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over time ( Flore and Layne, 1999 ). Wünsche et al. (1996) showed that total dry matter accumulation and tree yield efficiency [kilogram of fruit produced by a tree per trunk cross-sectional area (TCSA) in centimeters squared] are related to the total

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Dry matter accumulation and partitioning in plants of Zantedeschia Spreng. `Best Gold' aff. Z. pentlandii (Wats.) Wittm. (syn. Richardia pentlandii Wats.) were quantified under a range of temperature and photosynthetic photon flux (PPF) regimes using plant growth analysis. The relative rate of dry matter accumulation [relative growth rate (RGRM), g·g-1·d-1] was highly correlated with the partitioning of the daily increment of dry matter into leaf tissue [leaf matter partitioning (LMP), g·d-1 per g·d-1]. In contrast, a poor correlation existed between RGRM and net assimilation rate (NAR, g·m-2·d-1). Maximum values of RGRM increased linearly with increasing temperature (from 13 to 28 °C), with a base temperature of 2.1 ± 2.7 °C. The optimum temperature for growth was PPF dependent with maximum total plant dry mass occurring under high PPF (694 μmol·m-2·s-1) at 25 °C. However, as the plant responded to PPF by altering LMP, final total plant dry mass was actually greater under the low PPF regime (348 μmol·m-2·s-1) at temperatures <22 °C. The optimum temperature for dry matter accumulation was close to the average daily air temperature during the growing season for the natural habitat of the parent species. Similarly, the greater dry matter accumulation under the combination of either low PPF and cooler temperatures or high PPF and warmer temperatures was paralleled by the diversity of PPF habitats in the natural open grassland and forest margin the parent species occupies. It is therefore suggested that Zantedeschia `Best Gold' is well adapted to optimize growth under these environmental conditions.

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Abstract

Changes in dry weights, total N, nitrate N, and reduced N in the aboveground parts of Chrysanthemum × morifolium Ramat. ‘Gt.#4 Indianapolis White’ were determined at intervals from planting of rooted cuttings until inflorescence maturity. Plant dry matter accumulation rate (mg/day) increased in the combined aboveground tissues with each successive harvest, while N accumulation rate (mg N/day) peaked early in the plants’ growth and decreased after the 6th week of growth. Continued dry matter accumulation in the leaves during inflorescence development suggested that photosynthetic capacity was in excess of the inflorescences’ needs. In contrast, a loss of N from the vegetative portions, and primarily the stems plus petioles, indicated that newly absorbed N was inadequate to meet the demands of the developing inflorescence. The partitioning of N between NO3 and reduced N indicated that enzymatic reduction of NO3 did not limit the availability of reduced N during inflorescence development.

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`Smooth Cayenne' pineapple plants were propagated from suckers of uniform size. The plants were grown in containers, and a large percentage of them naturally flowered in synchrony at 13 months. This provided an opportunity to study the accumulation and partitioning of dry matter in fruiting and nonfruiting plants of uniform age. Six plants with or without fruit were harvested when the syncarps developed color. Plants and fruit were separated into crown, syncarp, slips, peduncle, leaves, stems, and roots. Plants without fruit were separated into leaves, stem, and roots. There were no suckers, and the stem was divided at the ground level. Leaves were counted and all tissue was dried to a constant weight. Total dry matter accumulation and the ratio of below- to above-ground dry matter was not different between the two groups of plants. The plants were similar in size and leaf number at the time of flowering, but the number of leaves was fixed at that time in the plants with fruit. As a result, plants that did not flower had about twice as many leaves as the plants with fruit at the termination of the study. Thus, the vegetative growth of continued at a rate similar to that of the reproductive structures of the plants that did flower.

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A greenhouse experiment was conducted to examine the relationship between tissue B concentration and dry matter accumulation in broccoli. `Pirate ' was grown in fine silica sand and supplied nutrient solutions containing 0.2, 0.8, 1.4, 2.0, 2.6, 3.2, 3.8, and 4.4 mg·liter-1 B. Plants were sampled for the 5th, 10th, and 15th fully expanded mature leaf, and plant material was collected' for dry matter measurement and boron analysis at each growth stage. The lowest specific leaf weights for the 5th, 10th, and 15th leaves were obtained with the 4.4 mg·liter-1 treatment. At maturity, leaf, petiole stalk, and shoot dry weights were lowest at 4.4 mg·liter-1 B. Treatments supplying less than 3.2 mg· liter-1 B, resulted in a notable decrease in tissue B concentrations from the 5th to the 15th leaf. There was a linear increase' in B concentration in all leaf tissue samples as B treatment increased. At maturity, optimum B concentrations of 531.5, 73.7, 29.8, and 64.6 mg·g-1 were found for the lamina, petiole, stalk, and head, respectively. These concentrations occurred in plants receiving treatment levels of 2.0-3.8 mg·liter-1 B.

