The Effect of Production Systems on Strawberry Quality

Strawberry with high polyphenols is receiving much more attentions recently. Production systems were reported positive effect on improving crop quality. A complete randomized design with two replicates was employed, and the strawberry selection ‘SJ8976-1’ was planted under three production systems: matted row system (MRS), plastic mulch (PM) and plastic mulch with row covers (PMRC). Total yield, average fruit weight, soluble solids content (SSC), titratable acidity (TA), firmness, fruit postharvest quality, total phenolic content (TPC), total antioxidant content (TAC), oxygen radical absorbance capacity (ORAC) and phenolic composition analysed by high-performance liquid chromatography (HPLC) were evaluated at different harvest times. The results showed that PMRC advanced fruit maturity and improved average fruit weight compared to MRS. SSC, TA and firmness of the strawberry fruits from PMRC were significantly increased at all harvests. Fruit weight loss, juice leakage and presences of grey mould were lower, and fruit glossiness was higher for those harvested under PMRC than those from MRS. TPC, TAC and ORAC of strawberry were significantly changed under different production systems. The phenolic compounds assessed in strawberry were grouped into six major categories, which were anthocyanins, kaempferol, flavonols, hydroxycinnamic acids, ellagic acid and benzoic acids

Composition of phenolics and volatiles in strawberry cultivars and influence of preharvest hexanal treatment on their profiles

Biochemical changes of quality-determining components were evaluated in strawberry fruit subjected to preharvest spray treatments using a hexanal-containing formulation that is known to enhance shelf life and quality of fruits. Phenolic compounds and volatiles of fruits of four strawberry cultivars (Mira, Jewel, Kent, and St. Pierre) grown in southern Ontario were characterized by HPLC-MS and solid phase micro extraction (SPME) analysis. Qualitative and quantitative profiles of phenolic compounds varied among the cultivars. In all the cultivars, anthocyanins constituted the most prominent class of phenolic compounds. Volatile profiles of strawberry homogenate differed among the cultivars. Changes in phenolics and volatiles composition were determined in fruits of Mira and Jewel after spraying with a hexanal-containing formulation at weekly intervals. In Jewel, preharvest hexanal spraying altered the profiles of polyphenolic components, while minimal changes were noticed in Mira. Interestingly, very few differences were identified in ester profiles of treated and untreated Mira. In general, hexanal spray application resulted in a decrease in the abundance of several volatile components including esters, ketones, and lactones in treated Jewel compared with the control. The results suggest that cultivar-specific quality changes may result from a preharvest application of hexanal formulations, which may also imply different patterns of metabolite channeling and delay of fruit ripening processes

Influence of colonization by arbuscular mycorrhizal fungi on three strawberry cultivars under salty conditions

Plant adaptation to hyperosmotic environments is generally associated with reduced growth and ultimately yield loss, making farming difficult. The potential of mycorrhizal symbioses to alleviate salt stress has been documented and benefits to plant revealed to be specific and dependent to both plant cultivars and fungal strains.  A factorial greenhouse experiment was performed to determine the effects of three arbuscular mycorrhizal fungi (AMF) species (Funneliformis caledonius, F. mosseae and Rhizophagus irregularis) on three ‘day-neutral’ strawberry (Fragaria × ananassa Duch.) cultivars (‘Albion’, ‘Charlotte’ and ‘Seascape’), and a mixture of R. irregularis and F. mosseae on ‘Seascape’, under four salt conditions (0–200 mM NaCl).  The overall results showed that plant biomass decreased with increasing salinity.  The cultivars responded differently to both AMF and salinity, and ‘Seascape’ was more tolerant to salinity than the other cultivars.  AMF enhanced plant growth and improved salt tolerance by increasing the proportion of medium (0.5<ɸ≤1.5 mm) and coarse (ɸ>1.5 mm) diameter roots. The mixture of two AMF species increased root and shoot mass to a higher degree than each species alone at low salinity (0–50 mM) but reduced fruit quality.  At higher levels (100–200 mM), R. irregularis alleviated salt stress and improved fruit quality to a higher degree than the other AMF species.  Our results support the use of bio-inoculants in saline horticultural areas.  Because cultivars respond differently to fungal inoculants, and inoculants prefer specific environmental conditions, fungal inoculants need to be screened on a cultivar- and condition-specific basis

Effect of mulching systems on fruit quality and phytochemical composition of newly developed strawberry lines

The effects of three mulching systems on total yield, average yield per plant, average fruit weight, soluble solids content (SSC), titratable acidity (TA), firmness and oxygen radical absorbance capacity (ORAC) of two newly developed lines (‘Orléans’ and ‘Saint Pierre’), one advanced selection (‘SJ8976-1’) and two commonly used cultivars (‘Jewel’ and ‘Kent’) were evaluated. The studied mulching systems were: plastic mulch (PM), mulch with row cover (PMRC), and matted-row system (MRS). Results showed that plastic mulch with row cover (PMRC) generally increased yield per plant, average fruit weight, SSC, firmness and ORAC, but differences varied within harvest times. No significant differences in total yield and TA were observed under the selected mulching systems. Both PMRC and PM accelerated the harvest periods compared to MRS. ‘Kent’ and ‘Jewel’ had the highest total yield while ‘SJ8976-1’ and ‘St-Pierre’ had the highest average fruit weight. The highest SSC, TA and ORAC were found in ‘Jewel’. There was no interaction between the mulching systems and genotypes, indicating that the effect of production system is independent of cultivars. PMRC seems to be a better growing system, improving fruit quality and increasing the nutritional value of all genotypes. By allowing off-season fruit production in cool climates, PMRC can be an alternative method to the costly high tunnels