East-west crop row orientation reduces annual ryegrass fecundity

摘要

Light is an important resource that crops and weeds compete for, and so increased light interception by the crop can be used as a method of weed control. This research investigated the impact of altered light availability (from crop row orientation orseeding rate) on the growth and fecundity of annual ryegrass. Cereal crops were sown in an east-west or north-south direction, at a high or low seeding rate, in three field trials in 2010 and 2011 (at Merredin, Wongan Hills and Katanning. WA). The average light available to annual ryegrass in the inter-row space of east-west crops at anthesis was 28%, compared to 53% in north-south crops. Reduced light availability in the east-west crops resulted in reduced annual ryegrass fecundity in five of the sixtrials (average of2968 and 5705 seeds m~2 in the east-west and north-south crops). Light availability was not influenced by seeding rate, but the high seeding rate reduced fecundity in three of the six trials (average of 3354 and 5092 seeds m"2 in the crops with high and low seeding rate). Increased competitive ability of crops (through increased light interception or increased crop density) is an effective, environmentally friendly and inexpensive method of weed control.