Postharvest Weight Loss Research Articles

Response of carrot (Daucus carota Linn.) to different doses and sources of nitrogen in Sindhuli, Nepal

As a root crop known for its substantial nitrogen requirements, carrot responds well to both organic and inorganic fertilizers that supply different amounts of nitrogen. This study aimed to assess the efficacy of various proportions of farmyard manure (FYM) and recommended dosages of chemical fertilizers (RDF) in carrot production to address the issues posed by their sole use. A Randomized Complete Block Design (RCBD) was used to plan the field study, which consisted of five treatments and five replications with different nitrogen rates and sources, viz., T1 (100% FYM), T2 (25% RDF+75% FYM), T3 (50% RDF+50% FYM), T4 (75% RDF+25% FYM), and T5 (100% RDF) during December 2019 to April 2020 in the tropical region of Sindhuli, Nepal. Among the treatments, T3 exhibited the earliest germination (7.60 DAS) and the most desirable plant height (42.61 cm), root length (20.41 cm), root diameter (3.01 cm), fresh root weight plant-1 (96.04 g), total root dry matter content (15.01%), root biomass plant-1 (55.44 g), and total biomass plant-1 (85.33 g) at harvest. However, T5 resulted in the highest leaf count plant-1 (8.6) and fresh foliage weight plant-1 (42.96 g) at harvest. Similarly, T3 was significantly higher for quality parameters, such as cortex diameter (1.36 cm), pH (6.72), TSS (12.48 0Brix), TA (0.22 g liter-1), and organoleptic score (7.60). Although there were minimal root disorders in T3 (17%), T1 also had insignificant cases of cracking (8%) and postharvest weight loss (1.63%). Thus, reducing nitrogen input from the recommended dose and adding FYM improves carrot yield, quality, and shelf life. Furthermore, this guarantees higher economic returns with a B:C ratio of 1.65. Despite these positive results, the efficacy of the tested nutrient combinations needs to be analyzed on a larger scale, as well as in different ecological regions.

Exploring shelf-life predictability of appearance traits and fruit texture in blueberry

Improving the shelf-life of blueberries (Vaccinium spp.) has become a crucial breeding priority for the industry. However, the breeders have sparse empirical data to select genotypes with extended shelf-life. In this study, a large set of cultivars was evaluated for mechanical texture and appearance characteristics at harvest and after storage to understand their relationship and test multiple statistical models to assess the predictability of shelf-life. Blueberries harvested from 61 cultivars with extensive phenotypic variation were stored at 2 oC and 80% relative humidity (RH) for six weeks. The results indicated that weight loss, texture change, and fruit wrinkling could be predicted using fruit characteristics measured at harvest (T0) or two weeks post-harvest (T2). The berry size at T0 was able to predict postharvest weight loss with high accuracy; the larger the initial berry size, the less weight loss. This trend plateaued with berries larger than 18 mm in diameter. For texture, the measurements at T0 and six weeks after storage (T6) were positively correlated in all mechanical texture parameters, indicating that the initial texture is highly related to the final texture after storage. The overall change of texture could be best predicted using the texture parameter ‘distance to maximum force’ (DFM) measured at T0. Although the prediction accuracy was relatively low (R2 = 0.34), the model still effectively predicted the cultivars with the most texture change and those with the least. Interestingly, the prediction power improved to a moderate level (R2 = 0.45–0.66) when using all the texture and appearance parameters measured at T0 and T2. Wrinkling was best predicted by either the initial fruit size or the texture parameter ‘force linear distance’ (FLD) with low accuracy (R2 = 0.35–0.37); the larger the berry or FLD at T0, the less wrinkle after storage. These findings provide empirical data that blueberry breeders could use to select for shelf-life in blueberry. Predicting the variation of shelf-life indicators in a germplasm can substantially reduce the cost and time required to phenotype shelf-life performance.

