Publication Date
1993
Description
Short-term, whole-plant physiological responses of forage plants to defoliation and the characteristics that allow them to rapidly replace lost tissues are the focus of this review. The physiology of defoliationtolerant plants after moderate to severe defoliation has two distinct phases; the first is a transient period of one to a few days and the second is a readjustment of physiological activity and plant morphogenetic Integration that occurs over several weeks. When whole-plant photosynthetic capacity is reduced by substantial defoliation the effects of reduced carbon supply rapidly propagate through a growing plant, affecting shoot growth, root respiration, nutrient uptake and root growth. I review these transient effects with special attention to their timing relative to depletion of carbohydrate pools. These transient effects are observed in both defoliation-tolerant and defoliation-intolerant plants. However, the duration of the "transient" disturbance is often prolonged and regrowth delayed when developmental constraints prevent initiation of the second, recovery, phase. Physiological recovery after defoliation-induced transients depends on interactions with morpho-developmental characteristics of plants. Shoot meristematic sink activity drives the readjustment of allocation and compensatory changes in plant carbon and nutrient uptake capacity observed in plants after defoliation. Increased photosynthetic rates after defoliation require allocation of nitrogen and developmental changes in leaves. Increased allocation of carbon and nutrients to shoots allows increases in relative growth rate that are necessary for recovery. I discuss the relationships of these physiological processes to defoliation characteristics, environmental conditions and to pla nt morphological and developmental characteristics that allow rapid recovery.
Citation
Richards, J H., "Physiology of Plants Recovering from Defoliation" (2024). IGC Proceedings (1993-2023). 2.
https://uknowledge.uky.edu/igc/1993/session8/2
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Physiology of Plants Recovering from Defoliation
Short-term, whole-plant physiological responses of forage plants to defoliation and the characteristics that allow them to rapidly replace lost tissues are the focus of this review. The physiology of defoliationtolerant plants after moderate to severe defoliation has two distinct phases; the first is a transient period of one to a few days and the second is a readjustment of physiological activity and plant morphogenetic Integration that occurs over several weeks. When whole-plant photosynthetic capacity is reduced by substantial defoliation the effects of reduced carbon supply rapidly propagate through a growing plant, affecting shoot growth, root respiration, nutrient uptake and root growth. I review these transient effects with special attention to their timing relative to depletion of carbohydrate pools. These transient effects are observed in both defoliation-tolerant and defoliation-intolerant plants. However, the duration of the "transient" disturbance is often prolonged and regrowth delayed when developmental constraints prevent initiation of the second, recovery, phase. Physiological recovery after defoliation-induced transients depends on interactions with morpho-developmental characteristics of plants. Shoot meristematic sink activity drives the readjustment of allocation and compensatory changes in plant carbon and nutrient uptake capacity observed in plants after defoliation. Increased photosynthetic rates after defoliation require allocation of nitrogen and developmental changes in leaves. Increased allocation of carbon and nutrients to shoots allows increases in relative growth rate that are necessary for recovery. I discuss the relationships of these physiological processes to defoliation characteristics, environmental conditions and to pla nt morphological and developmental characteristics that allow rapid recovery.
