Universidad Nacional de Córdoba

Agronomic performance of high and low canopy temperature maize genotypes

— Biasutti, CA

From a breeding maize population (CEC5), one hundred and forty seven individual plants were chosen at random during the vegetative stage. Canopy temperature (CT) was recorded from each plant using a hand-held infrared thermometer. Five measurements were taken from the same plant during the vegetative phase. Temperature was recorded around noon (11–13 hs) on sunny, cloudless days. Medium values were utilized to classify plants as high (HCT) or low (LCT) canopy temperature. Besides CT, agronomic attributes included in a routine index selection were considered for each plant.

During the years 2002–2003, a field experiment with 163 half-sib families (93 HCT and 70 LCT families, 14 families derived from an index selection and the population CEC5 as check) was conducted at the Experimental Station of Facultad de Ciencias Agropecuarias of Córdoba, at Córdoba province, Argentina. The families were arranged in an incomplete block design, with three replications in plots of one row 5 m long, with plants at 0.2 m, and rows spaced 0.7 m apart. Canopy temperature was recorded in the same way as described above. Data was collected for grain yield (at 14% grain moisture), canopy temperature, leaf elongation, tassel size (1 small; 5 large), plant height, stalk lodging, prolificacy and ear length.

Significant differences (P<0.05) were obtained among families groups for stalk lodging, prolificacy and ear length. LCT families showed higher grain yield; no significant differences were detected. Results indicated that the inclusion of CT in an index selection was not detrimental to the performance of the half sib families evaluated.

Heritability estimates by parent offspring regression showed lower values for TP (0,10), so this character is highly environment dependent. Crop stage and time of day also influence CT values. From these results, it can be concluded that the utilization of this trait as a selection criterion needs further research.

Table 1. Medium values for grain yield, prolificacy, plant height, stalk lodging and ear length in maize half sib families.

Genotype Yield
Plant height
Stalk lodging
Ear length
LCT Families 56.66 1.24 197 5.66 18.38
HCT Families 44.68 1.27 194 9.00 19.26
Index Families 52.06 1.00 203 9.07 15.82
Check 50.84 1.00 199 11.16 16.93
DMS (0.05) 13.67 0.20 0.14 4.67 2.49
C.V (%) 30.89 14.75 7.73 49.85 11.63

Table 2. Medium values for canopy temperature, leaf elongation and tassel size in half sib maize families.

Genotype Canopy
Temperature °C
Leaf Elongation
Tassel Size
LCT Families 26.62 30.67 3.05
HCT Families 26.51 31.03 2.37
Index Families 26.87 34.19 3.11
Check 26.65 33.50 3.00
DMS (0.05) 0.84 8.89 1.06
C.V (%) 3.37 29.48 39.88

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