Florida is the primary producer of winter strawberries in the United States because of its mild subtropical climate. The price received by Florida strawberry growers is highly variable throughout the season, with the greatest prices typically seen during the early-season months of November, December, and January. According to U.S. strawberry market data from 2012–17, the average grower price in November was $22.80 per 3.6-kg flat, followed by $18.94, $14.38, $11.40, and $8.88 for the months of December through March, respectively (U.S. Department of Agriculture, 2018). Because the Florida strawberry industry is threatened by new challenges such as international competition, rising production costs, and growing labor shortages, Florida strawberry growers require further improvements in early yield to remain profitable (Wu et al., 2015).
Historically, Florida strawberry growers have planted in early to mid October. Bare-root transplants are typically established in raised beds covered with black plastic mulch, which has long been considered important to achieve adequate wintertime soil warming (Brooks, 1959). After planting, the fragile transplants can be exposed to high daily air temperatures exceeding 30 °C for up to 6 weeks. During this time, flower buds initiate and develop in the crowns while the plants establish a leaf canopy capable of supporting fruit production, which usually begins in mid November. Yields increase slowly throughout the winter, with peak production occurring in March.
To speed up establishment and increase early yields, Florida strawberry growers have recently begun to advance transplanting dates from mid October to late September. As a result, plants are exposed to even greater heat stress conditions than they normally would when planted in October. For example, maximum daily air temperatures were ≈34 °C in the third week of Sept. 2016, but only 28 °C in the second week of Oct. 2016. Combining advanced planting dates with black plastic mulch can likely cause excessive heat stress conditions, especially because establishment period soil temperatures often exceed 35 °C under black plastic mulch. A number of studies indicate that temperatures above 30 °C can induce physiological complications in strawberry, including slowed, abnormal growth (Geater et al., 1997; Hellman and Travis, 1988; Zhang et al., 1997); reduced protein content (Gulen and Eris, 2015); and low root-oxygen consumption (Sakamoto et al., 2016). Plants could experience excess heat stress, which leads to inhibited growth and fruit development when planted on black plastic mulch in late September. To avoid this, growers need an alternative to black plastic mulch.
Metalized mulch films have the potential to improve early-season fruit development by alleviating, at least in part, heat stress conditions during the establishment period (Andino and Motsenbocker, 2004; Vos et al., 1995). In general, reflective metalized mulch films can reduce soil temperatures compared with black mulch by reflecting a greater proportion of incoming solar radiation (Ham et al., 1993). Reflective metalized mulch films have proved widely effective at increasing marketable fruit yields compared with black mulch for a number of horticultural crops, including tomato (Solanum lycopersicum) and bell pepper (Capsicum annuum), which are both major crops in Florida (Andersen et al., 2012; Díaz-Pérez, 2010; Greer and Dole, 2003; Hutton and Handley, 2007). Relatively few studies have compared reflective mulch films to the standard black plastic mulch for subtropical strawberry production. Perhaps most notably, Albregts and Chandler (1993) found entirely white- and yellow-painted mulch films to improve early-season yields compared with black plastic mulch for Florida strawberry production. However, black plastic mulch outperformed yellow mulch and white mulch in the late season, possibly resulting from insufficient wintertime soil warming by these two more reflective mulch films. Consequently, we believe that subtropical winter strawberry growers would benefit from a multicolored mulch design that is reflective in the center and black on the shoulders. We hypothesized that by having the dual benefits of reflective mulch and black mulch, metalized-striped mulch should maintain sufficiently cool RZTs during establishment, and sufficiently warm RZTs during the cool winter months.
