6.23
EFFECT OF SEED DAMAGE AND FUNGICIDE SEED TREATMENTS ON SEEDLING EMERGENCE AND YIELD OF FIELD PEA

SF HWANG1, KF CHANG2, RJ HOWARD2 and GD TURNBULL1

1Alberta Research Council, Vegreville, Alberta, Canada T9C 1T4; 2Crop Diversification Centre South, Brooks, Alberta, Canada T1R 1E6

Background and objectives
Field pea cultivation has increased dramatically in the northern prairies of Canada in the past decade, but seed rot and seedling damping-off due to Pythium spp. infection threaten to become major limiting factors to the production of the crop. Due to the short growing season, seeding takes place early in May. Unpredictable periods of cold weather and excess soil moisture impede germination and predispose seeds and seedlings of field pea to soilborne diseases [1]. Contact with augers and rough handling during harvest and cleaning can damage the seed coat. This further increases seedling vulnerability, since the resulting seedlings grow with less vigour, and damaged seed exudes glucose, imbibes cold water rapidly, and has reduced resistance to colonization by Pythium [2]. The objectives of this work were to study the effect of mechanically damaged seeds and fungicidal seed treatments on seedling establishment and yield of field pea.

Materials and methods
A split-split plot, randomized complete block design with four replications was employed to establish plots at one site in 1996 and at two sites in 1997. Two cultivars, Carneval and Montana, served as main plots and Pythium inoculum treatments served as sub-plots. Auger-damaged, drop-damaged and undamaged seeds were sown with and without Apron fungicide applied in sub-sub plots. Inoculum was incorporated at the time of seeding (40 ;ml/row). Treatments were seeded in four-row plots, 100 seeds per row, with a 25-cm row spacing, 6-m row length, and 5-cm seeding depth. Emerged seedlings were counted 2 ;weeks after seeding. Plants were dried and threshed at maturity. Seeds were weighed to determine yields. ANOVA and Duncan's Multiple Range test were used to analyse germination and yield data.

Results and conclusion
In 1996, Apron seed treatments significantly improved seedling emergence in both Carneval and Montana, and yield in Carneval. Auger damage reduced both emergence and yield where seed was not treated with Apron, but reduced emergence only in Montana where Apron seed treatment was applied. Drop damage reduced emergence only in Carneval. Inoculation with Pythium reduced emergence and yield in Montana, but not in Carneval.

In 1997, treatment with Apron improved seedling emergence in Montana and in undamaged seed of Carneval at both sites, and reduced seedling losses in plots inoculated with Pythium. Plots sown with damaged seed had lower seedling emergence than those sown with undamaged seed. Seed yield was reduced by seed damage in untreated plots of Montana at one site and in treated plots of Carneval at both sites. Pythium inoculation significantly reduced emergence and seed yield in both cultivars at one site, and seed yield for Carneval at the other.

The results of this study showed that fungicidal seed treatment increased stands where mechanically damaged seeds had been planted and that planting of fungicide-treated high quality seeds was the most effective means of increasing emergence and stand in the field.

References
1. Xi K, Stephens JHG, Hwang SF, 1995. Canadian Journal of Plant Pathology 17, 19-24.
2. Schlub RL, Schmitthenner AF, 1978. Phytopathology 68,1186-91.