Maize
Genetics Cooperation Newsletter vol 86 2012
MNLCORCUERA20121.DOC
CASTELAR, ARGENTINA
INSTITUTO DE GEN�TICA DR. E. A.
FAVRET, CICVyA INTA CASTELAR
AND COMISI�N DE
INVESTIGACIONES CIENT�FICAS PCIA. BUENOS AIRES (C.I.C.)
Argentinean High-Lysine and Modified Starch Corn Hybrids. I. Days and Growing-degree days to silking.
Corcuera V.R.1-3,
Kandus M.2-3, Salerno J.C.2-3
1. Com. Inv.
Cient�f. Pcia. Bs. As. (C.I.C.) 2. INTA 3. Inst. Gen�tica Dr. Ewald
A. Favret, CICVyA INTA Castelar.
The duration
of the different phenology phases expressed in days vary among environments due
to changes in relative humidity, air and soil temperature, sun radiation and
photoperiod. Because of the poor correlation between the number of days and the
growing-development of the plants it is not possible to obtain acceptable
results when the genotypes are classified according to the number of days to
flowering though it must be admitted its utility as guidance. Most part of the
variation in days to flowering and maturity may be explained thru differences
in temperatures amongst locations and years, so it is evident that this is the
main factor affecting the development rate of maize. The effect of the
temperature over the development rate can be described using the concept of
thermal time (e.g.= growing-degree days
or GDD). Consequently, the duration of the vegetative cycle of maize may
also be defined by the sum of temperatures or thermal time (TT) required to
reach silking (R1).
Use
of diverse foundationals as well as obtain new crosses between adapted
genotypes and exotic materials introduced from other research centres made it
possible to count on enough initial genetic variability since new inbred lines
were developed and these were later used to give raise to the single and double
crosses tested in the field.
The hybrids tested may be grouped according to their
grains characteristics within four types or categories= I. materials with modified
starch (MS) by action of the single mutant genes waxy and/or amylose-extender,
II. double mutant genotypes with starch and protein modified by the action of the
mutant genes waxy and opaque-2 and/or its variant opaque-5 (DR), III. materials with high-lysine content or high quality proteins by action of the
genes opaque-2 or its allele opaque-5 (HL) and IV. the flint hybrids ACA 929 and ACA 2000 used as
testers.
The cycle to flowering of thirty single
and double-crosses was field evaluated in the Instituto
de Gen�tica Dr. E.A. Favfret
(IGEAF-INTA Castelar) and the results are shown in
Table 1 and the basic statistics estimated for the
different groups of hybrids are shown in Table 2.
The single-crosses
reach silking in average at 54.3 � 3.0 days from emergence and after accumulating
693.6 � 43.7 �C (ranges= 50 to 59 days and
631.2 to 759.9 �C; see Table 1). Some very precocious genotypes to R1
were detected among these materials, as for example the waxy hybrids HC52 and HC98 and the double mutant HC55. These single-crosses must be included within the class FAO 200
because they reach R1 as soon as they accumulate 630.0 to 660.0 �C. In average, double-crosses reached silking after 56.1 � 2.3 days from emergence (range= 51 to 59 days) and their mean
heat requirement to the same phase was 713.1 � 22.8 �C (range= 645.2 �C
to 759.9 �C). The double-mutants HC67, HC80, HC82
and HC95 stand out amongst them due to their high degree of precocity (class
FAO 200). Some other double-crosses (e.g.=
HC72, HC73, HC90, HC92, HC93, HC94, HC96 and HC97) belong to class FAO 300-400 because
they reach silking after piling up 689.7 to 721.8 �C from emergence. The single-crosses HC50 and HC58, the same as the double-crosses
HC69, HC70, HC75, HC77, HC78, HC83, HC85 and HC91 must be included within the
classes FAO 5OO and FAO 600. Consequently, these latter hybrids are considered
as non-precocious and have an intermediate or complete cycle to flowering like
the testers ACA 929 and ACA 2000.
The mean contrasts (tStudent),
revealed that the MS hybrids do not differ statistically from double mutants in
the number of days or thermal time necessary to reach silking
(� t= 1.7 n.s. for
both physiological traits). Nevertheless, highly significant differences
were observed between the MS materials and both testers ACA 929 and ACA 2000 (�t= 3.6
and 3.7 for days and thermal time respectively; p� 0.01). Likewise, the double
mutant hybrids (DR) differ in a highly significant way from the testers ACA 929
and ACA 2000 both in the necessary number of days and thermal time to reach R1
(�t= 2.7 and 2.9 respectively; p� 0.01).
A very strong correlation between the number of days
and the thermal time necessary for silking was found
in the hybrids evaluated in Castelar (r= 0.99; p� 0.01).
