Publicação on-line; 26 ref.; 2 tables; 4 illus.; Summary (En)

ABSTRACT
Background: Continuous use of commercial herbicides is posing a
severe threat to environment and creating herbicide resistant weeds.
Allelopathy offers a promising alternative to commercial herbicides for
sustainable weed management. The farmers are highly concerned with
maximum yield as well as cost of the weed control techniques.
Objective: To investigate economic and weed control efficiency of
allelopathic crop water leachates mixed with lower rates of herbicide.
Methods: Rapeseed (Brassica napus L.), sunflower (Helianthus annuus
L.) and sorghum (Sorghum bicolor L.) crop leachates (18 L ha-1 each) tank
mixed with lower doses (25, 33 and 50% of recommended dose) of
S-metolachlor+atrazine were sprayed as pre-emergence for horse
purslane (Trianthema portulacastrum L.) management in maize (Zea mays
L.). Label dose (1,080 g a.i. ha-1) of herbicide (S-metolachlor+atrazine) and
a weedy check treatment were also maintained.
Results: The results showed that rapeseed+sunflower+sorghum
allelopathic leachates mixed with half dose (540 g a.i. ha-1) of
S-metolachlor+atrazine was effective against horse purslane and
increased maize yield (grain) by 45% and 5% as compared with control
and label dose of herbicide, respectively. Likewise, economic analysis
showed that the same treatment was most economical with 40% and 9%
higher net benefits than control and label dose of herbicide, respectively
and 2407% marginal rate of return. It also gave an additional benefit of
US$ 24.07 for investment of every US$1.
Conclusions: By using this technique, herbicides use can be minimized
by 50% for sustainable weed management without compromising maize
yield and net benefits.

Keywords:
Allelopathy
bioeconomic
integrated weed management
marginal analysis
Trianthema portulacastrum
Zea mays.