Growth, development, and yield of head lettuce cultivated on paper and polyethylene mulch

Lettuce plants (Lactuca sativa L. cv. Ithaca) were transplanted into organic soil and onto beige paper, black paper, and coextruded white/black polyethylene mulches in 1997 and 1998. A weeded bare ground plot was also tested. Transplanting in 1997 occurred in July under warm and dry conditions. Plants grown on mulch established better when the mean air temperature during the week after transplanting was 22.5 degreesC. The mortality rates of the bare ground control were 30%. All mulches significantly reduced plant mortality in 1997. In 1998, air temperature during the week after transplanting (June) was 14.6 degreesC. Plant mortality in 1998 was 1.3% for the control and 1.5% for the mulched plots. For both 3 ears, plants grown on mulched plots had higher relative growth rates than the control at the start of the season. Head fresh weight was 3.6 times (1997) and 1.2 times (1998) greater for lettuce grown on mulch compared with lettuce grown in a weeded control. Soil bulk density was lower under mulch than in the control plots in 1997.