The relationships among lodging, stem anatomy, degree of lignification, and resistance to mycosphaerella blight in field pea (Pisum sativum)

Abstract

The relationships among lodging, stem anatomy, degree of stem lignification, and resistance to mycosphaerella blight (Mycosphaerella pinodes (Berk. & Blox.) Vestergr.) in field pea (Pisum sativum L.) were investigated in field experiments in Saskatchewan from 2000 to 2002. Disease severity, lodging resistance, plant height, internode length and diameter, and the cellulose, lignin, and fibre contents of stems were measured from 9 (2000) and 20 (2001, 2002) cultivars of field pea. Significant differences were observed in resistance to mycosphaerella blight and lodging among cultivars. In all years, ‘AC Tamor’ was among those cultivars with the highest disease ratings and lodging scores, whereas ‘CDC Striker’, ‘Carneval’, and ‘Integra’ were among those with the lowest ratings. Disease severity was positively correlated with lodging scores of plants. Lodging was negatively correlated with the proportions of supportive tissue (formerly parenchyma cells in the pith periphery, which have differentiated to sclerenchyma) and xylem in stem sections, whereas disease ratings were negatively correlated with xylem. Lignin and fibre contents in pea stems were negatively correlated with both lodging and mycosphaerella blight severity. Cellulose content was also negatively correlated with lodging scores. This study establishes an anatomical and biochemical basis for further research into pea stem lodging and disease resistance. Key words: cellulose, fibre, lignin, sclerenchyma, supportive tissue, xylem.