Maize Genetics Cooperation Newsletter vol 84 2010

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of authors.

Texas AgriLife Research, Texas A&M University, College Station, TX; Texas AgriLife Research, Lubbock, TX

Identifying maize germplasm with extremely late flowering and photoperiod sensitivity in Texas

Murray, SC; Xu, W; Mayfield, KL

Maize cultivars that are extremely late to flower or fail to flower in the temperate/ sub-tropical summer are of interest: 1) to develop tall dedicated cellulosic feedstocks (non-grain), 2) to better understand genetic mechanisms of flowering, 3) to create genetic mapping populations for flowering time and other traits of interest, and 4) to identify genetic diversity in linkage with extreme flowering time genes that may otherwise be inadvertently selected against. We are also very interested in these tropical lines as an untapped source of aflatoxin resistance but flowering time confounds this analysis. We planted 55 accessions obtained from GRIN (USDA-ARS) and up to three checks (B73, Mo17, CML254), in three Texas locations, Weslaco (planted 2/18/2009), College Station (planted 3/20/2009), and Lubbock (planted 5/8/2009) if enough seed was available. Accessions of interest were identified based on previous MGNL notes, data found in GRIN and suggestions found on blogs. Plants were managed with normal agronomic practices for a breeding nursery but stress was still evident from a record breaking hot and dry summer across Texas. Flowering dates (Anthesis) were taken every few days in College Station and Lubbock, but estimated in Weslaco on May 15^th by KLM and SCM. Because many of these accessions were heterogenous landraces, some within accession segregation was observed. For nearly all accessions, segregation was often no more than a week and plants appeared otherwise uniform. To increase seed and develop homozygous lines for future experiments, individuals were self or sibling pollinated in College Station. Many of the accessions that flowered very late failed to produce seed or had excessive ear rot due to late season stress. Asynchronous flowering was observed (always with silking after anthesis) within some accessions but attempts to sib pollinate were occasionally successful. The wild species Z. dipploperennis and Z. huehuetenangensis were the latest to flower while among domesticated accessions the latest were from Ecuador and Columbia.

Late flowering accessions were then also planted in a winter nursery in Weslaco, TX on August 10, 2009 to produce more seed for evaluation. Under winter nursery conditions (going into shorter days, moderate day temperatures, cool nights) most of the accessions flowered around the same time or slightly later than normal breeding material. This suggests that the delayed flowering in Summer was caused primarily by photoperiod response rather than by high temperatures. This confirms that the challenge of producing and evaluating genotypes that do not flower in the Summer can be overcome by making crosses and producing seed in a winter nursery under a short-day length.

Ultimately, we wish to develop extremely late flowering inbred lines out of landrace material that can be used for a variety of experiments, tests, and breeding objectives. It is clear that given the heat of Texas Summers and inbreeding of landrace material this is likely to be quite challenging and some crossing to elite adapted material may be necessary. We hope that crosses to elite material can also be utilized, in coordination with the Germplasm Enhancement of Maize (GEM) program, as sources of genetic diversity for continued maize improvement in areas such as aflatoxin resistance.

		Days After Planting to Anthesis
GRIN #	Origin	CS	WE	LB
Ames 17675	Ecuador	111	>103	na
Ames 1768	Ecuador	77	87	70
Ames 19945	Nayarit, Mexico	95	na	100
Ames 19994	Oaxaca, Mexico	91	na	99
Ames 26959	Wisconsin	57	67	42
Ames 2758	New York	62	75	55
NSL 2833	Mexico	80	80	81
NSL 5618	Virginia	65	73	54
NSL 95717	Puerto Rico	81	83	na
PI 245133	Russia	70	76	68
PI 318728	Brazil	82	92	79
PI 331444	Ethiopia	95	>103	103
PI 357106	Ethiopia	90	103	82
PI 357127	Ethiopia	90	92	91
PI 369342	Benin	79	84	81
PI 377746	Thailand	71	83	68
PI 377746	Thailand	71	na	na
PI 390552	Equador	75	82	59
PI 390553	Equador	111	97	>114
PI 390553	Equador	111	na	na
PI 390554	Equador	95	96	113
PI 390554	Equador	95	na	na
PI 390573	Equador	90	92	104
PI 414181	Iowa	81	83	71
PI 414181	Iowa	81	na	na
PI 420250	Arizona	70	80	58
PI 420251	Arizona	57	73	54
PI 441932	Z. dipploperennis	>111	na	>114
PI 441934	Z. huehuetenangensis	>111	na	216
PI 443785	Montana, Columbia	83	na	100
PI 443788	Montana, Columbia	111	na	>114
PI 443793	Montana, Columbia	111	na	103
PI 445082	Columbia	111	>103	>114
PI 445144	Montana, Columbia	111	na	94
PI 451693	Iowa	67	80	54
PI 483809	Cuba	80	87	82
PI 484600	Puebla 94	105	>103	114
PI 488664	Peru	82	95	92
PI 498533	Cuba	83	88	90
PI 498703	Trinidad	88	94	96
PI 511650	Mexico	90	87	94
PI 515534	Mexico	75	95	82
PI 576019	CIMMT population	80	86	94
PI 612343	Florida	69	78	na
PI 612343	Florida	69	na	na
PI 614830	Florida	71	78	na
PI 614830	Florida	71	na	na
PI 628463	Nayarit, Mexico	88	na	99
PI 644099	Florida	72	80	na
PI 644099	Florida	72	na	na
PI 644100	Florida	74	na	na
PI 645923	Nayarit, Mexico	90	na	100
B73	check	78	na	69
Mo17	check	79	na	68
CML 254	check	95	na	na

CS - College Station, TX

WE -Weslaco, TX

LB – Lubbock, TX