New Challenges in Productivity of Berry Fruits

Poland is a major producer of various fruits, including strawberries. As growing consumer awareness of food quality, health, and wellbeing is increasing, farmers are receiving a new market opportunity for organic products of good quality. The integration of microbial solutions into agricultural practices can foster the transition of agricultural farms towards more resilient and sustainable production of quality food. The objective of this study was to assess the influence of novel microbial biopreparations (microbial fertilizing products) containing Bacillus sp., humic acids, and other organic compounds on the economic viability of three strawberry cultivars (‘Honeoye’, ‘Vibrant’, and ‘Rumba’) under organic farming conditions. This study was conducted in 2021 as a field experiment. Irrigated and non-irrigated strawberries were treated with five microbial fertilizing products (K2–K6). The single plot area was 16 m², with a total of 144 plots. The adopted planting density of strawberries was 30,052 per hectare. K3 treatment was found to be the most universal microbial treatment in terms of positive impact on yields, with significant yield increase on both the non-irrigated (yield increase of 3.76 t·ha⁻¹) and irrigated experiments (yield increase of 5.78 t·ha⁻¹). The K4 treatment on the non-irrigated strawberries resulted in a yield increase of 4.96 t·ha⁻¹, which at the same time had no effect on the yield of the irrigated experiment. On average, application of the K2–K6 combinations on the non-irrigated strawberries resulted in a yield increase from 13.4% (K2) to 33.5% (K4). The irrigated strawberries showed a yield increase from 3.9% (K4—non-significant yield increase) to as much as 36.1% (K3). The highest direct surplus for the non-irrigated strawberries was recorded for the K4 treatment (38,603 PLN·ha⁻¹) and for K3 for the irrigated experiment (42,945 PLN·ha⁻¹). The direct surplus for ‘Rumba’ and ‘Vibrant’ was higher than for ‘Honeoye’ on both the irrigated (22% and 53%, respectively) and non-irrigated (19% and 18%, respectively) experiments. The average profitability index for all tested non-irrigated and irrigated varieties improved when treated with microbial fertilizer products, with profitability indexes of 143.3–168.8% on the non-irrigated plantation and 129.2–169.7% on the irrigated plantation. The tested microbial fertilizing products proved to be valuable products to improve the productivity and economic effectiveness of organic strawberry production. At the same time, their use needs to be adapted to local plantation conditions. Full article

There is an increased interest in the hydroponic production of strawberries in protected cultivation systems, and it is, therefore, urgent to develop new, more sustainable growing media alternatives. This study investigated the physical properties of wood fiber produced from Norway spruce (Picea abies (L.) H. Karst.) and peat:wood fiber substrate blends as well as the performance of the wood fiber in comparison to the industry standards, i.e., peat and coconut coir in the cultivation of hydroponic strawberry. Tray plants of the June-bearing strawberry (Fragaria × ananassa Duch.) cultivar ‘Malling Centenary’ were transplanted into five different growing media: a peat (80%) and perlite (20%) mixture, stand-alone (100%) coconut coir and three stand-alone (100%) Norway spruce wood fiber substrates (including coarse textured fibers with compact and loose packing density and compacted fine-textured fibers). Ripe strawberries were harvested and registered throughout the production season. The overall marketable yield was comparable across all the tested growing media; however, after 4 weeks of harvest, both coarse wood fiber and fine wood fiber showed better fruiting performance than the peat-perlite mixture. A trend for earlier berry maturation was observed for all wood fiber-based substrates. Plant parameters recorded after the end of production showed that plant height, number of leaves, and biomass production were higher in coarse wood fiber than in the peat-perlite mixture. Moreover, plants grown in wood fiber-based substrates had less unripe berries and flowers not harvested in comparison to both the peat and coir treatments. Full article

