Present study was carried out from 1965 to 1970 in the orchard of the Horticultural Research Station, Ministry of Agriculture and Forestry, in order to confirm the interrelations between fruit productivity, mean fruit weight and ratios of plant parts as affected by the modification of training systems in pear trees.
Temperature treatments were conducted from early August to mid-September with 5-year-old bearing Kaki fruit trees (Cultivar. Fuyu) grown in clay pots. 1. When the trees were treated at night with temperature of 15°, 20°, 25° and 30°C and left in the field in the daytime from August 3, their fruits on September 21 showed no appreciable difference in the weight of a fruit among different temperatures except 30°C at which the fruit was lightest. Fruit color was already light yellowish green at 25° and 30°C. The chlorophyll content of the peel was lowest and the soluble solid content of the juice was highest at 25°C, followed by 30°, 20°, and 15°C in the order. However, the fruit quality on November 10 was most superior at 25°C and most inferior at 30°C. 2. When the trees were placed under constant temperature of 15°, 20°, 25°, and 30°C throughout day and night of August 6 to September 18, the weight of a fruit and its color at the end of treatments were best at 15°C, followed by 20°, 25°, and 30°C in the order. The fruit at 30°C was still green. However, the fruit quality on October 25 was most superior at 20°C and most inferior at 30°C. Brown specks resulted from the coagulation of soluble tannin substance developed more in flesh at 25° and 30°C than at 15° and 20°C.
1. Host tissues such as young leaves or stipules of chestnut trees around larva began to grow misshapenly, envelop the parasite and form galls from late July. In late August, gall tissues embraced the wasp commpletely to build a larval cavity. Since this period, in susceptible varieties individual gall became to adhere each other and more advanced successfully, but on the other hand, in the resistant ones brown necroses began to be formed in the vascular bundles between gall and healthy tissues and were many and extensive in a bud with the passing of time. And then early in the next year none of galls having non-necrotic tissues were observed, therefore, which is probably the main factor that their enlargement was reduced. In the other cases in which wasps attached to aged tissues (e. g. scales and aged leaves) or eggs were laid in apex, leaf petiole or other tissues, necroses were found in healthy tissue or gall ones around the larva in both varieties. 2. Reactions of nuclei, protein and others were the same in susceptible varieties and resistant ones at the beginning of gall formation, but after October, hyperplasia of cells of galls in susceptible hosts was progressed markedly more than in resistant hosts. 3. Several glands stained with fast green FCF or safranin 0 were observed in the mouth parts of larva around which gall formation was initiated. For these and other reasons, gall formation substances reported previously may be secreted from the mouth parts.
1. Field experiments were carried out to study about the influence of irrigation on the fruit yield, quality and the content of mineral nutrients in spring leaves of mature Satsuma orange trees grown in steeply sloping citrus groves during seven years from 1965 to 1971. 2. The effects of irrigation on the fruit growth and yield were greatly varied by year, and were especially remarkable in 1967 because of long drought, that is, fruit growth was much superior and the number of L, M fruits was greatly increased in the irrigated trees. The average increase during seven years by irrigation were 30.6 percent in yield, 6.7 percent in fruit weight and 19.2 percent in fruit size. 3. The contents of soluble solids and citric acid of fruit juice were greatly changed by year both in the irrigated and non-irrigated trees, but generally those in the irrigated trees were lower than in the non-irrigated trees. While the ratio of soluble solids to acid was higher in the irrigated trees. In the average of seven years′ results, the contents of soluble solids and citric acid in the irrigated trees were lower by 0.8 percent and 0.21 percent than the non-irrigated trees, respectively. 4. Only in 1967, phosphorous and calcium contents of spring leaves were increased by irrigation, while potassium content was decreased. In the average of seven years′ result, magnesium content was found to be lower in the irrigated trees.
Effects of water stress and H-ion concentration on the rate of translocation of 14C-labeled photosynthates in Satsuma mandarin trees were studied. When the root growth was suppressed, translocation to the remaining plant parts (growing areas) was decreased and more 14C was accumulated in the leaves. In the plot of pH 3.0 a little decrease in the rate of translocation to fruits was observed, while in the plot of water stress the accumulation of 14C in the juice was heavily decreased. Water stress caused an increase in total sugar concentration of the juice. It seems likely that this was partly a result of the concentration effect arisen from water stress. However, in this case other factors such as polisacharide metabolism may also play an important role in the process of sugar accumulation in the juice.
