Strawberry Fragaria ananassa belonging to family Rosaceae is a dicotyledonous angiosperm. The cultivated strawberry Fragaria ananassa Duch, was developed from hybrids of F. Virginiana and F.chiloensis (Hancock et al., 1999). The important genes for large fruit size, large crowns ,firm fruit and distinctive fragrance were inherited mostly from Chilean F. chiloensis (Otterbacher and Skirvin, 1978; Galletta and Bringhurst , 1990).Strawberry is known as the most delicious, refreshing fruit with high nutritive value (Cordenunsi, 2003) and high hexose/sucrose ratio (Nishizawa et al., 2005) to millions of people of the world. Strawberry plants have been generally classified by their response to day length (photoperiod) and its influence on flower induction. There are three recognized groups of plants: June bearers, Ever bearers, and Day-neutrals (Durner et al., 1984).
Strawberry fruit is a rich source of vitamins and minerals with delicate flavor. It contain reasonable amount of vitamin C (ascorbic acid) and phenolics compounds with high antioxidant activity, such as ellagic acid and anthocyanin (Grace, 2005). Strawberries generally require cooler summers, and are poorly adapted to the hot, arid climates and can tolerate -20°F. They have chilling requirements ranging from 800-1600 hr. However, it can be grown in varied climatic conditions, ranging from temperate to tropic climate. Since its cultivation is greatly influenced by specific regional adaptation due to critical photoperiod and temperature requirement, its cultural practices are highly variable (Sharma, 2002).
Strawberry is an early maturing fruit crop and can be planted round the year hence; it brings a high and quick economic return to growers. Winter planting is common in Pakistan. However, due to diverse agro-ecological zones in Pakistan, summer, autumn and spring plantings have also been successfully demonstrated by different agricultural research institutes. In Pakistan strawberry has a great potential due to the diverse climatic conditions which are conducive to its growth and can be successfully grown in the central and northern Punjab, and hilly areas of NWFP province, where the plants can be sustained for two to three years. Strawberry growers of the warmer plans are entirely dependent on hilly areas for their planting material requirements, which makes it cultivated in plains less remunerative. The runners, which are received from hilly areas have very limited growth due to short growing season (July - September) as compared to plains (May - November) and thus give ultimate weak runners with poor yield.
Strawberry crop has been recently introduced at the farm level in Pakistan and was demonstrated at various research stations. A few years ago it was adopted by a few innovative growers around Islamabad, Lahore, and Malakand division in NWFP. The main markets of strawberry are only Islamabad and Lahore. However, very little is known about its area, supply schedule, volume, price, etc. In Islamabad, the local and producers from other areas mainly supply strawberry directly to retail supermarkets, big hotels and to local assemblers' cum-processors. The local wholesale market in Islamabad generally does not deal with such perishable commodities. However, in Lahore, strawberry is being traded in the wholesale fruit and vegetable market through commission agents. Producers also supply directly to retailers and processors. The supply of strawberry starts at the end of January and continues until the end of May each year.
Pakistan is producing a limited quantity of strawberries as compared to USA, Russia, Spain, Turkey, South Korea, Japan, Poland, Mexico, Germany, Egypt, Morocco, United Kingdom, Ukraine, Italy and France. Among these USA is the biggest producer of strawberry (FAOSTAT, FAO statistics Division 2009).These are either eaten fresh or used in preparing ice-cream, jam, jelly, pickle, cake or milk shake. There are a number of reasons for restricted production, like the climate, size, taste, pre and post harvest handling. By overcoming problems related to quality, quantity and perishability of the fruit, Pakistan can also export it to Europe, the United States and Middle Eastern countries. Many varieties of strawberries are grown in Pakistan. Toro and Douglas obtained from USA are suitable for southern areas of the country and Tufts, Chandler, Cruz and Pocahontas are recommended for Islamabad. Chandler, Corona, Tufts, Honeyo and Gorella are suitable for Swat. The introduction of new varieties that have a longer shelf life would increase the potential of this crop.