Role of Exogenous Melatonin in Enhancing Shelf Life of Traditional Banana Varieties

Aims: An experiment was conducted to examine the effect of various concentrations of melatonin on post harvest weight loss and shelf life of three traditional banana varieties viz. Ney Poovan, Nendran and Red Banana.
 Study Design: Completely Randomized Design.
 Place and Duration of Study: Post Graduate laboratory, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore during 2022.
 Methodology: Banana hands were dipped in 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mM melatonin for 15 minutes and were stored at ambient temperature. The hands dipped in water were treated as control. Observations on physiological weight loss and shelf life were recorded till the fruits remained marketable.
 Results: The results depicted that fruits immersed in 1.0 and 1.5 mM melatonin for 15 minutes recorded lower weight loss (31.56, 30.55 and 24.90%) on 11th, 11th and 12th day of storage and longer shelf life by 3, 2.67 and 2.67 days in Ney Poovan, Nendran and Red Banana respectively.
 Conclusion: The effects of melatonin were due to its efficiency in reducing transpiration and respiration and thereby lowering weight loss. The lowered metabolic activity not only mitigated weight loss but also maintained firmness and turgidity of the fruits and thereby prolonging the storability. It was evident from the results that melatonin treatment could be a good practice for extending postharvest life of banana by reducing the physiological loss in weight simultaneously maintaining the appearance.

Effect of combined application of carbonate salts and hot water treatment for the management of postharvest anthracnose (Colletotrichum gloeosporioides) of papaya.

Postharvest anthracnose (Colletotrichum gloeosporioides Penz.Sacc) is the most economically important biological constraint to papaya production and consumption, which causes substantial yield loss worldwide. The effect of combined application of carbonate salts and hot water treatments on the development of postharvest anthracnose and maintenances of postharvest quality of papaya fruit was studied in completely randomized design (CRD) under laboratory condition. The results revealed that combined application of hot water treatment and carbonate salts significantly (p < .05) reduced the incidence and severity of postharvest papaya anthracnose disease. The disease incidence reached 100% 21 days after inoculation in the control treatment; this level was significantly reduced to 26.70% by dipping the fruits in NH4CO3 at 50°C and NH4CO3 at 54°C. Similarly, treatments significantly (p < .05) reduced the disease severity in different degrees from the first day of disease appearance to the date of 100% unmarketability of control fruits. Furthermore, the combined application of carbonate salt and hot water treatments significantly improves fruit marketability by 93.33%. Moreover, the treatments showed significant (p < .05) effect on maintaining pH, TSS, TA, and reducing postharvest weight loss of papaya fruit. In conclusion, postharvest treatment of papaya fruit with NH4CO3 at 54°C, NH4CO3 at 52°C, and NaCO3 at 54°C can significantly reduce anthracnose development and improve marketability of the fruits without pronounced effect on their edible qualities.

An in-depth study on post-harvest storage conditions depending on putrescine treatments of kiwifruit

The aim of this study was to determine the effects of different doses (0.4, 0.8, 1.2, 1.6 and 2.0 mM) of putrescine treatments on the post-harvest weight loss, decay, firmness, soluble solids content, titratable acidity, pH, respiration rate, L* , a* , b* , Chroma and hue angle and phenolic compounds, organic acids and vitamin C content of kiwi (cv. Hayward. The fruits were kept in a cold storage at 0 ± 0.5 °C and 90 ± 5% relative humidity for 140 days. The weight loss, soluble solids content, increases in respiration rate and high decreases in fruit density, firmness, and titratable acidity were detected in the control group fruits during storage. Among the putrescine treatments, 1.2 mM concentration was observed to be more effective than other concentrations and providing better protection for organic acids, while treatment with 2.0 mM was determined to be providing more protection in preventing the loss of vitamin C. The dominant organic acid of kiwi was determined as citric acid, followed by malic acid, succinic acid and vitamin C. Similarly, it was determined that treatment with 2.0 mM putrescine prevented the loss of phenolic acid and flavonoid more than the control group and other treatments. It was determined that the most common compound found among phenolic acids in kiwi was protocatechuic acid, followed by chlorogenic acid. At day 140 of storage, the minimum change was observed in protocatechuic acid with the application of 1.6 mM putrescine dose, while chlorogenic acid and catechin were the most conserved compounds under treatment with of 2.0 mM.

