Satsuma Mandarin Trees Research Articles

Sugar Contents in Parts of Fruit of Satsuma Mandarin Tree under Water Stress in Autumn

Satsuma mandarin trees were water-stressed severely (WS-s) and moderately (WS-m) by withholding in autumn. Sugar contents of juice and peel were determined by HPLC.Sucrose and reducing sugars in the juice and peel were increased by the water stress treatment, notably, fructose in the peel. Increase of sucrose in the juice and peel was inhibited by WS-s. Total and reducing sugar concentrations in the peel from the WS-s plot were lower than those from the WS-m plot at harvest on November 26.Although the sugar content of the stylar end of the fruit was greater than that of the stem end, the % reducing sugars in the stem end was consistently higher than that of the stylar end. This relationship was not changed by water stress treatment.The peel color gradient from the stylar to the stem ends paralleled that of the sugar gradient; the gradient for titratable acidity was the reverse.

Root System Activity of Fruit Trees in Response to Shoot Pruning, High Temperature, and Excess Water

Relationship between root system and shoot pruning was studied by three different pruning times (February, June, and August) and intensity (heavy, medium, and light) using satsuma mandarin trees (Citrus unshiu Marc.). Root weight, respiratory rate of fine root, and CO2 concentration in root zone were measured on the 90th day after starting each pruning treatment. The weight of fine root was more severely influenced by pruning intensity than by pruning time. Fine root of heavy pruned trees showed lower respiratory rate than those of medium- and light-pruned trees. Heavy-pruned trees showed the highest CO2 concentration level in root zone. Influence of high root temperature on root respiration was investigated using `Kyoho' grape (Vitis vinifera L. × V. Iabrusca L.), kiwifruit (Actinidia deliciosa), and satsuma mandarin trees. Respiratory rate of grape root increased more rapidly than those of mandarin and kiwifruit under high root temperature. Respiratory rate of mandarin root given immersion treatment in stagnated water began to decrease significantly at the 70th hour after starting the treatment. Photosynthesis of the trees decreased by 85% at the same time.

Root System Activity of Fruit Trees in Response to Shoot Pruning, High Temperature, and Excess Water

Relationship between root system and shoot pruning was studied by three different pruning times (February, June, and August) and intensity (heavy, medium, and light) using satsuma mandarin trees (Citrus unshiu Marc.). Root weight, respiratory rate of fine root, and CO2 concentration in root zone were measured on the 90th day after starting each pruning treatment. The weight of fine root was more severely influenced by pruning intensity than by pruning time. Fine root of heavy pruned trees showed lower respiratory rate than those of medium- and light-pruned trees. Heavy-pruned trees showed the highest CO2 concentration level in root zone. Influence of high root temperature on root respiration was investigated using `Kyoho' grape (Vitis vinifera L. × V. Iabrusca L.), kiwifruit (Actinidia deliciosa), and satsuma mandarin trees. Respiratory rate of grape root increased more rapidly than those of mandarin and kiwifruit under high root temperature. Respiratory rate of mandarin root given immersion treatment in stagnated water began to decrease significantly at the 70th hour after starting the treatment. Photosynthesis of the trees decreased by 85% at the same time.

施設栽培で根域制限を行ったワセウンシュウの着果量が樹体の水分ストレス,果実の品質, 収量ならびに花芽分化に及ほす影響

The effects of crop load on water stress, yeild, and fruit quality of 13-year-old rootrestricted satsuma mandarin (Citrus unshiu Marc. var. preaecox Tanaka) trees grown indoors were investigated. The trees were heated from early December to late May. The fruits were thinned to a leaf-to-fruit ratio of either 15 (L :F-15) or to 10 (L : F-10) in early April.1. Trees with L:F -5 had lighter crops of smaller frutis with higher Brix than had trees with L :F-10.2. As fruits ripened in June to July, soil water potential, pF, of L :F -15 plots nearly exceeded those in L :F -10 plbts. The leaf water potential was lower and early leaf abscission was greater on L :F -15 trees than on L :F -10 trees. Thus, satsuma mandarin trees with L :F-15 underwent a more severe water stress than did trees with L :F-10 trees.3. The total and reducing sugar contents in the bearing shoots at harvest were significantly higher in the L : F-15 treatment than shoots in the L: F-10 treatment, but there were no differences in the fine roots (< 2 mm diam.). However, no difference in the starch content was observed in shoots and fine roots between the two treatments.4. The number and length of shoots appearing after summer pruning in the L:F-10 and L : F-15 trees were nearly equal. In late October and late November, the starch contents of the new shoots were lower in the L :F -10 treatment than in the L : F -15 treatment. No difference existed in the number of flower buds between trees of the two treatments when they were forced in December of the second year.

