Effect of sedding date on chlorophyll dynamics in wheat and its relation with helmintosporium leaf blight
Mercado, D.
Effect of sedding date on chlorophyll dynamics in wheat and its relation with helmintosporium leaf blight - Kathmandu (Nepal) CIMMYT : 2004 - p. 93-103 - Printed
Helminthosporium leaf blight (HLB) is the major biotic constraint in the Gangetic plains, where wheat is grown during the winter season. The disease is principally caused by two fungal pathogens Bipolaris sorokiniana (Sacc.) Shoem. and Drechslera tritici-repentis (Died.) and causes yield losses up to 20% in farmer's field (6). Despite the efforts to introduce new sources of resistance to these pathogens, the low heritability of this trait and the high intluence of environmental parameters (temperature, humidity, planting dates, inoculum pressure, etc) make breeding for resistance difficult (14). Besides the biotic constraints, wheat production in the warmer areas of South Asia is affected by several abiotic stresses. In these environments, low-soil moisture, mineral nutrients deficiency and high temperatures affect the normal development of plants specially during anthesis and grain filling stages (7). All these constraints have an effect on the plant physiology and consequently on the host-pathogen interaction. In this way, previous studies have shown that development of spot blotch symptoms caused by B. sorokiniana on wheat is accelerated by high temperatures (5). Different authors have reported that soil fertility and moisture stresses also increased the HLB severity (12, 17). Abiotic constraints are associated with premature plant senescence and chlorosis of leaves (13) that might favour the development of necrotrophic fungi like B. sorokiniana and D. tritici-repentis (2). However, documenting crop senescence rates is often difficult because of the need for frequent sampling during periods of rapid change and the subjective nature of human visual observations. No-destructive methods for determining the status of plants in the field allow more frequent data collection than plant harvesting techniques and facilitate repeated measurements on the same plants. For small plot areas, greenness can be measured non-destructively with a chlorophyll-meter (1, 9, 23). This trait has also been used widely as indicator of heat tolerance in breeding programs, and partly as an indicator of disease resistance (13}. The objectives of this experiment were i) to study in field the effect of the stress caused by non-optimal sowing date on contrasting wheat genotypes regarding susceptibility to HLB and ii) to evaluate the stability of chlorophyll concentration of leaves as indicator of resilience to high temperature stress and its relationship with resistance to this disease.
English
Blights
Disease control
Drechslera
Environmental factors
Fungal diseases
Helminthosporium
Heritability
Pathogenesis
Wheat
Plant breeding
CIMMYT UCL
Effect of sedding date on chlorophyll dynamics in wheat and its relation with helmintosporium leaf blight - Kathmandu (Nepal) CIMMYT : 2004 - p. 93-103 - Printed
Helminthosporium leaf blight (HLB) is the major biotic constraint in the Gangetic plains, where wheat is grown during the winter season. The disease is principally caused by two fungal pathogens Bipolaris sorokiniana (Sacc.) Shoem. and Drechslera tritici-repentis (Died.) and causes yield losses up to 20% in farmer's field (6). Despite the efforts to introduce new sources of resistance to these pathogens, the low heritability of this trait and the high intluence of environmental parameters (temperature, humidity, planting dates, inoculum pressure, etc) make breeding for resistance difficult (14). Besides the biotic constraints, wheat production in the warmer areas of South Asia is affected by several abiotic stresses. In these environments, low-soil moisture, mineral nutrients deficiency and high temperatures affect the normal development of plants specially during anthesis and grain filling stages (7). All these constraints have an effect on the plant physiology and consequently on the host-pathogen interaction. In this way, previous studies have shown that development of spot blotch symptoms caused by B. sorokiniana on wheat is accelerated by high temperatures (5). Different authors have reported that soil fertility and moisture stresses also increased the HLB severity (12, 17). Abiotic constraints are associated with premature plant senescence and chlorosis of leaves (13) that might favour the development of necrotrophic fungi like B. sorokiniana and D. tritici-repentis (2). However, documenting crop senescence rates is often difficult because of the need for frequent sampling during periods of rapid change and the subjective nature of human visual observations. No-destructive methods for determining the status of plants in the field allow more frequent data collection than plant harvesting techniques and facilitate repeated measurements on the same plants. For small plot areas, greenness can be measured non-destructively with a chlorophyll-meter (1, 9, 23). This trait has also been used widely as indicator of heat tolerance in breeding programs, and partly as an indicator of disease resistance (13}. The objectives of this experiment were i) to study in field the effect of the stress caused by non-optimal sowing date on contrasting wheat genotypes regarding susceptibility to HLB and ii) to evaluate the stability of chlorophyll concentration of leaves as indicator of resilience to high temperature stress and its relationship with resistance to this disease.
English
Blights
Disease control
Drechslera
Environmental factors
Fungal diseases
Helminthosporium
Heritability
Pathogenesis
Wheat
Plant breeding
CIMMYT UCL