Varietal trial of alfalfa was made on 55 varieties collected from main alfalfa growing regions of the world to select varieties adapted to the warmer region of Japan. The seeds were sown in fall of 1962 and 63, and 5 clippings were made in each season as a rule. After three years test, following results were obtained : In varieties of sativa group, including Spanish, Italian, Australian, Argentina and American common alfalfa, the stands persisted fairly well throughout the test period, while, in varieties of media group, severe standloss was observed in the summer of the second and third harvest year. The correlation between standloss and yield decrease was significantly high. Generally yield level of sativa group ranked moderate or somewhat low in the early part of the test period, but increased later. A fairly large number of varieties of media group, including Du Puits and several Flemish type and some of German and American varieties, were highly productive in the first harvest year, but their yield was decreased after the summer growth depletion of the second harvest year. Thus the yield order was gradually reversed between sativa and media group and in the third harvest year, all varieties of top yield class belonged to sativa group. Plants attacked by anthracnose were frequently found in varieties of media group, which might be one of the reasons of summer standloss of this group. It was evident that sativa group showed better adaptation in the warmer region of Japan. Among the tested varieties, four Italian varieties introduced from Lodi in North Italy, were excellent in both yield and persistency.

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The main purpose of the present study was to determine the proper size of tower silo for experiments, from the standpoint of pH, organic acid formation, digestibility and storage lass. 1) First growth of orchard grass and Ladino clover mixture (84% of moisture content) was ensiled in each of 0.5, 2.0 and 15 tons tower silo under the same treatments without preserative. Herbage was cropped by mower bar type's forage harvester in early July 1966. 2) Results are summarized in the following Table 1. 3) In the silage in larger silo was ensiled higher dry matter per cubic meter than in that in smaller one. 4) The silage ensiled in larger silo showed lower pH, and butyric acid and higher lactic acid content and dry matter digestibility than that in smaller one. 5) Also dry matte losses were higher in larger silo than in smaller one. 6) As a result, it is suggested that the 2 tons capacity silo is suitable for observation of silage qualities, storage loss and digestibility from the experimantal point of view.

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Hydrocyanic acid content of total plant and various parts in hybrid sorgo was determined during growing season by the method described by HOGG and AHLGLEN, and recorded in ppm on dry matter basis. The results obtained were as follows : 1. The HCN content of the total plant was very high in young stage and decreased gradually as the plant grew older. 2. The HCN contents in the various parts were different at growing stages. The HCN was higher in the stalks than in the leaves before 55 days after sowing and 45 days after cutting, there-after the HCN was higher in the leaves than in the stalks. The HCN in the sheaths showed the lowest at any stages. The transition of HCN content in the leaves was similar to that in total plant, but the leaves were slightly higher in HCN than the total plant. 3. The HCN content in each leaf of the plant decreased as it approached to the maturity, and the upper leaves contained more HCN than the lower leaves at any stages. 4. The differences in HCN content in the parts of a leaf were recognized; i.e., the HCN content became higher in the order of the top, the middle part and then the base of the leaf. 5. Supposing the safety limit of the hydrocyanic acid to livestocks is 500 ppm on dry matter basis, it will be needed the hybrid sorgo to grow more than 50 days after sowing, or 37 days after cutting.

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The relation of the level of initial air inclusion in ensiling to the quality of silage in case of preserving the material at different temperatures was investigated. Both fresh and wilted Italian ryegrass, each included three kinds of grasses of different water soluble carbohydrate (WSC) contents were ensiled at three levels of initial air inclusion (low, middle or high) by means of air-tightening and preserved for 5 weeks at the high (25℃) or the low (12℃) temperature. The quality of the silage was generally poor in case of preserving the fresh material of very low WSC contents (0.7% on fresh matter basis) at the high temperature, but it was not so bad at the higher levels of initial air inclusion as at the lower levels. In preserving this material at the low temperature, the quality of the silages of low and middle levels of initial air inclusion was fairly improved and the quality of the silage became higher at the lower levels of initial air inclusion. In case of preserving the fresh materials of 1.7% or 1.9% of WSC at the high temperature, the quality of the silage was highest at the middle level of initial air inclusion in the former and at the low level of it in the latter respectively. In the low temperature preservation of these materials, the quality of the silage was generally improved and it was higher at the lower levels of initial air inclusion. The quality of the silage prepared from the wilted material obtained from the fresh one of very low WSC contents was satisfactory in general even at the high temperature and the difference in quality between the silages of different levels of initial air inclusion was scarcely observed. In preserving this material at the low temperature, the quality of silage was improved at every levels of initial air inclusion and it was higher at the lower levels of initial air inclusion. The quality of the silage prepared from the wilted materials of 2.5% or 3.6% of WSC was very good even at the high temperature and it was much better at the lower levels of initial air inclusion. At the low temperature, the quality of the silages of middle and high levels of initial air inclusion was improved, then the difference in quality between the silages was scarcely observed.

