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microclimate in the summer by decreasing leaf temperature and leaf transpiration rate, thus alleviating heat stress ( Aberkani et al., 2008 ). The cultivation area under shade is constantly increasing in Mediterranean countries such as Israel, Morocco, and
Influence of irrigation regime on growth of select field-grown tree species in a semiarid climate J. Environ. Hort. 27 134 138 Harlan, S.L. Brazel, A.J. Prashad, L. Stefanov, W.L. Larsen, L. 2006 Neighborhood microclimates and vulnerability to heat stress
fogging systems have been used to prevent plant heat stress during the day. In fact, shading is one of the conventional and familiar techniques used by growers to decrease solar radiation and reduce air and leaf temperatures ( Sandri et al., 2003 ). Many
several hours ( Ruter and Ingram, 1990 ). One method of dealing with heat stress in container production is to use containers with alternative colors or composition instead of black plastic. Black plastic pots act as heat sinks because of their ability to
.K. Yoza, K. Nagata, T. Hosoda, H. 1999 The study of heat stress in tomato fruits by NMR microimaging Magn. Reson. Imaging 17 767 772 doi: 10.1016/S0730-725X(98)00219-7 10.1016/S0730-725X(98)00219-7 Kagan-Zur, V. Tieman, D.M. Marlow, S.J. Handa, A.K. 1995
Container nurseries are generally more productive than field nurseries because plants can be produced faster and at higher densities. Increasingly, nursery stock is being propagated, grown, and marketed in containers. The prime biological advantage of container stock over bareroot and field-grown balled and burlapped (B&B) stock is that the root system is packaged and protected from transplant or mechanical stress; however, temperature stress limits container production. Plants overwintered in containers suffer greater winter injury than those in the ground because the roots are surrounded by cold, circulating air rather than the insulating environment of the soil. There are several methods for providing protection from cold winter temperatures that are used in the nursery industry; however, all are labor intensive, expensive and vary in effectiveness. Container stock also suffers from elevated summer root zone temperatures. Cultivar differences in the degree of summer injury have been reported. With increasing human population pressures and decreasing availability of fresh water supplies, the need for more water-efficient nursery cultural practices becomes increasingly important. Water and nutrient use efficiency are predominant factors restricting nursery container production. Cultural factors that improve root function and reduce root injury and container heat load are considered key to improving these efficiencies. This paper examines temperature stress issues and the effects of different nursery cultural environments such as conventional overwintering systems, conventional gravel production surfaces, pot-in-pot production, and retractable roof greenhouses.
seashore paspalum, and finally bahiagrass. Tall fescue did not go dormant at any time but discolored during summer heat stress. The turfgrass species and cultivars differed in their spring green-up response at both locations ( Tables 8 – 9 ). Intra and
The effect of increasing temperatures on the duration of postharvest flower development was determined for three specialty crop species: marguerite (Argyranthemum frutescens Webb ex Schultz-Bip.) `Butterfly' and `Sugar Baby'; swan river daisy (Brachycome hybrid Cass.) `Ultra'; and bacopa (Sutera cordata Roth.) `Snowflake'. Plants were grown in a greenhouse at 18 °C (65 °F) until flowering, and then transferred into a phytotron to determine heat tolerance. Plants were stored for 8 weeks at constant temperatures of 18, 23, 28, and 33 °C (65, 73, 82, and 91 °F) for 2-week intervals. Flower bud and flower number were recorded weekly. Sutera cordata `Snowflake' and B. hybrid `Ultra' had the greatest flower number at the 23 °C temperature, decreasing in the 28 °C environment. Argyranthemum frutescens `Butterfly' and `Sugar Baby' had greatest flower number at 28 °C, but flowers were of lower quality thanat 23 °C. Flower development of all cultivars ceased at 33 °C, at the end of 8 weeks at increasing temperatures, but when plants were returned to the 18 °C production greenhouse, flower development resumed. High temperatures (28 °C) reduce the postharvest performance of S. cordata, B. hybrid, and A. frutescens plants grown in hanging baskets; therefore, these species should be marketed as spring-flowering products since summer performance may be unsatisfactory in warm climates.
( Gosselin and Trudel, 1986 ), water stress ( Ingram et al., 1986a ), nutrient deficiencies ( Johnson and Ingram, 1984 ), or impaired plant growth and development ( Martin and Ingram, 1988 ). One way to deal with heat stress is to use containers with porous
The Southern Extension and Research Activities/Information Exchange Group-27 (SERA/IEG-27) is sponsored by the Southern Association of Agricultural Experiment Station Directors. Thirteen universities and the U.S. National Arboretum cooperate with official representatives from extension and research programs. The objective of the group is to identify, evaluate, select, and disseminate information on superior, environmentally sustainable, landscape plants for nursery crop production and landscape systems in the southeastern U.S. Plants are distributed to members responding to a request from cooperators for plant evaluation. Those who agree to cooperate are expected to grow the selected liner to landscape size, then transplant it in a landscape setting. The plant is rated for insect, disease, and cold damage, heat stress, growth rate, ornamental flowering and fruiting, fall color, commercial production potential, landscape potential, invasiveness potential, and insect disease transmission potential. Growth rate is evaluated annually by recording plant height and width. Initial bloom date is reported followed by bloom duration in days. Following evaluation, the group collectively and individually disseminates information gained from the plant evaluation system to a wide variety of audiences.