Substrate Temperature in Plastic and Alternative Nursery Containers

Abstract

<jats:p>The green industry has identified the use of biodegradable containers as an alternative to plastic containers as a way to improve the sustainability of current production systems. Field trials were conducted to evaluate the performance of four types of 1-gal nursery biocontainers [keratin (KR), wood pulp (WP), fabric (FB), and coir fiber (Coir)] in comparison with standard black plastic (Plastic) containers on substrate temperature, water use, and biomass production in aboveground nurseries. Locations in Kentucky, Michigan, Mississippi, and Texas were selected to conduct experiments during May to Oct. 2012 using ‘Green Velvet’ boxwood (<jats:italic>Buxus sempervirens</jats:italic> × <jats:italic>B. microphylla</jats:italic>) and ‘Dark Knight’ bluebeard (<jats:italic>Caryopteris</jats:italic> ×<jats:italic>clandonensis</jats:italic>) in 2013. In this article, we were focusing on the impact of alternative container materials on hourly substrate temperature variations and plant growth. Substrate temperature was on an average higher (about 6 °C) in Plastic containers (about 36 °C) compared with that in WP, FB, and Coir containers. However, substrate temperature in KR containers was similar to Plastic. Substrate temperature was also influenced by local weather conditions with the highest substrate temperatures recorded in Texas followed by Kentucky, Mississippi, and Michigan. Laboratory and controlled environment trials using test containers were conducted in Kentucky to evaluate sidewall porosity and evaporation loss to confirm field observations. Substrate temperature was similar under laboratory simulation compared with field studies with the highest substrate temperature observed in Plastic and KR, intermediate in WP and lowest in FB and Coir. Side wall temperature was higher in Plastic, KR, and FB compared with WP and Coir, while side wall water loss was greatest in FB, intermediate in WP and Coir, and lowest in plastic and KR. These observations suggest that the contribution of sidewall water loss to overall container evapotranspiration has a major influence on reducing substrate temperature. The porous nature of some of the alternative containers increased water use, but reduced heat stress and enhanced plant survival under hot summer conditions. The greater drying rate of alterative containers especially in hot and dry locations could demand increased irrigation volume, more frequent irrigation, or both, which could adversely affect the economic and environmental sustainability of alternative containers.</jats:p>

Container Type and Substrate Affect Root Zone Temperature and Growth of ‘Green Giant’ Arborvitae

“…These results support previous research documenting increased growth in white containers due to the deleterious effects of supraoptimal RZT. Root zone temperatures can commonly exceed 54 • C in container-grown crops, but RZT near 38 • C can cause indirect injury to plants leading to reduced shoot and root growth, increased water stress, interruption of physiological mechanisms (photosynthesis and respiration, and increased susceptibility to pathogens [3,4,7]. In our study, fewer roots were observed on the south-facing side of the solid wall containers, regardless of container color, suggesting supraoptimal RZT prevents root growth and development near the container sidewall even in light color containers.…”

“…Dark-colored containers absorb more solar radiation than light-colored containers leading to excessive heat buildup in the substrate. Containers with a more porous exterior facilitate evaporation from the substrate and reduce heat exchange between the container wall and the substrate [6,7]. Markham et al [3] evaluated the growth of red maple (Acer rubrum) and redbud (Cercis canadensis) along with RZT in conventional black containers and white painted containers.…”

Review: Characterization and Impact of Supraoptimal Root-zone Temperatures in Container-grown Plants

“…Container material also impacts the transfer of heat at the container/environment interface but generally less than container color or reflectivity. Thick paper containers or fiber pots absorb and conduct less radiant energy (Nambuthiri et al, 2015b;Ruter, 1995Ruter, , 1996aRuter, , 1997Ruter, , 1999Ruter, , 2000aRuter, , 2000bRuter, , 2000cRuter, , 2000dRuter, , 2001 than plastic or metal containers, and have been shown to reduce RZT and increase growth in some plants. Maximum RZT in fiber containers were often as much as 10°C lower than conventional black plastic containers and were correlated to increased dry mass of shoots and roots in garden mums, Hemerocallis L. 'Aztec Gold' and 'Stella de Oro', Leucothoe fontanesiana (Steudel) Sleumer 'Rainbow', Pieris japonica Thunb.…”

Nitrogen Fertilization and Irrigation Frequency Affect Hydrangea Growth and Nutrient Uptake in Two Container Types

“…Sustainable alternatives have been studied in recent years to reduce use of plastic containers in nursery and greenhouse production of a number of ornamental crops (Beeks and Evans, 2013;Evans et al, 2010;Koeser et al, 2013;Kuehny et al, 2011;Nambuthiri et al, 2015;Wang et al, 2015). Biodegradable containers, also known as biocontainers, are made from a variety of biodegradable materials, such as feather, fabric, rice hulls, and paper, thus introducing varying influence on plant growth and nutrient uptake.…”