Assessing the efficacy of wild basil (Ocimum americanum L. (Walp)) in the management of cowpea weevil (Callosobruchus maculatus)

Cowpea (Vigna unguiculata (L.) Walp) belongs to the family Fabaceae and is one of the pulses that suffer postharvest losses greatly. The major insect that attacks stored cowpea seed in Kenya is the cowpea weevil (Callosobruchus maculatus). The insect can damage 100% of stored cowpea seeds causing weight loss of up to 60%. Although insecticides are widely available, they have high potential risks to users and also pollute the environment. In drier areas of Kenya where the pest is common, small-scale farmers use botanicals with varying levels of success. This study sought to assess the effectiveness of a locally available botanical, Ocimum americanum, in the management of the cowpea weevil. Different plant parts of O. americanum, the leaves, flowers and whole mature young plants were dried and ground into powder. From each plant part, 0.5, 1.0, 2.0, 4.0 and 8.0 g were used to determine their effectiveness against the weevil in stored cowpea seed. Two controls were used, that is, no protectant and Actellic super dust. For each treatment, 10 g of cowpea seeds were placed in plastic vials containing ten pairs (male and female) cowpea weevil adults. The experiments were laid out in a completely randomized design at the Kenya Agricultural and Livestock Research Organization (KALRO), Nairobi, Entomology Laboratory. Lowest post-harvest weight loss (3.0 g) of cowpea seed and highest mortality (92.5%) of cowpea weevil was recorded when 8 g of leaf powder were used. Since wild basil is a common weed in drier parts of Kenya such as Mbeere, Tharaka-Nithi, Kitui, Makueni and Mwingi, it can be utilized in these areas as a cheap control bioinsecticide for cowpea weevil.

Foraging behavior and visit optimization of bumblebees for the pollination of greenhouse tomatoes

The tomatoes grown under greenhouse conditions require supplemental bee pollination for the better fruit set. The present study was conducted to evaluate the optimized role of bumblebees (Bombus terrestris L.) for tomato pollination under greenhouse conditions. The impact of increasing number of floral visits (i.e. 1 to 5) on physical and biochemical properties of tomato was studied on tomato variety ‘Grande’ grown on an area of 500 m2. The self-pollination and hand vibration treatments were maintained for the comparison. The foraging behavior in terms of colony traffic, stay time and visitation rate was also studied. The maximum average outgoing bumblebees (7.38 individuals) were recorded at 10:00 while the maximum average incoming (6.75) were recorded at 2:00 pm. The three visits of bumblebees on a single flower resulted in the maximum improvement in physical (higher fruit length, fruit weight, fruit weight, number of seeds per fruit, weight of 100 seeds) and biochemical properties (vitamin C, shelf life) as compared to hand vibration and self-pollination treatments. There was no improvement in physical and biochemical properties in fourth or fifth visit. Bumble bee pollinated fruits had low TSS, pH and postharvest weight loss than that of self-pollinated and hand vibrated treatments. Therefore, three visits of bumblebees per flower are enough to get the optimum production of tomato under greenhouse conditions.

Effect of chitosan and silicon oxide treatments on postharvest Valencia Late (Citrus × sinensis) fruits

The efficacy of chitosan and silicon oxide to prevent postharvest weight loss and fungi infection in 'Valencia Late' oranges was tested. Three silicon oxide concentrations (0.1%, 0.2%, 1%) were applied as preharvest treatments. Chitosan treatments were performed at the same concentrations in postharvest fruit. Preharvest applications were carried out by tractor spraying, while fruit were submerged for 30 seconds in baths with the chitosan concentrations in the postharvest applications. In both cases, a positive control (water treatment) and negative control (fungicide) were included. Treated fruit were stored in a chamber to simulate commercial storage conditions (4 ºC, 90% RH) for 9 weeks. After this time, the weight loss and damage caused by fungi due to natural infection were evaluated. Both silicon oxide and chitosan applications were effective in controlling natural infection by Penicillium species but had no positive effect on weight loss.

Comparative analysis of the cuticular waxes and related gene expression between ‘Newhall’ and ‘Ganqi 3’ navel orange during long-term cold storage

Previously, we obtained a wax-deficient mutant ‘Ganqi 3’ (MT) from ‘Newhall’ navel orange (Citrus sinensis [L.] Osbeck cv. Newhall, WT). The weight loss and postharvest decay in MT fruit were much higher than those in WT fruit after long-term cold storage. To understand the underlying mechanism, the changes in the morphology, chemical composition and gene expression of cuticular waxes between WT and MT fruit were compared during 150 days of storage at 4 °C. The density of epicuticular wax crystals and the contents of most of the aliphatic wax fractions in MT fruit were much lower than those in WT fruit over 90 days of storage. Further research revealed that the differences in the morphology and chemical composition of cuticular waxes might be important causes for the differences of postharvest weight loss and decay rates between WT and MT fruit. Notably, the expression profiles of 16 wax-related genes in WT and MT fruit were consistent with the change trends of corresponding cuticular wax components during cold storage. These results suggest that the morphology and chemical composition of cuticular waxes may be regulated by wax-related genes and play an important role in regulating the postharvest weight loss and the tolerances to postharvest decay in navel orange.

