Air temperatures that reached about 40oC along with major shortage of soil moisture at the beginning of June were the likely cause of the death of the top part of plants followed by development of saprophytic organisms generating a dark mass with aspect that resembles bunt (Fig. 2).

Symptoms of the Blackleg disease, incited by the fungi Leptosphaeria maculans (Phoma lingam), were not observed on susceptible genotypes (Y3000, Hyola 401 and Hyola 420) of the genotypes experiment and demonstration plots. In the region of the experimental area no blackleg was ever observed and likely because neither inoculum nor favourable environmental conditions for the disease were available.

Genotype trial

Initial plant population ranged from 10 to 21 plants/m² (except for Hyola 60 with 3 plants/m²), averaged 15 plantas/m² and did not present correlation with grain yield (data not presented). Seeds of Hyola 60 were more than a year old and had low vigour. Harvest was done from 26 July to 17 August.

Only the subjective assessment of the visual effect drought stress on plants presented a significant correlation explaining 31% of the variation in grain yield (Table 4).

Hyola 401 and H4816 presented the shortest cycle from emergence to harvest of all genotypes, 97 days, and differ statistically from the other genotypes. Although no significant difference in grain yield was observed Hyola 401 and H4816 presented the highest absolute yields of the trial. This has been observed whenever the rainy season is short and there is shortage of moisture at the end of the cycle as in the northern areas of the state of Paraná, such as Maringá (Tomm et al., 2003). Although oil content differed among genotypes no statistical significant differences among genotypes were detected on oil yield per area.

 

Demonstration plots

In the demonstration plots plant population at harvest ranged from 10 plants/m² (Hyola 401), to 17 plants/m² (Hyola 43) (Fig. 3).

As in the genotype trial the high coefficient of variation led to no significant grain yield differences between genotypes (Table 4). Hyola 420, not tested in the trial, presented the highest absolute grain yield, 1679 kg/ha.
Thousand grain weight was the only estimated characteristic presenting significant correlation with grain yield and explained 56% of its variation, which was not the case in the genotype experiment.

 

Commercial fields

As part of canola production support program launched by Bunge Alimentos S. A. in the state of Mato Grosso do Sul 5917 hectares were sown in 2006. One farmer seeded 1326 ha of Hyola 43 plus 1898 ha of Hyola 61, adding to 3224 ha. Another twelve farmers seeded areas of 100 to 340 ha each, all of Hyola 61, making a total of 2693 ha in which they averaged 726 kg of grain/ha (Table 3). Rainfall during the growing season averaged a total of 90 mm, and ranged from 70 to 126 mm, which likely limited crop performance.

The best average yields were obtained with the use of the 17 cm row spacing. This is in close agreement with results on experiments employing old open pollinated cultivars in colder environments of the state of Rio Grande do Sul as well as in more similar environments as those of the experiments and commercial fields in the state of Goiás (Tomm, et al, 2005). Samplings in places of the canola fields that visually suggested higher yield potential in the farm located at latitude 21º 47’ 03”, longitude 55º25‘23”, altitude of 442 m above the average sea level, in the municipality of Maracajú (Table 5), reached 2664 kg/ha.

Seeding of the trial and demonstration plot was done on 12 April, about one month after the recommendation. On farmers fields seeding went up to 4 May. Tomm et al. (2003) observed in Maringá, PR, also an environment with limited and decreasing moisture availability as seeding is delayed, that short cycle genotypes, such as Hyola 401, present higher grain yield. Likely due to this reason shorter cycle genotypes are more suitable whenever seeding time is delayed and environmental conditions are like these observed in 2006, year in which rainfall was low and stopped on 20 July, many days before the end of the maturation of longer cycle genotypes on 17 August.

Observations on the performance of Hyola 61 in areas with more soil moisture, because they were in lower spots, present with higher soil organic matter content, suggest that this hybrid is very suitable for the growing conditions of this region of the state of Mato Grosso do Sul. Grain yield of 1074 and 1100 kg/ha in two fields of 340 and 320 ha, with only 126 and 92 mm rainfall, respectively, indicate that Hyola 61 is very suitable and will express adequate grain yield potential if more normal rainfall conditions are available, which is likely to happen by following the seeding time that has been recommended.