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  • Author or Editor: K. Ryugo x
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To learn why embryos of early ripening stone fruits abort or fail to germinate, the growth and nutrition of developing seeds of `Independence' nectarine and `Fay Elberta' peach (Prunus persica, Batsch.) were compared. Seeds were collected at weekly intervals, beginning 2 months after full bloom until the fruits were ripe. Fruit diameter, seed and embryo lengths, and fresh weights of nucellus and endosperm were recorded. Parts of the seeds were analyzed for soluble carbohydrates, fats, and total N. At the same phonological stages of fruit development, concentrations of these seed fractions were nearly equal for both cultivars. Percentage composition of all fractions varied with time, but increased on a per-seed basis. Sucrose was the major soluble carbohydrate in embryos of both cultivars. Nitrogen content of the embryos, on a percent dry matter basis, gradually decreased from the 12th week after full bloom to harvest.

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Authors: and

Abstract

Buds along dormant canes of kiwi (Actinidia chinensis Planch. cv. Hayward) vines are potentially 100% reproductive. Flowering potential declines sharply at budbreak under the influence of actively growing shoots.

Open Access
Authors: and

Abstract

Large clonal variations and seasonal fluctuations were observed in gum and mucilage content of hulls from 17 cultivars of almonds, (Prunus amygdalus Batsch.). Analysis of ethanol insoluble substances revealed that their content of neutral sugar and uronic acid residues were nearly the same. Additional analyses indicated a variety of polysaccharide types in the gum samples.

Open Access
Authors: and

Abstract

Fruit on shoots trained to grow above the main foliar canopy (exposed) of 6-year-old ‘pergola’-trained kiwifruit vines were significantly larger than fruit on shoots trained to grow below the canopy (shaded). Fruit size increased with seed number in both fruit groups, but fruit from exposed shoots were consistently larger than shade-grown fruit with the same seed count. Shade-grown shoots had smaller basal diameters and less dry matter than exposed shoots. Winter mortality among buds on formerly shaded and exposed shoots was 34% and 5%, respectively. Formerly shaded shoots had fewer mixed buds with less flowers per inflorescence than exposed shoots the following spring.

Open Access
Authors: and

Abstract

Radioactivity in almond seedlings treated with (2-chloroethyl)-trimethylammonium chloride (CCC, Cycocel) labelled in the 1 and 2 positions was initially translocated acropetally from the fully expanded treated leaf to younger leaves and growing point. After 2 days, basipetal movement occurred, establishing a shoot to root gradient for 6 days after which 14C became randomly distributed within the plant. 14CO2 was evolved in the highest amount within 2 hr after application, then the rate diminished until the 4th day; the amount evolved thereafter, until the 10th day, was fairly constant. Paper chromatography of methanolic extracts disclosed 17 known amino acids and an unidentified ninhydrin-positive substance, plus malic and citric acids which were all radioactive. Two other radioactive bands which co-chromatographed with choline and 2-chloroethylamine were also detected in extracts of treated leaves. Based on these observations, a tentative pathway of Cycocel catabolism is proposed.

Open Access

Abstract

Ascorbic acid content in kiwi fruit (Actinidia chinensis Planch, cv. Hayward) decreased by 20% when the pulp was boiled for 2 hours. Frozen samples when left to thaw at room temperature also lost ascorbic acid to an equal degree; whereas, homogenization for an hour resulted in complete oxidation of ascorbic acid to dehydroascorbic acid. Reacting polyphenoloxidase prepared from mature kiwi fruit with extracts of the same revealed that the latter contained low amounts of polyphenols. Since ascorbic acid inhibits the oxidation of many polyphenols, our finding may account for the lack of browning reaction in tissues of bruised fruits.

Open Access

Abstract

Movement of 14C-photosynthates in bearing and nonbearing branches of pistachio (Pistacia vera L.) was examined during the period of inflorescence bud abscission. Most of the 14C transported from leaves accumulated in developing nuts. Inflorescence buds on defruited trees accumulated twice as much 14C-photosynthate as those on fruiting trees. Inflorescence buds competed poorly against the developing fruit for photosynthate and this might be responsible for inflorescence bud abscission and resultant alternate bearing.

Open Access

Abstract

The CO2 assimilation characteristics of walnut leaves (Juglans regia L.) were measured on excised branches using controlled, open-system, infrared gas analysis techniques in the laboratory and on large bearing trees with a CO2 depletion method in the field. The mean maximum rate of net CO2 assimilation measured by both techniques was 1.3 nM CO2 cm-2s-l on a leaf area basis of 6.0 nm CO2 mg N-1s-1 on a leaf nitrogen basis. Leaves approached light saturation at 600-800 µEs-1m-2, and exhibited an otpimum range for CO2 assimilation at 18 to 26°C. CO2 assimilation increased linearly with increases in intercellular CO2 concentrations between 60-250 µl liter-1. The daily pattern of field CO2 assimilation was highly correlated with leaf conductance to H2O but exhibited a midday depression that was independent of the daily pattern of incident photosynthetic photon flux density at the surface of the leaves.

Open Access

Abstract

Leaf number, area and chlorophyll content, and specific leaf weight were greater in light-exposed spurs of ‘Hartley’ walnut (Juglans regia L.) than those grown in the shade. Starch content increased early in the season in shaded spurs, but the accumulation ceased while the nuts stored dry matter. In exposed spurs, starch increased steadily until harvest. After harvest, starch level decreased in exposed and shaded spurs. Light intensity did not affect percentage composition of spurs and fruit with respect to carbohydrates or oil content in kernels. Increased exposure to light resulted in higher percentage of return bloom, greater spur growth, and more pistillate flowers per spur the following season.

Open Access

Abstract

When walnut trees were bark-grafted leaving nurse-limbs, xylem exudation was observed at a few slashes made low on the tree but not at graft junctures. Scions grew equally well on trees with slashes (74%) as those without slashes (86%). When the same treatments were made without nurse-limbs, 83% of the scions grew where exudates did not appear but only 21% grew where xylem sap exuded nearby. No dormant patch-bud placed in August-September grew the following spring if the sap flowed from any side of the patch, whereas 96% grew where no exudation occurred. Analysis of the xylem exudate revealed the presence of substances which inhibited growth of walnut calli and cucumber seedlings. A strong zone of inhibition on paper chromatograms coincided with the Rf of juglone, a powerful toxin which was identified by absorption spectrophotometry.

Open Access