Vol. 51—1997 - NorthEastern Weed Science Society

95
COMMON P
SLANE AS A LIVING MULCH IN VEGETABLE CROP PRODUCTION
D.R. Ellis!, R.G. Adams' and K Guillard"
ABSTRACT
Many of th characteristics of common purslane (portulaca oleracea L.) that categorize this
species as a "w " have been described as desirable traits for a living mulch. These characteristics
include: 1) aggr ssive growth during late spring and summer months; 2) establishment of a dense,
prostrate canop 3) vegetative reproduction by adventitious root formation on fragmented stems;
and, 4) prolific production. Common purslane was investigated as a living mulch in vegetable
crops and camp red with conventional methods of weed management, which included mechanical
and chemicalme ods as well as the use ofblack plasticin broccoli. Field trials were conducted from
1993 to 1994 i Storrs, Connecticut on spring broccoli (Brassica oleracea L. 'Packman') and sna~
beans h vul&arisL. 'Gator Green'). Common purslane seed was broadcast over the soil 1o
to 14 days prior to transplanting broccoli or sowing snap beans. Fresh weight yields, harvest date,
leaf developme and soiltemperatures were determinedfor each crop. Plots in each treatment were
rated for weed ntrol and percent ground cover by common purslane. Noncrop biomass, which was
comprised of c mmon purslane and weed biomass, was measured under each method of weed
management. ritical levels of weed control and noncrop biomass for optimum crop yields were
estimated using linear-plateau model.
Springbroc li and snap bean yieldsfrom plantsgrown in purslane living mulch were comparable
to yieldsfrom pI ts grown under conventional methods of weed management. No differences were
found in harvest ate or leaf development for either crop across all methods of weed management in
comparison wi h control treatments where weeds were not managed. Late afternoon soil
temperatures ere significantly lower under purslane living mulch in comparison with soil
temperatures w .ch occurred when either crop was grown under mechanical weed management Of
when spring bro coli was grown under black plastic. Common purslane as a living mulch was able
to effectivelyco pete with weeds in spring broccoli and snap beans when between-row areas were
kept relatively eed-free during the first two weeks after transplanting or sowing. High levels of
weed control a d ground cover occurred through the establishment of common purslane between
crop rows. Sp ng broccoli and snap bean plants were tolerant of purslane living mulch and weeds
up to critical th eshold levels, without any significant reductions in yield.
A periodic Itivation of common purslane and/or weeds between crop rows during the critical
weed-free peri d in the first two weeks after spring broccoli transplanting or snap bean seedling
emergence pro .ded a minimal level of weed management which produced acceptable crop yields.
Noncrop biom s measured under purslane living mulch was below critical threshold levels and
therefore did no reduce yield. While the inclusion of a purslane living mulch into a spring broccoli
or snap bean cr p production system may be a novel approach to controlling weeds, the strategies
involved in this system rely on basic weed management principles, as presented in the study.
'Program Spec' list, Dept. of Plant Science, Univ. of Connecticut, Storrs, CT 06269
2Assist.Dir., C operative Extension System, Univ. of Connecticut, Storrs, CT 06269
3Assoc. Prof, ept. of Plant Science, Univ. of Connecticut, Storrs, CT 06269