Effect of Vesicular-Arbuscular Mycorrhizal Fungi on the Growth, Photosynthesis, Transpiration and the Distribution of Photosynthates of Bearing Satsuma Mandarin Trees.

The response of satsuma mandarin (Citrus unshiu Marc. cv. Okitsu wase) on trifoliate orange (Poncirus trifoliata Raf.) rootstocks to inoculation of vesicular-arbuscular mycorrhizal (VAM) fungi, such as Glomus ambisporum Smith and Schenck, Gloumus fasciculatum (Thaxter) Gerdemann and Trappe emend. Walker and Koske, Glontus mosseae (Nicolson and Gerdemann) Gerdemann and Trappe, and Gigaspora ramisporophara Spain was studied at low phosphorus (P) application.Under high air temperature stress conditions in August, the photosynthetic (Pn) and transpiration (Tr) rates of VAM-inoculated trees were faster than non VAM ones. But in September when air temperature decreased, the Pn and Tr rates did not differ significantly between VAM-inoculated trees and non infected ones. In general, infected trees had larger leaf area and higher leaf P concentration and the tree growth was more vigorous than was that of non infected ones.When 13CO2 was fed to fruit-bearing trees under the optimal air temperature conditions, fruits were the strongest sink for photosynthates and new leaves were the second strongest. The leaves of VAM and non VAM trees assimilated 13CO2 equally fast per unit leaf area, and the distribution of 13C into various parts of the bearing trees did not differ. VAM trees, however, had 3 times more photoassimilates per tree than uninfected ones because the former had a leaf area 3 times larger than the latter and grew more vigorously.

PENGARUH PACLOBUTRAZOL TERHADAP PERTUMBUHAN DAN PEMBUNGAAN JERUK SATSUMA MANDARIN PADA BEBERAPA KONDISI SUHU

Two experiments were conducted at phytotron to investigate the effects of paclobutrazol on vegetative growth and flower bud differentiation of Sat sum a Mandarin (Citrus unshiu Marc.) grown under different temperature conditions. One-year-old Satsuma Mandarin trees budded onto trifoliate orange rootstocks were used in these experiments. The trees were planted in root observation chamber (Experiment I) or Wagner's pot (Experiment II) in late, March of 1988. In experiment I the treatments were temperature (20 & 30 o C) and paclobutrazol (treated and not treated). Paclobutrazol was applied 3 times to the soil at the rate of 0.5 gram a.i. per tree per application. The growth of shoots and roots were observed at 5-day intervals. In experiment II the treatments were temperature (15, 20, 25, 30°C and field condition) and paclobutrazol (sprayed to the leaves, drenched to the soil, and none). Paclobutrazol was applied 3 times; foliar application was 1000 ppm and soil application was 0.05 grams a.i. per tree per application. Temperature treatments were done from June to December, 1988. At the end of the treatments, the trees were defoliated and then exposed to 25°C to observe flower bud development. . Paclobutrazol inhibited shoot and root elongation effectively. Paclobutrazol decreased dry weight of the plant top (trunk, stem and leaves), but increased root dry weight. Paclobutrazol also increased the root diameter by increasing the number of-cortex cells, although the cell diameter was not different. Paclobutrazol affected nutrients distribution; it decreased nutrients in the top part of trees, and increased nutrient in the root. Effects of paclobutrazol in flower bud differentiation was not significant.