Pakistani strawberry can easily be air freighted to European markets with high efficiency cooling facilities from farm to air transport. The consumer base is restricted to those who have been abroad or have a wide exposure to the outside world especially Europe. The other main users of this commodity in Pakistan are processors of ice cream, jam and cake, marmalade and drinks. It is also used in different medicines and cosmetics. It can be used in both fresh and frozen form around the year. Moreover, a growing awareness regarding the nutritional value of strawberry and overall changing tastes and preferences of urban society suggest that it has bright growth prospects. Also, the available evidence shows that due to the low cost of production and conducive agro-climatic conditions in Pakistan, the export potential of strawberry substantial. Also, it has potential benefits for small farmers in terms of generating rural income and employment. The superior size of the European market indicates that it may be the prime potential market for Pakistani strawberry and it has a sufficient seasonal edge to be a viable competitor. In the European market, Germany is the largest single potential market which can absorb approximately 6,000 metric tons of fresh strawberries per week and still maintain prices which would be profitable to a reasonably efficient Pakistani exporter of strawberry. In addition to Germany, UK, France and Japan are other potential markets and all four markets can absorb roughly 10,000 metric tons per week at prices profitable to a Pakistani producer.
The market "window of opportunity" for Pakistani exporters in these markets is from July to March. However, quality is the key in penetrating these potential markets. The major constraint to strawberry export is the lack of post harvest technology in packing, grading standards and cool chain distribution. Refrigerated transport for such fruit is a vital part of any successful marketing operation under the prevailing climatic conditions in Pakistan. Since this is a new commodity for Pakistani farmers, it requires reasonable production and post-harvest technology. Of course, this can be done through very effective research and development in potential areas of Pakistan.
1.1 Quality attributes and shelf life of strawberry fruit
Quality is a combination of agronomic practices, variety characteristics, grading, processing and finally packaging. The absence of even a single factor makes the product inferior in quality and thus less acceptable in international markets. Strawberries are among the most favorable consumed fruit. The balance between sugars and acids, which define sweetness and tartness respectively of fruits, give the characteristic flavor of strawberries, while aroma is derived by the combination of volatile molecules (Ayala-Zavala et al., 2004). Superficial color of berries determines the time of harvest, while fruit firmness is associated with shelf life. Recently, the determination of ascorbic acid and anthocyanin has been of major interest (Aaby et al., 2005: Scalzo et al., 2005).
Ascorbic acid
The strawberry fruit is a good source of ascorbic acid (Robards et al., 1999).Ascorbic acid levels varies substantially among cultivars (Darrow et al., 1947). There was no reduction in total ascorbic acid contents of strawberry fruits that have been stored at 0, 10, 20 and 30oC for up to 8 days (Kalt et al., 1999). Vinokur et al., 2002 concluded that the ascorbic acid contents in strawberries kept in controlled atmosphere differed significantly of that in control.
Soluble solids
The soluble solid contents of fruit are a good indicator of the sugar content (Haffner and Vestrheim, 1997). It seems that a high fruit load on plants reduces the soluble solid contents in fruit (Anagnostou and Vasilakakis, 1995).Fructose; glucose and sucrose were found to be the major sugars, comprising more than 65% of the total soluble solid contents in strawberry fruit of different cultivars.
Firmness
Even in early studies there were efforts to breed strawberry verities for firmness (Barritt, 1979). Fruit with firm flesh have a longer shelf life (Mokilla et al., 1999).Firmness is affected by the variety, the nutritional status of plants and type of fertilizers used (Mukkun et al., 2001). Low temperature during the storage of strawberry fruit increases flesh firmness (Lara et al., 2004).
Shelf life
Strawberry is one of the most perishable fruits with short shelf life due to the susceptibility of berries to mechanical injury, water loss, decay and physiological deterioration (Nunes et al., 1995).Much research has been conducted and there were efforts of manipulating preharvest (Mukkun et al., 2001) and post harvest factors (Cordenunsi et al., 2005) that affect fruit quality in order to enhance strawberry shelf life. Moreover, special packaging (Saz et al., 1997) or even photochemical (Baka et al., 1999) and chemical (Morris et al., 1985) treatments, have been tested to improve post harvest quality and shelf life of strawberries.
1.2 Pre-harvest factors for quality and shelf life
1.2.1. Varietals response
In previous years researchers conducted many experiments on the cultivars of strawberries in different areas, region and countries. Results vary from place to place due to many external and internal factors. The same experiment was conducted by Nuzzi et al., (2005) and explained that fruits of strawberry cultivars Miss and Queen Elisa from experimental fields in Cesena and Verona in Italy were picked at full ripeness over 2 weeks during May in 2002 and 2003. Quality was assessed objectively according to the main quality parameters, such as weight, flesh consistency, dry refractometric residue, titratable acidity and ascorbic acid content. Storability parameters were assessed following refrigeration for 3 days at 40C and 1 day at 200C. Sensorial quality of the fruit was evaluated by a taste panel. Queen Elisa differed significantly from Miss, having higher values for fruit weight, acidity and ascorbic acid content. Quality of Miss was more affected by the different areas of cultivation than was Queen Elisa quality. Miss was the more distinctive for most volatile constituents.
