1. Lecture # 13 Light Acclimatization Acclimatization

2. ACCLIMATIZATION: Adaptation of a Species to a New Environment

3. What Is Acclimatization? Favorable environment for maximum growth Interior environment low light, low relative humidity high light, high nutrition, high water supply, high temperature : :

4. The Two Sides of Acclimatization * Light Acclimatization * Soil Acclimatization reduce nutrient application, reduce nutrient application, reduce water frequency. reduce water frequency. low light = less growth = less need for nutrients = less water need = less water need

5. Organ Level: Leaf

6. The Plant Leaf - An Overview of Structure upper epidermis lower epidermis palisade mesophyll spongy mesophyll xylem phloem vascular tissues vascular parenchyma stomates chloroplasts

7. Anatomical Differences Between 'Sun' and 'Shade' Plants

8. The Chloroplast - An Overview of Structure

9. Electron Micrographs Of Chloroplasts High Light Low Light

10. Organelle Level : Chloroplast Internal Organization Internal Organization High light chloroplast Low light chloroplast smaller chloroplasts less thylakoids / more stroma More grana stacks Taller stacks less chlorophyll per volume larger chloroplasts more thylakoids / less stroma Fewer grana stacks Spreadout thylakoid more chlorophyll per volume

11. Acclimatization This Peperomia went from a low light environment to a high light environment. Its appearance has changed due inhibition of chloroplast development in light-sensitive cells.

12. Light Overload Can Cause Death! Placing a low light adapted plant under very bright light will cause chloroplasts to adsorb too much light energy. The will disrupt biochemical pathways and they will cease to operate. Leaf scorch is the result. These three leaves were subject to increasing amounts of time for acclimatization. The smaller leaf was most acclimatized and thus could better handle the light load.

13. Structural and Physiological Differences Between 'Sun' and 'Shade' Plants

14. Changes in Natural Light Penetration Occur Within Interior Spaces Because of Changes in the Sun's Inclination Summer sun Winter sun

15. General Characteristics of Sun and Shade Leaves Descriptive Sun leaves Shade leaves level level often, a mosaic leaf arrangement, phototropic leaf petioles, Thin leaves leaves thicker Due to cuticle and denser cell walls Morphological

16. General Characteristics of Sun and Shade Leaves Descriptive level Sun leaves Shade leaves level Sun leaves Shade leaves more stomata Linear leaves Fewer palisade layers, shorter cells, tighter packing fewer stomata Leaves broader, More palisade layers, longer palisade cells more intercellular spaces Anatomical

17. General Characteristics of Sun and Shade Leaves Descriptive Sun leaves Shade leaves level level smaller chloroplasts, fewer and smaller grana larger chloroplasts more grana, phototactic - chloroplasts more grana, phototactic - -chloroplasts -chloroplasts Ultrastructural

18. General Characteristics of Sun and Shade Leaves Descriptive Sun leaves Shade leaves level level lower chlorophyll high respiration high LCP high light saturation levels more chlorophyll low respiration low LCP low light saturation levels Biochemical

19. Differences Between Acclimatized And Non-acclimatized Plants Acclimatized Medium to dark green leaves Large leaves Flat leaves Thin leaves Leaves widely spaced Non-acclimatized Yellowish to light green leaves Small leaves Partially folded leaves Thick leaves Leaves crowded together High Sun Grown,

20. Acclimatized Non-acclimatized Internodes long Thin to medium stems Leaf position horizontal or slightly reflexed Few new leaves Wide branch angles Internodes short Thick stems Leaf position upright Many new leaves Acute angles Differences Between Acclimatized And Non-acclimatized Plants

21. Nursery: 6000-1000ft-c 85-95% RH Greenhouse: 1500-2000ft-c 90-97% RH Lighted Warehouse: 300-500ft-c 40-50% RH To Job: 1/2 x xy weeks Time = x

22. Light Acclimatization Pathways  Initial Response.  Improving Acclimatization Level.  Reverse Acclimatization.

23. high light low light PS rates PS rates R rates R rates Stored reserves  beginning of acclimatization: reorientation of chloroplast and grana; increase in chlorophyll levels; reduction in respiration rate; production of new foliage. 1 - 2 wks

24. acclimatization complete changes lead to lower compensation point changes do not lead to lower compensation point plant lives plant dies 2 - 8 wks

25. Time Required for Acclimatization  Depends on species, plant size, previous treatment and magnitude of the change. 1 - 10 weeks or more; Examples: Philodendron, Aglaonema - very little time required; Sun - grown Ficus benjamina and Brassaia Philodendron, Aglaonema - very little time required; Sun - grown Ficus benjamina and Brassaia in 40 to 80 % shade - approx. 5 wks; Ficus nitida in 50 % shade - 10 wks. in 40 to 80 % shade - approx. 5 wks; Ficus nitida in 50 % shade - 10 wks.

26. Acclimatization Strategies fertilized w/ slow release fertilizer remove pellets from the surface; leach thoroughly continue with the new fertilization and water schedule fertilized w/ soluble fertilizer underfertilized

27. ACCLIMATIZATION 60 % 75% 100 % Field Production ON SITE Greenhouse ( INTERIM ACCLIMATIZATION) Time line

28. 0 6 12 18 24 Photosynthesis (rate) Leaf life span (months) Leaf life span varies with species and cultivar Dieffenbachia Palm

29. 0 50 100 150 200 250 Photosynthesis Light intensity (ft-c) 12 hours per day +2 +1 0 -1 LCP Ficus benjamina (nonacclimatized) Ficus benjamina (acclimatized)

30. Summary Tips: * Learn as much as possible about the extent of acclimatization of the purchased plants. of acclimatization of the purchased plants. * Provide necessary conditions : Light is the most important factor. Light is the most important factor. * Apply fertilizer and water at reduced rates. !

31. The Cheapest Plant To Buy Is An Acclimatized Plant