畑作における麦類の自生作物化と作付体系の関する研究 ＩＩＩ 茨城県内農家にみる麦種交互作における自生コムギ発生の事例分析

Abstract

Contamination of barley grain by mixing of volunteer wheat grain is now causing a serious problem in barley production under the alternating cropping system between barley and wheat. We chosed 8 upland fields of 7 farmers, whose growing area was rather large, and 7 upland fields converted from paddy fields by 4 farmers. We investigated the growth of volunteer wheat plants in those fields and discussed how harmhul volunteer wheat was to the production of barley in Ibaraki Prefecture.The fields were investigated regarding cropped barley and wheat alternately so as to prevent a yield decrease caused by continuous cropping or the yellow mosaic disease.In the fields where barley was planted after harvesting wheat, the contamination of barley grain by mixing of volunteer wheat grain occurred in the upland fields, regardless of summer cropping.The volunteer wheat plants grew on both the inter-row spaces and ridges in the barley fields, so it was difficult to control volunteer wheat plants using cultivators.The benefit of barley production decreased by 14-57% due to the contamination of barley grain by mixing of volunteer wheat grain. The alternate cropping system between barley and wheat has been of interest to the farmers in the areas infected with yellow mosaic. However, the best way to control volunteer wheat plants is still being sought.