61-80

• Causes of Decline in Soil Fertility

  • Soil erosion
  • Crop removal
  • Conversion of nutrients to unavailable forms
• Types of Soil Erosion

  1. Geological erosion

  2. Wind erosion

  3. Water-borne erosion
• Conversion of nutrients to unavailable forms

  1. Combination with other elements forming insoluble forms

  2. Microbial mediated transformations

  3. Volatilization

  4. Leaching
• Passive ions move with water


  Without metabolic involvement; the characteristics of the apoplast (non-living) path determines the rate of passive uptake of nutrients; transpiration creates the force necessary for the ascent of sap
• Active-ions


  Cross the plasmalemma with the involvement of metabolic energy from ATP and ions move from one cell to another through the plasmodesmata; this type of uptake moves ions from a region of lower concentration to a region of higher concentration
• Factors affecting nutrient uptake

  • Availability of nutrients partly determined by the pH of the solution
  • Stage of growth and development
• Essential nutrients/elements

  • C
  • H
  • O
  • N
  • P
  • K
  • Ca
  • Mg
  • S
  • Fe
  • Mn
  • B
  • Cu
  • Zn
  • Mo
  • Cl
• Macronutrients

  • C
  • H
  • O
  • N
  • P
  • K
  • Ca
  • Mg
  • S
• Micronutrients


  • Fe
  • Mn
  • B
  • Cu
  • Zn
  • Mo
  • Cl
  • Ni
• Calculation of fertilizer requirement based on nutrient recommendation

  1. Weight of nutrient (kg N or P or K / ha) = Weight of fertilizer x (%nutrient/100)

  2. Weight of fertilizer (kg fertilizer/ha) = Weight of nutrient / (%nutrient/100)
• The following is a table of common forms and known functions of the essential elements (adopted from Opik and Rolfe, 2005)
• Harvesting


  The separation of the economic yield (whether the whole plant biomass or the portion of the whole plant biomass when crops have reached highest or optimum level of productivity (physiological maturity onwards)
• Postharvest handling


  Refers to the movement of farm products or operations through which the commodities undergo from harvest to possession by the final consumer
• Postharvest handling process

  1. Harvesting

  2. Packing house (sorting/grading, cleaning, or primary processing, packaging, etc)

  3. Transport

  4. Storage

  5. Marketing

  6. Consumer
• Postproduction technology


  Practices and operations from harvesting to consumption; aim is to deliver good quality products
• Primary processing


  Original plant part can still be recognized
• Secondary processing


  Conversion of produce into more stable forms that can no longer be changed into other forms
• Types of secondary processing

  • Heat sterilization-canning
  • Dehydration-dried fruits and vegetables
  • Fermentation-pickling, wine making, vinegar making
  • Freezing-frozen fruits and vegetables
• Types of crops based on postharvest characteristics

  • Durables-low moisture content (less than or equal to 14%); com, rice, mungbean
  • Perishables-high moisture content (80-95%); fruits, vegetables, ornamentals
• Kinds of packages

  • Flexible - burlap or gunny sacks, mesh or net bags, PEBS, palm leaves, sacks of woven plastic fabric
  • Rigid and semi-rigid-bamboo and rattan baskets, wooden crates, cartons, wood-paper laminated container, plastic crates, foamed plastic boxes
• Methods to prolong shelf-life of perishables

  • Cold storage
  • Evaporative cooling
  • Modified atmosphere (MA) storage
  • Controlled atmosphere (CA) storage
• Biological factors involved in deterioration

  • Respiration
  • Ethylene production
  • Compositional changes
  • Transpiration or water loss
  • Condition of crops
  • Growth and development
• Environmental factors involved in deterioration

  • Temperature
  • Relative humidity
  • Atmospheric Composition
  • Ethylene
  • Light
  • Sanitation
• Classification of Respiration patterns

  • Climacteric-harvested at optimum maturity and ripened after harvest; show dramatic changes after harvest; apple, avocado, banana, mango, peach, pear, plum, tomato
  • Non-climacteric-continuously declining rate of respiration from maturation to the end of senescence; no burst of Rs during postharvest; harvested ripe and ready for consumption; bell pepper, cherry, citrus, grapes, pineapple, snap bean, strawberry, watermelon
• Maturity indices

  • Age-related/Phenological
  • Morphological
• Age-related/Phenological maturity indices

  • Number of days from planting to maturity
  • Days from flower induction (mango)
  • Days from anthesis (durian, beans)
  • Days from shooting (appearance of false hands in banana)
  • Heat units/growing degree days (GDD)
• Morphological maturity indices


  • Change in peel color (pineapple, lanzones, tomato)
  • Change in pulp color (mango, tomato)
  • Drying of plant part (banana, onion, ginger, potato)
  • Flattening of eyes (pineapple)
  • Development of abscission zone (melon, durian)
  • Greater prominence of netting (melon)
  • Appearance of bloom (mango, grapes)
  • Increase in size (eggplant, cucumber)
  • Fullness of pods (cowpea, peas, snap beans)
  • Change in shape (banana, mango)
  • Compactness of curd/bud (cauliflower, broccoli)
  • Bud opening (roses)
  • Bud opening change in angularity of fingers
  • Appearance of corky spots (banana)
  • Development of waxy layer on the epidermis (plum, grape, melon)
  • Formation of gel-like material surrounding the seeds (tomato)
  • Prior to tip opening (asparagus)
• Degreening


  Process of hastening the peel color change from green to orange or yellow of citrus fruits which have attained full flavour and aroma
• Vapor Pressure treatment


  Pressure exerted by water vapour in a given space or atmosphere
• Aril


  The fleshy edible pulp adhering to seeds of fruits as in rambutan, durian and lanzones
• Commercial maturity


  The stage of growth when a commodity has developed sufficient desirable characteristics to make it marketable or desirable for its intended purpose
• Curing


  Process of toughening and self-healing of bruises and skinned areas in root and tuber crops or the rapid closing of the neck of bulb crops under favorable conditions
• Dehaulming


  Cutting or killing of potato vines a week before harvesting
• Fumigant


  Chemical which at required temperature and pressure can exist in the gaseous state in sufficient concentration to be lethal to a given pest organism
• Grading


  The process of classifying into groups according to a set of recognized criteria of quality and size, each group bearing an accepted name and size grouping
• Horticultural Maturity

  Commercial maturity
• Internal breaking of mango

  White starchy area in the middle portion of the pulp near the seed of a ripe fruit, sometimes with air pockets in the middle of the starchy areas
• Precooling


  Rapid cooling (48 hr. or less) of a commodity to a desired transit or storage temperature soon after harvesting before it is stored or move in transit
• Shelf life

  Post-storage market life
• Sorting


  The process of classifying of commodity into groups, designated by the person classifying the produce either according to a set criteria or whatever criteria he may desire