The Influence of Irrigation, Fertilizing and McPa on the Competition Between Spring Cereals and Weeds

Abstract

Summary. The average air‐dry yield of weeds on fallow plots was about four times as large (2660 kg/ha) as the yield of weeds which developed among spring cereal crops (740 kg/ha). Application of fertilizers increased the number of weeds and their average weight on both irrigated and non‐irrigated plots. Treatment with MCPA reduced the weed yield to 36% on fallow plots and to 26% on weedy cereal plots. It was more effective on fertilized plots than on unfertilized plots, but irrigation made little difference to its effectiveness. The space left by the destroyed weeds was mainly occupied by Agropyron repens. Oats were better able to compete with weeds than were wheat and barley. On unfertilized and non‐irrigated plots spraying with MCPA (1‐26 kg/ha) at the beginning of shooting significantly reduced the yields of weed‐free barley. The yields of sprayed oats and wheat were also below the yields from the unsprayed although the reductions were not significant at the 5% level. However, on a number of fertilized and irrigated plots, both weedy and hand‐weeded, on which the plants had better growing conditions, MCPA resulted in a significant increase in the grain yield of barley and oats. Influence de l'irrigation, de la fertilisation et du MCPA sur la compétition entre céréales de printemps et mauvaises herbes

Growth of weeds in cereal populations

“…at Viikki gave an average of 740 kg/ha (Suomela and Paatela 1962). In the present study the average weed yield in 1966-68 was 1590 kg/ha, somewhat higher than the yields reported in literature.…”

“…A spring cereal population of normal density consists of an approximately equal number of cereal plants, and it is important in the interest of plant production to study the competitive abilities of weeds under different environmental conditions. Winifred and Brenchley (1917), Rademagher (1940Rademagher ( , 1950, Granström (1959Granström ( , 1962 and Suomela and Paatela (1962), among others, have made such studies. The effects of cereal seed rate and nitrogen fertilization on the growth of weeds among cereals were studied at the Institute of Plant Husbandry of the University of Helsinki, Viikki, in the years 1966-68.…”

Crop Seed‐Rate and MCPA Effectiveness

“…This confirms results of other workers reviewed elsewhere (Hammerton, 1967), but this appears to be the first report of an effect of crop seed-rate or density on the LD50; other workers have assessed herbicide effectiveness in terms of number or weight of weeds (e.g. Suomela & Paatela, 1962). Lack ofa nitrogen effect may be attributable to the dry conditions.…”

A comparision of the competitive effects and nutrient accumulation of fat‐hen and groundsel

“…Experiments with Cabbaee and Lettuce: Differences between different crop species, or different varieties of the same species in their competitive abilities against weeds, have been well documented (Pavlychenko and Harrington, 1934;Philp, 1953;Suomela and Paatela, 1962;Stilwell and Sweet, 1974;Yip et al, 1974;Kolar et al, 1979). Differences in the response of the plants to varying elemental regimes and in their accumulation of nutrient elements has been previosuly confirmed by Qasem (1987).…”

“…Different crop species or varieties are equally different in their competitive ability when copping with weeds (Pavlychenko and Harrington, 1934;Philp, 1953;Suomela and Paatela, 1962). This ability depends on the density of the competing species as well as the fertility level of the soil.…”