Publication Date
1993
Description
Lignin modification is one method of improving plant nutritive value and is used to illustrate methods and consequences of plant manipulation. The effect of modifying lignin organ, tissue or enzyme levels on plant performance is inferred from recent scientific work on a range of species. Selection for higher whole plant digestibility is sometimes negatively correlated with plant yield. However, there is sufficient variation in both characters that improvement new not inevitably lead to decreased yield. Cultivars selected for low leaf strength or more digestible stems usually have lesser amounts of sclerenchyma and vascular tissue with less lignin and thinner walls. Selection for decreased vascular tissue news to ensure that essential biological functions of structural integrity and biochemical function are not disrupted. Little evidence could be found to support the idea that selection for low lignin would increase susceptibility to drought or cold. The role of phenolics, llgnin and tannins from the phenylpropanoid pathway as defence chemicals against fungi, nematodes and insects is now accepted. Down-regulation of enzymes early in these pathways could inhibit production of these compounds; however targeting later enzymes could reduce lignin without affecting other chemicals. Plants selected for improved nutritive value usually have lo pcrfonn in complex pastures, often with nutrient limitations, and under a range of defoliation pressures. Sewling establishment is seen as a critical phase, when small changes in insect or disease susceptibility can drastically affect final plant numbers. The contribution of an improved plant species to an animal's diet will depend on changes in preference and plant growth rate. Our knowledge in this area is still insufficient to milke many useful predictions. However, there is scope in tropical grasses to improve leaf bulk density, and hence intake, by decreasing stem elongation without decreasing canopy photosynthesis. The importance of f aster particle size reduction, improved protein quality and high soluble carbohydrate for improved ruminant nutrition is now well established. Recent advances in plant science suggest Iha! these improvements can be made without jeopardising the capacity of an individual plant lo perform and persist. At present we cannot conceptually model the whole system in which the plant must perform. Therefore, improved plants must be evaluated under commercial systems at an early stage.
Citation
Clark, D and Wilson, J R., "Implications and Improvements in Nutritive Value on Plant Performance and Grassland Management" (2024). IGC Proceedings (1993-2023). 31.
https://uknowledge.uky.edu/igc/1993/session14/31
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Implications and Improvements in Nutritive Value on Plant Performance and Grassland Management
Lignin modification is one method of improving plant nutritive value and is used to illustrate methods and consequences of plant manipulation. The effect of modifying lignin organ, tissue or enzyme levels on plant performance is inferred from recent scientific work on a range of species. Selection for higher whole plant digestibility is sometimes negatively correlated with plant yield. However, there is sufficient variation in both characters that improvement new not inevitably lead to decreased yield. Cultivars selected for low leaf strength or more digestible stems usually have lesser amounts of sclerenchyma and vascular tissue with less lignin and thinner walls. Selection for decreased vascular tissue news to ensure that essential biological functions of structural integrity and biochemical function are not disrupted. Little evidence could be found to support the idea that selection for low lignin would increase susceptibility to drought or cold. The role of phenolics, llgnin and tannins from the phenylpropanoid pathway as defence chemicals against fungi, nematodes and insects is now accepted. Down-regulation of enzymes early in these pathways could inhibit production of these compounds; however targeting later enzymes could reduce lignin without affecting other chemicals. Plants selected for improved nutritive value usually have lo pcrfonn in complex pastures, often with nutrient limitations, and under a range of defoliation pressures. Sewling establishment is seen as a critical phase, when small changes in insect or disease susceptibility can drastically affect final plant numbers. The contribution of an improved plant species to an animal's diet will depend on changes in preference and plant growth rate. Our knowledge in this area is still insufficient to milke many useful predictions. However, there is scope in tropical grasses to improve leaf bulk density, and hence intake, by decreasing stem elongation without decreasing canopy photosynthesis. The importance of f aster particle size reduction, improved protein quality and high soluble carbohydrate for improved ruminant nutrition is now well established. Recent advances in plant science suggest Iha! these improvements can be made without jeopardising the capacity of an individual plant lo perform and persist. At present we cannot conceptually model the whole system in which the plant must perform. Therefore, improved plants must be evaluated under commercial systems at an early stage.
