In the previous paper, it was recognized that the poor growth of onion which followed cabbage was always accompanied with the poor absorption of phosphorus which seemed to be due to the stronger acidity resulting mainly from the heavy application of ammonium sulfate for cabbage cropping, In this report the authors describe the results of several investigations which have been executed to meet this situation as well as to ascertain our sup-position. The results obtained can be summarized as follows. 1) To get enough yield of onion, basic application of a large amount of water soluble phosphorus (as superphosphate) was required overall in this area and it was especially so when it followed cabbage. For example, to get yield over 20 tons per acre, no more than 200 to 300 pounds of phosphorus per acre for the onion following barley and much more than 400 to 500 pounds of phosphorus per acre for the onion following cabbage was required respec-tively, while without phosphorus application almost no yield could be obtained in both cases. The differ-ence of onion yields due to the kind of preceding crop, therefore, was most pronounced when 100 to 200 pounds of phosphorus per acre was applied, which is the most common practice in this area. To increase onion yield overall in this area and especially in the cases following cabbage, basic ap-plication of phosphorus as much as 500 pounds per acre was most effective and in addition controlling of soil acidity with lime or dolomite and application of increased potassium were also desirable in strongly acid soils. 2) A wide variation in onion yields was observed also in the area where onions had been grown suc-cessively year after year. The survey carried out in this area indicated that the yield of onion had the highest correlation with y1 value of the soil and succeedingly high correlation with pH (H2O), pH (KCl) and base saturation percentage in this order, while with 0.002N sulfuric acid extractable phos-phorus or exchangeable potassium no correlation could be found. 3) In the experiment field of our station onion was shown to be more sensitive to high soil acidity than cabbage. At soil reaction about pH 5. 2, the growth of onion was remarkably inferior to that of cabbage and at pH 4.2 almost no growth could be seen, while cabbage showed considerable growth 70 to 80% as much as at pH 6.2. 4) Among several properties of acid soil which influence on the plant growth, aluminum toxicity to which onion was thought to be especially sensitive and the influence of high concentrations of hydrogen ion were investigated by water culture method with onion and cabbage comparatively. The data showed that at 1 ppm aluminum the growth of onion as well as of cabbage was inhibited equally and to high concentrations of hydrogen ion cabbage was more sensitive than onion, though more precise investigations are necessary for this kind of comparison. 5) Besides the poor growth of onion which fol I-owed cabbage, abnormal growth of cabbage itself had become to be seen especially in the area where cabbage had been grown successively. Some of the distinctive features of this abnorma-ity, for example, the hooking and the development of thin and water soaked areas of light brown color around the margins of headed leaves and the dis-tortion, undulation and browning of tips of older leaves were quite similar to some of calcium defi-ciency symptoms induced in our laboratory by exclud-ing calcium supply in the middle stage of growth. In spite of this resemblance, however, there remains some possibility of boron or magnesium deficiency and much work should be done in order to evaluate this abnormality and further the possibility of its participation on the inferior growth of onion following cabbage.
1. In order to obtain the basic data for breeding and seed production in spinach, experiments were carried out on the low temperature induction of bolting using the following 13 varieties of spinach differing in photoperiodic requirement: Nihon-zairai, Ujô, Jirômaru, Wakakusa, Hôyô (those are early bolters) ; Hollandia, Viroflay, Long Standing, Minsterland, Nobel, King of Denmark, Seiyôôba, Sapporoôba (those are slow bolters). The seeds were subjected to 2±1°C for two weeks and then sown in clay pots or on beds in greenhouses in spring (March 5), in summer (June 5) and in autumn (October 5). 2. The time of initiation of floral primordia of all the varieties tested was accelerated by the low temperature treatment, as compared with the con-trols in each season, and the floral initiation of the treated plants of those varieties started at about the same time. 3. The promotion of bolting and flowering was also markedly shown in the treated plants, but varietal differences remained unchanged in the time of development of flower stalks, especially under short-day conditions in autumn or winter. From these results, it was assumed that the after effect of the vernalization treatment might shorten the length of photoperiod required for induction of each variety, but it did not alter the varietal order in their photoperiodic requirements necessary for inducing flowering. 4. The possibilities for getting high yields of seeds of the slow bolting varieties planted in spring by the vernalization treatment seemed to be promising.
