**2.1. Strawberry material**

rich natural sources of phenolic compounds with high antioxidant capacities, which protect our bodies against free radicals and reactive oxygen species [3, 4]. The large amounts of phenolic compounds offered in strawberries have also been proved to make certain contributions in enhancing the quality of fresh fruits and extending shelf life by delaying senescence induced by oxidative degradation [5]. Therefore, due to the nutritional value and human health benefits in strawberry, the daily demand for strawberries was increasing as time went on. Research on the protective effects of plant-derived polyphenols has developed notably in recent years. In particular, their antioxidant properties have been the objective of extensive research [6–9].

198 Phenolic Compounds - Natural Sources, Importance and Applications

Many factors including genotype, planting date, mulch type, temperature, fertilizer and production systems have been reported to affect strawberry yield and quality [10–12]. Among these factors, production systems play an important role in strawberry growth by enhancing berry size and marketable yield. Matted row system (MRS) is widely used in strawberry planting in north area in terms of lower cost and easy operation [13], but with the development of new technology, many disadvantages of MRS were reported such as poor picking efficiency, waste of fertilizer and high risk of fruits decay. Alternatively, plastic mulch (PM) and plastic mulch with row covers (PMRC) became the most recommended production systems in strawberry planting in recent years [14–16]. Fruit quality and phenolic content were improved under plastic mulch system and resulted in variety of benefits to the crop, including improved fruit cleanliness, prevention of bed erosion, extended harvest season, early ripening, increased yield, better weed control, ease of harvest and more efficient irrigation and fertilizer application [12, 17]. Furthermore, early fruit harvest under plastic culture especially with row covers provides higher income to growers in cool northern climate because of off-season fruit production. Research on bell pepper grown along the Mediterranean coast in raised soil beds (ridge) covered with plastic mulch showed that the use of impermeable plastic mulch in bell pepper cultivation affects water fluxes and may change crop water use and distribution compared to open-field conditions [18]. It also has been reported that the combination of hill plasticulture system and genotype leads a better result of higher flavonoid content and antioxidant capacity than the traditional cultivation system [19]. Plastic mulch affects the microclimate around the crop by modifying the radiation budget (absorptivity vs. reflectivity) of the mulch surface as well. Colour also affects the surface

temperature of the mulch cover and consequently the underlying soil temperature [20].

'SJ8976-1', at different harvest times during the growing season.

Strawberries are of great nutrition amongst other fruits and have been found to contain 2- to 11-fold more antioxidant capacity than apples, peaches, pears, grapes, tomatoes, oranges or kiwifruit [21]. Therefore, to meet the everyday demands of strawberry with increasing antioxidant levels through breeding and/or cultivation systems is of great value in Canada. For the above reasons, a series of strawberry programs were set, and some cultivars were released by Agriculture and Agri-Food Canada (AAFC). 'SJ8976-1' is a new hardy strawberry selection with extra long storage life (*Fragaria* × *ananassa* Duch.) of the AAFC programme. The objective of the present study was to evaluate the effects of PM and PMRC, versus the conventional MRS, on total yield, yield per plant, 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) in strawberry selection 'SJ8976-1' is a new hardy strawberry selection with large fruit size, excellent flavour and long storage life (*Fragaria* × *ananassa* Duch.). The pale fruit colour of 'SJ8976-1' in combination with firmness, resistance to fruit rot and long shelf life makes it a good candidate for fresh market and transportation. The fruit colour of 'SJ8976-1' darkens during storage [22].