Citrus Red Mite Control on ‘4-40’ Satsuma Selection in Louisiana, 1991

Abstract The study was conducted on a plot of‘4-40’ satsuma mandarin trees located at the Louisiana State University Agricultural Center’s Citrus Research Station, Port Sulphur, LA. Pretreatment mite counts were made 11 Jun, and all treatments were applied 13 Jun with the aid of a FMC model 100 CP airblast sprayer and a tractor speed of 3rd low 1200 RPM to generate an operating pressure of approximately 200 psi. The study consisted of 5 treatments with 10 single tree replications from which mite counts were determined by taking 5 leaves per tree and counting the number of live mites on the right bottom half of the leaf and then doubling the count to obtain the number of mites per leaf. After treatment application mite counts were made at 7, 14, 30, 60, 90, and 120 DAT. All miticide spray solutions were buffered to a pH of approximately 6.0 with the addition of Triton AG-44 M (Latron AG-44 M).

ヒ酸鉛がウンシュウミカン果肉中のクエン酸縮合酵素活性に及ぼす影響

The effects of lead arsenate on citrate synthase (CS) activity were examined in order to obtain information on the mechanism of lead arsenate in decreasing the concentration of citrate in citrus fruits, with the hope of finding non-toxic acid-reducing chemicals. Solution of 0.3% lead arsenate was sprayed on satsuma mandarin (Citrus unshiu) trees 3 to 7 weeks after full bloom.Free acidity of juice at harvest was 15 to 36% lower in fruits sprayed with lead arsenate than in fruits unsprayed. Lead arsenate sprays did not affect protein content of the pulp. At the stage when juice acidity increased rapidly, CS activity was lower in the sprayed fruits than in the unsprayed ones. An interrelation between the reduction of CS activity and the reduction of free acidity was observed. A correlation between rate of decrease in CS activity by lead arsenate 9 to 12 weeks after full bloom and rate of decrease in free acidity at harvest season was also seen.When lead arsenate was added to measuring cuvettes containing enzyme extract from unsprayed fruits picked in August, CS activity decreased in proportion to the amount of lead arsenate added to the cuvettes.When fruits began to color, CS activity of sprayed fruits exceeded that of unsprayed fruits. The fact that high CS activity at fruit coloring stage did not increase the free acidity of juice may be explained by the changes in metabolism of organic acids.

ヒ酸鉛がウンシュウミカン果肉中のコエンザイムAに及ぼす影響

The effect of lead arsenate on coenzyme A (CoA) was examined in order to investigate the involvement of CoA in the reduction of free acidity of juice by the chemical in hopes of finding non-toxic acid-reducing chemicals.0.3% lead arsenate solution was sprayed on satsuma mandarin (Citrus unshiu) trees 3 to 5 weeks after full bloom.Total CoA concentration was not affected apparently, but acetyl coenzyme A (AcCoA) concentration decreased meaning a proportional decrease of AcCoA to total CoA. Meanwhile the free acidity of juice in lead arsenate sprayed fruits was 16 to 22% lower than that in unsprayed fruits.The decrease in proportion of AcCoA in total CoA about five weeks after lead arsenate spraying showed a high correlation with the decrease of free acidity of juice at harvest in sprayed fruits. It was suggested that arsenolysis could cause acidity of juice to decrease by reducing production of citric acid.

