000			03089nam a22004337a 4500
001			G65839
003			MX-TxCIM
005			20230704201318.0
008			121211s ||||f| 0 p|p||0|| |
020			_a968-6923-93-4
040			_aMX-TxCIM
072		0	_aF30
072		0	_aP35
082	0	4	_a633.153 _bEDM
100	1		_aLagarda Murrieta, R. _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	_aMaize landraces: _b Sources of tolerance to low soil nitrogen?
260			_aMexico, DF (Mexico) _bCIMMYT : _c1997
340			_aPrinted
520			_aA total of 209 tropical maize accessions from the CIMMYT germplasm bank were evaluated over the course of three experiments to identify sources of tolerance to N deficiency. We measured grain yield, plant height and maturity under both high and low soil nitrogen. Under low N we also measured N uptake, N harvest index, ear leaf area, and ear leaf chlorophyll concentration. Maturity and season of evaluation had large effects, so results were analyzed separately for early and late landraces in winter and summer experiments. Landraces could be grouped using cluster analysis. Accessions from certain locations tended to have similar maturities. Some Cuban accessions were characterized by superior performance under low N. We identified 54 accessions with high total N recovery, harvest index, and grain %N, from various regions. These were grouped by maturity and intercrossed to form early and late source populations. After three cycles of intercrossing as half-sibs in a low-N nursery with very slight selection pressure for ear formation and reduced plant height, the populations underwent three additional cycles of improvement with 20-50% selection pressure for yield and plant type under low N. 171 two evaluations where N stress reduced mean yields to 1.05 t ha-1, yields of C6 of the source populations were not significantly less than the yields of improved check varieties. Yield of the early population increased by 15% per cycle between C4 and C6, and that increase was 11% per cycle in the late population. With continued improvement, these source populations may provide valuable traits for low N environments.
536			_aResearch and Partnership Program
546			_aEnglish
591			_a9802|AGRIS 9702|anterior|R97-98PROCE|FINAL9798
593			_aJose Juan Caballero
594			_aINT1888
595			_aCPC
650	1	0	_aNitrogen content
650	1	0	_aNutrient uptake _91191
650	1	0	_aSelection
650	1	7	_aVarieties _gAGROVOC _2 _91303
653	0		_aCIMMYT
650	1	0	_91314 _aZea mays _gAGROVOC
650	1	0	_91952 _aSoil fertility _gAGROVOC
650	1	0	_91134 _aGenotypes _gAGROVOC
700	1		_aEdmeades, G.O., _ecoaut.
700	1		_aEdmeades, G.O.|Banziger, M.|Mickelson, H.R.|Peña-Valdivia, C.B. _eeds.
700	1		_aBanziger, M. _gResearch & Partnership Program _gExcellence in Breeding _8INT1888 _9834
942			_cPRO
999			_c3730 _d3730