Description of commercial hybrids and mutant inbreds incorporated into a waxy maize breeding plan in Argentina
--Corcuera, VR; Naranjo, CA

During the growing season 1995/96 new materials were incorporated into a maize breeding plan carried out at the IFSC and in collaboration with CITIM.

By the end of 1994, a group of 18 mutant inbred lines was sent to the IFSC from the Maize Genetics COOP Stock Center (Urbana, Illinois, USA). These inbreds have mutant genes of interest for industrialization processes such as ones for modified starches and semolas with high protein quality. Such is the case with the genes wx1, o2, o5, o9, o12, o13 and ae.

Table 1 shows the list of the lines studied, their genotype and the average values found for the traits measured. The measurements were based on different descriptors grouped as follows:

A. PLANT TRAITS: stalk diameter in cm (SD), total leaf number (TLN) and number of leaves above the uppermost ear (NLUE).
B. PROLIFICITY TRAITS: ears per tiller (ET) and ears per plant (EP).

Except for the inbreds 90-1863(4), 92-1540(4) and 87-3533-2, the lines show excellent prolificity values. Evolutive cycle traits were not measured as these lines were sown in the greenhouse during 1995. Nevertheless, it could be concluded that they have normal or short evolutive cycle if the total leaf number is considered.

Two commercial hybrids, Zeneca 8340 (long evolutive cycle) and Zeneca 8543 (short evolutive cycle), were studied and used as testers of our waxy inbreds to measure the general combining ability of them through a comparative yield trial during 1996/97. Hybrids of different evolutive cycle length were chosen to make possible the crosses among them and the waxy inbred lines. Both testers were sown in two dates during October and November 1995.

Both hybrids were evaluated through the use of several descriptors grouped as follows: pBR> A. PLANT TRAITS: the same as measured in the mutant inbreds, and stalk number (SN).
B. PROLIFICITY TRAITS: those measured in the mutant inbreds plus number of productive nodes per tiller (PN) and number of ears in the uppermost node (EUN).
C. EAR TRAITS: ear length in cm (EL), number of rows (RN), ear weight in grams (EW), cob percentage (%C) and humidity percentage of kernels at harvest (%H).

Tables 2 and 3 show the average values, standard deviation, variance, standard error and range of variation for each trait measured in both hybrids.

In Table 4, the statistical differences found between the two hybrids for the traits measured can be seen. There are significant differences for total leaf number. This is reasonable, as the hybrids studied have different evolutive cycle lengths. There are not significant statistical differences when prolificity traits are analyzed. Nevertheless, there exist significant differences for ear traits between Zeneca 8340 and Zeneca 8543.

Table 1. Average values found for plant and prolificity traits measured in mutant inbreds sent by Maize Genetics Coop Stock Center in 1994.
 
Inbred Genotype SD* EP ET TLN NLUE
83-2205-2 C1 sh1 wx1 AR 1.36 2.00 2.00 10.80 4.80
87-3614-1 c1 sh1 wx1+/v1 AR 1.20 2.00 2.00 9.00 4.00
94W-140-5 w23/L317/ae1 td1 1.68  1.82 1.82 11.91 4.91
88-3553-8 su1/su1 1.48 1.50 1.00 9.34 4.67
90-1863(4) su1/su1 1.81 1.20 1.00 11.90 5.50
93W-1273-3 o11 1.23 1.56 1.56 10.22 4.78
85-154-4 o9 1.79 1.62 1.62 11.25 5.75
92-158-4 +/o5 1.64 1.82 1.82 12.53 5.47
94-1590-1 +++/c1 sh1 wx1 1.57 1.40 1.40 11.00 4.50
92-1540(4) +/ae1 0h43 1.39 1.00 1.00 9.86 4.86
94-1275-1 a1 sh2/a1 sh2 1.49 2.86 2.86 11.14 4.43
93-1291(2) wx1 +/d3 1.46 2.00 2.00 10.64 4.64
93-4042-1 y1 Bh1 c1 sh1 wx1 1.22 1.87 1.87 9.87 4.25
86-1535-1 wx1-a^Oh43 1.34 1.62 1.62 10.25 4.87
87-3533-2 C1 wx1 ar1 AR 1.32 1.22 1.22 10.67 4.44
93W-1275-4 o13 1.00 1.40 1.40 9.60 3.60
93-3675-1 +/o12 1.51 2.38 2.38 12.77 5.69
92-1560-3 02^Oh43 1.50 2.00 2.00 10.60 5.00
*= see abbreviations in the text.

Table 2. Descriptive statistics for plant, prolificity and ear traits measured in Zeneca 8340.
 
Trait* Average Values±S.D. Variance Standard Error Range of Variation
DT 2.18±0.25 0.06 0.03 1.60-2.70
NH 14.33±1.21 1.46 0.15 11.00-17.00
NHEE 6.21±0.77 0.60 0.09 4.00-8.00
NT 1.00±0.00 0.00 0.00 1.00
NP 2.29±0.67 0.45 0.08 1.00-6.00
ENS 1.08±0.27 0.07 0.03 1.00-2.00
ET 1.89±0.53 0.28 0.06 1.00-3.00
EP 1.89±0.50 0.25 1.41 10.00-22.00
LE 12.00±6.78 46.00 0.60 12.00-18.00
PESp. 17.48±48.03 2307.22 10.02 94.00-277.00
%M 17.68±3.29 10.86 0.69 12.80-23.60
%H 18.71±2.82 7.93 0.59 14.00-24.40
* = see abbreviations in the text.

Table 3. Descriptive statistics for plant, prolificity and ear traits measured in Zeneca 8543.
 
Trait* Average Value±S.D. Variance Standard Error Range Of Variation
DT 2.20±0.21 0.05 0.03 1.70-2.70
NH 12.80±0.84 0.71 0.10 10.00-14.00
NHEE 5.89±0.53 0.28 0.06 5.00-7.00
NT 1.00±0.00 0.00 0.00 1.00
NP 2.27±0.63 0.39 0.07 1.00-4.00
ENS 1.03±0.17 0.03 0.02 1.00-2.00
ET 1.88±0.71 0.51 0.09 1.00-3.00
EP 20.36±2.75 7.55 0.55 12.50-23.00
LE 14.08±1.47 2.16 0.29 12.00-18.00
Pesp 225.64±53.69 2882.32 10.74 103.00-333.00
%M 12.59±1.21 1.47 0.24 10.70-15.20
%H 14.90±0.96 0.91 0.19 13.70-17.20
* = see abbreviations in the text.

Table 4. Statistical differences between both hybrids used as tester.
 
Plant And Prolificity Traits
Tester SD* TLN NLUE SN PN EUN ET EP
ZENECA 8340 2.18a 14.33 a 6.21a 1.00a 2.29a 1.08a 1.89a 1.89a
ZENECA 8543 2.20a 12.80 b 5.89b 1.00a 2.27a 1.03a 1.88a 1.88a
Ear Traits
Tester EL RN EW %C %H
ZENECA 8340 12.00a 17.48a 197.04a 17.68a 18.71a
ZENECA 8543 20.36b 14.08b 225.64a 12.59b 14.90b
*= see abbreviations in the text.
1= average values followed by the same letter do not differ significantly at 0.01% level.


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