Greenhouse Environmental Control Quiz

Controlling CO2 in Greenhouses

• A single sensor receives information from multiple sampling tubes and controls CO2 generators in each greenhouse

Controlling Light in Greenhouses

• Light Quality:
  • Broad light spectrum from 400 to 700 nm is desirable
  • Red light is important for photoreceptor
  • Reducing far-red and increasing blue light results in shorter, darker, and stronger plants
  • Greenhouse glazings can filter specific wavelengths to change light ratios
• Light Quantity:
  • Different species have different optimal light levels
  • Plant spacing, nutrition, and age can affect light levels
  • Cucurbits, capsicum, brinjal, and sweet potato require 32.2 to 86.1 klux light levels
  • Cabbage and potato require 21.5 to 86.1 klux light levels
• Recommended Light Levels (in moles/m2/sec):
  • African violet:  150 – 250
  • Foliage plants: 150 – 250
  • Carnation, Chrysanthemum, Geranium, Cucumber, Lettuce, and Strawberry: 250 – 450
  • Roses and Tomato: 450 – 750
• Greenhouse Shading Methods:
  • Shading compounds on glazing
  • Retractable shade systems

Greenhouse Sanitation

• Disinfecting Facilities:
  • Propagation rooms, containers, flats, knives, working surfaces, benches, etc. can be disinfected using formalin or sodium hypochlorite solutions
  • Regular insecticide spraying addresses insects
  • Seed or planting materials should be disinfected before moving into the greenhouse
• Greenhouse Entry:
  • Disinfectant solutions like trisodium phosphate or potassium permanganate at the entry helps eliminate pathogens from personnel

Benching

• Benches raise plants off the greenhouse floor, preventing diseases and improving light conditions
• Tiered benches optimize space utilization
• Benches can be made of metal, wood, or plastic
• Wooden benches require preservative treatments to prevent rot and pests

Irrigation and Drainage in Rose Cultivation

• Rose plants require a lot of water, at least 6 mm/day (about 60 cum/ha/day)
• Drainage lines below beds are essential for excess water disposal

Cultural Practices for Rose Cultivation

• Initial Plant Development:
  • Pinch first flower to promote branching growth
  • Bend the mother shoot towards the path to initiate bottom break ground shoot
• Plant Structure Development:
  • Bend weak ground shoots at ground level
  • Cut strong ground shoots after four and a half months from plantation
• Bending:
  • Maximizes leaf area for strong root system
  • Removes suckers and buds to control pests and diseases
  • Breaks apical dominance
• Support System:
  • Provides stability and makes intercultural operations easier
• Pruning:
  • Stems are cut back to 4-5 nodes, removing weak shoots
  • Phased pruning ensures flowering from September to March

Rose Harvesting, Post-Harvest Management, and Pests/Diseases

• Harvesting:
  • Roses should be cut at the right stage, when buds are opening and color is visible
  • Cut stems are immediately placed in citric acid solution or chrysal – RVB
  • Ideal flower yield is 250-350 stems/m2
• Hydration:
  • Recut stems and place them in warm water with citric acid to prevent vascular blockage
• Preservatives:
  • Preservatives with citric acid, HQC/captan, sucrose, STS, and cytokinin are used to extend longevity
• Packing:
  • Roses are bunched, wrapped, and packed in boxes
  • Boxes can contain one variety, one grade, or mixed colors
• Pests:
  • Red spider mite
  • Leaf rollers
  • White fly
  • Thrips
  • Aphids
  • Nematode
• Diseases:
  • Powdery mildew
  • Downy mildew
  • Botrytis
  • Pruning die back
  • Black leaf spot
• Control:
  • Preventive spray program with Dithane M-45, Metasystox, and Karathane

Perpetual Carnation – Dianthus caryophyllus

• Important cut flower due to its long vase life, diverse colors, and forms
• Two main types: Standard and Spray carnations

Test your knowledge on controlling CO2 and light in greenhouses. This quiz covers various aspects including light quality, light quantity, and optimal levels for different plant species. Understand how these factors influence plant growth and development in greenhouse settings.