000			04203nam a22005177a 4500
001			G79726
003			MX-TxCIM
005			20240919021103.0
008			121211s ||||f| 0 p|p||0|| |
040			_aMX-TxCIM
072		0	_aF01
072		0	_aH20
090			_aCIS-4084
100	1		_aMercado, D. _uFourth annual progress report: Year 2003. Evaluation of cropping systems on the development of wheat pathogens and research for better resistance to foliar blights. The non-specific foliar wheat pathogens. Phase II
110	0		_aCentro Internacional de Mejoramiento de Maíz y Trigo CIMMYT, Nepal (India)
245	0	0	_aEffect of sedding date on chlorophyll dynamics in wheat and its relation with helmintosporium leaf blight
260			_aKathmandu (Nepal) _bCIMMYT : _c2004
300			_ap. 93-103
340			_aPrinted
520			_aHelminthosporium 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.
536			_aResearch and Partnership Program
546			_aEnglish
591			_a0407|AGRIS 0401|AL-Wheat Program
593			_aJuan Carlos Mendieta
594			_aINT1237
595			_aCSC
650	1	0	_aBlights
650	1	0	_aDisease control
650	1	0	_aDrechslera
650	1	0	_aEnvironmental factors
650	1	0	_aFungal diseases _gAGROVOC _91539
650	1	0	_aHelminthosporium
650	1	0	_91386 _aHeritability _gAGROVOC
650	1	0	_aPathogenesis
650	1	0	_aWheat
653	0		_aCIMMYT
653	0		_aUCL
650	1	7	_aPlant breeding _gAGROVOC _2 _91203
700	1		_aDuveiller, E.|Mercado, D.|Maraite, H.
700	1		_aMaraite, H., _ecoaut.
700	1		_aRosyara, U., _ecoaut.
700	1		_aSharma, R.C., _ecoaut.
700	1		_aVromman, D., _ecoaut.
700	1		_9826 _aDuveiller, E. _gDG's Office _8INT1237
942			_cREP
999			_c7089 _d7089