Production Practices and Quality Assessment of Food Crops. Vol. 1

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increase in the release of P i from vacuoles can therefore initiate the respiratory burst correlated with fruit ripening (Woodrow and Rowan, 1979). Delayed fruit ripening in phosphorus deficient tomato plants (Pandita and Andrew, 1976) may be related to this function of P i. ADP-glucose pyrophosphorylase is allosterically inhibited by P i and stimulated by triose phosphates. The ratio of P i to triose phosphates therefore determines the rate of starch synthesis in chloroplasts (Herdt et al., 1977). The enzymes being ‘switched off’ at high ratios. 3.3.5. Nitrogen Elevated nitrate levels are uneconomical in relation to nitrogen utilization and are also undesirable nutritionally. Sometimes nitrite is formed from nitrate during either the storage or processing of vegetables. Infants fed on nitrite-containing foods run the serious risk of developing methemoglobemia. 4. EFFECT OF THE ENVIRONMENTAL CONDITIONS ON QUALITY OF SPECIFIC VEGETABLES In this section specific examples of disorders caused by environmental factors are covered in a few chosen vegetables. The vegetable examples presented include tomato and squash which are two very different fruits, cabbage, a leaf vegetable and sweet potato a root vegetable crop. 4.1. Tomato Tomato is a warm season vegetable belonging to the Solanaceae family. The tomato is adapted to a wide range of climatic and soil conditions. It is produced throughout the whole world from near the Arctic Circle under protected environments to the equator. The optimum range of temperature for tomato is 21–24 °C. Mean temperatures above 27 °C are not desirable while temperatures below 12 °C cause chilling injury. Tomatoes are a major source of vitamins and minerals to human nutrition. Production of tomatoes can be either in the field or in the greenhouse. The tomato crop has several disorders that are caused by environmental factors that ultimately reduce yield and quality. These are discussed below. 4.1.1. Chilling injury Effect of Preharvest Factors 19 This disorder shows surface pitting, poor colour development upon ripening, premature loss of firmness and increased susceptibility to decay. This is a result of very low above freezing temperatures especially night temperatures. Chilling injury in mature green tomato fruits could be alleviated by pre-harvest heat treatment for 20 days in greenhouses (maximum of 39 °C, average day temperature of 32 °C) compared to 27 °C. This could be achieved by reducing ventilation in the greenhouse (Kang and Park, 1999). Recent studies have indicated that heat treatment administered prior to chilling reduces the incidence and severity of chilling injury
20 R. M. Madakadze and J. Kwaramba in tomato fruits and other organs. Pre-storage heating of tomatoes at 38 °C for 3 days can extend their storage life and shelf life (Lurie et al., 1993). There was a correlation between maintenance of heat – shock protein mRNA during storage and the inhibition of chilling injury in heated tomatoes. Under certain conditions, however, heat treatment of tomato fruits may not reduce chilling injury as effectively as partial ripening (Whitaker, 1994). 4.1.2. Sun scald Tomatoes at the mature green stage or beginning to show the pink colouration (breaker stage) are most susceptible to sun scald. The fruits develop a white necrotic tissue surrounded by a yellow halo. The patch often becomes sunken and wrinkled. The damage to the fruit occurs on the side or top half exposed to sunlight. The area may remain white or yellow or become dry and papery and may later become infected by fungal infection when the fruit ripens. It is caused by a sudden exposure of the fruit to direct sunlight during hot dry weather and can be worsened by practices such as pruning or harvesting or other operations involving working moving through the field and exposing the fruits. Sudden defoliation leads to exposure of the fruits to sunlight. When supports collapse they expose fruit to direct sun. Heat and light cause direct irradiation with sunlight. The fruits fail to turn red and in severe cases turn white and blistered. The exposed side of the fruit turns pale at first and becomes sunken and wrinkled as the fruit ripens. Temperatures above 35 °C inhibit lycopene (red pigment) formation, while carotene continues to be produced at temperature of up to 40 °C, causing the tomato to remain yellow. At temperatures above 40 °C the yellow tissues then turn white. 4.1.3. Catface This is a typical malformation with deep cavities of the fruit which occurs at the blossom end of tomato fruit. These can range from mild to extreme deformations and scarring of the fruit. The fruit will have many bulges and be larger than the unaffected fruit produced by the same cultivar. Although hereditary, occurrence in larger fruited cultivars is mainly worsened by exposure of the plant to cool temperatures at the time of flower initiation. Cultivars may vary in their susceptibility to this disorder. The large fruited cultivar like Moneymaker is very susceptible. High nitrogen has also been recorded as a cause for catfacing. 4.1.4. Cracked fruits/Growth cracks Cracks in tomatoes may radiate from the stem end or may appear in concentric rings on the shoulders of the fruit. The cracks usually form on unripe fruit often cutting deep into the flesh. The shallow ripe cracks are known as bursting. This disorder is hereditary although it is facilitated by continuous rain and heavy dew during maturity of the fruit. It may extend even into harvesting period when there is frequent flood irrigation with small amounts of water. Sudden changes in soil moisture and atmospheric humidity cause this disorder due to alterations in growth rate. It is
Page 2 and 3: Production Practices and Quality As
Page 4 and 5: Production Practices and Quality As
Page 6 and 7: CONTENTS Preface List of Authors Ef
Page 8 and 9: PREFACE Today, in a world with abun
Page 10 and 11: LIST OF AUTHORS Rufaro M. Madakadze
Page 12 and 13: EFFECT OF PREHARVEST FACTORS ON THE
Page 14 and 15: 2.1. Temperature Effect of Preharve
Page 16 and 17: e beneficial to the water economy a
Page 18 and 19: Other responses that can also be ca
Page 20 and 21: 06. Failure of fruits to ripen in t
Page 22 and 23: of more than 13 hours of night temp
Page 24 and 25: temperatures. Some show serious int
Page 26 and 27: Effect of Preharvest Factors 15 bet
Page 28 and 29: 1) High rainfall conditions where B
Page 32 and 33: however, more severe when foliage i
Page 34 and 35: temperatures and luxuriant growth a
Page 36 and 37: development of chilling injury symp
Page 38 and 39: conditions followed by sudden high
Page 40 and 41: season. The main environmental fact
Page 42 and 43: 4.4.5.2. Water blisters Storage roo
Page 44 and 45: Effect of Preharvest Factors 33 REF
Page 46 and 47: Effect of Preharvest Factors 35 men
Page 48 and 49: EFFECTS OF AGRONOMIC PRACTICES AND
Page 50 and 51: Effects of Agronomic Practices 39 F
Page 52 and 53: Effects of Agronomic Practices 41 6
Page 54 and 55: Effects of Agronomic Practices 43 F
Page 56 and 57: Effects of Agronomic Practices 45 R
