000			04239nam a22004697a 4500
001			G79723
003			MX-TxCIM
005			20240919021103.0
008			121211s ||||f| 0 p|p||0|| |
040			_aMX-TxCIM
072		0	_aF30
072		0	_aH20
090			_aCIS-4081
100	1		_aSharma, R.C. _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 helminthosporium leaf blight on performance of timely and lat-seeded wheat under optimal and stressed levels of soil fertility and moisture
260			_aKathmandu (Nepal) _bCIMMYT : _c2004
300			_ap. 47-65
340			_aPrinted
520			_aHelminthosporium leaf blight (HLB) is the most serious disease constraint to wheat (Triticum aestivum L. ) yields in the warm plains of South Asia. It occurs either singly or as a complex of spot blotch ( caused by Cochliobolus sativus) and tan spot ( caused by Pyrenophora tritici- repentis). Several abiotic stresses in the region affect the development and severity of HLB. A field study was conducted using three wheat cultivars (Sonalika=RR21, Bhrikuti and BL1473) during the 2001 and 2002 wheat seasons at two sites (fanner's field and research station) in Nepal, where HLB is a serious problem every year. The objective was to detennine the effect of low soil moisture and poor soil fertility in combination with foliar blight severity under natural inoculum pressure on the agronomic performance of timely and late-seeded wheat. The experiment was conducted in a multiple-strip layout in a randomized block with three replicates. Soil fertility stress was evaluated by using the recommended doses ofN, P and K as opposed to no chemical fertilizer. Three irrigations and no irrigation were used to assess the effect of soil moisture stress. The experiment included normal and late seeding dates to take into account the average air temperature which increases as the wheat season progresses. Multiple HLB scores were recorded to calculate the area under the disease progress curve (AUDPC) and AUDPC/day was determined. Soil fertility stress increased AUDPC by 28.4%. Overall, soil fertility stress had a more pronounced effect on disease levels than reduced moisture stress, probably because rain had diminished the difference between moisture stress. HLB induced reductions of 20.5% and 15.5% in grain yield and thousand-kernel weight (TKW), respectively, under late seeding, compared to 13% and 7.8% under timely sown conditions. Under low soil fertility, reductions in grain yield and TKW due to HLB were 52.1% and 15.5%, respectively, compared to 26.1% and 8.0% under optimum soil fertility .HLB caused yield reduction of 22.1% under low soil moisture compared to 11.8% under optimum soil moisture. Compared to timely sown wheat, AUDPC/day and reductions in grain yield due to HLB were always higher under late seeding suggesting that AUDPC/day explained yield losses better than AUDPC. These findings demonstrate the joint effects of crop management factors on HLB severity and associated grain yield losses both under fanner's field and research station conditions. The results imply that optimum crop husbandry must be adopted to minimize wheat yield losses due to HLB.
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	_aCochliobolus sativus _92193
650	1	0	_aDisease control
650	1	0	_aGrain yield _91339
650	1	0	_aHelminthosporium
650	1	0	_aPyrenophora tritici-repentis _gAGROVOC _92707
650	1	0	_aWheat
653	0		_aCIMMYT
653	0		_aUCL
650	1	0	_91296 _aTriticum aestivum _gAGROVOC
650	1	0	_91952 _aSoil fertility _gAGROVOC
650	1	0	_91134 _aGenotypes _gAGROVOC
650	1	7	_aPlant breeding _gAGROVOC _2 _91203
700	1		_aDuveiller, E.|Mercado, D.|Maraite, H.
700	1		_9826 _aDuveiller, E. _gDG's Office _8INT1237
942			_cREP
999			_c7086 _d7086