AGRI 32 PART 3

• Direct seeding


  Seeds are directly planted in the field
• Applicable to direct seeding

  • Seeds that easily germinate
  • Inexpensive seeds
  • Seedlings sensitive to root disturbances
  • Big seeded crops
  • Stem cuttings of siniguelas, cassava, sugarcane, sweet potato
  • Propagules
• Forms of direct seeding


  • Broadcasting
  • Hill method
  • Drill method
  • Dibble
• Broadcasting


  Seeds are uniformly distributed on the field, requires thorough land preparation
• Hill method


  Seeds are sown at a specified distance between hills or between rows
• Drill method


  Specifies number of seeds are sown within rows of specified distances
• Dibble


  Land doesn't require plowing but needs thorough cleaning, holes with no spacing are dug to accommodate seeds, seeds are put into holes and covered with a thin layer of soil
• Transplanting method


  Seeds are initially raised in the nursery and later planted in the field or greenhouses
• Applicable to transplanting


  • Seeds that are difficult to germinate
  • Expensive seeds
  • Small-seeded plants that give rise to small seedlings
  • Rooted cuttings
  • Grafted plants
• Population density (PD)


  Refers to the number of plants per unit area, important for planning purposes, optimum PD needed to achieve maximum yield
• Benefits of optimum PD


  • Early build up of sufficient leaf area index for efficient use of solar energy
  • Early and better control of weeds
  • Increase efficiency in use of land, light, and water
• Factors affecting PD


  • Crop species and varieties
  • Soil fertility and soil management practices
  • Season
  • Method of propagation
  • Mechanization to be employed
  • Cropping system to be adopted
• Ratooning


  Letting suckers grow to serve as the next crop
• Objectives in controlling plant growth and development

  • Control direction of growth (lateral vs vertical) for ease in harvesting
  • Restrict plant size in the case of ornamentals like poinsettia and mums
  • Easier cultural management practices like pruning and crop protection
  • Earlier flowering
  • Control timing and synchrony of flower or fruit production for year-round supply
  • Induce rooting or shoot formation for propagation
  • Delay senescence or inhibit germination
• Approaches to controlling plant growth and development


  • Use of chemicals like Plant Growth Regulators
  • Physical methods like training, pruning, girdling, smudging
• Plant Growth Regulators (PGRs)


  Organic compounds other than nutrients that in minute amounts promote, inhibit, or modify growth and development, can be synthetic or natural (phytohormones)
• Classes of phytohormones


  • Auxins
  • Gibberellins
  • Cytokinins
  • Abscisic acid
  • Ethylene
• Uses of PGRs in crop production


  • Promote rooting of stem cuttings
  • Promote seed germination
  • Increase fruit set/control fruit drop
  • Reduce stem elongation
  • Induce/modify flowering
  • Stimulate latex flow
  • Accelerate priming or uniform ripening for easier/synchronous harvesting
• PGRs sold in the Philippine market must be registered with the Fertilizer and Pesticide Authority to maintain a high level of reliability
• Training


  Techniques that direct/modify the growth of plants in terms of canopy size, shape, and direction, to improve yield and quality and facilitate cultural processes
• Trellising techniques


  • Fence type
  • Overhead
  • A-type
  • T-type
  • Single pole
  • Teepee type
• Pruning


  Judicious removal of plant parts to achieve specific objectives
• Objectives of pruning


  • Control size of the plant
  • Control the form (number, placement, angle of branches)
  • Better quality by better light distribution
  • Remove diseased, criss-crossed, dried, and broken branches
  • Remove non-productive parts
  • Proper proportion of root-shoot ratio
• Pruning techniques


  • Topping/Cutting Back/Pinching
  • Bending
• Kinds of pruning


  • Preventive
  • Formative
  • Corrective
  • Rejuvenative
• Types of pruning cuts


  • Cutting out
  • Cutting back
  • Stubbing
• Rejuvenation of trees is required when they become unproductive, cannot be induced to flower due to overlapping canopy, and are relatively young (12 years old) with no production for the last 4 years
• Causes of unproductive trees are not following the allotted space, allowing trees to grow beyond the limits imposed by the planting distance
• Windbreak establishment


  Minimizes or avoids wind damage to crops through abrasion, tearing of leaves, defoliation, breakage of branches, flower and fruit fall, blow down of whole trees, and uplifting
• Characteristics of good windbreak trees


  • Strong and extensive root system
  • Strong branches and twigs
  • Tall with dense canopy
  • Fast growing
• Windbreak planting


  Planted in single or double rows near the fence line and within the orchard, the most important role is to reduce windspeed and protect crops from damage
• Factors affecting windbreak effectiveness


  • Height (taller windbreaks protect a larger area)
  • Canopy density (denser canopy provides more protection)
• Water management


  An integrated process of timely application of the needed amount of water and the removal of excess water from the field to ensure optimum growth and crop productivity

  
• Rainfall occurrence and intensity is erratic and changing, leading to insufficient water during the dry season and too much water during the rainy season, aggravated by El Niño and La Niña
• Effects of lack of water


  • Poor crop stand, stunted growth
  • Reduction in yield (amount and quality)
  • Predisposes the plants to pests/diseases and nutrient deficiency
• Effects of excess water


  • Leaching of nutrients from the soil and lead to high acidity
  • Waterlogged condition which leads to reduced root development and death of roots due to lack of oxygen
  • Predisposes the plant to root-rotting pathogens
  • Fruit cracking
• Factors to consider in irrigation


  • Soil factors (water holding capacity, percolation)
  • Climatic factors (evaporation, transpiration, rainfall)
  • Plant factors (rooting characteristics, drought tolerance, growth stages)
• Critical stages affected by water stress


  • Early vegetative growth/establishment period
  • Flowering
  • Fruit setting
  • Fruit development
• Methods of determining irrigation schedule


  • Estimating available soil moisture
  • Measuring evapotranspiration rates

  
• Factors


  • Rooting characteristics
  • Drought tolerance
  • Growth stages