During water stress, non-drought acclimated (NDA) rose plants had a lower leaf water potential, stomatal conductance (g), and net photosynthesis than drought acclimated (DA) plants. DA plants conserved water (lower g prior to water stress) which allowed for better maintenance of gas exchange and water relations than NDA plants during stress. Osmotic adjustment (lower Ψπ) occurred in DA plants which allowed for greater turgor than NDA plants during stress. DA leaves had decreased leaf sucrose and total soluble carbohydrates. Mycorrhizal (VAM) plants colonized with Glomus intraradices had higher relative growth rates, net assimilation rates and water use efficiency than noncolonized (NVAM) plants, regardless of stress. Root growth was greater in VAM plants, but there were no differences in shoot mass, leaf area and macro-elements (P, N, K, Ca, Mg) with NVAM plants. DA-VAM plants had higher sucrose and total soluble carbohydrates than DA-NVAM plants. DA enhanced mycorrhizal colonization. Any mycorrhizal enhancement of plant water relations was not attributable to higher leaf P or confounded by differences in plant transpirational surface.
la Rosa et al., 2004 ; Díaz et al., 2007 ). They have also been used in pollination studies, identifying cases of full self-incompatibility ( Díaz et al., 2006a ; Mookerjee et al., 2005 ) and cross-incompatibility ( Díaz et al., 2007 ; Seifi et al
vitro propagation are scarce. There are some reports for Beaucarnea recurvata ( Bettaieb et al., 2008 ; Osorio-Rosales and Mata-Rosas, 2005 ; Reyes et al., 2013 ; Sajeva et al., 1994 ; Samyn, 1997 ), Beaucarnea gracilis ( Osorio-Rosales and Mata-Rosas
established on 1 May and 21 Aug. 2007 for a respective late spring and fall bacterial spot trial at the University of Florida's PSREU in Citra, FL. For both trials, tomato seedlings of the cv. Bella Rosa were transplanted at 46-cm spacing to raised, fumigated
point) had four hybridizations (two with each dye: Cy3 and Cy5) with independent biological samples and as much balance as possible ( Rosa et al., 2005 ). The resulting microarray experiment set-up can be seen as a combination of eight loops, with four
Prestorage treatment of avocado fruit (Persea americana Mill. cv. Fuerte) with a low-O2 atmosphere (3% O2 + 97% N2) for 24 hours at 17C, significantly reduced chilling injury (CI) symptoms after storage at 2C for 3 weeks. Fruit softening was also delayed by this treatment. The treated fruit had lower respiration and ethylene production rates during storage at 2C and subsequently at 17C. Electrolyte leakage was significantly lower in peel disks from treated fruit. Reducing power, expressed as total sulfhydryl groups, was higher in the peel and pulp of low-O2-treated fruit. The amount of peel chlorophyll was inversely correlated with the severity of CI symptoms.
A large group of horticulture species are propagated vegetatively through shoot-tip cuttings harvested from stock plants and planted to form adventitious roots. Adventitious rooting leads to establishing a carbohydrate sink in the region of root regeneration that is highly dependent on energy and carbon skeletons. We hypothesized that the timing of exogenous applications of cytokinin (CK) and boron (B)–molybdenum (Mo)-based products during adventitious root development can affect the flow of sugars from leaves to sinks, carbon allocation to the adventitious roots, and the quality of rooted cuttings. During this project, we aimed to determine if the application time of a CK/B-Mo-based product during the adventitious root development of unrooted cuttings would impact the source-to-sink relationship and, hence, affect plug growth and quality. A sink-strengthening commercial product based on cytokinin, B, and Mo was applied at four plug development stages plus a negative control as follows: T1, plants without product (control); T2, sticking stage (starting 24 hours after the sticking); T3, callus formation stage; T4, root development stage; and T5, toning stage. The root and shoot lengths and dry matter, number of leaves, leaf chlorophyll content, root-to-shoot ratio (based on dry matter), and nonstructural carbohydrate contents were measured. The timing of the application of the product impacted the root development, quality of the cuttings, and nonstructural carbohydrate content. Product application during the adventitious root dedifferentiation and induction phases (T2) resulted in the shortest root and shoot lengths, lowest dry matter accumulation, lowest nonstructural carbohydrate contents, and some phytotoxicity. Application during the initiation phase (T3) resulted in greater root length, total dry matter, and total soluble sugar contents compared with the control. Application during the expression phase (T4) resulted in the largest root length and mass and the highest sucrose contents. Applying the product when the roots had grown and reached all the edges of the growing media (T5) did not have any benefits compared with the control. This study provides new insights into the application timing of exogenous CKs, B, and Mo to generate a well-toned rooted coleus cutting and potential explanations in relation to nonstructural carbohydrate metabolism.
Heritability of length of the reproductive period and rate of seed mass accumulation in beans (Phaseolus vulgaris L.) was estimated using 170 randomly derived F6 and F7 lines from three populations evaluated in the field in Puerto Rico and Honduras during two growing seasons. Narrow-sense heritability for length of reproductive period ranged from moderate (0.43) to high (0.83), and transgressive segregation for shorter and longer reproductive period was observed for the three populations. Heritability of rate of seed mass accumulation was low (0.24) to intermediate (0.49). Lines with high yield potential, which matured 4 to 7 days earlier than the later parents L227-1 and `Catrachita', were selected. Most of the superior lines combined earlier maturity with high yield potential by having greater rates of seed mass accumulation than the early parents `Cuarentena' and `Cuarenteño'. Low to intermediate heritabilities for rate of seed mass accumulation suggest that selection for this trait would be more effective by evaluating advanced generation lines in replicated trials. Several lines yielded significantly more than L227-1 or `Catrachita' by combining long reproductive period with fast rate of seed mass accumulation.
Bananas have a short shelf life after ethylene treatment and there is a high commercial demand to increase the storage life of individual clusters at the retail stage. To extend the shelf life of ethylene-pretreated banana, two different forms of modified atmosphere packaging (MAP) were used. In the first, individual clusters of ethylene-pretreated bananas were stored in a range of microperforated polyethylene (PE) bags (25 μm) creating various MAPs. Storage in PE bags with low microperforation (PE8) that created an atmosphere with 11% CO2 and 12% O2 was the most effective treatment for delaying banana ripening. The banana clusters kept firmer with nice peel color after 1 week at 20 °C, but the humidity inside the bags caused some decay development on the crown cut. In the second type of MAP individual clusters of ethylene-pretreated bananas were stored in air-evacuated PE bags (80 μm) under light vacuum (550 mm Hg) for short periods of 24 to 48 hours followed by storage in the same PE bags after releasing the vacuum. Storing bananas in air-evacuated bags for 24 to 48 hours reduced O2 levels to 1% and increased the production of CO2 up to 30%, but perforating the bags dramatically reduced the CO2 level to around 9% and increased the O2 level to 12%. Storing ethylene-pretreated banana clusters under vacuum for a limited time (24 to 48 hours), did not cause any damage, although the levels of acetaldehyde (AA) and ethanol increased dramatically. The AA and ethanol levels of 150 and 300 μL·L–1, respectively, that accumulated in the PE bags did not cause any off-flavors; on the contrary, the taste panelists preferred these bananas. Adding ethylene absorbents (EAs) to the air-evacuated PE bags reduced the ethylene levels as well as the AA and ethanol levels in the bags, which indicate that EAs also absorbed the AA and ethanol volatiles. Storing ethylene-pretreated banana clusters under vacuum for 24 to 48 hours was the most effective treatment for delaying ripening and senescence in yellow bananas (stage 3 to 4).