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  • Author or Editor: R. W. Langhans x
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Abstract

Picture yourself a million miles from earth; it’s lunch time. What will you eat: meat, fish, bread, fresh vegetables (cooked or uncooked), or food from a tube? What will happen to the waste products from the processed food or even from yourself? What will you breathe? These and hundreds of detailed questions must be answered. At present, we have little knowledge about a totally closed environment life support system (CELSS). We have developed in this paper a list of references that are pertinent to the problem. It is divided into subject areas and listed chronologically, rather than alphabetically.

Open Access

Abstract

Dianthus caryophyllus L., a quantitative long day plant, was used for studies of the effect of photoperiod on the different stages of plant development. The anatomical structure of the vegetative shoot apex and the changes during floral transformation are described. These stages were not affected by the various photoperiod lengths, i.e., 9, 13, and 18 hr.

The developmental cycle of D. caryophyllus may be divided into 3 stages: vegetative, floral initiation, and floral development. The influence of photoperiod on the duration of each of the 3 stages was different. The length of the vegetative stage was inversely related to the length of the photoperiod (the longer the photoperiod, the shorter the vegetative stage). Daylength had no effect on the period of floral initiation, but did affect the period of floral development (i.e., the longer the photoperiod, the longer the developmental stage). The rate of stem elongation under all treatments increased exponentially until the floral initiation state, and then the plants grown under photoperiods of 13 hr or longer elongated significantly faster than those under the 9-hr photoperiod. After flower initiation was completed, the rate of stem elongation suddenly increased linearly until the flower opened. In contrast to the vegetative shoot, the rate of stem elongation of flowering plants was completely independent of photoperiod, and the rate was the same in the 9, 13, and 18 hr photoperiods.

Open Access

Abstract

Epicuticular wax fine structure on leaves from carnation (Dianthus caryophyllus L.) grown in the greenhouse or regenerated from shoot tip culture was compared by scanning electron microscopy. Wax rods densely covered the glaucous leaf surface of greenhouse-grown plants. Irregularly-shaped wax plates were observed on leaves of glaucous plantlets, but no structured wax was seen on non-glaucous plantlets, which comprised the majority of plantlets. During 2½ weeks in the greenhouse, increasing amounts of structured epicuticular wax developed on leaves of glaucous plantlets but not of non-glaucous plantlets. The low survival rate of carnation plantlets regenerated in vitro may be explained by their lack of epicuticular wax structure which results in excess desiccation when they are transferred from in vitro conditions to the greenhouse.

Open Access

The objective of this study was to determine the dry weight, height, and leaf area growth responses of impatiens (Impatiens walerana Hook. f.) plug seedlings to air temperatures ranging from 18 to 29C. The conditions maintained in the controlled-environment growth rooms (CEGR) were ambient C02 levels, 24-h lighting, and photosynthetic photon flux (PPF) ranging from ≈215; to 335 μmol·m-2·s-1. Mean daily temperatures of the plug medium ranged from 19.6 to 27.7C. At the higher PPF level, shoot dry weight decreased at plug medium temperatures (PMT) > 25C; at lower PPF levels (<300 μmol·m-2·s-1), shoot dry weight continued to increase with PMT > 25C. The mean relative growth rate (MRGR) of shoot dry weight was positively correlated with PMT during the initial growth period (up to 14 days from sowing) and was negatively correlated thereafter. The maximum MRGR was predicted to occur at 11.7 days from sowing for a PMT of 19.6C, at 10.8 days for a PMT of 21.6C, and at 9.7 days for a PMT of 23.6C. Linear regression coefficients of shoot height as a function of PMT were substantially higher for seedlings grown at lower PPF than those for seedlings from the highest PPF level. Seedling leaf area consistently increased with increasing temperature. Net assimilation rate (NAR) decreased with increasing seedling age NAR increased with increasing PPF. A decrease in NAR was apparent at 29C relative to values at the lower temperatures. Leaf area ratio (LAR) declined with increasing seedling age and PPF; a quadratic relationship of LAR as a function of PMT indicates a minimum LAR at 22.5C. The seedlings grown at 29C were excessively tall, had thin succulent leaves, and were judged unacceptable for shipping and transplanting. Maximum quality indices (i.e., dry weight per height) were found at PMT of 24.3 to 25.OC for 10- to 14-day-old seedlings and at PMT of 23.0 to 24.OC for 16- to 20-day-old seedlings.