Page 58 and 59: MODELLING FRUIT QUALITY: ECOPHYSIOL
Page 60 and 61: Modelling Fruit Quality 49 the dens
Page 62 and 63: Is it the only level to be consider
Page 64 and 65: To calculate the hydrostatic pressu
Page 66 and 67: on an analysis of the biophysical p
Page 68 and 69: Modelling Fruit Quality 57 fructose
Page 70 and 71: Modelling Fruit Quality 59 Figure 4
Page 72 and 73: f(dd) = dd max - dd dd max - dd min
Page 76 and 77: which depends on climate and irriga
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distributed over the period during
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Modelling Fruit Quality 71 Figure 1
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Modelling Fruit Quality 73 Pruning
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with Fo, Pe and Pr being local ‘d
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Modelling Fruit Quality 77 than in
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Modelling Fruit Quality 79 Dann, I.
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Modelling Fruit Quality 81 Huguet,
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SPRAY TECHNOLOGY IN PERENNIAL TREE
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Spray Technology in Perennial Tree
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With centrifugal energy systems dro
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fruit orchards is described as 1000
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According to Furness (2000), the nu
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sprayers which were developed prima
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air-blast sprayers in an attempt to
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Most agricultural chemicals have be
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educing dosage rates to one quarter
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CHESTNUT, AN ANCIENT CROP WITH FUTU
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2. WORLD AREA OF CHESTNUT AND PRODU
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Table 2. Chestnut production in the
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vineyards and north facing to chest
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Chestnut, an Ancient Crop with Futu
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Table 5. Continued. Chestnut, an An
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Table 6. Continued. Chestnut, an An
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size. When the trees develop too mu
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6.5. Management of old orchards Che
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the disease is already established
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where ink disease is rampant, disea
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8.4. Micropropagation Several in vi
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9.3. Hybrids Chestnut breeding in E
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IMPROVEMENT OF GRAIN LEGUME PRODUCT
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Improvement of Grain Legume Product
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2.8. Field experiments The greenhou
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IMPACT OF OZONE ON CROPS S. DEL VAL
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Impact of Ozone on Crops 191 observ
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Impact of Ozone on Crops 193 1996).
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Impact of Ozone on Crops 195 Figure
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Impact of Ozone on Crops 197 al., 1
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Impact of Ozone on Crops 199 techni
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species show a progressive decline
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Impact of Ozone on Crops 203 Chaime
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Impact of Ozone on Crops 205 Junge,
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Impact of Ozone on Crops 207 Polle,
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SAFFRON QUALITY: EFFECT OF AGRICULT
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1.2. Commercial interest Saffron Qu
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1.3. Uses Saffron Quality 213 There
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oriental-type perfumes (Sampathu et
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Saffron Quality 217 Figure 5. Chemi
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Straubinger et al., 1997; Straubing
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and Micheli, 1979; Curro et al., 19
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Saffron Quality 223 Figure 9. Chemi
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(1984) gives the following data: δ
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Saffron Quality 227 Table 3. HPLC a
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Saffron Quality 229 464/2001, OJ L6
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Saffron Quality 231 Saffron in fila
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Saffron Quality 233 sium were the q
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Saffron Quality 235 Figure 11. The
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Saffron Quality 237 Figure 12. Harv
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Morocco. Ait-Oubahou and El-Otmani
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and Micheli, 1979a; Sampathu et al.
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Saffron Quality 243 Table 8. Drying
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Saffron Quality 245 space for sorti
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unpleasant sensory characteristics
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Saffron Quality 249 The effect of
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Saffron Quality 251 Table 10. Effec
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Saffron Quality 253 Alonso, G. L.,
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Saffron Quality 255 Escribano, J.,
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Saffron Quality 257 tion combined w
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Saffron Quality 259 Selim, K., M. T
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FRUIT AND VEGETABLES HARVESTING SYS
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3. PRINCIPLES AND DEVICES FOR THE D
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exert a vertical pulling force to t
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Fruit and Vegetables Harvesting Sys
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- fingers or spikes; - oscillatory
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- frequency and - amplitude of vibr
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To calculate the number of directio
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For the cleaning and separation of
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