In an other experiment Yommi et al., (2003) evaluate fruit quality of different strawberry (Fragaria ananassa) cultivars, cold-stored (frigo) plants (FGP) of Aromas, Camarosa, Gaviota and Selva and fresh plants (FHP) of Camarosa, Earlibrite, Gaviota, Rosa Linda, Sweet Charlie and Tud New were grown in a winter production system. Fruits were harvested periodically and samples of 15 fruits (>75% red colour) per cultivar were analysed during June and July (FGP) and August (FHP). Fruit quality was evaluated in terms of fruit weight, external and juice color, firmness, soluble solids (SSC) and ascorbic acid contents, acidity and SSC/acidity ratio. Levels of acidity were different within cultivars, with Camarosa as the most acidic of the group. Within FHP, Tud New had high fruit weight, firmness, ascorbic acid content, which is desirable in terms of quality, SSC ratio were low. Camarosa had relatively high values of firmness, SSC and acidity, and low values of external and juice. Earlibrite had relatively high values of fruit weight, firmness, SSC, acidity and ascorbic acid. Sweet Charlie had high SSC, intermediate firmness and low acidity and ratio.
Cordenunsi et al., (2002) narrated that six strawberry cultivars grown on the same commercial plantation in Brazil were evaluated for their chemical composition and quality attributes at the ripe stage. The profiles of the main soluble sugars, ascorbic acid, and anthocyanin were also obtained during the developmental stages. Results showed significant differences among cultivars in all of the investigated parameters
1.2.2. Mulching
Rajbir Singh (2005) reported that, in northern plains of India, to get an early and high yield of the best quality under a micro-irrigation system, Chandler strawberry could be planted in mid-September if mulched with black polyethylene. J.Lareau and M. Lamarre (1990) compared straw mulch with black plastic mulch and concluded that black plastic mulch increased yield, number and weight of crowns but decreased fruit size of Tribute and Tristar strawberries.
1.2.3. Environmental conditions
Strawberry can be grown in wide climatic conditions, ranging from temperate to tropic climate. Since its cultivation is greatly influenced by specific regional adaptation due to critical photoperiod and temperature requirement, its cultural practices are highly variable (Sharma, 2002). Its cultivars grown in specific areas are adapted to the day length and temperature of that region. Nevertheless, heat stress is one of the challenges that face strawberry production. Reduction in plant growth by high temperature is well established in horticultural crops such as tomato (Adams et al., 2001) grape (Chaumont et al., 1997) and strawberry (Renquist et al., 1983). Damage to crops by high temperature has been reported in many regions around the world. Temperature above 350C is common during the growing season.
High temperature adversely affects the vegetative growth and fruit quality. Heat stress affects photosynthesis, which is highly sensitive to thermal inhibition (Henning and Brown, 1986) whether stress occur early or late in the growing season. Strawberry cells subjected to 300C grew slowly and did not proliferate normally in suspension cultures (Zang et al., 1997), strawberry vegetative growth (Hellman and Travis, 1988), root growth (Fukuda and Matsumoto, 1988), fruit set (Nishiyama et al., 2003), pollen viability (Ledesma and sugiyama, 2005), fruit weight (Mori, 1998), fruit quality (Polito et al., 2002) and leaf protein expression (Gulen and Eris, 2004; Ledesma et al., 2004) were negatively affected by high temperatures, however strawberry plants resistant to high temperature have the ability to maintain high rates of photosynthesis, stabilize proteins and synthesize new proteins (Gulen and Eris, 2004) and by proper selection of cultivars to the region.
1.2.4. Chilling
Some strawberry cultivars behave as short-day plants requiring day lengths shorter than about 14 hour or temperatures less than about 15oC for flower induction. Whereas low temperatures between 10 and 15oC induce flower formation even in long photoperiods, temperatures less than about 10oC resulted in a chilling response (Guttridge, 1985).According to studies of Kronenberg et al., (1976) plants need to be dormant to give chilling response. Judged by the subsequent vegetative growth of plants transferred into warm glasshouses at different times in autumn and winter, deepest dormancy is attained in November in northern latitudes (Jonkers, 1965; Lee et al., 1970).
