Linda L. Dodge

Cold storage and flower keeping quality of cut tuberose (Polianthes tuberosa L.)

Summary The vase life and floret opening of cut tuberose inflorescences were signifiantly decreased by cold storage. The ideal storage temperature was found to be 0˚C for short durations because even storage at 2˚C for only 3.d significantly decreased floret opening and the vase life of stored inflorescences. There was no signficant difference between “wet”storage in a preservative solution (250.ppm 8-hydroxyquinoline citrate, 2% sucrose) and “dry” storage (spikeswrapped in polythene film to reduce water loss). Pre-storage pulsing with a 20% sucrosesolution (containing HQC) significantly improved the vase life and opening of cold-stored spikes. The vase life and floret opening of spikes treated in this way were equal, after 6.d of storage at 2˚C, to those of fresh cut inflorescences. The end of the vase life of cut tuberosespikes coincided with the time taken to return to their initial fresh weight. Cold storage resulted in a pronounced increase in ethylene production by the florets, particularly by immature buds. Ethylene treatment of fresh cut tuberose spikes reduced floret opening, but ethylene induced by cold storage did not appear to be thecause of reduced floret opening.Pretreatment of spikes with STS eliminated the effects of exogenous ethylene on fresh spikes, but had no effect on the reduced vase life of cold-stored flowers and substantially increased ethylene production by their florets. Ethylene production by florets of sucrose-pulsed spikes was similar to that of the controls. It appears that the shortened vase life of cold-stored tuberose is not due to the induction of ethylene biosynthesis.

Carbohydrate traffic during opening of gladiolus fiorets

Summary The opening of gladiolus florets was accompanied by a substantial increase in fresh and dry weight and carbohydrate content of the perianth. The principal soluble carbohydrate was fructose, with substantially lower concentrations of glucose and sucrose. Although stored carbohydrate, apparently starch, disappeared during floret opening, its contribution to the total carbohydrate content of the open flower was minor. Removal of basal florets from the freshcut spike substantially reduced the dry weight of the opening upper young buds. During development of the inflorescence it appears that there is a transfer of carbohydrate from the senescing lower florets to those developing acropetally.

Wireless Sensor Network for Precision Irrigation Control in Horticultural Crops

Wireless sensor networks for crop monitoring have become more common, but typically support sensing only and not control. Much of the work on wireless sensor networks with integrated control has been conducted in academic research. To promote the accessibility of commercially-available wireless sensing and control networks, valve control hardware and software were developed to be compatible with a commercial wireless sensor node. The work was conducted in collaboration with a wireless network vendor such that the research conducted with this wireless system and the product itself would be available to growers. The valve actuation system included custom node firmware, actuator hardware and firmware, and base computer communication software and a web interface. Network range, energy consumption, and actuator operation were characterized. A commercial soil moisture sensor was selected to monitor nursery container water content for closed-loop irrigation control in container nurseries.

Respiration of geranium and petunia in response to low night temperature

Abstract The morphology and rate of development of some bedding plant species is altered by growth at low night temperatures. This cultural practice is of interest because it results in lower greenhouse energy costs and higher productivity at low photosynthetic photon flux. Low night temperatures and changes in the carbohydrate content of the plants may alter energy losses from maintenance respiration. To test this hypothesis, seedlings of geranium (cultivar ‘Red Elite’) and petunia (cultivar ‘Snow Cloud’) were grown at day temperatures of 25°C and night temperatures of either 7°C or 15.5°C. Thereafter, CO2 evolution in the dark at 21°C was measured and starch, soluble sugar and total nitrogen levels were determined. The respiration rates at 21°C of plants grown at 7°C night temperature were consistently higher than those of plants grown at 15.5°C night temperature. Plants grown at the low night temperature had higher starch and soluble sugar levels, even after 112 h in darkness. Effects of night temperature in winter on maintenance respiration and reserve carbohydrate accumulation are discussed.