In order to examine the role of sugar for aerial tuber formation, sterile culture of vine segments was undertaken using various nutrient media. The results may be summarized as follows: (1) No tuber formation was seen in the medium containing inorganic salts alone. But when sucrose was added to the medium, the vine segment was rendered to form aerial tubers, an evidence show-ing the necessity of sugar for tuber formation. (2) The size of tubers became increasingly larger in proportion to the concentration of sugar applied to the nutrient media. (3) So long as uniform materials were used, the initiation of tubers occurred simultaneously re-gardless of the sugar concentration in the medium. (4) The time required for tuber initiation was correlated with the growth stage (or maturity) of vines, namely, less time was required for mature vines. (5) At the time the tubers began to emerge, progressively more sugar was found in the vine tis-sue as the sugar concentration in the medium in-creased. However, in case of the medium containing 2% sugar, the sugar content of the vine segment became lower than the initial content. Nevertheless the tuber formation occurred. Hence the increase in sugar content in the tissue itself seems not responsible for the induction of aerial tubers, though it is conceivable that sugar is necessary for tuber formation and subsequent growth of tuber depends upon the sugar concentra-tion in the medium.
The flowering habit of an early peanut variety “Java” was studied. The results obtained were as follows: (1) The higher the node from which a branch arises, the later the 1st flower of the branch opens. The 1st flower of the main stem opens later than those of some lower branches. Flowers are born from the 1st node in the branches, but in the main stem the 1st flower is born at the 6th_??_8th node. (2) The flowers open indeterminately in each branch and in the stem. (3) The number of flowers which are born on one node tends to decrease from the lower nodes towards the upper nodes in each branch and in the stem, but there are some irregularities. One node bears 2 to 3 flowers in average and bears sometimes even about 10 flowers. (4) The flowering period of flowers of one node is fairly long. It is not seldom that the period ex-tends over more than one month. (5) Usually only one flower per day opens in one node, but sometimes two flowers and rarely three flowers open. (6) The number of nodes which bear flowers and the number of flowers of the stem are both much less than those of the lower branches. The number of flowering node and the number of flowers per branch are more numerous in lower branches than in higher ones, but among higher branches such tendency is more or less confused.
1. In the previous report(5) it is shown that the histological evidence of blossom bud differentiation can not be found until March when the meristematic activity of the growing point initiate. 2. The work has been conducted to determine the time range during which buds can be influenced to initiate blossom primordia. The technique employed in those investigations to determine the extent of the period in which floral differentiation can be induced consisted of bark-ringing, defoliation and defoliation accompanied by ringing at intervals during the fall and winter, Also, forked branches ringed at the base were employed to obtain evidence as to the movement of the flower-inducing substances from leafy branch to the defoliated branch. In the following spring detailed records were taken of the number of blossoms formed on these branches. 3. The trend of blossom/node ratio reflecting the respective periodic ringing or defoliation treatment are diagrammatically represented in figures. Here the percentage value of blossom/node ratio counted in May are plotted as ordinate with the date on which the treatment performed as abscissa. 4. The curve declined as later the ringing is performed and the curve rose as later the defoliation was performed. Later performed the treatments, as the both curves tend to approach each other, the influence became less, and at the point of intersection or closest approach, susceptibility to influence was practically nil. It was near the beginning of March and the percentage value of the nontreated branch was found just to coincident with the point of inter-section. 5. It is assumed very often that the periodic de-foliation of branches offered a means of determining the percentage of buds in which flower inductionn had occurred by the date of treatment. This means that the blossom differentiation took place succes-sively as time elapse. The histological examination, however, as above stated(1) showed that no blossom-bud initiation was found before March. 6. The declining tendency of the curve reflectingthe effect of ringing showed that the blossom-bud differentiation became more and more restricted as time elapsed. It seems that later more and more buds had passed beyond the stage in which ringing-could influence blossom-bud differentiation. 7. It may be safely concluded that earlier ringed the shoot, more abundantly the leaf-synthesizedd substances accumulated by March, this, in turn, in-duced more plorific blossom production in March. Accumulation of the leaf-synthesized substances. by means of bark-ringing induced the blossom for-mation even in the early fall(1) Even fruited branch is proved to bear blossoms by means of ringing. Fruited branch bearing blossoms, is shown in Fig. 4., accompanied by the spring flush and ringed at the base of the both branches. Earlier defoliation induced less accumulation of the leaf-synthesized substances by March (It is shown in the carbohydrate content in the defoliated shoots “Table 1”), and induced only a few blossomm production.
