Effect of sowing rate on the infestation of winter oilseed rape by stem-boring pests and on yields
The effect of sowing rate and the resulting plant density and plant architecture on the larval infestation of winter oilseed rape by cabbage stem flea beetle, Psylliodes chrysocephala L., rape stem weevil, Ceutorhynchus napi Gyll., and cabbage stem weevil,Ceutorhynchuspallidactylus (Mrsh.), was studied in three field experiments in 1999/00, 2000/01 and 2001/02. Sowing rates of 30,60 and 90 seeds/m2 (2001/02:30 and 60 seeds/m2) were compared in randomised block experiments with 6 replicated plots for each treatment. An open-pollinating cultivar was sown in 1999/00 and a hybrid cultivar in 2000/01 and 2001/02. The abundance and within-plant distribution of larvae was determined from plant samples. Petioles and stems were dissected under a microscope. Seed yield was assessed at harvest.The sowing rate of 30 seeds/m2 resulted in significantly lower plant density and oilseed rape plants of significantly larger size and higher numbers of leaves and lateral buds. At 30 seeds/m2, the number of stem-boring larvae/plant was significantly greater compared to high sowing rates (66 and 90 seeds/m2). In contrast, the number of stem weevil larvae/m2 was little affected by plant density; only the number of P. chrysocephala larvae/m2 increased with increasing plant density in all years. The different plant architecture in plots of various plant density resulted in different within-plant distributions of larvae in shoots and leaves. This was possibly due to the oviposition preference of females for specific plant growth stages and organs. Seed yield and the 1000-kernel-weight was not affected significantly by plant density. Despite of higher levels of stem infestation at low plant density,the seed yield per plant significantly increased as plant density decreased. The results provide evidence that reduced seed rates of oilseed rape which are increasingly used by European rape growers do not increase the damage potential of stem-boring pests.
Oilseed rape sowing rate stem-boring pests Psylliodes chrysocephala Ceutorhynchus napi Ceutorhynchus pallidactylus yield
Helene Nuss Bernd Ulber
Department of Crop Sciences, Plant Pathology and Crop Protection Division, Entomology Section, University of Goettingen, Grisebachstrasse 6, D-37077 Goettingen, Germany
国际会议
第十二届国际油菜大会( The 12th International Rapeseed Congress)
武汉
英文
1554-1557
2007-03-26（万方平台首次上网日期，不代表论文的发表时间）