Information was collected on yield and fruit quality in ‘Festival’, ‘Fortuna’, ‘Red Rhapsody’, ‘Fronteras’, ‘Grenada’ and ‘Petaluma’ strawberry (Fragaria × ananassa Duch.) in southern Queensland, Australia. Marketable yield was similar in the cultivars and ranged from 352 to 416 g/plant. Fruit were smaller in ‘Festival’ and ‘Grenada’ (21.3 or 23.7 g), intermediate in ‘Fortuna’ and ‘Red Rhapsody’ (25.0 or 24.7 g), and larger in ‘Fronteras’ and ‘Petaluma’ (27.6 or 27.8 g). Fruit soluble solids content (SSC) was lower in ‘Fronteras’, ‘Grenada’ and ‘Petaluma’ (6.9% to 7.2%) than in the other cultivars (7.4% to 8.3%). Fruit titratable acidity (TA) was lower in ‘Fortuna’ and ‘Fronteras’ (0.55% to 0.58%) than in the other cultivars (0.63% to 0.69%). The cultivars had similar estimates of stability for fruit weight (0.74 to 1.27) using the method of Finlay and Wilkinson (1963), where a cultivar with a value of one has average stability in a group. This suggests that the cultivars behaved similarly to changes in conditions over the season. The estimates of stability for SSC were lower than one or higher than one in some cultivars (0.45 to 1.75). The estimates of stability for TA were lower than one for some cultivars (0.33 to 1.33). None of the cultivars had high values of fruit quality and stable values of fruit quality for all the three traits. ‘Festival’ would be an acceptable parent in a breeding programme used to increase fruit SSC. In contrast, the other cultivars would be acceptable parents to increase fruit size. Efforts need to be made to develop cultivars with high and stable values of quality and that are suitable for production under global warming. Full article

Light, temperature and rainfall affect the growth and yield of strawberry plants (Fragaria × ananassa Duch.). The objective of this review was to determine the impact of global warming on the yields of strawberry in a temperate (summer crop) and subtropical environment (winter crop) in southern Queensland, Australia. Information was collected on the changes in temperature over five decades in two locations in this area. The relationship between relative yield and temperature from published data was used to determine the impact of global warming on productivity in the two locations. Finally, the impact of elevated concentrations of CO₂ and temperature on yield was examined from studies in the literature. The average daily mean temperature has increased by 2 °C over the season on the Sunshine Coast (winter crop) since 1967 (p < 0.001, R² = 0.69). The impact of global warming has been less severe on the Granite Belt (summer crop), with a 1 °C increase in temperature (p < 0.001, R² = 0.37). Information was collected from the literature on the yield in individual temperature regimes in an experiment and these data were compared with the maximum yield in the same experiment (relative yield). There was a negative linear relationship between relative yield and temperature in most of the published literature. The mean (± s.d. or standard deviation) estimate of the slope from the regression was −0.14 (± 0.14), the median was −0.11 and the range was from −0.51 to 0.11 (n = 14 studies). Increases in temperature were associated with a decrease in yield of 14% to 28% in the two areas in Queensland. The results of other research indicated that elevated concentrations of CO₂ do not benefit productivity when combined with elevated temperatures. Further decreases in yield are expected in the next few decades in the absence of heat-tolerant cultivars or other mitigating strategies. Full article

Cultivation of strawberries in greenhouses and polytunnels is increasing, and new sustainable growing media are needed to replace peat and coconut coir. This study investigated the effect of wood fiber and compost as growing media on hydroponically cultivated strawberries. Two experiments were conducted, where the everbearing cultivar ‘Murano’ was grown in mixtures of wood fiber and compost (Experiment 1) and the seasonal flowering cultivar ‘Malling Centenary’ was grown in mixtures of wood fiber and peat (Experiment 2). Additionally, in Experiment 2, the effect of adding start fertilizer was assessed. The yield potential of ‘Murano’ plants was maintained in all substrates compared to the coconut coir control. However, a mixture of 75% wood fiber and 25% compost produced the highest yield, suggesting that mixtures of nutritious materials with wood fiber may improve plant performance. The chemical composition of the berries was not affected by the substrate composition; however, berries from plants grown in the best performing blend had a lower firmness than those grown in coconut coir. ‘Malling Centenary’ plants produced higher yields in substrates enriched with start fertilizer. Generally, the productivity of ‘Malling Centenary’ plants was maintained in blends containing up to 75% of wood fiber mixture even without start fertilizer. Full article