1. Experiments were carried out to clarify the mechanism of after-ripening and germination of apple seeds from the viewpoint of natural growth substances. The apple veriety “Jonathan” was used for both germination and Avena tests. 2. Germination tests of intact seeds and excised embryos showed that embryos and intact seeds required about 35-day and 77-day stratifications, respectively, for maximum germination. 3. The embryo contained an unidentified acidic growth-promoter at the outset which increased rapidly as a result of stratification. The breaking of embryo dormancy apparently coincided with the increase in activity of this acidic growth-promoter. 4. A growth-promoter was found to occur in both stratified and non-stratified endosperm, but the production of the growth-promoter was much higher in stratified endosperm. The relationships between the production of growth-promoter in the endosperm, afer-ripening, and embryo germination is not clear. 5. Seedcoats were found to contain both a strong growth-inhibiting substance and a growth-promoting substance. During stratification the growth-inhibiting substance decreased and the growth-promoter increased. After 77-day stratification, ether extracts showed a striking promotion of the elongation of Avena coleoptile. Germ-inhibition was apparently dependent on the inhibitor, but the possible associations between after-ripening of the embryos and fluctuations in natural growth-substances in seedcoats is not clear.
(1) Tree growth and nutrient content of leaves as related to the soil reaction were observed with one year old trees of apple, grape and Japanese pear planted in pots with volcanic-ash soil. (2) For an adjustment of soil reaction, ground limestone and slag were used respectively, though the latter contained silica and magnesia beside lime. (3) In every species, tree growth was much promoted by an addition of either these two lime fertilizers. In apples and grapes, the effect of slag was more striking than that of limestone, especially the tendency being conspicuous in apples, while in pears no distinct difference was found between the two fertilizers. (4) As a result of leaf analysis, N content of leaves decreased with an increase of slag supplied. P content of leaves increased slightly in accordance with an increased application of limestone and of slag. However, no relation existed between the K content of leaves and the amount of the lime fertilizers added. The content of Ca, Mg and SiO2 was closely related to the amount of limestone and of silica-slag supplied, especially Ca to the limestone, and Mg and SiO2 to the slag. (5) Finally it is noticeable that growth of apple trees was correlated intensively with the content of Mg and SiO2 in leaves. And it might be a reason why slag was much superior to limestone as a fertilizer for apples planted in the volcanic-ash soil.
1) Continuing to the previous reports on the water culture studies of apple tree, experiments were carried out on the absorption of nitrogen, phosphorus, potassium, calcium and magnesium determined during the leaf fall period from Novem-ber to April of the years 1951_??_1957. Apple varieties used were American Summer Pearmain, Jonathan and Rall's Janett, and these trees were two-year old in the first year and become older by years. 2) Although the absorption of nitrogen and phos-phofus was limited to very little quantity in se-vere winter, before and after of which their absorbed quantity was relatively high. As for potassium, its appreciable amount was discharged by the roots from the later November to the end of the March. 3) The absorbed amount of nitrogen and phos-phorus per unit weight during the leaf fall period decreased as the tree ages increase, especially with phosphorus. The potassium and calcium absorption in this period was minus in each year, but magnesium absorbed very slightly. 4) The rate of nitrogen absorption in the leaf fall period (five months) to annual absorption was about five per cent and slightly higher rate was observed an phosphorus (5_??_8 per cent).
In this study, the germination responses of Petunia hybrida seeds to light were investigated, and the following results were obtained. 1) The increase of germinative capacity of petu-nia seeds during the dry storage at room tem-perature was accompanied by the increased light-sensitivity. High sensitivity was gained 6 months after the harvesting. 2) The light-sensitivity of petunia seeds increased with the lengthening of presoaking, up to 48 hours, before the illumination. Moreover, as short as 5 minutes' illumination brought high germination, when it was given 20 hours after the imbibition. 3) Red light was more effective than green or blue light in increasing the germination percentage. 4) Petunia seeds were similar to lettuce seeds in the photoreversibility of their response to red and infra-red radiation. 5) The promoting effect of gibberellin was very remarkable, though nitrates and thiourea could not increase the germination.