Cut flowers of eight cultivars of Rosa hybrida L. were held in preservative solutions containing up to 4 mg F-/liter. Leaf diffusive resistance was increased by holding flowers in F-solutions. In most cultivars, fresh weight gain was decreased, the degree of flower opening was affected, and visual symptoms of injury were noted in the presence of. F- in the holding solution. Damage at 2 mg F-/liter was almost as severe as at 4 mg/liter. Number of days to petal abscission or bent-neck was shortened by F- for `Samantha' and `Bridal Pink'.
Many inorganic chemicals that commonly occur in drinking water are known to reduce the life of certain cut flowers (Hitchcock and Zimmerman, 1929). One ion that is very toxic to many cut flowers is fluoride (Spierings, 1969; Tjia et al., 1987; Waters, 1968). Fluoride occurs naturally in some water sources and is often added to drinking water to reduce tooth decay in humans. According to the National Revised Primary Drinking Water Regulation, which went into effect on 2 Oct. 1987, the maximum contaminant level for F- was raised from 2.4 to 4 mg liter-1 (U.S. Government, 1986). More cases of F- injury to plants may be seen in localized regions with this regulation change.
Lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), cucumber (Cucumis sativus L.), and marigold (Tagetes patula L.) transplants were grown from seed in leached and unleached media containing 0%, 25%, or 50% (by volume) peat and/or fresh or aged spent mushroom compost with 50% vermiculite. Reduced growth and symptoms of ammonium toxicity were seen in transplants grown in fresh spent mushroom compost. Transplants grown in 0% or 25% compost were larger than those grown in 50%, probably due to high salinity in 50% compost. Leaching reduced media soluble salts and generally improved plant yields. K and Ca were higher and P and Mg were lower in the tissue of transplants grown in spent mushroom compost than of those in the peat-lite control mix. High quality transplants were produced in 25%, aged spent mushroom compost, while acceptable plants of slightly reduced quality were produced in 50%, aged compost.
Foliage plants were added to different environments, including an office and a computer lab. Relative humidity and air-borne particulate matter were monitored in the presence and absence of the plants. When the relative humidity was low, the addition of plants increased the relative humidity slightly, but significantly, over that when no plants were present. Particulate matter accumulation was not increased in the presence of plants. Some have hypothesized that the growing medium could be a source of increased particulates when plants are used indoors. Some of our experiments used self-watering containers, irrigated from below, resulting in very dusty conditions in the top of the container. If the growing medium could contribute to increases in particulate matter, we should have detected it in this study.
Selected physical and chemical properties of fresh spent mushroom compost were evaluated and compared to the properties of spent mushroom compost which was aged aerobically for 6 weeks. Bulk density, total pore space, total water at saturation, and percentage air space in fresh and aged spent composts were acceptable for plant growth. Both contained very high levels of soluble salts which were readily leachable. Concentrations of metals were acceptable, but concentrations of K, Ca, and Mg could lead to plant nutrient imbalances. Concentrations of NH4-N in fresh spent mushroom compost were high.
Many of the research questions that have been posed regarding the effects of plants on people can only be answered using methodologies from the social sciences. Lack of familiarity with these methods and their underlying concepts has limited the role that horticulturists have taken in this research. Horticulturists, because of their particular sensitivity to the various aspects of plants and the nature of the ways that people interact with plants, must be involved in this type of research to generate the information that is needed by horticultural industries. This paper reviews many of the common methods that have been used in research on human issues in horticulture and presents examples of studies that have been conducted using these techniques. Quantitative and qualitative methods are discussed.
Spent mushroom compost (SMC) was used as a soil amendment for field-grown vegetables. Four rates (0, 2, 10, or 20 kg/m2) of SMC were applied to a fine sandy loam in 1981 and 1982. SMC application decreased bulk density and increased the percentage of small pore space, pH, and electrical conductivity. Yields of cucumber and snap bean increased and yield of onion decreased, as the rate of SMC increased in 1981. Yields of cabbage, radish, and tomato were not affected significantly by the addition of SMC. Tomato yield was maximum at 10 kg/m2, then declined as SMC was increased to 20 kg/m2 in 1982. Yield responses of cucumber, fall-planted radish, spinach, and mustard were similar to that of tomato. Salt sensitive crops, such as snap bean, onion, and spring-planted radish, suffered severely reduced plant stands and, consequently, decreased yields. Yield of cabbage, a relatively salt tolerant crop, was not affected by SMC. Concentrations of K in all leaf tissues increased significantly as the level of SMC increased. Mg content in leaf tissue decreased.
In the United States, urban population growth, improved living standards, limited development of new water supplies, and dwindling current water supplies are causing the demand for treated municipal water to exceed the supply. Although water used to irrigate the residential urban landscape will vary according to factors such as landscape type, management practices, and region, landscape irrigation can vary from 40% to 70% of household use of water. So, the efficient use of irrigation water in urban landscapes must be the primary focus of water conservation. In addition, plants in a typical residential landscape often are given more water than is required to maintain ecosystem services such as carbon regulation, climate control, and preservation of aesthetic appearance. This implies that improvements in the efficiency of landscape irrigation will yield significant water savings. Urban areas across the United States face different water supply and demand issues and a range of factors will affect how water is used in the urban landscape. The purpose of this review is to summarize how irrigation and water application technologies; landscape design and management strategies; the relationship among people, plants, and the urban landscape; the reuse of water resources; economic and noneconomic incentives; and policy and ordinances impact the efficient use of water in the urban landscape.