The germination of strawberry (Fragaria grandiflora EHRH.) seeds was studied. All 13 varieties tested showed a strong photosensitivity in their seed germination, that is, the germination was much inhibited in the dark. Alternating temperatures of 15°C and 30°C much stimulated germination in both light and dark. Among constant temperatures of 15°, 20°, 25° and 30°C, 25°C was the best for germination, followed by 30°C and 20°C, and the low temperature of 15°C was the worst. This indicates that the relatively wide range of constant temperatures between 20°C and 30°C are adequate to their germination. In about 10 months after harvest, no diminution of dormancy was shown in strawberry seed. Among chemicals tested for stimulating germination, potassium nitrate was the most effective at concentrations of 0.1 and 0.2%. Ethrel and gibberellin were also effective, but their effectivenesses were not so large as potassium nitrate. Thiourea was only slightly effective at much lower concentration of 0.05%. Low temperature treatment was ineffective in the short period of 10 days, but effective in the relatively long period of one month or more, and the longer the treatment period, the larger the stimulative effect. Scarification of seed coats with concentrated sulphuric acid for two to three minutes was rather effective for stimulation in both light and dark. This indicates that the cause of dormancy of strawberry seeds lies mainly in thei fruit and seed-coat, not in the embryo. Far-red light showed very strong inhibition on the strawberry seed germination. This inhibition was not recovered even by alternating temperatures, but overcome to some extent by low temperature treatment. In this experiment, strawberry seeds were stored well in dry condition of room temperature, or in either dry or open condition at 5°C.
The experiment was carried out to see the effects of basipetally moving endogenous substances on the root primordium differentiation of Portulaca cuttings and to determine whether the exogenously applied IAA or NAA acts as the substitute of the substances. One side of the stem of the cutting was cut out at a slight distance from basal end for the purpose of blocking downward movement of root promoting substances, and then an agar block containing various concentrations of IAA or NAA was inserted into the cut-out portion. The experiments were conducted in two cases: one with leaves and the other without leaves. Root initiation at the base of the cutting was observed morphologically in order to see the difference between the side under the cut and the intact side. 1. The formation of the root primordia was inhibited by removing the leaves from cuttings. Furthermore, the root primordia were not formed at all at the side under the cut portion, but the advancing tendency to form root primordia were somehow exhibited by the application of IAA or NAA to the cut-out portion. 2. On the cuttings with leaves, the formation of the root primordia was also inhibited at the side under the cut portion, but it was promoted a little by treatments with a low concentration of IAA or NAA. 3. On the cuttings with leaves, many root primordia were formed at the opposite side of the cut-out portion and a tendency to promote the formation of the root primordia was shown by the application of IAA to the cut-out portion. In this case, IAA at a concentration of 10-11M was more effective than the other concentrations. 4. Most of the root primordia were formed near the cut-end of cuttings by IAA or NAA applied to the cut-out portion. 5. On the cuttings with leaves, IAA or NAA applied to the cut-out portion promoted the formation of the root primordia at the medullary ray.
The Easter lily from Uotsuri-jima (Hoa-pin-su) Island, referred as ′Senkaku′ in this paper, was propagated by scale, and the scale bulblets were grown at 4 different temperatures in a phytotron. Their growth responses were compared with those of cultivars ′Hinomoto′ and ′Munakata′. ′Senkaku′ had more slender and glossy leaves and also the stem elongation was greater than the others. When scaled at 15°C, ′Senkaku′ produced scaly leaves earlier than others during the scaling period. When scaled at 25°C, no leaves emerged in any lilies until the end of the scaling period. ′Hinomoto′ scaled at 15°C bolted in some degree before the beginning of the growing period. When scaled at 25°C, ca. 60% of scale bulblets bolted in ′Senkaku′ and ca. 30-40% in ′Hinomoto′ and Munakata′ within 1-2 months after they were moved to the growing temperatures. All of these bolted plants did not have any scaly leaf but had stem one. ′Hinomoto′ and ′Munakata′, however, began to bolt in 3-4 months on some bulblets which had scaly leaves. These plants had both scaly and stem leaves. When scaled at 15°C, ′Senkaku′ did not bolt during the growing period at any temperature. ′Hinomoto′ and ′Munakata′ did not bolt within 1-2 months, but began to bolt in 3-4 months at 15 and 20°C of growing temperature. These bolted plants had both scaly and stem leaves whereas non-bolted plants had scaly leaves only. As mentioned above, the growth responses of ′Senkaku′ were rather different from other lilies. Above results made clear about the growth sequence from the scale bulblets to the yearling as follows.
This study was carried out to clarify the effect of chilling treatment for seed-bulbs or seedlings on the bulb formation of bulbous Oxalis, i.e. O. bowieana, O. cernua, O. variabilis and O. versicolor. The results obtained were summarized as follows: 1. When the seed-bulbs or seedlings of Oxalis were exposed to 5°or 10°C for 30 days and thereafter were grown under a daylength of 16-hour at 20°C, the plants of Oxalis turned yellow and formed the new bulbs. While those of O. bowieana, O. variabilis Lavender and O. versicolor grown without chilling treatment failed to form new bulbs. 2. When the seed-bulbs of O. variabilis Lavender and O. versicolor treated with both chilling at first and then heat treatment of 30°C or 35°C for 10 or 20 days, the development of new bulbs was suppressed though grown under a daylength of 16-hour at 20°C. 3. From these results, it may be assumed that the low temperature of 5°°C to 10°C caused the physiological state of seed-bulbs of Oxalis to be favourable for their bulb formation, but the high temperature of 30° to 35°C vanished the above-mentioned physiological state. 4. Based on the aforesaid results, both the practical method of year round culture of Oxalis by the control of the period of its bulb formation and the relationship between the development of bulbs of O. bowieana and shrinking of its contractile roots were discussed.
