Carbon and Nitrogen Reserves in Perennial Strawberry Affect Plant Growth and Yield

Abstract

<jats:p>Early spring growth of perennial strawberry (<jats:italic>Fragaria</jats:italic> ×<jats:italic>ananassa</jats:italic> Duch.) plants is supported by the carbohydrate and nitrogen (N) reserves accumulated from the previous growing season. The limitations of these reserves on the initial spring growth and yield of perennial strawberries have not been studied in detail, particularly the influence of N reserves. Differential N fertigation (0 to 20 m<jats:sc>m</jats:sc> N) was applied to potted strawberries during the growing season and a supplemental foliar urea application was applied to a portion of the plants in the fall to modify reserve N during dormancy. Plant N content and spring vegetative growth the year after fertigation increased nearly twofold with increasing N fertigation. Photosynthesis per unit leaf area also increased up to 10 m<jats:sc>m</jats:sc> of fertilizer N and then stabilized through 20 m<jats:sc>m</jats:sc>. Foliar urea application in fall further increased total plant N content and size, decreased carbohydrate concentration, and also decreased yield in plants with the most total N. Nitrogen fertigation was resumed on a portion of these plants in early spring, but new growth and subsequent yield were unaffected by spring N application. In a second experiment, CO<jats:sub>2</jats:sub> enrichment with and without soil and foliar N application in the fall was used to vary carbon (C) and N reserves. CO<jats:sub>2</jats:sub> enrichment in fall increased plant size and yield the next July by ≈20%, but total nonstructural carbohydrate and N concentrations were unaffected. Foliar urea application also increased N and C reserves (but not concentration) as well as yield in both enriched and unenriched plants. Although foliar urea in fall decreased carbohydrate concentration, total reserve levels were unaffected because treated plants were larger. In this experiment, spring N increased plant size by ≈50%, but yield was increased only 12%, suggesting that yields are mostly dependent on reserves. Increasing N reserves with a late fall foliar application is one strategy growers can use to efficiently enhance growth and yield in low to moderately fertilized plants.</jats:p>

Carbon Dioxide Enrichment May Increase Yield of Field-grown Red Raspberry under High Tunnels

“…The CO 2 concentration of about 400 ppm in this study may have been too low to affect noncrop biomass accumulation. Interestingly, average strawberry size was not increased by CO 2 concentrations higher than we achieved in our study for plants grown in pots in semiopen chambers (Acuña-Maldonado and Pritts, 2008) or field-grown under tunnels (Hartz et al, 1991).…”

“…By contrast, CO 2 application did not affect the number of baskets (Table 3, P = 0.43), raspberry cane height, pruned cane biomass, cane diameter, or fruit carbohydrate content (data not shown), suggesting that increased carbon was used to increase fruit size rather than fruit quantity or chemical properties or cane size. Carbohydrate content of strawberry fruit grown in pots was similarly unaffected by CO 2 enrichment to 1000 ppm (Acuña-Maldonado and Pritts, 2008). CO 2 enrichment also did not affect the height of two herbaceous skullcap (Scutellaria spp.)…”

“…Early yield (the first 4 weeks of harvest) was also increased (Hartz et al, 1991). Plant biomass and fruit yield for potted strawberry in ''semi-open polyethylene chambers'' increased 21% and 17%, respectively, with a constant CO 2 concentration of 1000 ppm (Acuña-Maldonado and Pritts, 2008). Additionally, CO 2 enrichment significantly increased endogenous concentrations of antioxidants and ascorbic acid (vitamin C) for field-grown strawberries (Wang et al, 2003), a potential health benefit for consumers.…”

Nutrient Management Practices in Perennial Strawberry are Informed by Understanding the Relationships among Carbohydrate Status, Nitrogen Availability, and Soil Composition

“…Ulrich and Martin (1987) and Kirsch (1959) reported negative effects on fruit quality from springapplied N, but not with all cultivars. In another study, doubling N above what is considered an optimal rate increased leaf area by 50% but yield by only 12% (Acuña-Maldonado and Pritts, 2009). Applying 30 lb/acre in spring before fruiting resulted in excessive vegetative growth and increased gray mold (Botrytis cinerea) on fruit in each of 3 years (Cooley et al, 1996).…”

“…The carbohydrate status of the plant can interact with N uptake and utilization. Plants usually grow better and yield more when grown under supplemental carbon dioxide [CO 2 (Bushway and Pritts, 2002;Chen et al, 1997aChen et al, , 1997bChen et al, , 1997c] and the total yield of a strawberry plant is closely correlated with the total nonstructural carbohydrates (TNSC) in the plant (Acuña-Maldonado and Pritts, 2009). However, when TNSC is limited, too much N can result in a yield decrease (Acuña-Maldonado and Pritts, 2009).…”