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If Ifnonoselective fertilization occurred, about
50 50percent maize teosinte crosses would be be
expected in inallall cases.
However, 58 58percent of of
the themaize races pollinated with withthe themaize-T 2 2
mixture showed that that there was wasa adefinite selectionininfavor
of ofmaize pollen.
Thirty five fiveper­
pertiocencent
of of the themaize races permitted some crosses
with withGuerrero teosinte to tooccur, but but there was was
a astrong bias biasininfavor of ofmaize pollen.
Two Two
races of ofmaize, Camelia Vicuna and andArrocillo
Amarillo, showed no noevidence of ofany anymech­
anism which prevented teosinte pollen from
fertilizing maize ovules, even in incompetition
with withmaize pollen.
As Ascan canbebeseen in inTable
18, 18, a asimilar situation was wasobserved in inthe
the
group of of maize races that that were pollinated with with
maize plus plus maize-T1 1 mixtures.
TABLE 18. 18. Estimated percentages of ofmaize-teo­
sintecrosses that that may mayhappen in innature if if differenentraces
were associated and andtheir theirflowering
periods coincide. Tepalcingo, Mexico, 1969.
sinte -rhe -rheraces of ofmaize Celaya, Maiz Mai·zDulce,
Bolita, Vandeno, Palomero Toluquei'io~ Jala,
C6nico, Zapalote Grande, Zapalote ~hico,
Nal-Tel, Arrocillo Amarillo, Harinoso de de acho, ~cho,
Dzit Dzit Bacal and andthe thecollection Martinica 2 2were
used as asfemales in incrosses with withpure pol~n
of ofteosinte and andininallallcases a agood seed set. sel-.
was wasobtained. Thus, in inmost cases, competition
between the thetwo twosources of of pollen seems
to tobebethe thereason for forthe thelack, or orreduced
number, of ofmaize teosinte crosses.
A Asimilar study on onindividual plants of ofthe
the
F 2 F 2 of of the thecrosses of of Camelia Vicuna and andArro­
cilloAmarillo, with withcollections that that do donot not cross
with withteosinte, might provide a abetter understanding
of ofthe thegenetic mechanism (if (ifany)
any)
cillo
involved in inthe theselective fertilization observed
in in maize-teosinte associations. Similarly, a a
better understanding could
be begained of ofthe
the
mechanism by bywhich teosinte and andmaize populations
can cangrow together:
remaining compatiblibleinincrosses,
yet yetmaintaining their identities
even when their flowering
periods overlap.
pop­
! !
! ... c
~ ! ~ .;;
c
'!
0
Ow
c c
~ ~ of-tit -S -;;
~..:i ~..ca
o
.- 2
o .~ .':'"
.- 2
Maize Maize Race Race ]~ 1l~'" ... Maize Maize Race Race ] 11 ~ ~ 0 0
> > .. .. 0 0 l: l: t t
t=~ t!~ •.. • S ... S :: ::
.se~ .Jl .Jl 0 0 " "
Ouu OUU
Obel
.. ...
oli"
Jala Jala 31.8 31.8 Canario de de 8 8 0 0
Cuba Cuba 12 12 8.8 8.8 Martinlca Martinlea 2 2 0 0
Guatemala 127 127 6.9 6.9 Clmelll Camella Vicui'il Vicuna 42.4 42.4
Arrocillo Arroeillo Amarillo 4.9 4.9 Arrocillo Arroeillo Amarillo 40.4 40.4
Cuba Cuba 54 54 3.8 3.8 Tuxpei'io Tuxpeno 22.4 22.4
Vandeno 3.4 3.4 GUltemal1 Guatemala 55H 55H 12.3 12.3
Bolitl Bolita 3.3 3.3 Jala Jala 9.1 9.1
Nal·Tel Guat. Guat. 2.9 2.9 Tibionclllo Tabionelllo 5.9 5.9
C6nico Conieo 2.8 2.8 Cuba Cuba 54 54 4.2 4.2
Tabloncillo Tabloneillo 2.4 2.4 Tehul Tehua 3.8 3.8
Honduras 19 19 • • 2.2 2.2 Zlpllote Zapalota Grande 3.8 3.8
Guatemall Guatemala 806 806 1.8 1.8 Olotillo 2.4 2.4
C6nico Conieo Norteno 1.5 1.5 Flint Flint Guarani 1.6 1.6
Cuba Cuba 63 63 1.2 1.2 Chlpalote Chapalota 0 0
Chapalote 0 0 Reventldor Reventador 0 0
Reventador 0 0 Vlndei'io Vandeno 0 0
Harinoso de de ocho oeho 0 0 Harinoso de de ocho oeho 0 0
Maiz Maiz Dulce Dulce 0 D Mliz Maiz Dulce Dulce 0 0
Guerrero 250 250 0 0 C6nico Conieo Nortei'io Norteno 0 0
Celaya Ce'aya 0 0 Bolitl Bolita 0 0
Jalisco Jaliseo 78 78 0 0 C6nlco Conico 0 0
Palomero Toluquei'io Toluqueno 0 0 Guerrero 200 200 0 0
Serrano '0 '0 Clinging Calngang 0 0
Guatemlla Guatemala 114 114 0 0 Comiteco 0 0
GUltemlla Guatemala 145 145 0 0 PepitJIII Pepltllla 0 0
NilNal Tel Tel de de 8 8 0 0 Comun Segregaclones Segregacion.. 0 0
Quicheno Quieheno precoz preeoz 0 0 PUYI Puya Segregaclones Segregaelon.. 0 0
Cubl31 Cuba 31 0 0 Entrelocldo Entraloeado duro duro 0 0
Costa Costa Rica Rica 30 30 0 0
Other Genetic Studies
Investigations of ofpossible uses of ofgenetic
mutants in inmodifying plant height is isnow nowun­
der derway. way. The The "square stem" character rep­
rep­
unresents
one onesuch possible mutant and andappears
to toshow height reduction in inthe theF 1 F l crosses,
although the thegenetics of ofitsitsuse useare arenot notyet
yet
clear. Other characters, both bothidentified and and
unidentified types, are areunder study. stUdy.
The Theuse useofofmutants in inthe thedevelopment of of
higher quality protein is isbeing investigated,
also.
This Thisinvolves study of ofthe theeffects of ofa
a
combination of oftwo twoorormore protein quality
endosperm mutants on on grain texture. The The
search for formarker genes as asananaidaidininthe
the
identification of ofkernels homozygous for forthe
the
Opaque-2 and andFloury-2 genes is isbeing continued.
PHYSIOLOGY
Leaf Leaf orientation: One Onethousand SI SIlines
derived fromTuxpei'io composite were evaluated
for forleaf leafangle and and5050lines with witherect.
leaves and and5050with withfloppy leaves were selected
to togenerate two twopopulations.
Two Twogenerations
of ofsynthesis were carried out outatatPoza Rica in in
con­
1969. The Theresulting populations will will be bestudied
to toinvestigate the the probable effects of ofleaf
leaf
orientation on onyield and andother important characteristics.
31 31