizing was next. Root of cover crop plus fertiliztng plots and especially cover crop plots developed poor as top growth. The same characteristic root systems as those of the previous experiment were obtained from different soil managements in 1951 experiment. In the lower parts of the soil under 30cm depth, the differences in soil temperature and soil moisture among soil managements were never found, and therefore root development under 30cm of soil in every treatment was nearly identical. 4. The potassium content of the leaves and exchangeable potassium in the topsoil were incrased significantly by mulching. There is no increasing of available phosphorus content even in 10cm depth soil of fertilized plots. In experiments in 1951, much the same as those in 1950, cover crops system caused the least nitrogen content of peach leaves. The difference of organic matter contents was seen only on top soil, but straw mulch caused the best, cover crop the next and clean cultivation the least increasing of them.
For the apple orchards in Aomori Prefecture, clover sod has been extensively used recently. The culture system is beneficial not only to the yield and the quality of the fruit, but also to the protection of soil erosion. The experimental results conducted on the soils of grass sod and ordinary plot may be summarized as follows: The humus content and base exchange capacity are little higher in the sod plot soils than in the ordinary plot soils. But soil reaction is more acidic in the sod soils than in the ordinary plot soils, and on nitrogen, available phosphorus and potash contents no significant difference is found between the two soils. On the microbial action studied, ammonification, nitrification, nitrogen fixation and cellulose decomposition in the sod plot soils are distinctly superior to those in the ordinary plot soils. Nitrification is the most distinct of the four. On aggregate analysis the higher degree of aggregation is found in the sod plot soils than the ordinary plot soils. The favourable effect of clover sod will be partly attributed to the above results.
Field and pot experiments were practised during the years 1951 and 1951 in the Aomori Apple Experiment Station to research whether apple leaves absorb urea of foliar fertilization. The principal results obtained in these years summarized as follows. 1. Apple trees were possible to absorb the nitrogen through the leaves from spray solution of urea and the concentration of 5 pound of urea per 100 gallons of water resulted in no burning of leaves, while the concentration of 10 pounds per 100 gallons caused some marginal burning of leaves. 2. Urea sprays increased the leaf color, average nitrogen content (total nitrogen and protein-nitrogen) of the leaves and terminal-growth of apple trees, but did not show significant effects on good fruit color and fruit size. 3. Urea spray recovered the tree vigor of the extremely weakened young Jonathan apple tree which did not form the flower buds for years and consequently about 28 per cent of the treated terminal buds formed blossoms. On the other hand, the flower buds of a plot receiving no urea spray was only 2.9 per cent of the terminal buds. 4. Sprays of urea mixed with lime sulphur and Bordeaux mixture during the end of July to mid August were absorbed through the leaves at the same rate of urea alone and did not burn the leaves by mixing with these chemicals.
(1) Soil survey and survey of the development of fruit trees or forest trees were made at some places in the village of Nishi and Shikai, Shodo Gun, Kagawa Prefecture. These places were of two kinds, the one of which was presumed to be tales gloscier or talus and the other was in marked contrast with the former regarding topography and soil profile. (2) Because of presumably the block structure of the soil, the root of olive tree penetrated to a depth of 1 meter in the II Horizon notwithstanding the highly clayey texture of the soil which originated from metamorphic clayslate, in the Oki Island. On the hill of Oe the roots of olive tree penetrated more deeply than in the of Oki Island and the maximum depth was recorded to be 1.45 meters. It was supposed that there is close relation between the root development of olive trees and the soil moisture. (3) The fact that the roots of olive trees in Mr. TAKAHASHI'S olive grove in the village of Nishi penetrated shallowly into the soil was supposed to be a case of the phenomenon due to so-called“Leachy Substrata”.
1. With the aim of studying the physiological mechanisms of the occurrence of the pithy tissue in root crops, various radishes have been investigated as to easiness of its occurrence as well as characters concerned in it. 2. Ones which had a great deal of pithy tissue were found generally in such varieties that the corpulent roots were grown prematurely and also the decrease of T/R ratio was sharp, whereas in the late varieties of which corpulent roots were grown slowly, the occurrence was rather less. 3. From the view-point of internal morphology, the varieties in which the development of internal tissue system accompanied by the corpulency of the roots was rapid and the xylem parenchyma grew and further their cells were large were liable to yield more pithy tissue. On the contrary, the ones which had opposite tendency to the former characters showed less occurrence of it. 4. Generally speaking, the roots of radish which became slowly corpulent contained starch and the high concentration of soluble matter, while the early varieties which had a great deal of pithy tissue contained sugar in place of starch, and their con centration of the soluble matter was less. 5. Regardless of varieties the pithy tissue occurred when the ratio of T/R decreased and on the period when the ratio of leaf weight to the increased value of root weight indicated the minimum, and during the same period the degree of fullness in the root tissue was at the least. 6. The locality and the form of pithy tissue in the roots differed by the varieties, and it is presumed that this is mainly due to the distribution of the conducting tissue of them being different among the varieties. 7. The growth and corpulency of roots being vigorous and their corpulency being carried more abruptly than the assimilative capacity of leaves, the occurence of pithy tissue will be ascribed to the retardation of the fullness of the root tissue. 8. It was seldom to find pithy tissue in such a variety as“Tokinashi”of which the corpulency of its root was rapid and its fullness was good and the greatness of the assimilative capacity of top. seemed to be a big factor at least. At any rate, this kind of radish will offer a useful suggestion in breeding of more resistant varieties to the occurrencee of pithy tissue.
(1) The experiments on the influence of soil moisture, especially drought, and low temperature upon the flower-bud differentiation of D. nobile were conducted from Oct. 20, 1951 to March, 1952 at Hodogaya, Yokohama. (2) The materials used were consisted of 60 pots; each pot has 4 or 5 plants having pseudo-bulbs. These pots were divided into following 4 plots, i. e. High temperature-dry, High temperature-wet, Low temperature-dry, and Low temperature-wet. (3) In the low temperature plots, both dry and wet, the predifferentiation stages of flower-buds were observed on November 29. Since then they developed normally and opened first flowers at March 23. No difference was observed between dry and wet plots about following points, i. e. date of flower-bud differentiation, date of blooming, and total number of buds, including flower-buds, on the pseudo bulbs. (4) In the high temperature plots, both wet and dry, no flower-bud differentiation occurd, and they developed to“young vegetative growth.” (5) From these results, the author could not find any influence of drought upon flower-bud differentiation of D. nobile, but found distinct effects of low temperature to promote the flower-bud differentiation.