Strawberry is one of the most popular fruits throughout the world and contains numerous important dietary components, as it is high in minerals as well as vitamins. Strawberry is an important crop worldwide in terms of its commercial value as well. Thus, increases in productivity and strawberry quality are required. Cultivated strawberries are now a commercially important fruit around the world Strawberry production has increased over the years.
Environmental factors such as temperature, photoperiod, and light intensity have significant effects on growth, yield, and fruit quality it is known that changes in environmental conditions determine the development of strawberry plants, affecting flowering, fruiting, and the quality of strawberry fruits.
The temperature factor is one key target effect on strawberry growth. Low temperatures (below 7 °C) increase the possibility of damaged fruits as well as changes in fruit size and color. On the other hand, high temperatures reduce the plant’s photosynthetic rate by up to 44%, reducing crop yield and causing a decrease in sugars at the fruit level and, as a result, decrease sweetness. Higher temperatures affect the photosynthesis process and electron transport chain. Moreover, high temperatures on the fruit surface can hasten ripening, and a high rate of ripening could be argued to be factor that reduces the duration of the crop cycle . A high strawberry growth rate is maintained at day temperatures of 23–28 °C, and the optimum night temperature is between 5–10 °C .
The influence of environmental factors on strawberry fruit quality, the weight, shape, and soluble sugar content were recorded and compared to each other. According to the environmental data, the average temperature between day and night at peak harvest was around 12 °C, which was suitable for high-quality strawberry cultivation. However, the average temperature difference between day and night was approximately 4 °C at the end of the season. In addition, there were no significant differences in solar radiation and relative humidity between both seasons. Increasing temperatures led to the decline in the soluble sugar content at the end season. Thus, it can be concluded that the temperature difference between day and night is a major factor affecting strawberry production. The assessment of the impact of environmental conditions on strawberry quality can be used as a guideline not only in temperate climates, but also in other climates, such as in tropical countries
Impacts of plant growth regulators in strawberry plant
Strawberry (Fragaria × ananassa), the family Rosaceae, is a small fruit that has great importance. It is triggered by a number of physiological, genetic, and biochemical processes. Phytohormones or plant growth regulators are organic substances produced naturally in many plants and responsible for controlling growth and other physiological functions. Therefore, plant growth regulators such as Gibberellin, NAA (auxin) and triacontanol, and chlormequat are essential factors that cause strawberry ripening, maturity indices, and determine the quality of fruits. Moreover, Gibberellin stimulates cell division and breaks dormancy whereas NAA (auxin) stimulates root growth. Similarly, triacontanol plays a special role in plant growth and development. Additionally, chlormequat is effective in controlling the height of the plant
Different plant growth regulators perform different function on strawberry. Various PGR like Auxin, gibberellin and cytokinin are used in strawberry in order to increase the fruit size, enhance fruit set, growth, and yields. Among them, auxin are used for enlargement of receptacle, fruit size growth and delay fruit ripening, gibberellin inhibit the fruit ripening, abscisic acid develop a color on fruit and nitric oxide extent the post-harvest life of ripe fruit (Roussos et al., 2009; Marcos et al., 2009). Auxins are also called as key phytohormones, applied in controlling the growth and ripening the fruit which is associated with increase in pectin and reduction of hemicelluloses content (Bustamante et al., 2009)
Influence of gibberellin on strawberry
Plant heights, number of runners, number of flowers, fruit set percentage, number of fruits, fruit size, fruit weight, and fruit quality are all affected by gibberellic acid (Kumra et al., 2018) Gibberellic acid (GA3) treatment promoted flowering in non-chilled strawberry plants, shortened the cropping season, and increased vegetative growth and fruit number (Paroussi et al., 2002). It acts as a fruit ripening inhibitor (Marcos et al., 2009). It Increases vegetative development, increases runner formation, lengthens the main stem internode, initiates flower development, promotes stolon formation, petiole length, and leaf area, destroys rosette habit, and slows blossom initiation ( Sharma and Singh, 2009; Guttridge and Thompson, 1964; Tafazoli & Vince-prue, 2015). The effects of a long photoperiod or chilling are also caused by GA3 (Guttridge, 1970). Gibberellins are well-known for acting as a long-day hormone in short-day plants. Gibberellin treatment increases vegetative growth but limits flower development (Kender et al., 1971). The GA 3-oxidase enzyme prevents runner and crown branch development, increasing berry output (Hytonen, Elomaa, Moritz and Junttila, 2009). By hydrolyzing protein and releasing tryptophan, GA promotes pollen germination, pollen tube expansion, and auxin biosynthesis. GA3 boosts diphenols while inhibiting IAA oxidase activity, resulting in a high auxin level. In the absence of fertilizer, the use of GA resulted in fruit set (Kumar, Saravanan, Bakshi, & Sharma, 2013).
Influence of auxin (NAA) and tricontanol on growth yield and quality
Auxins such as IBA (Indol-3-butyric acid) and NAA (Naphthyl acetic acid) are used to promote rapid and abundant rooting of cuttings from a variety of trees, vines, shrubs, annual and perennial ornamentals (Rademacher, 2015). The effect of NAA on plant growth is greatly reliant on the time and concentration of entry, as well as promoting cellulose production and limiting fruit drop (Suman et al., 2017). GA treatment could only maintain emasculated flower receptacle growth for 6 days, according to Archbold and Dennis (1985), whereas growth of fruit treated with synthetic auxin Naphthalene acetic acid (NAA) could continue for up to 30 days, albeit at a slower rate than pollinated flowers (Roberts and Hooley, 1988). The application of NAA to strawberry fruits enhances fruit size, delays ripening, and boosts anthocyanin accumulation, as well as delaying the flowering time and enhancing fruit output and quality (Csrl, 2016). As stated, using GA3 and Napthalene acetic acid alone or in combination enhances plant height, number of crowns, runners, and leaf area. . The dormant bud has a lot of auxin activity, while the non-dormant bud has a lot of cytokinin activity, according to researchers. Decapitation and pharmacological studies on dormant buds also demonstrated that reducing auxin levels and administering exogenous cytokinins increases strawberry vegetative shoot regrowth (Li et al., 2021). Auxin plays a vital function in fruit growth and ripening by transcriptionally activating Aux/IAA genes (Liu et al., 2011). The skin hardness and hardiness of the underlying flesh define the firmness of strawberry fruit, and this hardiness is linked to the formation of hard achene growth, resulting in the hardiest fruit in NAA treated plants (Rathod et al., 2021). Tricontanol (TRIA) is a natural plant growth regulator found in epicuticular waxes which is used to increase fruit production. enhances vital plant physiological processes such as water and mineral nutrient uptake, essential oil yield, secondary metabolites, early bolting, nitrogen assimilation, proline metabolism, and glycine betaine accumulation thereby protecting plants from variety of environment stresses (Zaid et al., 2020).