The Effect of Plastic Mulch and Greenhouse‐Raised Seedlings on Yield of Maize

The yield of maize ( Zea mays L.) can be increased appreciably if canopy closure is brought forward. In France and Germany, the use of plastic mulch has boosted dry matter yields of silage maize by approximately 4 t/ha. In Germany, the grain yield of maize plants grown from greenhouse‐raised seedlings was 2.4 t/ha more than that of plants grown conventionally. The present study aimed to review and quantify the effect of the use of plastic mulch and greenhouse‐raised seedlings on yield of maize. In field trials the effect of a photo‐degradable transparent plastic mulch on the yield of two hybrids: Clipper (early‐maturing) and Dea (late‐maturing) was tested. In two of these trials the effect of using seedlings raised in the greenhouse up to the five‐leaf stage was also tested. Crops with plastic mulch required 10 % fewer growing degree days from planting to silking than the unmulched crops, and this number was more constant between years and sites. On average, plastic mulch increased whole plant dry matter content from 29 % to 33 %, and the dry matter of the ear from 45 % to 52 %. In Dea , dry matter yields of the whole plant and of the ear rose by 2.6 and 2.1 t/ha respectively. In Clipper the yield increases were half as large. The regression of whole plant dry matter yield on the sum of global radiation from silking to harvest was similar for mulched and unmulched crops. This suggests that the yield increases obtained with the plastic mulch were largely attributable to advancement of canopy establishment. The whole‐plant dry matter yield of plants initially raised in the greenhouse was similar to that of maize sown in situ, but the ear dry matter yield was 2.4 t/ha higher.