Maintaining the Quality and Storage Life of Button Mushrooms (Agaricus bisporus) with Gum, Agar, Sodium Alginate, Egg White Protein, and Lecithin Coating.

Button mushrooms have a very short shelf life after harvesting and are sensitive to mechanical damage and browning. This can be a severe problem in enlarging the market and the long-distance exportation of this product. In this respect, edible coatings could be an alternative treatment to extend the shelf life of button mushrooms, maintaining their quality during long-term storage. The aim of this study was to investigate the impact of gum, agar, sodium alginate, egg white protein, and lecithin on the postharvest weight loss, color, browning, respiration rate, ethylene production, and storage life of button mushrooms. The results showed that the above-mentioned edible coatings are a promising way to extend the life and maintain the quality of button mushrooms. Significant differences (p < 0.05) were observed between the control and edible coating-treated samples in all parameters. Sodium alginate and gum were more effective in preventing weight loss, coloring, and browning than other edible coatings. On the other hand, the respiration rate and ethylene production were more suppressed by the agar and lecithin coatings compared to the others. In conclusion, it can be recommended that the above-mentioned edible coatings could be used as novel coatings in commercial treatments for maintaining the quality of button mushrooms during a long-term storage period.

Growth, yield, and postharvest quality of cabbage (Brassica oleracea L.) in response to different levels of nitrogen fertilizer

In the Philippines, vegetable farmers generally apply excessive amounts of fertilizer to maximize yield while not understanding the cost impacts and environmental effects. This study aimed to evaluate the effects of different rates of nitrogen fertilizer on the productivity of two cabbage cultivars. The experiment was conducted as a factorial using a randomized complete block design in two growing seasons. The two factors included level of nitrogen (21, 141, 191, 241, 291, 341 and 391 kg N ha-1) and cultivar ('Resist Crown' and 'KEX-734') with each treatment combination replicated four times. The study showed that application of 291 kg N ha-1 resulted in the highest dry matter, largest heads (polar and equatorial) and highest average yield (35.49 t ha-1) in the two growing seasons. At 391 kg N ha-1, cabbage yielded the highest number of leaves and leaf count increased concomitantly with increasing N application rate. Results further showed that N application at the highest rate (391 kg N ha-1) resulted in the highest postharvest weight loss (33.7%) and shrivelling of cabbage heads. The cultivar 'Resist Crown' produced a greater number of leaves, largest polar head size and consequently highest mean yield (25.7 t ha-1) than cultivar 'KEX-734' in both cropping seasons. The results indicate that an application rate of about 291 kg N ha-1 is recommended for cabbage production since it increases yield through enhancing the size and weight of the cabbage head. 'Resist Crown' was a better cultivar than 'KEX734' having greater yield and postharvest quality. © 2021 International Society for Horticultural Science. All rights reserved.

GROWTH, YIELD AND POST-HARVEST EVALUATION OF LETTUCE PLANTS SUBJECTED TO DIFFERENT LEAF SILICON CONCENTRATIONS

Lettuce is considered the most produced and consumed leafy vegetable; however, it has short post-harvest life, which generates significant losses for both producers and consumers. Studies have proven the beneficial effect of silicon on fruits and vegetables. Therefore, the aim of the current study is to evaluate the influence of leaf calcium silicate application on the growth, biomass production and postharvest conservation of curly lettuce. The experiment was carried out in greenhouse at Federal Rural University of Amazonia, Parauapebas Campus / PA. It followed a completely randomized design (CRD) with five Si concentrations (0.0, 2.0, 4.0, 6.0 and 8.0 mg L-1) and eight repetitions, which totaled 40 plants. Plants were grown in plastic pots (capacity = 3 dm3) filled with soil classified as Red-Yellow Argisol. Different Si concentrations were applied to plant leaves, at the 20th and 27th days after transplantation (DAT). Silicon has favored the growth and development of lettuce plants, as well as reduced their post-harvest weight loss. It was possible concluding that the herein tested Si concentrations, which were applied to leaves - in the form of calcium silicate - had beneficial effect on lettuce plants.