ウンシュウミカンの開花誘導と生理的変化に及ぼす秋季の気温と地温の影響

Potted satsuma mandarin trees (Citrus unshiu Marc. cv. Okitsu Wase) budded onto trifoliate orange rootstocks were exposed to different air and soil temperatures in the greenhouse or growth chambers and then transferred to constant temperature growth chamber.In Experiment I, the greenhouse air temperature was not controlled but ambient, while the pot soil temperatures were kept at below 15°C, or above 30°C or ambient. Four-year-old trees, exposed to these conditions for three months until December 1, were transferred to a growth chamber kept at 30°C. Trees exposed to soil temperature below 15°C bloomed profusely, whereas, those in pots kept at above 30°C produced much less flowers.In Experiment II, the treatments. which lasted 2.5 months until December 16, combined air and soil temperatures of 15° and 30°C, followed by a constant 30°C in the growth chambers. These four-year-old trees kept at the air/soil temperatures of 30/15°C bore some flowers after they transferred to constant 30°C, but those exposed to 30/30°C were barren of flowers. Trees kept at 15/15°C bore more flowers than did those kept at 15/30°C.In Experiment III, temperature treatments were the same as those in Experiment II except that they lasted three months until December 1. The trees were then defoliated before being transferred to a 25°C of growth chamber. Analysis for gibberellin-like activity in summer leaves and for carbohydrate, nitrogen, and free proline contents in spring leaves were conducted. Observation on the flower development revealed that as in Experiment II, air/soil temperatures of 15/15°C promote flowering, whereas, 30/30°C did not. Gibberellin-like activity was the lowest in the trees that bore the greatest number of flowers, and the highest in leaves of trees that barren of flowers. Starch content of leaves was higher at soil temperature of 15°C than it was at 30°C; sugar content was unaffected by air/soil temperatures. Nitrogen content in leaves was greater at a soil temperature of 30°C than it was at 15°C. The C/N ratio was higher at soil temperature of 15°C than it was at 30°C; it was unaffected by air temperatures. A positive correlation was found between proline content of leaves and the number of flowers produced.Experiment IV conducted in 1989 was a replicate of Experiment III; the results of the two seasons were similar.

ウンシュウミカンの果実及び枝葉中のジベレリン様物質の経時的変化

Changes of GA-like activity in 2 types of spring flush including vegetative and leafy-inflorescence shoots of satsuma mandarin trees were investigated seasonaly. Effects of fruit thinning on GA-like activity were also studied. Results are discussed in relation to flower-bud formation.GA-like activities in leaves and stems of the 2 types of shoots were high in April, followed by a decrease in July, and thereafter showed marked increase until November. In November the activity in leafy-inflorescence shoots was higher than in vegetative shoots.Fruit thinning had an influence on GA-like activity in stems of the spring flush in autumn; early thinning (in May and June) caused lower levels, similar to vegetative shoots, than did late thinning (in August) and non-thinning.These results suggested that endogenous GA levels before morphological flower-bud differentiation play a regulatory role in the modulation of flower-bud formation.

キボシカミキリ由来の天敵糸状菌Ｂｅａｕｖｅｒｉａ ｔｅｎｅｌｌａのゴマダラカミキリに対する病原性と殺虫効果

The use of the entomogenous fungus, Beauveria tenella, isolated from the yellowspotted longicorn beetle, Psacothea hilaris, was evaluated both in the laboratory and in the field for the control of the whitespotted longicorn beetle, A noplophora malasiaca, in citrus orchards. The adult beetle was susceptible to the infection with the spraying of a spore suspension of B. tenella and then killed within 10 days at a spore dose of 10 7/ml, under laboratory conditions. In the field cage test, the application of wheat bran containing B. tenella conidia (10 7-10 8/g of dried wheat bran, 20g/tree) on the soil surface around the trunk of a 5 year old satsuma mandarin tree resulted in 95-100% mortality within 10 days for the adult beetles. A high mortality rate was also obtained by the banding of a polyurethane form containing culture substrates on which B. tenella had been cultured for about 3 weeks, around the lower part of the trunk of the citrus tree. These results suggest that it may be possible to use B. tenella as a biological control agent for the whitespotted longicorn beetle.

ウンシュウミカン樹におけるたんぱく質の分別と春季における消長

The proteins of the stem bark, stem wood and leaves of 23-year-old satsuma mandarin trees were separated into tris-soluble, alkaline-soluble and insoluble proteins. The tris-soluble proteins were separated further into five and six groups, using gel filtration and DEAE-cellulose column chromatography. Variations in the fractionated protein group were examined during spring and summer. Most of the proteins isolated, contributed to nitrogen mobilization in varying degrees. In leaves a protein of molecular weight of about 55, 000 showed the largest decrease. Amino acid analysis of six protein groups from the tris-soluble proteins of the bark showed no difference in their amino acid composition. The nitrogen storage function of proteins is discussed.