It is well known that cultivars have different chilling needs (Bailey and Rossi 1965; Lee et al., 1986 & 1970). Those cultivars with small chilling requirement, such as Tioga, need only 2-4 weeks cold; others, like Sequoia, Glass and Gorella, need 5-8 weeks and Redgauntlet, a cultivar with a large chilling requirement, needs more than eight weeks cold (Kronenberg and Wassenaar, 1972). Changes in vegetative growth induced by chilling are striking and resemble the effects of increasing day length. The responses to chilling and to long day lengths are at least additive, and neither substitutes for the other, at least not for petiole responses. Chilling increases the plant's response to daylength (Guttridge, 1985)
Existing fruit trusses are increased in size by chilling. The length of peduncles, secondary branches and pedicels are increased by chilling. The magnitude of the chilling response depends on the stage of development reached by the truss at dormancy (Guttridge, 1985). Piringer and Scott (1964) studied responses to chilling in Sparkle, Tennessee Beauty and Missionary by recording runner production during forcing. In all three cultivars, chilling stimulated runner production. Wahdan and Waister (1984) confirmed the need for a chilling stimulus to induce runner formation. In a study by Bailey and Rossi (1965) on Catskill, it was indicated that plants required greater than 504 hours below 7.2o C to stimulate runner production. They also suggested that more chilling was necessary to affect runner growth than petiole length, leaf number, or size.
In the literature the temperature at which it is assumed strawberry perceive chilling, ranges from -2oC to 10oC. The evidence to the effect of chilling on the production of flowers and fruit is not consistent. The data for Catskill indicate strongly that the numbers of flowers produced increased with increased field chilling (Bailey and Rossi, 1965). Conversely, the result of Guttridge (1960), and Voth and Bringhurst (1958) showed a decrease in flower production with increased chilling. Bailey and Rossi (1965) pointed out that this discrepancy is probably due to the different environment and different methods used in the experiments. In fact they wondered if the increase in the number of flowers was due to increased flower bud initiation in the field with later digging or to increased chilling or both.
In a study conducted by Guttridge (1958a) on Royal Sovereign, chilling for 36 and 72 days in a cold room (1.1-3.8oC) delayed flower initiation. Durner and Poling (1988) pointed out that cultivars vary in their response to photoperiod and chilling with respect to induction, initiation, and differentiation. Yangi and Oda (1993) claimed that the number of inflorescences produced by Hokowase (Junebearer) and Kletter (Intermediate) decrease with the duration of chilling. In this work plants had different lifting dates in autumn (6 Nov, 15 Nov, 15 Dec, and 15 Jan) and were put in the glasshouse at different times. Therefore, the lifting date and duration in glasshouse may have affected the number of flowers initiated and subsequent flower production.
Independent greenhouse forcing tests by Durner and Poiling (1987) indicated that short days tended to enhanced floral induction and initiation but delayed differentiation. Slight chilling (50 hrs at 4.4oC) enhanced macroscopic flower production while greater amounts (150 hrs) delayed emergency by up to three weeks in Earl Glow. Voth and Bringhurst (1985) indicated that increased nursery chilling increased vegetative vigor and concentrated fruit production into a brief harvest. Durner et al. (1987) in a work on four cultivars of strawberry (Douglas, Tufts, Pajaro and Chandler) concluded that chilling enhanced early season yield if it was accumulated prior to the optimum photoperiod date. Nestby (1989) concluded that the forcing period could be shortened by increasing the chilling period. However, the effect of chilling on fruit production has not been explored properly.
1.2.5 Gibberellic acid (GA3)
Gibberellic acid is hormone that seems to have been explored most widely in relation to its effect on dormancy. Application of GA3 to some plants has produced growth responses which are similar to those caused by certain natural environmental factors such as long days and chilling. It has induced flowering on non-chilled biennial plants (Lang, 1957) and broken the dormancy of seeds (Fogle, 1958) and buds (Walker, 1959), thereby substituting for chilling.
