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Rebecca L. Darnell and Keith B. Birkhold

Rabbiteye blueberry (Vaccinium ashei Reade) cultivars differ in timing of floral and vegetative budbreak and in final fruit size. For example, `Bonita' exhibits concomitant floral and vegetative budbreak and has relatively large fruit size, while floral budbreak precedes vegetative budbreak in `Climax' and fruit size is smaller. Mobilization of carbohydrate before and during fruit development in `Bonita' and `Climax' rabbiteye blueberries was examined to determine if differences in carbohydrate availability between these two cultivars were correlated with differences in fruit size. Root dry mass (DM) of both cultivars decreased from dormancy (31 days before anthesis) through fruit development. Sugar concentrations in roots and stems of both cultivars decreased significantly between dormancy and anthesis, then remained relatively steady throughout fruit development. Starch concentrations in roots and stems of `Bonita' decreased significantly between dormancy and anthesis. The extent of total starch depletion in `Climax' was similar; however, the decrease was more gradual, extending from dormancy to 28 days after anthesis (DAA); at which time, vegetative budbreak in `Climax' occurred. Thus, although total reserve carbohydrate pool sizes were similar between the two cultivars, remobilization patterns were different, resulting in increased starch mobilization in `Bonita' compared to `Climax' in the period leading up to anthesis. Concentration of 14C from reserve carbon sources was similar in flowers of both cultivars at anthesis. These values declined throughout fruit development as a result of dilution of the labeled carbon by unlabeled carbon from current photosynthesis. There was a sharper decline in 14C concentration of `Bonita' fruit compared to `Climax' fruit between anthesis and 51 DAA. This, coupled with differences in timing of vegetative budbreak between the two cultivars, suggests that `Bonita' fruit were accessing current (unlabeled) assimilate earlier (i.e., before 51 DAA) than `Climax' fruit. Smaller fruit size in `Climax' compared to `Bonita' may be a consequence of a decrease in reserve carbohydrate mobilization to `Climax' flower buds before anthesis relative to `Bonita', as well as a delay or reduction in the availability of current carbohydrates to developing `Climax' fruit between anthesis and 51 DAA.

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Karen Mesa, Sara Serra, Andrea Masia, Federico Gagliardi, Daniele Bucci, and Stefano Musacchi

Annual accumulation, mobilization, and allocation of carbohydrates in fruit trees among individual organs is greatly affected by the availability of stored carbon reserves, assimilates from photosynthesis, and crop-load within a tree ( Keller and

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Xuan Liu and Catherine Grieve

Two statice cultivars, Limonium perezii cv. Blue Seas and L. sinuatum cv. American Beauty, were grown in greenhouse sand tanks to determine the effect of salt stress on carbohydrate accumulation and partitioning. For the first experiment, irrigation waters were prepared to simulate typical saline-sodic drainage effluent in the San Joaquin Valley of California with electrical conductivities of 2.5, 7, 11, 15, 20, 25, and 30 dS·m−1. A second experiment compared responses to two types of irrigation waters with salinity levels of 2.5, 6, 8, 10, 12, 16, and 20 dS·m−1: 1) San Joaquin Valley drainage waters, and 2) solutions mimicking concentrations of Colorado River water, a major irrigation water source for southern California. In addition to the presence of myo-inositol and three common sugars (fructose, glucose, and sucrose), chiro-inositol was for the first time isolated and identified in leaf and root tissues of both Limonium species. As salinity increased from 2.5 to 30 dS·m−1, leaf chiro-inositol concentration increased from 6.4 to 52.8 and from 2.6 to 72.9 μmol·g−1 dry weight for L. perezii and L. sinuatum, respectively, suggesting that chiro-inositol contributes substantially to osmotic adjustment in the stressed plants. Meanwhile, leaf myo-inositol concentration remained low in both species and showed little response to salinity. Before salt stress, the seedlings contained little chiro-inositol, indicating that salt enhanced chiro-inositol synthesis per unit of biomass formation. Significant (P ≤ 0.05) increasing trends for fructose and glucose and a decreasing trend for sucrose with increasing salinity were observed in the leaves of L. perezii but not L. sinuatum. As a result, the leaves of L. perezii had higher glucose and fructose but lower sucrose levels than that of L. sinuatum. However, no significant (P > 0.05) salt effect was found on the sum of the three common sugar concentrations in either species. Therefore, the accumulation of chiro-inositol resulted in a change in carbon partitioning among the soluble carbohydrates (i.e., the ratio of leaf chiro-inositol over a sum of the three common sugars rose from 0.034 to 0.29 dS·m−1 and from 0.012 to 0.32 dS·m−1 for L. perezii and L. sinuatum, respectively, as salinity increased from 2.5 to 30 dS·m−1). Salt stress did not affect starch accumulation and caused no carbon reserve deficiency. Furthermore, it was observed that salinity increased chiro-inositol phloem transport. The chiro-inositol response might be a physiological process for Limonium salt adaptation. The types of saline irrigation waters (i.e., sodium sulfate-dominated waters vs. a sodium chloride system) appear to have little effect on carbohydrate accumulation and partitioning in L. perezii.

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Jer-Chia Chang and Tzong-Shyan Lin

, suggesting that the clusters on these thicker branches were able to draw and access much greater amounts of carbon reserves for sustaining fruit growth. Fruit retention of shoots with three flushes in both of the present girdling experiments was similar to

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Laura Elisa Acuña-Maldonado and Marvin P. Pritts

maintained in the field through July and total yield per plant was measured during fruiting. Expt. 2: Increasing carbon reserves. On 10 May 2001, 60 plants were fertigated weekly through the irrigation with 7 m m N using Peters ® 20N–8.7P–16.6K with

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Teresa Eileen Snyder-Leiby and Shixiong Wang

normal carbon cycling and may severely limit the carbon reserves in roots over several seasons. The occurrence of lipid bodies within chloroplasts is also associated with late-season senescence ( Smith et al., 2000 ). Lipid bodies are seen earlier than

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Amir Rezazadeh and Eric T. Stafne

break and carbon reserves in two co-occurring Mediterranean oaks Plant Biol. 11 142 151 Stafne, E.T. Alexander, K. 2017 A web-based chill hours app for fruit growers J. Ext. 55 6 6TOT11 5 Oct. 2018. <

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Gerhard C. Rossouw, Jason P. Smith, Celia Barril, Alain Deloire, and Bruno P. Holzapfel

.C. Candolfi, M.P. Koblet, W. 1994 Retranslocation of carbon reserves from the woody storage tissues into the fruit as a response to defoliation stress during the ripening period in Vitis vinifera L Planta 192 567 573 Castellví, F. Perez, P.J. Villar, J

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Yan Xu and Bingru Huang

leaves and their relationship to senescence and remobilization of carbon reserves in rice subjected to water stress during grain filling Planta 215 645 652 Yang, S.F. Hoffman, N.E. 1984 Ethylene biosynthesis and its

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Mwanarusi Saidi, Francis M. Itulya, Joseph N. Aguyoh, and Mathieu Ngouajio

plants, offering a higher photosynthetic surface. Hence, there is better accumulation of carbon reserves for grain formation. Similarly, Karikari and Molatakgosi (1999) recorded higher grain yield with 50% defoliation compared with 75% defoliation of