ウンシュウミカン樹によるアルギニン-&amp;epsilon;-&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;2&lt;/sub&gt;, 尿素-&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;2&lt;/sub&gt;及びアンモニウム-&lt;sup&gt;15&lt;/sup&gt;Nの代謝

Arginine-e-15N2 was supplied to intact 1-year-old shoots of a 21-year-old satsuma mandarin tree, and arginine-e-15N2, urea-15N2 and ammonium-15N were each fed to excised 2-year-old stem sections. The 15N was traced in the bark, wood, new shoots, and new leaves. Arginine-e-15N2 was steadily metabolized via γ-guanidinobutyric acid in the bark and wood. The 15N of arginine was most markedly incorporated into the glutamine-amide N, but also into glutamine-amino N, alanine and γ-aminobutyric acid. Some 15N was also used for proline formation. The labelling patterns of amino compounds when urea-15N2 or ammonium-15N was fed were both similar to when arginine-e-15N2 was fed. This finding strongly suggests that the 15N of arginine-e-15N2 is used for amino compound synthesis via urea and/or ammonium. Arginine-e-15N2 was translocated, and appeared in an unmetabolized form in new shoots where it was incorporated into protein. The 15N of arginine was also transferred to other amino compounds, and then incorporated into protein in new shoots. Several differences in N metabolism were found between the bark and wood: whatever the source of 15N, asparagine-amino N had a higher 15N enrichment than aspartic acid in the bark, but a lower enrichment in the wood. Glutamine, asparagine and proline were more actively synthesized and accumulated in the bark, while in the wood, arginine was.

ウンシュウミカン樹の切り枝における&lt;sup&gt;14&lt;/sup&gt;C-アルギニン及び&lt;sup&gt;14&lt;/sup&gt;C-プロリンの代謝

Arginine and proline, which are the major forms of soluble reserve N, were fed singly in uniformly labelled 14C-form to excised 2-year-old stem sections with a new shoot, to wood sections, and to burst buds from a 21-year-old satsuma mandarin tree. Metabolism was studied by radioassay and autoradiography.In stem sections with a new shoot, both 14C-compounds were metabolized to acidic and neutral components, insoluble components, and 14CO2. This conversion occurred to a greater extent in sections fed with arginine than with proline. When 14C-arginine was fed, the highest 14C-activity in the cationic fraction of stem sections, bark, wood and new shoots was found in γ-guanidinobutyric acid, followed by γ- aminobutyric acid and proline; low levels of 14C was also found in ornithine and trace amounts in citrulline. These findings demonstrate that arginine is metabolized by at least two routes: via ornithine and via γ-guanidinobutyric acid. In every organ, the major metabolic products of 14C-proline were pyrrolidone-5-carboxlic acid, glutamic acid, aspartic acid, asparagine, an unidentified compound(U5 in Fig. 4), γ-aminobutyric acid and arginine. The basic metabolic pathways in the conversion of both 14C-compounds were the same in burst buds, new shoot, bark and wood, although there was a slight difference autoradiographically.

ウンシュウミカン樹の春梢形成に用いられる貯蔵窒素の形態と貯蔵部位

To elucidate the form and localization of nitrogen reserves in the satsuma mandarin tree (Citrus unshiu Marc.), the nitrogenous compounds were analyzed before (February) and after (July) new shoot formation using a 21-year old tree.Total N contents decreased in both the bark and wood during the sprouting period. Greater decreases in the content on a dry weight basis were found in parts with higher levels of nitrogen, i.e., leaves, shoots and fine roots. The decreases in the total N contents suggest that the wood of large branches, the trunk and big roots are main nitrogen reservoirs for new shoot development.The nitrogen was reserved mainly as protein, free proline, arginine, and asparagine. Protein decreased in parallel with total N in various parts. Proline decreased markedly in the leaves and bark of shoots; arginine in wood of shoots; asparagine in bark of fine roots.No storage protein characterized by a high content of specific amino acid, e.g., proline and/or arginine, was found in satsuma mandarin tree.