Several previous studies have examined the effect of combining two different colors in one plastic mulch type, mostly by adding a black center stripe to reflective silver mulch. The positive effects of this multicolored mulch type compared with entirely black or silver mulch include increased canopy-level light capture, soil warming during spring establishment, improved yield of bell pepper, and reduced incidence of virus symptoms in tomato (Csizinszky et al., 1999; Díaz-Pérez, 2010; Hutton and Handley, 2007). Metalized mulch with a black center stripe is meant to warm transplants during spring establishment and reduce soil temperatures during hot summer months, which is the opposite soil warming pattern that we expected to observe using black mulch with a metalized center stripe. To our knowledge, the strategy of using black plastic mulch with a metalized center stripe has never been evaluated for strawberry production, or any other crop production system.
The objective of our study was to examine the effects of metalized-striped plastic mulch on soil temperature, plant growth, fruit yield, and earliness using two of Florida’s most current early-yielding strawberry cultivars. ‘Florida Radiance’, which currently accounts for about 60% of Florida’s strawberry market, is a short-day cultivar not recommended for September planting because it has a relatively weak plant habit and fruit can become elongated and unmarketable under high temperatures (Whitaker et al., 2008). ‘Florida Beauty’ is an early-yielding, weak day-neutral that possesses a compact canopy, making it well-suited for advanced planting dates (Whitaker et al., 2017). ‘Florida Radiance’ is a seasonal flowering genotype, so its flowering and fruiting are tightly controlled by photoperiod and temperature, whereas ‘Florida Beauty’ is an everbearing genotype that can basically produce flowers and fruit throughout the entire growing season (Heide et al., 2013). To understand the potential importance of using a multicolored mulch film, we compared metalized-striped mulch against fully metalized mulch as well as the industry standard black plastic mulch. To follow recent Florida strawberry-growing trends of advancing planting from mid October to late September, we examined the effect of metalized-striped mulch when planting was advanced to late September in two seasons.
Albregts, E.E. & Chandler, C.K. 1993 Effect of polyethylene mulch color on the fruiting response of strawberry Soil Crop Sci. Soc. Fla. 52 40 43
Andersen, P.C., Olson, S.M., Momol, M.T. & Freeman, J.H. 2012 Effect of plastic mulch type and insecticide on incidence of tomato spotted wilt, plant growth, and yield of tomato HortScience 47 861 865
Andino, J.R. & Motsenbocker, C.E. 2004 Colored plastic mulches influence cucumber beetle populations, vine growth, and yield of watermelon HortScience 39 1246 1249
Brooks, A.N. 1959 Polyethylene film as mulch for strawberry. Fla. Agric. Exp. Stn. Annu. Rep. p. 394–395
Csizinszky, A.A., Schuster, D.J. & Polston, J.E. 1999 Effect of ultraviolet-reflective mulches on tomato yields and on the silverleaf whitefly HortScience 34 911 914
Díaz-Pérez, J.C. 2010 Bell pepper (Capsicum annum L.) grown on plastic film mulches: Effects on crop microenvironment, physiological attributes, and fruit yield HortScience 45 1196 1204
Díaz-Pérez, J.C. & Batal, K.D. 2002 Colored plastic film mulches affect tomato growth and yield via changes in root-zone temperature J. Amer. Soc. Hort. Sci. 127 127 135
Díaz-Pérez, J.C., Phatak, S.C., Giddings, D., Bertrand, D. & Mills, H.A. 2005 Root zone temperature, plant growth, and fruit yield of tomatillo as affected by plastic film mulch HortScience 40 1312 1319