Pre-harvest root application of soluble silicon improves postharvest quality and induces antifungal compounds in bitter gourd (Momordica charantia L.)

Beneficial effects of Silicon (Si) on disease control have been shown in a number of plant pathosystems. The present study ascertained the effect of root application of soluble Si on postharvest quality of bitter gourd (Momordica charantia L.) with special reference to the disease development by Fusarium oxysporum. Plants were treated with Potassium silicate (Si+) by amending the soil mix (200 mgSi /kg soil). Treatments were started at the four leaf stage and continued up to 28 days at seven days intervals. Soil amendments with Si significantly reduced the postharvest weight loss and extended the shelf life by 2 days through delayed ripening and reduced fungal rot development. Si analysis in bitter gourds, harvested from Si + plants revealed that fruit tissues accumulated nearly1.5 times as much silicon (0.54% dry weight) as those grown in control (Si-) mix (0.36% dry weight). Extracts from Si + plants exhibited a stronger antifungal activity on thin layer chromatography (TLC) against Cladosporium cladosporioides. Methanolic extracts of fruit pericarp separated on TLC plates showed four antifungal zones at Rf 0.17, 0.51, 0.64 and 0.93. Compound separated at Rf 0.64 was observed in samples from Si + and/or challenged with F.oxysporum. Antifungal zone at Rf 0.51 was present only when Si + fruits were challenged with the fungus. These results suggest that by using soil application of soluble Si, postharvest quality of bitter gourd can be improved and shelf life can be enhanced by 2 days compared to the control. Enhanced fungitoxic activity may have some role in Si-induced disease resistance againstpostharvest fungal pathogens.

Repeated applications of CPPU on highbush blueberry cv. Duke increase yield and enhance fruit quality at harvest and during postharvest

Applications of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) can increase blueberry (Vaccinium corymbosum L.) yield and fruit size, but their impact on postharvest is unknown. We studied repeated CPPU applications effects on yield and quality (harvest, postharvest), over 2 yr on mature 'Duke' plants in South-Central Chile. The first year, 5 or 10 mL L-1 CPPU was applied at 3, 10, and/or 17 d after full bloom (DAFB) plus a non-sprayed control. The second year, 5 or 10 mL L-1 CPPU were sprayed 10 and 17 DAFB plus a control. The first year, only 10 mL L-1 CPPU sprayed 3+17 DAFB increased yield (32.5% > control); 10 mL L-1 CPPU applied 10 or 3+17 DAFB had highest fruit diameter; and 10 mL L-1 CPPU at 17 DAFB or at 3+10+17 DAFB had highest soluble solids. Overall, 10 mL L-1 CPPU applied 3+17 DAFB, was the best treatment for year one, since it increased fruit yield and diameter, while soluble solids and postharvest weight loss were similar to control. The second year, 10 mL L-1 CPPU reduced fruit coloration (blue color coverage index: BCCI) and soluble solids, but not firmness at harvest. This rate increased berry weight (24.2%) and fruit wax (59% > wax coverage index: WCI) at harvest. Harvest and postharvest WCI increased consistently as CPPU rate increased. CPPU reduced fruit rotting (15% at 45+5 evaluation). During storage, CPPU-treated-fruit had a slower decrease in firmness (30.5% < control at 30+1), but no difference at 30+5. CPPU-treated-fruit usually had higher post harvest soluble solids. Ten mL L-1 CPPU retarded color evolution at harvest and at 30+1, but not at 30+5, 40+1 or 40+5.

Assessment of rind quality of ‘Nules Clementine’ mandarin during postharvest storage: 1. Vis/NIRS PCA models and relationship with canopy position