Blueberries are highly perishable and temperature sensitive. The main purpose of the study was to determine whether logistics processes in the beginning stages of the blueberry supply chain have an influence on the temperature profiles and quality of the fruit further downstream. Temperature trials were conducted on three farms in the Gauteng and three in the Western Cape provinces of South Africa. Observations were made, and iButton^® temperature monitoring devices were used to record ambient temperatures experienced by blueberries from harvesting until after forced cooling in the cold store. Descriptive statistics were used to analyse the temperature data. The results showed poor adherence to protocols and a large number of temperature and chilling injury spikes and breaks. Many trials did not reach pre-cooling and forced cooling protocol temperatures within the required time. Quality reports indicated that pallets were downgraded owing to cartons being underweight, probably as a result of moisture loss, and other quality defects such as collapsed berries and mould. By minimizing the breach of protocols and improving the beginning stages of the blueberry supply chain, a better-quality product will be ensured, thus reducing costs, food loss and food waste. Full article

Warmer conditions under climate change will alter plant, flower and fruit development in strawberry (Fragaria × ananassa Duch.). Most of the studies examining the relationship between soluble solids content (SSC) and temperature have been conducted in areas with a temperate or Mediterranean climate. I investigated the link between SSC and temperature in Queensland, Australia. Potted plants of ‘Festival’, ‘Fortuna’, ‘Brilliance’, ‘Beauty’ and ‘Red Rhapsody’ were planted on 19 April 2021 and information collected on productivity, SSC and titratable acidity (TA) from 14 July to 6 October. Additional data were collected on the concentrations of the main soluble sugars in the fruit from 4 August to 6 October. Nights were 2 to 4 °C warmer than the long-term average conditions from 1965 to 1990. Marketable yield was lower in ‘Beauty’ and higher in the other cultivars. Fruit were smaller in ‘Festival’, ‘Fortuna’ and ‘Beauty’ and larger in ‘Brilliance’ and ‘Red Rhapsody’. Mean (±SE or standard error) SSC pooled across the cultivars was 7.6 ± 0.05%, and mean TA was 0.59 ± 0.005%. Fructose (30.2 ± 0.2 mg/g FW) and glucose (27.1 ± 0.3 mg/g FW) were the main sugars in the fruit, with lower concentrations of sucrose (0.05 ± 0.02 mg/g FW) and maltose (less than 1 mg/g FW). The mean concentration of all the sugars was 57.4 ± 0.5 mg/g FW. Soluble solids content decreased from 8.6 to 6.8% as the average daily mean temperature in the eight days before harvest increased from 14.5 to 19.5 °C (p < 0.001, R² = 0.72). These results are consistent with similar studies in Florida and suggest that higher temperatures in the future will decrease fruit quality in subtropical locations. Full article

Environmental conditions during plant raising determine the yield potential of everbearing strawberries. We studied the effect of three rooting dates in the cultivars ‘Favori’ and ‘Murano’ in a greenhouse with 18 ℃ and 20-h long day and under outdoor conditions in Norway. The highest yield of 1.350 g/plant was obtained in ‘Favori’ plants rooted on 1 August and raised outdoors, being at level with ‘Favori’ plants produced in The Netherlands. High yields were mainly related to fruit size and less to fruit number, and determined by a complex three-factor interaction of rooting date, raising environment, and cultivar. The seasonal pattern of fruit flushes and off periods varied significantly between cultivars and treatments. The large first flush of high yielding ‘Favori’ plants was associated with a long off period, while the small first flush in ‘Murano’ resulted in a more even crop distribution. Earliness of ripening and berry harvest was superior in ‘Favori’, which had a larger share of its crop during the first half-season. We conclude that it is possible by choosing the right rooting date and raising environment to produce plants with the same high quality and yield potential under the cool Nordic conditions as those currently produced in Central Europe. Full article

