Effectiveness and crop seletivity of pre-emergence herbicides under different methods of application in puddled rice
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Date
1995
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Department of Agronomy, College of Horticulture, Vellanikkara
Abstract
A field experiment was conducted at the Agricultural Research Station,
Mannuthy under the Kerala Agricultural University during the second crop season of
1992-93 to find out the effectiveness and crop selectivity of pre-emergence herbicides
under different methods of application in puddled rice. Twelve treatments were com-
pared with two controls (hand weeded and unweeded). The experiment was laid out
in Randomised Block Design with three replications.
Sedges and broadleaved weeds dominated the weed flora. Among the
sedges, Schoenoplectus lateriflorus, Cyperus iria, C. difformis and Fimbristylis
miliacea were the prominent species, and the broadleaved weeds included Mono-
choria vaginalis, Marsilia quadrifoliata, Sphenochlea zeylanica and Nymphaea
nouchali.
The broad leaved weeds were effectively controlled by pretilachlor +
safener, oxyflourfen and pendimethalin, besides butachlor and thiobencarb. All the
herbicides except pendimethalin and anilofos gave good control of sedges. Oxyflour-
fen spray showed the highest weed control efficiency among the herbicides tested.
Sand mixed broadcasting of herbicides was found to be lesser toxic than
spray in all the herbicides except pretilachlor + safener, where the safener present
protected the crop completely from phytotoxicity.
Crop growth characteristics were highly influenced by the herbicide and
method of application. Pretilachlor + safener, oxyflourfen and thiobencarb were
found superior. Yield attributes were relatively unaffected by the different treatments.
Pretilachlor + safener spray recorded the highest yield, among herbicides. Sand
mixed broadcasting of all other herbicides produced a slightly higher grain yield
compared to spray.
Nutrient uptake by crop was directly related to the dry matter accumula-
tion. The lowest weed index value was registered by pretilachlor + safener spray.
Pretilachlor + safener spray recorded the highest total returns and its sand mixed
broadcast realised the highest return per rupee invested on weed control.
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170625