This research was conducted to examine the relationships between fruit position in the canopy, limited light by fruit bagging, rind biochemical composition and susceptibility of ‘Nules Clementine’ mandarin to rind breakdown disorder (RBD) during storage. A secondary aim of this study was to explore diffuse reflectance visible and near infrared spectroscopy (Vis/NIRS) as a non-destructive technique to sort mandarin fruit based on preharvest canopy position. Vis/NIRS signals of fruit from four orchards in the Western Cape Province in South Africa (Citrusdal, Paarl, Porterville and Stellenbosch) were obtained using a LabSpec® spectrophotometer. In all four orchards, bagged fruit inside the canopy had significantly (p<0.001) higher incidence of RBD compared to unbagged outside fruit. Concomitant to this, bagged fruit inside the canopy had significantly higher postharvest weight loss and lower dry matter (DM) content in the rind tissue, suggesting involvement of these parameters in fruit susceptibility to RBD. Bagged fruit inside the canopy harvested from Porterville and Paarl had higher concentration of non-structural carbohydrates (fructose, glucose, and sucrose) than outside fruit without bagging. In Stellenbosch, fruit from the outside position without bags had lower rind sucrose (95.3mg/g DM) compared to inside bagged fruit (114.9mg/g DM) but higher glucose concentration (92.0mg/g DM) compared to inside bagged fruit (66.9mg/g DM). Principal component analysis (PCA) of Vis/NIRS signals was executed to separate fruit according to canopy position. The projection of the samples in the PCA score plots displayed clusters that allowed distinction between fruit from different preharvest treatments. The ability of PCA to discriminate inside and outside fruit using Vis/NIRS signal suggests the potential of this technology to discriminate fruit based on their susceptibility to RBD.

Effects of carboxymethyl cellulose and chitosan bilayer edible coating on postharvest quality of citrus fruit

There is increasing public interest in development of edible natural biodegradable coatings to replace the currently used commercial synthetic waxes for maintaining postharvest quality of citrus fruit. We tested the efficacy of a newly developed polysaccharide-based edible bilayer coating comprising carboxymethyl cellulose (CMC) and chitosan in preserving postharvest quality of various citrus fruit, including ‘Or’ and ‘Mor’ mandarins, ‘Navel’ oranges, and ‘Star Ruby’ grapefruit after simulated storage and marketing. In all citrus species, it was found that the CMC/chitosan bilayer coating was equally effective as the commercial polyethylene wax in enhancing fruit gloss. Furthermore, the CMC/chitosan bilayer coating slightly increased fruit firmness, especially of oranges and grapefruit, but was mostly not effective in preventing post-storage weight loss. Both the CMC/chitosan bilayer coating and the commercial wax had no significant effects on juice total soluble solids and acidity levels, and had similar effects on gas permeability, as indicated by only slight increases in internal CO2 levels and in juice ethanol accumulation after storage. Sensory analyses revealed that neither the CMC/chitosan bilayer coating nor the commercial wax coating had any deleterious effects on flavor preference of ‘Navel’ orange and ‘Star Ruby’ grapefruit. However, application of the commercial wax, and moreover the CMC/chitosan bilayer coating, resulted in a gradual decrease in flavor acceptability of ‘Or’ and ‘Mor’ mandarins because of increased perception of off-flavors. Overall, we showed that the CMC/chitosan bilayer edible coating sufficiently enhanced fruit gloss, but was not effective in preventing postharvest weight loss. Furthermore, flavor quality was slightly impaired in mandarins but not in oranges and grapefruit.

Effects of Organic Fertilization and Cover Crops on an Organic Pepper System

With the continuing 20% growth rate in the organic industry, organic vegetable crop production has increased to 98,525 acres in the United States. The requirement for certified organic vegetable producers to implement a soil-building plan has led to the development of soil fertility systems based on combinations of organic fertilizers and cover crops. To determine optimal soil fertility combinations, conventional and organic bell pepper (Capsicum annuum) production was evaluated from 2001 to 2003 in Iowa, comparing combinations of two synthetic fertilizers and three compost-based organic fertilizers, and a cover crop treatment of hairy vetch (Vicia villosa) and rye (Secale cereale) in a strip-tilled or fully incorporated cover crop system. Organic pepper growth and yields equaled or surpassed conventional production when nitrogen (N) was provided at 56 or 112 kg·ha−1 from compost-based organic fertilizer. Soil analysis revealed higher N in plots where cover crops were tilled compared with strip-tilled plots, leading to recommendations for sidedressing N in strip-tilled organic pepper production. Increased incidence of disease was also detected in strip-tilled plots. Postharvest weight loss after 6 weeks in storage was similar in organic and conventional peppers. The addition of calcium and sulfur products in conventional or organic fertilizer regimes did not increase pepper production or postharvest storage potential. Despite application challenges, cover crops will remain as critical components of the organic farm plan for their soil-building benefits, but supplementation with approved N sources may be required for optimal pepper production. Organic growers should conduct their own tests of organic-compliant soil amendments to determine cost effectiveness and value for their site before large-scale application.