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Efficiencies of solar energy utilization (E_u) have been determined for primary canopies and subsidiarily for their regrowth in five forage crop species, for the purpose of clearing up the components of the maximal or average efficiency as an indicator of potential productivity of a sward. For the observation on primary canopies, we chose three grass species; perennial ryegrass (Lolium perenne, Danish S.φ.D.S 56), Italian ryegrass (Lolium multiflorum LAM. Tottori) and orchardgrass (Dactylis glomerata, Danish, Rsk. S 61), as those of an erect leaf habit and two legumes; alfalfa (Medicago sativa, Du Puits) and ladino clover (Trifolium repens L., Danish, P.M.K & V. S 57), as those of horizontal one. Plants were sown late in April on extraordinarily well fertilizer-applied soil (N : P_2O_5 : K_2O=240 : 420 : 420kg per ha.) and grown through the spring season (about eleven weeks on vegetative stage) for which period the temperature and soil moisture did not limit the growth. Weekly dry matter increase was measured from the time when a sward first attained around eighty percent in light interception. The sward with the area of (4×2)m^2 was harvested every week with two or four replications for dry matter above ground, and that of (0.5×0.5)m^2 was examined duplicately for stratified clip method and for the ratio of material underground to the top on dry matter basis. For the continuous measurements of total incident solar energy, transmittance and reflection of a sward, several tube type solarimeters (0.3〜4.0μ) were used. CdS-cell type light meter for the vertical distribution of relative light intensity, the automatic leaf area meter for leaf area, and the automatic calorimeter for combustion heat of dry matter were also used, respectively. 1. Total dry matter (W), crop growth rate (ΔW), leaf area index (LAI) and net assimilation rate (NAR) are given in Table 2, together with leaf and root weights. Perennial ryegrass sward produced the highest ΔW of 32.8g/m^2・day with the optimal leaf area index (L_<opt>) of 12.6, and the orchardgrass 26.0g/m^2・day with L_<opt> 11.1. These values were extraordinary high records in our country for these species and have been scarcely observed in autumn-sown sward. 2. Heat of combustion per gram (ΔH) for each organ in vegetative stage around L_<opt> ranged from 4600 to 3600cal/g in following order; leaf blade>root>leaf sheath, stem or stubble. For the total plant materials, ΔH ranged from 4300 to 3800cal/g and was as follows : alfalfa>ladino clover>perennial ryegrass, Italian ryegrass>orchardgrass(Table 3). 3. Total incident radiation (S) was in the range of 3800-3900kcal/m^2・day for the former half of the season and 2900-3400kcal/m^2・day for the latter half. The rate of reflection (r) to S was almost constant (23〜27%) for the swards with enough leaves to cover the ground. Transmittance (t) decreased with growth till 3-5% at L_<opt>, whereas the rate of absorption (α) increased in inverse proportion to t up to 70〜75% (Fig. 1, Table 4). 4. The efficiency of solar energy utilization (E_u) was calculated as the ratio of the fixed and stored energy of daily production of total organic matter (ΔH・ΔW) to the total incident solar energy (S); E_u=ΔH・ΔW/S. The efficiency of converting energy (E_φ) from the absorbed energy (S_α) to the stored was expressed as E_φ=ΔH・ΔW/S_α. The value of E_φ correlated well with those of E_u (r=0.988^<**>) because the examination was carried mainly for the period when the sward absorbed no little amount of radiation and r was nearly constant. 5. E_u averaged through the whole examined period (11 weeks) of vegetative growth was different among species, showing higher values in grass swards as 1.23% for perennial ryegrass and 1.17% for orchardgrass than in the legumes as 1.01% for alfalfa and 0.72% for ladino clover. But a different trend was found in case of the E_u values avera

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