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020			_a968-6923-93-4
040			_aMX-TxCIM
072		0	_aF30
072		0	_aF60*H50
082	0	4	_a633.153 _bEDM
100	1		_aVasal, S.K. _uDeveloping Drought- and Low N-Tolerant Maize. Proceedings of a Symposium; El Batan, Tex. (Mexico); 25- 29 Mar 1996
110	2		_aCentro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico DF (Mexico)
245	0	0	_aChoices among breeding procedures and strategies for developing stress tolerant maize germplasm
260			_aMexico, DF (Mexico) _bCIMMYT : _c1997
340			_aPrinted
520			_aAbiotic stresses, particularly those related to water and nitrogen, are widely distributed and may occur at practically all stages of crop growth. Improvement efforts through breeding are rather limited for such traits, and perhaps only international agricultural research centers, the larger private seed companies, and a few strong national programs have the necessary resources and manpower to pursue such research efficiently. In the absence of major genes, the breeding of such traits is difficult, and requires some skill in managing selection environments. Variation for stress traits has been observed in maize populations under improvement by recurrent selection, as well as among inbred lines and hybrids derived from those populations. recurrent selection procedures for improving stress tolerance characteristics have been successfully demonstrated. Choices among various kinds of breeding procedures appropriate at different stages of the improvement process are outlined, with the appropriate time to switch from one procedure to another indicated. The merits and drawbacks of procedures involving testers in intensifying such traits are discussed. The usefulness of selecting for hybrid-oriented features in stress-tolerant populations is emphasized, as tolerance to inbreeding is itself a valuable source of general stress tolerance. The integration of selection for stress tolerance traits in the on-going improvement process is emphasized. Relative efficiency and cost-effectiveness of recurrent selection procedures are compared with evaluating elite germplasm (particularly inbreds). Results to date suggest that alleles related to stress tolerance are present in most elite maize populations (and hence in any group of inbred lines) at a relatively low frequency, and that controlled stress environments play a key part in their identification. Efficient inbred line development procedures will be indicated, and alternate strategies involving inbreeding at high plant density will be suggested to improve secondary traits known to increase stress tolerance. Finally, cost- effective procedures and strategies most appropriate for breeders operating in developing countries are emphasized.
546			_aEnglish
591			_a9802|AGRIS 9702|anterior|R97-98PROCE|FINAL9798
593			_aJose Juan Caballero
595			_aCPC
650	1	7	_aBreeding methods _gAGROVOC _2 _91030
650	1	0	_aDrought resistance
650	1	0	_91081 _aDrought stress _gAGROVOC
650	1	7	_aGermplasm _gAGROVOC _2 _91136
650	1	0	_aRecurrent selection
653	0		_aCIMMYT
650	1	0	_91314 _aZea mays _gAGROVOC
650	1	0	_91151 _aHybrids _gAGROVOC
650	1	7	_aPlant breeding _gAGROVOC _2 _91203
700	1		_aBeck, D.L., _ecoaut.
700	1		_aCordova, H.S., _ecoaut.
700	1		_aEdmeades, G.O., _ecoaut.
700	1		_aEdmeades, G.O.|Banziger, M.|Mickelson, H.R.|Peña-Valdivia, C.B. _eeds.
942			_cPRO
999			_c3735 _d3735