Waxy endosperm maizes: their response to photoperiod

--Victor R. Corcuera*, Luis B. Mazoti and Carlos A. Naranjo

*Assistant Technician of C.I.C.

The maize plant is essentially neutral to photoperiod, though short days speed up its induction to flowering.

With the sole purpose of obtaining waxy endosperm commercial hybrids qualified for industrialization proceedings (such as WET MILLING and others), different types of waxy endosperm maizes were studied: three inbred lines, three populations and one hybrid.

The inbred lines analyzed were:

a. "c-tester" (c sh wx), introduced to Santa Catalina during 1937 from Cornell University, and kept under inbreeding since then.

b."CEL WAXY SMC2" and "CEL WAXY SMC3", introduced to Santa Catalina during 1990 from CIMMYT (Mexico).

The populations studied were: SCV1, SCV2 and WEM of the Instituto Fitotécnico de Santa Catalina.

Finally, the hybrid measured was FUNKS WAXY, sent to Santa Catalina from CIMMYT (Mexico) during 1990.

Three different evolutive cycle traits were measured and analyzed in all these materials: T, days to tassel (number of days computed from the date of emergence); S, days to silking; Po, days to pollen. All of these traits were measured as is recommended in the General Catalog of Maize Descriptors by IBPGR (International Board for Plant Genetic Resources).

In addition, to make the results obtained comparative amongst themselves and with others coming out from our next studies, the value of the Heat Units necessary to flower has also been calculated according to a residual method (method of the degrees/day), taking as a baseline temperature 12.8 C (approximately 55 F).

All of the measurements were practiced on the basis of individual plants (nearly 300).

As is well known, the evolutive cycle traits are closely related amongst themselves, therefore the analysis of the results can be done without discriminating each trait.

Table 1 shows the commonest statistical measurements (means, standard deviation, variability %, variance and range) for all the traits studied in each of the materials. The variability % obtained for most of the traits considered was low. This tendency is also observed in the ranges. It must be pointed out that the materials sent by CIMMYT showed a long evolutive cycle in our country. They were protoginous as well. This fact may be due to the latitude in which these maizes were grown, and consequently to the photoperiod. It is known that when maizes adapted or grown in low latitudes are moved to high latitudes, the evolutive cycle becomes longer.
 

Table 1. Statistical measures for evolutive cycle traits in all the materials studied.
 
Material   x S.D. Var.% G2 Range
  T 52.45 2.03 3.88 4.12 49-55
c-tester S 59.10 1.59 2.70 7.29 55-60
  Po 55.35 2.60 4.70 22.09 52-60
  T 52.29 3.21 6.15 37.82 48-60
SCV1 S 55.38 2.63 4.75 22.56 52-60
  Po 54.97 3.36 6.11 11.29 51-60
  T 51.94 2.42 4.67 21.81 48-57
SCV2 S 56.36 2.40 4.27 18.23 54-60
  Po 54.73 2.45 4.48 20.07 51-58
  T 49.92 2.91 5.83 8.47 48-56
WEM S 55.10 1.50 2.72 2.25 53-58
  Po 52.50 6.96 13.26 48.44 51-60
  T 56.29 1.81 3.21 3.28 53-60
FUNKS WAXY S 59.86 1.34 2.25 1.79 58-61
  Po 59.04 1.55 2.63 2.40 56-60
  T 66.42 2.73 4.11 7.45 60-71
CEL WAXY SMC2 S 70.37 2.11 3.00 4.45 66-74
  Po 74.49 2.64 3.54 6.97 70-78
  T 66.24 3.49 5.27 12.18 60-70
CEL WAXY SMC3 S 70.47 1.61 2.29 2.59 68-73
  Po 74.30 2.29 3.08 5.24 71-78

Table 2 shows the existence of statistically significant differences among the maizes evaluated when their evolutive cycle traits are considered.

Table 2. Differences between means for evolutive cycle traits.
 
Material T S Po
c-tester 52.45a* 59.10a 55.35a
SCV1 52.29a 55.38b 54.97a
SCV2 51.94a 56.36b 54.73a
WEM 49.92b 55.10b 52.50b
FUNKS WAXY 56.29c 59.86a 59.04c
CEL WAXY SMC2 66.42d 70.37c 74.49d
CEL WAXY SMC3 66.24d 70.47c 74.30d
*Individual means within a column followed by different letters are significantly different at 5% level.

Table 3 shows the Heat Units, the average number of days to silking, and a classification of each of the materials studied according to these data.

Table 3. Evolutive cycle traits, general data and classification for each material studied.
 
Material S Heat Units ( C) Cycle
c-tester 59 530.85 short
SCV1 55 494.40 short
SCV2 56 506.50 short
WEM 55 494.40 short
FUNKS WAXY 60 541.25 intermediate
CEL WAXY SMC2 70 628.40 long
CEL WAXY SMC3 70 628.40 long
S: days to silking (approach values).

The single fact that the waxy endosperm maizes show a short evolutive cycle of precocity makes them doubly interesting: 1. On the one hand commercial hybrids of waxy endosperm and short evolutive cycle could be obtained. 2. On the other hand, their precocity could be incorporated into the most cultivated maizes of our country.

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

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