The results obtained show a great degree of precocity in the materials studied. Due to their degree of precocity, 7/30 hybrids could be recommended for late sowings in the Northern Pampa zone and also in the argentinean Corn Region VI. Likewise, due to the length of their evolutive cycle, -measured in number of days or thermal requirements-, the precocious genotypes could be used indifferently in the Western or Southern Pampa areas, characterized by having a shorter period free of freeze than other areas of the argentine corn region. A higher degree of precocity helps adaptation to areas with short summers and humid falls making possible a further increase of the culture surface of this species but in this case making use of specialty germplasm suitable for diverse industrial and feeding purposes.
Table 1= Evolutive cycle to flowering of the single
and double-crosses tested in the IGEAF-INTA Castelar during the growing season 20010/11
|
HYBRID |
CROSS |
TYPE |
DAYS TO R1 |
GDD (�C) R1 |
FAO CLASS |
|
HC49 |
single |
MS (wxae1) |
54 |
689.7 |
300-400 |
|
HC50 |
single |
MS (wx) |
59 |
759.9 |
500 |
|
HC52 |
single |
MS (wx) |
50 |
631.2 |
200 |
|
HC55 |
single |
DR (wxo2o5) |
52 |
659.5 |
200 |
|
HC57 |
single |
HL (o2o5) |
54 |
689.7 |
300-400 |
|
HC58 |
single |
MS (wx) |
57 |
737.6 |
500 |
|
HC59 |
single |
DR (wxo2) |
56 |
721.8 |
300-400 |
|
HC66 |
doble |
DR (wxo2/Oh43) |
59 |
759.9 |
500 |
|
HC67 |
double |
DR (wxo2) |
51 |
645.2 |
200 |
|
HC69 |
double |
DR (wxo2) |
59 |
759.9 |
500 |
|
HC70 |
double |
DR (wxo2o5) |
57 |
737.6 |
500 |
|
HC72 |
double |
DR (wxo2/Oh43) |
56 |
721.8 |
300-400 |
|
HC73 |
double |
DR (wxo2) |
56 |
721.8 |
300-400 |
|
HC74 |
double |
DR(wxo2o5) |
56 |
721.8 |
300-400 |
|
HC75 |
double |
DR (wxo2) |
58 |
748.1 |
500 |
|
HC77 |
double |
DR (wxo2/Oh43) |
58 |
748.1 |
500 |
|
HC78 |
double |
DR (wxo2) |
59 |
759.9 |
500 |
|
HC80 |
double |
DR (wxo2) |
52 |
659.5 |
200 |
|
HC82 |
double |
DR (wxo2) |
53 |
674.0 |
200 |
|
HC83 |
double |
DR (wxo2/Oh43) |
59 |
759.9 |
500 |
|
HC85 |
double |
DR (wxo2o5) |
57 |
737.6 |
500 |
|
HC90 |
double |
MS(wxae1) |
54 |
689.7 |
300-400 |
|
HC91 |
double |
DR (wxo2) |
58 |
748.1 |
500 |
|
HC92 |
double |
MS (wx) |
55 |
706.0 |
300-400 |
|
HC93 |
double |
DR (wxo2o5) |
56 |
721.8 |
300-400 |
|
HC94 |
double |
MS (wx) |
56 |
721.8 |
300-400 |
|
HC95 |
double |
DR (wxae1) |
53 |
674.0 |
200 |
|
HC96 |
double |
DR (wxo2o5) |
56 |
721.8 |
300-400 |
|
HC97 |
double |
DR (wxo5) |
56 |
721.8 |
300-400 |
|
HC98 |
single |
MS (wx) |
52 |
659.5 |
200 |
|
ACA2000 |
single |
Flint or vitreous |
59 |
759.9 |
500 |
|
ACA 929 |
three way |
Flint or vitreous |
62 |
794.1 |
600 |
Table 2= Basic statistics calculated for the
different groups of hybrids evaluated in the IGEAF-CNIA Castelar
(growin season 20010/11)
|
|
Days to R1 |
||
|
|
average � s.d. |
variance |
variance/n |
|
MS |
54.4 � 2.7 |
7.3 |
0.8 |
|
V�treous (Testers) |
60.5 � 2.1 |
4.5 |
2.2 |
|
DR |
56.2 � 2.5 |
6.1 |
0.3 |
|
|
|
|
|
|
|
Thermal time (�C) to R1 |
||
|
|
average � d.s. |
variance |
variance/n |
|
MS |
696.6 � 39.8 |
1583.9 |
176.0 |
|
V�treous (Testers) |
777.0 � 24.2 |
584.8 |
292.4 |
|
DR |
722.5 � 35.8 |
1278.2 |
63.9 |
Please Note: Notes
submitted to the Maize Genetics Cooperation Newsletter may be cited only with
consent of authors.