|Abstract or Summary
- In CIAT, Centro Internacional de Agricultura Tropical, located
in Palmira, Colombia, a series of experiments were conducted to study
the biology and control of mudplantain (Heteranthera reniformis Ruiz
et Pavon), a member of Pontederiaceae family.
Mudplantain is a perennial aquatic plant which reproduces by both
seeds and stolons. It is found in rice in some areas of Colombia,
especially in thin rice stands, and is spreading rapidly because of its
resistance to the traditional rice herbicides.
The biological aspects studied were: (a) life cycle; (b) effect of
light reduction on growth; (c) effect of water depth on growth; (d) germination
requirements; and (e) vegetative propagation ability. The
weed control experiments included the control of mudplantain in flooded
rice planted with either pre-germinated or dry rice seed.
The life cycle of mudplantain was observed in the field from 20
days after germination to 118 days later at 14-day intervals. It was found that fresh weight, number of nodes, number of leaves, number
of capsules and length follow an approximate sigmoid curve. Capsules
appear between the 48th and 62nd day after germination and their production
increases progressively during the cycle.
The effect of 0, 33, 53, 59, 79, 88, 96, and 100% light reduction
on fresh weight, number of nodes, number of leaves, number of capsules,
and capsule length observed 60 and 120 days after germination
indicated that mudplantain is more adpated to grow under reduced light.
Only when light is reduced by more than 75% is growth seriously inhibited.
Seed germination decreased when light intensity was reduced
by 88% or more.
The effect of 0, 5, 10, 15, and 20 cm water depths on mudplantain
growth was determined in plants in the 3- and 10-leaf growth
stages. Younger seedlings were more affected by water depth. However,
a depth of 5 cm was the most favorable, while lower or higher
depths reduced growth. This shows why mudplantain is adapted to
grow in flooded rice and that it would be impossible to control mudplantain
by flooding since the rice would not tolerate more than 10 cm
of water in the initial stages and the weed is not killed by this or greater
Results of germination trials indicated that seeds germinate only
under light and that light intensity controls total germination. Light,
however, had to be combined with alternating da.y/night temperatures to stimulate germination.
Moist or dry chilling as well as scarifying with sandpaper or
sulfuric acid, or soaking the seeds did not promote germination under
dark conditions nor improve germination under light.
Seed germination was affected by germination media and seeding
depth. Water gave the highest germination followed by puddled soil,
and then by moist soil. Seeding at soil depths greater than one centimeter
The vegetative propagation studies demonstrated that mudplantain
propagates by stolons. Regrowth ability, however, was higher for
stolons with leaves and low for stolons without leaves regardless of
whether or not the roots had been removed.
Control studies in flooded rice showed that mudplantain generally
exhibits a great resistance to herbicides. Only butachlor (2-chloro-
2', 6-diethyl-N-(butoxymethyl) aceta.nilide) at 2. 5 kg ai/ha and oxadiazon
(2 -tertiobuty1-4 -(2 , 4-dichloro-s -is o -propyl-oxyphenyl) 5-oxo - ,
3,4-oxadiazoline) at 1.0 kg ai/ha in he dry-seeded rice experiment
gave excellent control. The best control can be obtained by a rapidly
established, dense rice stand growing under optimum conditions for
pre-germinated rice. A dense stand and the use of chemicals is recommended
for dry-seeded rice.