The growing interest in using everbearing (EB) strawberry cultivars to extend the cultivation period has faced some challenges. These include poor runner production due to its perpetual flowering nature; irregular flowering behavior and extended periods of high temperature have caused floral inhibition and reduced yield. As flowering is an interplay between temperature and photoperiod, it is important to investigate the effects of this interaction on the cultivation. Therefore, this study used meristem dissection as a tool to study the effect of temperature and photoperiod on meristem development. Tray plants of two EB strawberry cultivars ‘Florentina’ and ‘Favori’ were grown at 20 °C, 25 °C, and 30 °C under short day (SD) conditions, and subsequently at 20 °C under long day (LD) conditions. The meristem development was analysed every 6 weeks for a 15-week period in SD and for 14 weeks in LD conditions using meristem dissection. The plants showed similar flowering patterns to previously studied everbearing cultivars, which was qualitative LD plants at high temperatures and quantitative LD plants at lower temperatures. Our results show that meristem dissection can be used to determine the temperature and photoperiodic effect on meristem development, and for the occurrence of cropping peaks, and can therefore be used to decide the environmental input and to evaluate yield potential. Full article

The effect of antagonistic bacteria to control Macrophomina phaseolina was evaluated under in vitro, growth chamber, greenhouse and field conditions. A total of 177 bacteria, isolated from Athrocaulon macrostachyum rhizosphere of the Lebrija marsh, were screened for their potential against M. phaseolina (causes charcoal rot in strawberry) by dual culture assay. Of these isolates, 14 most promising strains were molecularly identified by the 16S rDNA sequencing method using the EzBioCloud database. These strains were tested for in vitro hydrolytic enzymes, HCN production, and biocontrol against M. phaseolina in strawberry plants. All the 14 strains produced, at least, one hydrolytic enzymatic activity and one of them, which belongs to Brevibacterium genus (Hvs8), showed the lowest records of disease incidence (20%) and severity (0.4). With these results, greenhouse and field trials were carried out with the Hvs8 strain, compared to non-treated control. In the greenhouse assays, Hvs8 strain increased root dry mass by 30%, over the control. In the field trials, production and fruit quality were not significantly different between Hvs8 treatment and non-treated control, but plant mortality and plant mortality associated to M. phaseolina decreased by more than 24% and 65% respectively, in Hvs8 treatment. This study suggests that Brevibacterium sp. Hvs8 strain could be a candidate for controlling charcoal rot in strawberry. Full article

It is not known to what degree growth and fruit yield are source-limited in everbearing strawberry plants. The growth and yield performance effect of bi-weekly removal of all runners and/or one or two leaves during the cropping season of tunnel-grown ‘Favori’ everbearing strawberry plants was determined. Plants were grown on a table-top system in an open plastic tunnel under natural light conditions in Norway from May to October. Removal of runners and leaves was bi-weekly from 5 June until 25 September. Fruits were harvested from 5 July to 7 October. Bi-weekly runner removal increased total and marketable yield and number and size of fruits, while increasing leaf thinning had the opposite effects. However, none of the treatments affected the fruit number and yield of the first fruiting flush. The treatments did not affect realization of the yield potential of the plants at planting, whereas the continued floral initiation and fruit growth were enhanced by runner removal. Increasing leaf thinning had the opposite effects. Both floral initiation and fruit growth in heavily flowering and fruiting everbearing strawberry are source-limited owing to the high fruit/leaf ratio of such plants. Full article