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‘Songold’ plums (Prunus salicina Lindl.) were harvested at optimum and post-optimum maturity with a flesh firmness of 64 and 44 N, respectively. After cold storage for 10 days at −0.5 °C, followed by 18 days at 7.2 °C, the plums were ripened for 14 days at 10 °C. The fruit was analysed for soluble solids, internal conductivity, pectic composition and viscosity of water soluble pectin at eight examination stages during storage and ripening. Insoluble pectin levels declined during cold storage and ripening while soluble pectin levels increased to make up the difference. Neither harvest maturity nor storage time had a significant effect on the concentration of calcium pectate, and this pectic fraction did not appear to influence development of gel breakdown (GB). Water soluble pectin and availability of cell fluids, as indicated by viscosity and internal conductivity, respectively, indicated a high gel potential in plums of both maturities, but at different stages during storage and ripening. Significant levels of GB developed only in plums harvested at post-optimum maturity. In this fruit, significantly higher sugar levels and loss of cell membrane integrity early in storage probably enhanced formation of pectin-sugar gels as cell fluids bind with pectins in cell walls.

SummaryPlums (Prunus salicina cv. Songold) were cold stored according to a single-temperature regime comprising 28 d at −0.5°C, and a dual-temperature regime comprising 10 d at −0.5°C followed by 18 d at 7.2°C. After cold storage, the plums were ripened for 8 d at 10°C. Pectolytic enzyme activity, pectic composition, internal conductivity and gel breakdown were determined at seven stages during storage and ripening. Although not exposed to chilling temperatures prior to harvest, approximately 10% of the plums exhibited gel breakdown at harvest, indicating that the disorder cannot be classified solely as a cold-storage chilling disorder. The higher temperatures of the dual-temperature regime resulted in higher polygalacturonase activity than with the single-temperature fruit. Consequently, protopectin degradation and the concomitant production of water- soluble pectins were greater in the dual-temperature fruit. Single-temperature storage resulted in higher pectinmethylesterase activity during the latter s...

Plums (Prunus salicina cv. Songold) were stored at -0.5°C for up to 50 d. On the day of harvest and thereafter at ten-day intervals, sub-samples were stored at 15°C and allowed to ripen for eight d...

Ultrastructure et recherche biochimique des changements se produisant au niveau des lipides, acides amines libres et sucres sur l'embryon et le gametophyte femelle de semence 24 semaines apres fecondation

Summary Cytokinin-like activity which co-chromatographed with zeatin, ribosylzeatin and glucosylzeatin was detected in the epimatium, female gametophyte and embryo sporophyte of germinating Podocarpus henkelii seeds. The level of endogenous cytokinins increased markedly in the embryo sporophyte prior to the onset of radicle elongation. From the results it can be concluded that the endogenous cytokinins play an important role in the germination process. They are apparently involved in those reactions which stimulate radicle elongation, particularly as these cytokinins disappear immediately after the radicle starts to elongate. As bound cytokinins do not increase at this time it would appear that the cytokinins are metabolised and/or utilized rapidly in the metabolically active embryo.

Etude ultrastructurale et biochimique sur l'embryon et le gametophyte femelle des semences de Podocarpus henkelii neuf jours apres scarification et incubation sur un milieu humide