Free access

Uniformity of growth response of impatiens (Impatiems wallerana Hook. f.) plug seedlings was examined in four identical growth rooms. Differences among growth rooms for dry weight, height, and leaf area of 10- to 24-day-old seedlings were generally not significant. During six experiments over 6 months, an individual growth room was maintained under contant baseline environmental conditions. Differences in growth response over time appear to be related to nutrition and irradiance levels. For three experiments with nearly identical irradiance, temperature, and nutrition levels, dry weight and height growth differences over time were only rarely significant. These results illustrate that rather unsophisticated growth rooms can provide consistent growth response over time among experimental units.

Free access

Abstract

Since Derek Smith (23) in 1963 used the term vernalization to describe the cold storage requirement of Easter lilies, the appropriateness of the term periodically has been questioned. Even among those who now accept this terminology, differences of opinion have arisen in interpretation of past and current experimental results. It is with this in mind we wish to clarify our reasons for enthusiastically accepting the vernalization concept for Easter lilies.

Open Access

Abstract

A procedure for rapid multiplication of Chrysanthemum morifolium Ramat by tissue culture techniques is described. Excised stem-tips are placed on semi-solid Murashige and Skoog medium supplemented with growth regulators to form callus and then rotated in the liquid form of the same medium to increase proliferation. The callus pieces are transferred to the same semi-solid medium but kept stationary to induce shoot elongation. The shoots when 2 cm long are transferred to Hoagland’s solution and in a few weeks plantlets are of sufficient size to be planted in soil in the greenhouse. We estimate that 1 chrysanthemum tip could produce 100,000 plantlets in less than 1 year.

Open Access

Abstract

The feasibility of utilizing different patterns of air temperature changes over the light and dark periods was investigated to provide a basis for greenhouse energy conservation. ‘Grand Rapids’ lettuce was grown hydroponically in microprocessor controlled growth chambers, under a light level of 325 µmol s-1m-2 PPF. Air temperatures were: a) increased from 15° to 35°C (late-peak), b) decreased from 35° to 15° (early-peak), and c) increased to 35°, then back to 25° (mid-peak) during the 16-hr light period. The late and mid-peak patterns had a gradual decrease in night air temperature, whereas the early peak pattern had a gradual increase in night air temperature. Each of these patterns averaged 25° during the light period, and 20° during the dark period. “Early-peak” plants grew poorly, whereas plants grown under the mid- and late-peak regimes grew well. Early morning diffusive resistance was similar for early- and mid-peak plants. Transpiration rates followed the air temperature changes.

Open Access

Abstract

Growth of chrysanthemum (Chrysanthemum morifolium Ramat) was studied as a function of quantum flux density (QFD), QFD duration, and temperature. Unrooted cuttings were rooted under high-pressure sodium (HPS) lamps in a controlled environment (CE) at 4 QFD, 3 QFD durations, and 3 temperatures, and plants were grown to flowering in a greenhouse to determine treatment effect on flowering time and plant size at flowering. Increasing QFD duration was more effective in increasing root and shoot dry weight than increasing QFD. Root and shoot dry weights were greatest at 21°C after 13 days rooting. Light treatment during rooting had no effect on flowering time or shoot length at flowering, but there were differences of up to 35% in fresh weight at flowering. A photochlorosis was observed on all treatments irradiated with HPS lamps; the photochlorosis was irreparable at a QFD of 420 μEm−2s−1.

Open Access

Abstract

Growth of chrysanthemum (Chrysanthemum morifolium Ramat) was studied as a function of quantum flux density (QFD), QFD duration, and temperature. Plants were grown under high-pressure sodium (HPS) lamps in a controlled environment (CE) for 13 long days and during the first 2 weeks of short days. Treated plants were also grown to flowering in a greenhouse to determine treatment effect on flowering time and plant size at flowering. Dry weight of vegetative shoots was greatest at 27°C after cuttings were rooted. Rooting and growing chrysanthemum cuttings vegetatively in a CE under HPS lamps appeared best at 280 μEm−2s−1 for 18 hours/day when plants were grown to flowering in a greenhouse. Flower initiation was not accelerated at QFD greater than 140 μEm−2s−1 provided 12 hours/day. A photochlorosis was observed on all treatments irradiated with HPS lamps; the photochlorosis was irreparable at QFD of 420 μEm−2s−1.

Open Access