Annual bedding and garden plants are valued at ≈$2.56 billion in the United States. and accounted for almost half (44%) of the market value of floriculture crops sold in 2014 ($5.87 billion; U.S. Department of Agriculture, 2015). Excluding plants produced in flats and hanging baskets, ≈70% (416 million of ≈600 million units) of bedding plants were produced in containers less than 5 inches in diameter. These small-container annuals are an economically important category among annual bedding plants. It is likely, however, that most of these units were produced in nonrenewable petroleum-based plastic containers, a practice that consumes large amounts of finite fossil fuel resources (Montalbo-Lomboy et al., 2016) and creates a waste disposal concern (Evans et al., 2010).
Petroleum-based plastic plant containers are easily manufactured in a variety of shapes and sizes (Evans and Hensley, 2004) and are inexpensive now (Hall et al., 2010). Intensive use of these containers creates copious persistent waste (Schrader, 2013). Biocontainers, manufactured from renewable, bio-based materials, offer an alternative to container-crop producers that may be as or more sustainable than petroleum-based plastic containers (Koeser et al., 2014). Although fossil fuels are used in the manufacture, distribution, or both of all types of plant containers, large-scale use of biocontainers could become an effective means to greatly reduce persistent waste produced by the container-crops industry. Research demonstrates that high-quality potted and annual bedding plants can be produced in biocontainers (Kuehny et al., 2011; Lopez and Camberato, 2011). However, many commercially available biocontainers, particularly those made of bio-based fibers such as peat or coconut coir, are less durable than petroleum-based plastic pots, and their use can result in poor WUE during plant production (Conneway et al., 2015; Evans and Hensley, 2004; Evans et al., 2010; McCabe et al., 2014).
Bioplastic-based biocontainers are a newer biocontainer technology (Currey et al., 2013, 2014, 2015). These containers are made from bioplastics, bioplastic blends, or biocomposites that are processed and formed on the same equipment used to make petroleum-based containers, and, therefore, are very similar in form and function to those of conventional petroleum-based pots, yet are inherently more sustainable (Montalbo-Lomboy et al., 2016). Although few are fully commercialized, bioplastic plant containers have yielded positive results with respect to plant quality, and container appearance and durability of many bioplastic container types are similar to those of petroleum-based plastic containers (Flax et al., 2017; Kratsch et al., 2015; McCabe et al., 2016; Schrader et al., 2015). However, certain bioplastic container types, particularly those designed to provide bio-based fertilizer nutrients (Schrader et al., 2013) or to biodegrade after use, exhibited algal growth on the container surface, diminished aesthetic quality, and poorer grower-perceived durability at the end of crop production when compared with petroleum-based plastic containers (Flax et al., 2017). Algal growth on surfaces and variation in container strength of other types of biocontainers (such as peat fiber containers) have been observed by other researchers (Conneway et al., 2015; Evans and Karcher, 2004; Evans et al., 2010).
Flax et al. (2017) postulated that moisture management during plant production affected the appearance of certain bioplastic containers, and proliferation of algae on the surface of peat-based biocontainers was attributed to irrigation practices and absorption of water by the containers (Evans et al., 2010). Research shows that plant growth can be controlled without compromising plant quality by reducing substrate VWC (Alem et al., 2015; Bayer et al., 2013). Although we have found no reports quantifying the effect of VWC on bioplastic container appearance and strength, commercial growers have reported potential injury liability and product loss due to easily broken biocontainers (Koeser et al., 2013; Nambuthiri et al., 2015). We contend that reducing substrate VWC may also reduce algal growth improve postproduction appearance and strength of certain bioplastic biocontainers. Therefore, our objectives were to quantify the effect of moisture management practices on the aesthetic quality of four distinct bioplastic biocontainer types and elucidate any effects that moisture management may have on bioplastic container strength.
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