Gallardo, R.K., Li, H., McCracken, V., Yue, C., Luby, J. & McFerson, J.R. 2015 Market intermediaries’ willingness to pay for apple, peach, cherry, and strawberry quality attributes Agribusiness 31 259 280
Geater, C.A., Nonnecke, G.R., Graves, W.R., Aiello, A.S. & Dilley, C.A. 1997 High root-zone temperatures inhibit growth and development of Fragaria species Fruit Var. J. 51 94 101
Gonzalez-Fuentes, J.A., Shackel, K., Heinrich Lieth, J., Albornoz, F., Benavides-Mendoza, A. & Evans, R.Y. 2016 Diurnal root zone temperature variations affect strawberry water relations, growth, and fruit quality Scientia Hort. 203 169 177
Greer, L. & Dole, J.M. 2003 Aluminum foil, aluminium-painted, plastic, and degradable mulches increase yields and decrease insect vectored viral diseases of vegetables HortTechnology 13 276 284
Guan, Z., Feng, W. & Whidden, A.J. 2016 Top challenges facing the Florida strawberry industry: Insights from a comprehensive industry survey. Fla. Coop. Ext. Serv. FE972
Gulen, H. & Eris, A. 2015 Some physiological changes in strawberry (Fragaria ×ananassa ‘Camarosa’) plants under heat stress J. Hort. Sci. Biotechnol. 78 894 898
Ham, J.M., Kluitenberg, G.J. & Lamont, W.J. 1993 Optical-properties of plastic mulches affect the field temperature regime J. Amer. Soc. Hort. Sci. 118 188 193
Heide, O.M., Stavang, J.A. & Sønsteby, A. 2013 Physiology and genetics of flowering in cultivated and wild strawberries: A review J. Hort. Sci. Biotechnol. 88 1 18
Hutton, M.G. & Handley, D.T. 2007 Effects of silver reflective mulch, white inter-row mulch, and plant density on yields of pepper in Maine HortTechnology 17 214 219
Kadir, S., Gaganpreet, S. & Al-Khatib, K. 2006 Strawberry (Fragaria ×ananassa Duch.) growth and productivity as affected by temperature HortScience 41 1423 1430
Kumakura, H. & Shishido, Y. 1994 The effect of daytime, nighttime, and mean diurnal temperatures on the growth of Morioka-16 strawberry fruit and plants J. Jpn. Soc. Hort. Sci. 62 827 832
Ledesma, N. & Sugiyama, N. 2005 Pollen quality and performance in strawberry plants exposed to high-temperature stress J. Amer. Soc. Hort. Sci. 130 341 347
Ledesma, N.A., Nakata, M. & Sugiyama, N. 2008 Effect of high temperature stress on the reproductive growth of strawberry cvs. ‘Nyoho’ and ‘Toyonoka’ Scientia Hort. 116 186 193
Peres, N.A. 2015 2015 Florida plant disease management guide: Strawberry. Fla. Coop. Ext. Serv. PDMG-V3-50
Sakamoto, M., Mayuka, U., Kengo, M. & Takahiro, S. 2016 Effect of root-zone temperature on the growth and fruit quality of hydroponically grown strawberry plants J. Agr. Sci. 8 122 131
U.S. Department of Agriculture 2006 United States standards for grades of strawberries. U.S. Dept. Agr., Washington, DC.
U.S. Department of Agriculture National Agricultural Statistics Service. 2018 Quick Stats 2.0. U.S. Dept. Agr. Natl. Agr. Statistics Serv., Washington, DC.
Vos, J.G.M., Uhan, T.S. & Sutarya, R. 1995 Integrated crop management of hot pepper (Capsicum spp.) under tropical lowland conditions: Effects of rice straw and plastic mulches on crop health Crop Prot. 14 445 452
Whitaker, V.M., Chandler, C.K., Santos, B.M. & Peres, N.A. 2008 ‘Florida Radiance’ strawberry. Fla. Coop. Ext. Serv. HS1151
Whitaker, V.M., Peres, N.A. & Agehara, S. 2017 ‘Florida Beauty’ strawberry. Fla. Coop. Ext. Serv. HS1307
Wu, F., Guan, Z. & Whitaker, V. 2015 Optimizing yield distribution under biological and economic constraints: Florida strawberries as a model for perishable commodities Agr. Syst. 141 113 120
Yuri, J.E., de Resende, G.M., Cista, N.D. & Mota, J.H. 2012 Cultivo de morangueiro sob diferentes tipos de mulching Hort. Bras. 30 424 427
Zhang, W., Seki, M. & Furusaki, S. 1997 Effect of temperature and its shift on growth and anthocyanin production in suspension cultures of strawberry cells Plant Sci. 127 207 214