EFFECTS OF PLANTING DENSITY ON CROP GROWTH AND SUGAR CONTENT FOR THREE SWEET SORGHUM [SORGHUM BICOLOR (L.) MOENCH] GENOTYPES IN EASTERN CANADA A. Saita1,2, A. Tubeileh2, C. Patanè3, S.L. Cosentino1 1DISPA,
Sezione Scienze Agronomiche, Università degli Studi di Catania (Italy) E-mail:
[email protected] 2 University of Guelph, PO Box 2003, 830 Prescott St. Kemptville, ON K0G 1J0, Canada 3CNR-Istituto per i Sistemi Agricoli e Forestali del Mediterraneo (ISAFoM), Sede di Catania (Italy)
INTRODUCTION Within the project “Evaluation of biomass crops in eastern and northern Ontario” funded by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) of Canada, a field experiment was carried out with the aim of investigating the effects of planting density on crop growth and sugar content of three genotypes of sweet sorghum cultivated under Eastern Canada climate conditions.
MATERIALS AND METHODS Site: Eastern Ontario (University of Guelph) Kemptville campus, (45°00’59.53’’N Lat;75°38’44.70’’W Long, 99 m a.s.l.) Sowing: May 21th 2011 Factor on the study: Genotype: 3 cultivar of sweet sorghum for energy Plant densities: 10, 20, 30, 40 plants m-2 Measurements: • plant heigh • LAI • dry biomass • brix degree Data of dry biomass was analyzed by two-way ANOVA and means were separated by using the SNK (Student-NewmanKeuls) method. Software used was the COSTAT (CoHort Software 6.003).
RESULTS densities.
30 258.5 173.5 177.5 203.3a * * ns
40 257.8 179.7 204.8 213.8a
Mean 246.2 171.8 178.6
a b b
three sorghum varieties as affected by 4 planting densities. Dry biomass (t ha-1) plants m-2 cultivar 10 20 30 Bulldozer 8.83 7.72 15.9 CSSH45 5.20 7.99 7.78 Sugargraze 8.69 7.00 9.54 Mean 7.57 b 7.57b 11.1a significance cv * plant density * cv x plant density ns
The final stem height differed significantly between the different plant densities ranging from 188.6 to 213.8 cm respectively for 10 and 40 plant m-2.
Total dry biomass as well was significantly affected by plant population, ranging from 11 t ha-1 (30 and 40 plants m-2) to 7 t ha-1 (10 and 20 plants m-2).
varieties and plant densities.
LAI plants m-2 cultivar 10 20 Bulldozer 2.33 2.03 CSSH45 1.91 2.04 Sugargraze 1.71 2.28 Mean 1.98b 2.11ab significance cv plant density cv x plant density
Brix° plants m-2 cultivar 10 20 Bulldozer 8.0 8.65 CSSH45 16.3 14.8 Sugargraze 18.3 18.7 Mean 14.2b 14.0ab significance cv plant density cv x plant density
40 2.51 2.22 2.56 2.43°
36 32
48
T min T max rain solar radiation
44 40 36
28
32
24
28
20
24
16
20 16
12
12 8
8
4
4
0
0 May
June
July
August
September
Fig. 1 - Meteorological course with time.
Tab.4 - Stalk sugar content at harvest as affected by
and plant densities.
30 2.35 2.13 1.46 2.31ab * * ns
Mean 10.8a 7.4b 10.0b
*significant at p≤0.05 level; ns: not significant. Means separated by the Student-Newman-Keuls test
*significant at p≤0.05 level; ns: not significant. Means separated by the Student-Newman-Keuls test
Tab.3 - Leaf Area Index (LAI) as affected by varieties
40 10.6 8.33 14.9 11.3a
40
Mean 2.30° 2.07ab 2.25b
*significant at p≤0.05 level; ns: not significant. Means separated by the Student-Newman-Keuls test
The LAI was the highest in 40 plant m-2 and the lowest in 10 plant m-2, with a wide variation among the genotypes. The highest value was observed in “Bulldozer” genotype (2.30) and the lowest one was obtained in the earliest genotype “CSSH45” (2.07). Leaf area index increased with the higher population density, thus resulting in higher biomass production.
30 9.7 16.2 19.2 15.9ab * * ns
40 11.1 17.0 22.3 16.8a
Mean 9.4c 16.1b 19.6a
*significant at p≤0.05 level; ns: not significant. Means separated by the Student-Newman-Keuls test
The percentage soluble carbohydrates on average of the two experimental factors was equal to 15.1°Brix. It increased significantly with sowing rate, from 14.2 (10 plants m-2) to 16.8 °Brix (40 plant m-2). Among genotypes the greatest content corresponded to “Sugargraze”, with 19.6°Brix, on average of plant densities.
CONCLUSIONS The planting densities studied in this experiment were probably too low, and higher densities needed to be studied. In addition, the water is not a limiting factor in these environments and therefore competition for water is not usually a concern. The wide variability found for the analyzed characters among the studied genotypes allows to suggest the possibility of selecting, through specific breeding programs, genotypes with characters suitable for the considered environment.
(mm) rainfall
Plant height (cm) plants m-2 cultivar 10 20 Bulldozer 245.6 222.5 CSSH45 157.9 176.7 Sugargraze 162.0 170.1 Mean 188.6b 189.8b significance cv plant density cv x plant density
Tab.2 - Total above-ground dry matter production for -2 Air Temperature (°C) and Solar Radiation (MJ m )
Tab.1 - Plant height as affected by varieties and plant