In strawberry the effect of GA3 has been considered more as a substitute of long days and has been shown to have some effects similar to chilling such as; increasing heights of the trusses, inhabitation of flower formation and increasing the number of flowers (Porlingis and Boynton, 1961; Tafazoli and Vince-Pure, 1978). Application of gibberelic acid can replace the chilling requirements for some fruit tree buds (Hatch and Wlaker, 1969). This suggests that gibberellic acid may play a part in dormancy release. The involvement of endogenous gibberellins in the chilling requirement of strawberry has also been investigated by Avigdori-Avidov et al., (1977). Plants pre-chilled for 2 months had low levels of gibberellins-like substances which increased several fold upon transfer to the growth chambers, indicating a high gibberellins biosynthesis potential which comes into action mainly after the termination of chilling. However, it is more likely that the onset, control and termination of dormancy are regulated by a balance of growth inhibitors and promoters than by one single chemical (Amen, 1968).
Nigam (2001) reported that L. chinensis (cv. Rose Scented) fruits harvested from 16-year-old trees grown in Pantnagar, Uttar Pradesh, India, on 3 and 6 June [year not given] were subjected to various post harvest treatments (dipping of fruits in 200 ppm gibberellic acid or in 16.6, 20.0, and 25.0% wax emulsion for 2 minutes) and stored under ambient (21.8-29.00C and 41.0-98.0% relative humidity) or cold (50C and 85% relative humidity) storage conditions for 8 days. Physiological weight loss (PLW) and spoilage increased, whereas, titratable acidity decreased with the increase in storage duration. Total soluble solid content increased up to 5 days of storage, and then decreased thereafter. Fruits harvested on 3 and 6 June had lower PLW when treated with 25% wax emulsion (3.94 and 4.76%, respectively) and stored under cold conditions (4.32 and 4.43%, respectively). Fruits harvested on 3 June exhibited lower spoilage incidence when stored under ambient temperature (25.64%) than under cold conditions (26.33%). For fruits harvested on 6 June, cold storage resulted in lower spoilage incidence (39.86%) than ambient temperature storage (51.12%). Gibberellic acid treatment gave the lowest spoilage incidence (15.75 and 32.47%, respectively) and highest total soluble solid content (20.74 and 20.550 Brix, respectively) in fruits harvested on 3 and 6 June.
1.3 Post harvest treatments for quality and shelf life
1.3.1 Storage temperature
Storage temperature is an important factor that affects shelf life of strawberry fruits. Strawberries are stored at room temperature ranging around 18 - 200C (Perez et al., 1999). Most researcher have pointed out that temperature under 0oC (-1and -2oc) give optimum storage, especially during long term storage (Anderson, 1982; 1989). In trials no reliable differences in production were found between plants stored at -1oC or at -3oC, however with storage at +1oC or +3oC plant quality was severely decreased. In general a temperature of -2oC has been recommended (Dijkstra, 1989). Sometimes gradual freezing has given somewhat better results; this is done by first keeping the plants at +1oC for a week (Dijkstra, 1989). Storing at -1oC had a slightly greater effect on growth (petiole length and runner production) of strawberry plants than storing at +5oC (Risser and Robert, 1993). However, the effect of temperature in cold storage has mostly been considered in terms of temperature on survival of plants long terms cold storage rather than on their growth and cropping.
Increasing the duration of the cold storage period of strawberry plants result in a reduction of their flowering potential (Kinet et al., 1993). These authors found a reduction of their flowering potential in cold-stored strawberry plants, and this was associated with decreased starch level in the crowns. Alteration of carbohydrate metabolism by temperatures is well documented. Usually insoluble reserve carbohydrates are hydrolysed and soluble carbohydrates accumulate (AP Rees et al., 1981; Millers and Langhands, 1990). This process, referred to as low temperature sweetening, probably occurs during cold storage of strawberry plants and affects their survival and subsequent vigor in the cropping beds (Kinet et al., 1993).
1.3.2 Packing materials
For strawberries, different types and sizes of packaging material are used. In Islamabad, 250 and 500 gm cardboard boxes and 500 gm cane baskets are usually used. On the other hand, in the Lahore market, the produce is traded in cane baskets containing 8 to 9 kg and also in 250 gm capacity hard paper packets. Krivorot and Dris, 2002 stated that packing strawberries in polyethylene bags decreased respiration, maintained quality and prolonged the shelf life from 7 to 22 days depending upon the cultivar use.