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Abstract

Weekly foliar fertilizer applications of 10 ppm NO3-N [as Ca(NO3)2] or NH4-N [as (NH4)2SO4] significantly reduced dry matter, N accumulation, and yield of ‘Blue Lake 274’ snap bean (Phaseolus vulgaris L.) grown in solution culture. The reduction in dry matter and N accumulation were greatest with the NH4-N vs. the NO3-N foliar treatment. Data obtained in this study indicates that the cultural practice of applying NH4 or NO3 fertilizer through an overhead irrigation system may reduce snap bean yield.

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We investigated the development of leaf area (LA) and the distribution of dry matter within branches of 25-year-old, alternate-bearing `Kerman' pistachio (Pistacia vera L.) trees that were in their natural “on” (heavy) or “off” (light) bearing cycles to determine the immediate and delayed effects of fruiting on shoot growth. Compared to “off” trees, individual leaves of “on” trees were greater in number and expanded twice as fast during the first 30 days after full bloom (FB) (FB + 30). Mature, fully expanded leaves of “on” trees were smaller (124.1±3.26 cm2) than those from “off” tree (163.3±3.40 cm2), indicating delayed demands of fruiting on initial leaf growth. Total LA per current shoot was greater in “on” than “off” trees because shoots of “on” trees averaged eight leaves, compared with six for “off” trees. More inflorescence buds per shoot (seven vs. three buds) abscised from “on” than from “off” trees. About 60% of the young developing nuts had abscised by FB + 30 when they weighed <250 mg each and another 25% abscised between FB + 30 and FB + 60 when individual nuts weighed ≈400 mg. The average total dry mass (DM) of individual branches of “on” trees increased 1322% (5·9 to 83·9 g) compared to 598% (4·2 to 29·3 g) in “off” trees. Besides nuts, leaves accumulated the greatest amount of dry matter within individual branches followed in decreasing order by current wood, 1-year-old wood, and inflorescence buds. DMs of individual leaves of “on” trees averaged between 15% and 48% greater than leaves of “off” trees. “Off” trees invested 4.6 g of dry matter into individual 1-year-old wood and 2.1 g into current wood. “On” trees, however, invested 1.3 g of dry matter into 1-year-old wood and 4.3 g of dry matter into current wood. One-year-old wood was an important major source of carbohydrates for developing leaves, current wood, rachises, and nuts. The immediate demands of fruiting on individual components of a branch were measured as losses in DMs. Individual leaves, current wood, 1-year wood, and rachises lost 1.1%, 0.3%, 1.1%, and 1.0%, respectively, of the average total DMs of individual branches of “on” trees. This loss was equivalent to 5.7%, 5.9%, 26.7%, and 16.4%, respectively, of the seasonal average peak DMs of the respective individual components of the branch.

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Abstract

Field-grown early forsythia (Forsythia ovata Nakai) plants were harvested every 2 weeks from 15 Apr. through 30 Nov. 1980 and from 15 Aug. to 15 Oct. 1981. Following harvest, plants were divided into roots, shoots formed during previous growing seasons, current season's shoots, and foliage. Plant parts were oven dried, weighed, and analyzed for N, P, and K. Nonlinear regression models of seasonal dry weight and N, P, and K accumulation observed in plants and component parts indicated that maximization of these factors occurred from mid-September to mid-October. Regression analyses indicated statistically significant relationships between observed and estimated dry weights and nutrient element content of each plant part. Harvesting the foliage at the time of peak accumulation of these factors provided the most accurate estimation of dry weight and N, P, and K of maximum seasonal accumulation in whole plants.

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Dormant, 2-year-old, own-rooted `Chambourcin' grapevines (Vitis sp.) were subjected to two levels of root pruning (none, two-thirds roots removed) and were subsequently trained with either one or two canes. Vines were destructively harvested at bloom and after harvest when dormant to determine the effect of stored reserves in the root and competition between shoots for these reserves on vine growth and berry development. Removing 78% of the root system reduced shoot elongation and leaf area more effectively than did increasing the number of shoots per vine from one to two. Root pruning reduced the elongation rate of shoots for 45 days after budbreak, whereas increasing the shoot number reduced the shoot elongation rate for only 20 days after budbreak. A positive linear relationship was observed between leaf area per shoot at bloom and the number of berries per single cluster. These results demonstrate the importance of 1) the roots as a source of reserves for the initial development of vegetative tissues in spring, and 2) the rapid development of leaf area on an individual shoot for high set of grape berries on that shoot.

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yield increased when the RZT was cooled to 25 °C in high air-temperature conditions. The increases in growth and fruit yield were caused by phycological activities, such as root activity, stomatal conductance ( g S ), and dry matter partitioning ( Dodd

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