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

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Other responses that can also be caused by different daylenghts beside flowering in vegetables are listed below: a. Long days for bulbing in onions; b. Short days for tuber initiation in Irish potato, yams and Jerusalem artichoce; c. Short days for root enlargement in cassava and sweet potato. 2.6. Winds Winds are caused by differences in air pressure. Temperature differences produce pressure gradients which give rise to air movements. Winds affect the humidity in the atmosphere. They can remove the humid air adjacent to leaf surfaces, increasing transpiration rates and decreasing temperature. Winds can replenish the carbon dioxide supply to the leaves deep within the canopy thereby improving photosynthesis and vegetable growth. Winds can also injure or break the above ground portions of the plant thereby affecting quality of the product. All the above must be considered as they do not only affect growth and development of vegetable but the quality of the produce. It is therefore necessary to check before introducing any vegetable into the tropics or any area, if its optimal growth temperature and photoperiodic requirements are compatible with local climatic conditions. Even for the quality of local varieties, it is important not to ignore the environmental conditions as they also affect quality of the produce. Where local conditions are marginal, artificial means can be used to promote the growth of the crop for better quality. These can be windbreaks, shades and green houses to protect the crops from wind and high solar radiation respectively. 3. MAJOR PRE-HARVEST DISORDERS IN VEGETABLES 3.1. Chilling injury Effect of Preharvest Factors 7 Chilling injury is the permanent or irreversible physiological damage to mostly warm season plant tissues, cells or organs, which results from the exposure of chilling sensitive plants to temperatures below some critical threshold for that species or tissue. A chilling temperature is any temperature (above freezing) below the critical threshold temperature that causes injury. The critical temperature for chilling injury varies with commodity, but it occurs when produce is kept at below 10–12 °C. All stages of growth and development of the entire plant (except perhaps dry seed) are susceptible to chilling injury in warm season crops. Factors that determine the extent of this injury include the temperature, duration of exposure to that low temperature, whether exposure is continuous or intermittent, physiological age or condition of the plant, part exposed and the relative responsiveness (sensitivity) of the crop to chilling. Chilling sensitive species except asparagus and potatoes are mostly warm season crops of tropical and subtropical origin. Prolonged exposure to temperature below the chilling threshold in these species results in death. Low temperature limits the geographical areas and time of year for production of chilling – sensitive crops.
8 R. M. Madakadze and J. Kwaramba 3.1.1. Causes of chilling injury The primary cause of chilling injury is thought to be damage to plant cell membranes. Changes in molecular species composition of phospholipids during cold storage and after rewarming were determined in mature green tomatoes (L’-Heureux et al., 1993) the minor molecular species shifted significantly towards unsaturation during cold storage. The presence of these polyunsaturated species and their breakdown products may induce membrane damage and dysfunction. The membrane damage sets off a cascade of secondary reactions, which may include ethylene production, increased respiration, reduced photosynthesis, interference with energy production, accumulation of toxic compounds such as ethanol and acetaldehyde, electrolyte leakage and altered cellular structure (Skog, 1998). Some physiological parameters of chilling injury include electrolyte leakage, carbon dioxide and ethylene production in squash and cucumber (McCollum and McDonald, 1993). These parameters increase with increasing severity of chilling injury (Lee and Yang, 1999). Electrolyte leakage was shown to increase during cold storage (1 °C for 2 days) of mature green tomato fruits (L’-Heureux et al., 1993). In bell peppers chilling injury was also accompanied by high internal carbon dioxide and ethylene production (Lin et al., 1993). Ethylene – forming enzyme activity can also be used as an indice for thermotolerance of crops (McCollum and McDonald, 1993). Chilling injury can be measured non-destructively in fruits using pulse amplitude modulated fluorometry before tissue damage is visible (Lurie et al., 1994). Three photosynthetic characteristics could be measured by this method; quantum yield (F m/F o), photochemical quenching (Q p) and non-photochemical quenching (Q np). F m/F o decreased by 90% during the first week of storage at 2 °C and remained low thereafter, while Q np decreased after 2 weeks at 2 °C just before the fruits began to develop chilling injury. Q p was similar at both chilling and non-chilling storage temperature. Whether this method can be used in a field situation is not known. 3.1.2. Symptoms of chilling injury Symptoms of chilling injury as summarized by Morris (1982) and Skog (1998) include the following: 01. Surface lesions – pitting, large sunken areas, and discolouration. These symptoms occur most frequently in products with firm thick peel such as citrus or cucumber. 02. Water soaking of tissues – this disruption of cell structure and accompanying release of substrates favours the growth of microorganism. Water soaking commonly occurs in vegetables with thin or soft peels such as peppers and asparagus. 03. Water loss/desiccation/shrivelling 04. Internal discolouration (browning) of pulp, vascular strands, and seeds. 05. Breakdown of tissues.
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 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 30 and 31: increase in the release of P i from
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
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Modelling Fruit Quality 57 fructose
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Modelling Fruit Quality 59 Figure 4
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f(dd) = dd max - dd dd max - dd min
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which depends on climate and irriga
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distributed over the period during
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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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