ウンシュウミカン樹の芽, 葉, 皮質部及び木質部における主要窒素化合物の季節的消長

Buds, leaves and 2 to 3-year-old bark and wood were sampled from 21-year-old satsuma mandarin trees (Citrus unshiu Marc.) throughout the year and analysed for total nitrogen, 70% ethyl alcohol soluble and insoluble N, amino acids, mainly arginine and proline, and amides. Many nitrogenous components showed seasonal variations in their content. In old parts, it was the highest in April, the sprouting season, and the lowest in July, the final stage of new shoot development, while it was lowest in September in new leaves. Bark and wood showed temporary increases in the content of total and soluble N, free proline, and especially free arginine during the sprouting period from late March to mid April, and then declines in insoluble N. Buds, on the other hand, showed a marked decrease in proline together with a drastic increase in arginine during the sprouting period. These findings suggest that the soluble N components, such as proline and arginine, are used first for new shoot development, followed by the insoluble N. In old leaves, most of these components began to decrease in early May and the percentage decline of total N from early May to July was about 16% on a dry weight basis, about 40% of which was accounted for by the loss of free proline N. On the whole, all of these components increased in all parts of the tree from autumn to winter. The increases of proline in bark and leaves were particularly marked.

ウンシュウミカン樹の導管液に含まれる窒素化合物の季節的消長

Amino acids, amides and nitrate were determined in the xylem sap obtained by the vacuum extraction from sections of 2 to 3-year-old wood of 21-year-old satsuma mandarin trees (Citrus unshiu Marc.), and seasonal variations in their content were followed throughout the year. The main nitrogenous compounds identified were proline, arginine, asparagine and nitrate, all of which showed seasonal variations in their content. Proline showed a slight increase in April, the early stage of new shoot development, then a sharp decrease until early June, and again an increase from October to December. Arginine showed a similar seasonal variation to that of proline. Asparagine showed 2 peaks, one in mid May, the other in late July. Nitrate had a similar variation to that of asparagine. Other amino acids showed smaller variations compared with the above-mentioned compounds.

冬季ウンシュウミカンによる硝酸の還元および同化

In the coldest season, uptake, reduction, organization and polymerization of 15N-nitrate by a satsuma mandarin tree (Citrus unshiu Marc.) were examined. A satsuma mandarin tree was capable of nitrate-uptake and reduction to amino acids in a low temperature regime (minimum temp. -4°C, maximum temp. 9°C. mean temp. 2.5°C in both air and gravel bed). Nitrate reductive activity of fine roots in vivo showed 24% of the maximum activity at 5°C and 10% at 0.5°C. No accumulation of nitrate was found in the fine roots.Asparagine was most abundantly formed from 15N-nitrate in the fine roots in cold conditions, followed by γ-aminobutyrate, alanine, aspartate and glutamate. Proline formation was relatively low as compared with that in summer. In the leaves 15N-amino acids were formed in negligible amounts in cold temperatures, showing a sharp contrast to the intensive incorporation of 15N into amino acids in summer.Incorporation of the newly synthesized amino acids into protein proceeded steadily in the fine roots. Leucine (+isoleucine), phenylalanine, arginine and proline were abundantly incorporated as compared with in summer. This indicates that protein formed in the cold season is qualitatively different from that formed in summer.

ウンシュウミカンによる冬季吸収窒素(&lt;sup&gt;15&lt;/sup&gt;N)の分配と春季における再配分

The amount of 15N-nitrate taken up by a satsuma mandarin tree (Citrus unshiu Marc.) in the coldest season (minimum temp. -3°C, mean temp. 3°C) was about one tenth of that taken up in summer (maximum temp. 28°C, mean temp. 23°C). In gravel culture, 90% or more of total nitrogen taken up during the cold season was kept in the roots, especially in the fine roots. A large portion of it began to translocate upwards after late February/early March and was used, preferentially, to build up new organs, such as flower, leaves and twigs. This accounted for 40% of the total nitrogen taken up during the cold season; another 36% was partitioned to the existing organs in the top and 24% to the roots. This partitioning pattern is close to that in soil culture. One-year-old leaves acted as a sink for 15N even at the developing stage of flushed shoots. Data on 15N abundances in the amino acids and nitrate indicate that nitrate, which is taken up in winter, translocate upward mainly as nitrate and asparagine in the following spring.