000			02960nam a22003377a 4500
001			G94668
003			MX-TxCIM
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040			_aMX-TxCIM
041			_aeng
090			_aCIS-6197
100	1		_92252 _aAtlin, G.N.
245	1	0	_aForming double cross hybrids using two line synthetics
260			_c2010. _aLong Beach, CA (USA) :
300			_a1 page
500			_aAbstract only
520			_aIn maize breeding programs in the developing world, double cross hybrids remain of interest due to lower seed costs. However, their production is cumbersome for small seed companies, due to the need to maintain four parental inbreds and to manage the F1 parent crossing blocks as well as the double-cross seed production field. One way to simplify double cross production is to form hybrids from F2 bulks or two-line synthetics derived from each single cross parent. In such a scheme, single cross parents would be advanced to F2 and maintained as two-line synthetics, then crossed to form the certified seed. Allelic frequencies in gametes produced by an F2 or a two-line synthetic should be similar to those produced by an equivalent F1, and therefore the array of genotypes formed from an F2 x F2 or two line synthetic cross should be equivalent to that produced by a conventional F1 x F1 cross. Both methods should therefore generate hybrids with similar performance. We tested this hypothesis in the CIMMYT tropical lowland maize breeding program in 2009. Five conventional double cross hybrids (F1 x F1) and corresponding F2 x F2 crosses were compared in trials at five locations in Southern Mexico. There was no significant difference in yield between F1 x F1 and F2 x F2 crosses. Further trials are being conducted to confirm these findings in 2010 in eastern and southern Africa. Although seed yields on F2 or two-line synthetic parents will be slightly less than on F1 seed parents , the method should be of interest to small seed companies in Africa who often have difficulty managing inbred lines, and could help small, local seed companies currently producing only open-pollinated varieties to embark on hybrid seed production. This, in turn, will increase the availability of low-cost hybrid maize seed to African smallholders.
536			_aGlobal Maize Program
546			_aText in English
594			_aINT2825|INT2396|INT2714
595			_aCSC
650		7	_2AGROVOC _926603 _aCross-breeding
650		7	_2AGROVOC _91151 _aHybrids
650		7	_2AGROVOC _91253 _aSeed production
700	1		_aDas, B. _gGlobal Maize Program _gExcellence in Breeding _8INT2825 _9863
700	1		_9837 _aVivek, B. _gGlobal Maize Program _8INT2396 _ecoaut.
700	1		_aMagorokosho, C. _gFormerly Global Maize Program _8INT2714 _9854
773			_dCA (USA) : 2010 _tASA-CSSA-SSSA 2010 International Annual Meeting: Green revolution 2.0: Food+Energy and Environmental Security
942			_cPRO _2ddc
999			_c8040 _d8040