This research was conducted to determine the relationship between refractive index (Bx) pH value and sensory ratings for sweetness and palatability of commercial Satsuma mandarin (Citrus unshiu MARC.), and to examine whether Bx and pH value suited for the indices of edible quality of the fruits. 1. When sensory evaluation using the fruits classified into nine sections by Bx and pH values was carried out, sensory ratings of panels for the sections varied largely with the two parameters and were high significant and independent of each other. 2. Within a Bx level, the palatability depended on pH values exhibiting a maximum at 3.7-3.8 which was seemed to a point of inflection in the palatability curve. 3. There were least significant differences among the sensory ratings of palatability where the differences among the sections were at least 1.4-1.8 in Bx, or 0.3-0.4 in pH; as the differences in the two parameters increased more over, the differences of the ratings increased further. 4. Distribution ranges of Bx and pH values were 8-14 and 3.0-4.0 respectively. The numbers of the ranges diveded by Bx 2.0 and pH 0.35, which were values arising high significant difference in sensory ratings, were both about three. Therefore, it was considered that three grades were reliable for grading of edible quality. 5. when sensory ratings of palatability were showed by means of height on the plane consisting of Bx and pH axis intersecting at right angles, a shape of mountain, having a peak at about Bx 11-13, pH 3.7, was considered. It was suggested that some contour lines of the mountain were able to show the edible quality of commercial Satsuma mandarin.
A marked production of ethylene by immature Satsuma mandarin fruit (Citrusunshiu MARCOVITCH, cv. ISHIKAWA) harvested in June and July occurred during incubation at 20°C in the dark after picking. The ability of ethylene production by the fruit conspicuously diminished in August and a trace of ethylene was evolved by the fruit harvested in September and October. The rate of ethylene production per fruit was highest in the fruit harvested in early July. The remarkable ethylene production was accompanied by an increase in respiration, destruction of chlorophyll and abscission of calyx, the phenomenon being very similar to that revealed by the climacteric type fruits. When discs are prepared from albedo tissue of immature fruit and incubated at 20°C, a great increase in ethylene production occurred in a short period wich continued for 20 hr and then declined. Discussion was made on a mode of ethylene production and an accompanied rise in respiration exhibited by immature citrus fruit in relation to the climacteric induced by ethylene of climacteric type fruits.
It is well known that nitrate in tomato fruits causes heavy detinning in canned tomato juice. It is desirable that nitrate nitrogen (NO3-N) concentration in the fruit be below 3ppm for canning. To investigate the effects of plant growth regulators on the accumulation of NO3-N, and the yield and appearance of tomato fruit, a series of, studies were conducted in the winter of 1968 and in the summers of 1969 and 1970. Fourteen tomato cultivars were compared as to the fruit NO3-N concentration in the 1969 season. Gibberellin (GA3) 25 and 50ppm, whether applied to the flowers, the clusters, or a whole tomato plant reduced NO3-N concentration in the fruit, as well as fruit size and yields. Delayed maturation was also observed. When the tomato flowers and clusters were treated with the auxins, PCPA (p-chlorophenoxy acetic acid) 15ppm, TR (4-chloro-2-hydroxy methyl phenoxy acetic acid) 100 and 200ppm and RP (4-chloro-2-folmyl phenoxy acetic acid) 100 and 200 ppm, increased NO3-N concentration in the fruit was observed. Fruit size and yields were also increased. The time of maturation was accelerated by the auxin treatments. Among auxins, PCPA and TR were found to be highly effective on these points, while RP was less so. By treating clusters with GA3 and auxin together, it was found that the effect on fruit growth, yield and maturation time was approximately in between that caused by single treatments of GA3 or auxin alone. Fruit NO3-N concentration differed depending whether or not PCPA, RP, or TR had been combined with GA3 in the treatment. The heaviest yield of fruit, containing NO3-N below 3ppm resulted from a combined treatment of GA3 25ppm with PCPA 7.5ppm on the clusters. The effects of these plant growth regulators on a whole plant varied with their concentrations and spraying times. A single treatment of GA3 25ppm, and the treatment of GA3+RP decreased both the yield and NO3-N content in the fruit. The single treatment of RP 200ppm increased the yield and NO3-N content in the fruit but showed no significant effect of spraying times. Chico was found to be more sensitive to the plant growth regulators than Heinz 1370. The highest concentration of NO3-N in the fruit was found in Fireball and Coldset, followed by Epoch, Chico, Kurikoma and Taiho, Heinz 1409, ES-24, VF-36 and other late maturing cultivars of the large fruit type were of very low nitrate content. Heinz 1409 was judged to be the most suitable cultivar based on the yield and low nitrate concentration in the fruit.