1.3.3 Chemical treatments
Calcium treatment has been applied on different fruits and vegetables to increase their shelf life. By immersing strawberry fruits calcium chloride solution for five minutes and thereafter storing them in polythene bags showed on increase in firmness and weight loss is reduced in treated fruits (Morris et al., 1991). Dipping the strawberry fruits in 1% calcium chloride solution was the most effective treatment for increasing the calcium content of the fruit, for controlling post harvest decay and for maintaining their firmness and total soluble solids content (Garcia et al., 1996). Same results were observed by Bhattarai and Gautam, 2006 during their experiment on the effect of harvesting method and calcium on post harvest physiology of tomato. On the contrary, Souza et al.,1999 during their research evaluated the effects of calcium chloride on quality and prolongation of post harvest life of strawberry fruits stored in cold room, maintained at 4oC, observed that 0,0.5% and 1% calcium chloride had not significantly effected pH, total soluble solids (TSS), total and soluble pectin contents. Calcium chloride was also used in combination with other chemicals to enhance its functioning. Asrey and Jain, 2005 while studying the effect of certain post harvest treatments on shelf life of strawberry cv. chandler, using calcium salts and ascorbic acid found that 0.05% calcium chloride prolonged shelf life with lower acid, moderate total soluble sugar, higher Vitamin C and minimum physiological loss in weight. Another combined treatment of 1-Methylcyclopropene, calcium chloride and controlled atmosphere was studied on fresh cutted strawberries which showed less softening, deterioration rate, titrable acidity and microbial growth (Aguayo et al., 2006). Calcium chloride combined with chitosan increased the firmness and nutritional value by increasing the calcium content of fruit, during its post harvest application on strawberry kept under refrigerated storage (Pilar et al., 2008)
Use of plastic film maintains high humidity inside the package during the storage (Lil et al., 1998). The high humidity inside the package reduces the loss of weight. Decreased respiration, maintain quality and prolonged shelf life from 7 to 22 days (Krivorot and Dris, 2002). Same results were observed by Hietaranta et al., 2002 while using non perforated plastic film. Better color retention was also observed in fruits kept under plastic films (Collins and Veazie, 1993). Other forms of plastic material, like polystyrene foam trays covered with perforated polythene or stretched film were also successful for increasing storage life of strawberry cultivars (Koyuncu and Askin, 2000). Polythene covers together with UV-C light exposure reduce the %age of rotting (Malgarim et al., 2006). The PVC packing produces the rides of Botrytis, and gives the product with excellent quality, as the package being responsible for building up high level of carbon dioxide which in turn is effective on the control of fungus (Paulis, 1990). Same results were observed by Malgarim et al., in 2006 during their experiment on strawberries kept at UV-C light exposure and Polythene films.
Keeping quality of strawberries stored for 8 days was improved. Firmness was maintained at 0, 5 and 10oC but softening occurred at 15, 20 and 25oC (Kim et al., 1996). Similar results were obtained by Shin et al., in 2007. Storage conditions together with storage temperature also affect the shelf life of strawberry. By using polyethylene pouches and storing strawberries at room temperature (26oC) and fridge, resulted in higher weight loss at room temperature (26oC) and lower in fridge (Kumar and Manimegalai, 1998). The ascorbic acid contents in strawberries kept in controlled atmosphere differ significantly than that at room temperature.
Dris et al., (2000) reported that, 'Lobo' apple fruits were subjected to preharvest CaCl2 spraying treatment, pre-storage heat treatment, and CaCl2 + heat treatment and were held at 2oC and 90-95% RH for six months. Respiration and ethylene production rates were monitored and soluble solids, juice pH, firmness, total dry matter and macronutrient (P, K, Ca, Mg, and N) contents were determined. Additionally, the incidence of physiological disorder and pathological disease were recorded. Respiration and ethylene production rates slightly decreased in heat-treated apples and increased in CaCl2-treated apples. CaCl2 treatment did not increase fruit firmness or Ca concentration. Combined CaCl2 + heat treatment and heat treatment increased pH. At the beginning of storage, the firmness of heat- and CaCl2 + heat-treated fruits was lower but greater than that of the control fruits at the end of the storage period. After 6 months of storage, the lowest incidence of disorder and disease symptoms was observed in the CaCl2 + heat treatment.
Objectives of the study
The objectives of the study mainly aimed at the application of three ways to improve growth, yield, quality and shelf life in strawberry:-
Selection of varieties with better fruit quality and shelf life.
Improvement in growth, yield, quality and shelf life through appropriate pre-harvest treatments like mulching, chilling, use of GA3 and growing under suitable environmental conditions.
Evaluation of an appropriate post harvest treatment for shelf life and quality enhancement in strawberry fruit.