POSTHARVEST TREATMENTS FOR EXTENDING MARKET LIFE OF FRESH HORSERADISH

Horseradish (Armoracia rusticana) has one of the highest rates of postharvest weight loss among all vegetable crops. Postharvest studies were conducted to identify improved methods of extending the market life of fresh horseradish roots. Postharvest treatments included submerging or coating thoroughly washed and dried roots in chlorine (150 ppm), hydrogen dioxide (Storox), 2,6-dichloro-4-nitroaniline (Botran), carnauba-based wax, shellac-based wax, paraffin wax, and polyolefin shrink film (75–100 micron thickness). Two treatments, shrink wrapping and paraffin waxing, were superior in reducing postharvest weight loss and extending horseradish root market life. Roots from the non-paraffin waxed and nonshrink-wrapped treatments lost an average of 20% weight after only 4 days of ambient temperature storage. This resulted in significant root shriveling and unacceptable market appearance. Roots from the shrink wrapped treatments lost an average of 1% weight after 4 days of ambient temperature storage, while paraffin waxed roots lost about 3% weight. It is important to thoroughly dry the roots before shrink wrapping, to avoid moisture condensation on the inner surface of the film and subsequent microbial growth. All of the shrink-wrapped roots and paraffin waxed roots were marketable after 14 days of ambient storage, and no surface mold was detected. Less than 3% weight loss occurred after 14 days of ambient storage in all shrink-wrapped roots, while paraffin-waxed roots lost about 9% weight. Weight loss in the unwrapped roots from the other postharvest treatments ranged from an unacceptably high 44% to 48% after 14 days.

Organic Pepper Production Systems Using Compost and Cover Crops

ABSTRACT In a national survey and through statewide focus groups, organic farmers identified pest management and soil fertility as their most critical vegetable research needs. In response, a long- term experiment was established to compare pepper (Capsicum annuum L.) growth, productivity, insect populations, harvest cullage and postharvest weight loss under conventional and organic management. Treatments from the first 3 years (1998 to 2000) consisted of combinations of two synthetic fertilizer and three compost-based certified organic soil amendments. In addition to the compost treatments, effects of a cover crop of hairy vetch (Vicia villosa Roth) and rye (Secale cereale L.) were evaluated in the organic system from 1999 onward. Pepper growth, harvest weight and marketable fruit numbers were similar in conventional and organic production systems from 1998 to 2000 when 112 kg ha−1 N was applied through synthetic fertilizer or compost. Zone-tillage or incorporation of cover crops prior to planting resulted in pepper weights equivalent to compost treatments in 1999, but in zone-tilled plots in 2000, pepper growth was significantly reduced. Corn borer [Ostrinia nubilalis (Hübner)] larval populations were similar in both systems, with beneficial insect populations greater in the organic system in 1999 only. The number of culled peppers due to insect or disease damage was similar in conventional and organic systems in 1998 and 1999, but greater in the synthetic fertilizer plots in 2000. Postharvest weight loss was similar in the compost (112 kg ha−1 N) and synthetic fertilizer treatments in 1999 and 2000 after three to nine weeks in 10°C storage.

Effect of preharvest bagging and of embryo abortion on calcium levels in ‘Kensington Pride’ mango fruit

Bagging mango fruit during their development on the tree can reduce insect and disease damage. However, it is also possible that bagging can interfere with transpiration and associated calcium accumulation. Low calcium concentrations have been correlated with poor mango fruit quality. This study was conducted to evaluate the influence of bagging at various stages of fruit development on calcium concentration and postharvest quality of ‘Kensington Pride’ mangoes. Fruits were bagged at 41, 25 or 9 days before harvest. No statistically significant differences in either skin or flesh calcium concentration were found between the bagged (plastic or paper) and unbagged fruits. Postharvest weight loss was enhanced and shelf life reduced in the ‘plastic bagged’ fruits. In an ancillary study, calcium concentrations in ‘Kensington Pride’ nubbins (seedless fruit) were compared with those in seeded fruit, since it has been shown with apple fruit that greater seededness is positively correlated with increased flesh calcium concentrations. Conversely, however, calcium concentrations in the flesh of mango nubbins were found to be significantly higher (0.80 mg/g dry weight) than those in seeded fruit (0.58 mg/g dry weight) of similar size.