Comparative efficiency of herbicides in transplanted summer rice (Oryza sativa)

Comparative efficiency of herbicides in transplanted summer rice (Oryzasativa)

K. KURMI1 Regional Agricultural Research Station, Assam Agricultural University, Karimganj 788 710

Received: March 1992

A field experiment was conducted during control methods in transplanted summer rice summer 1990 at Karimganj, to find out the (Oryza sativa L.). The experiment, comparative efficiency of different weed- consisting of 18 weed-control treaiments

Table 1. Grain yield, yield-atnibuting characters and dry weight of weeds as influenced by different weed-control treatments June I9931 HERBICIDAL EFFICIENCY IN TRANSPLANTED RICE

Treatment Dose Time of Dry weight Panicles1 Grains1 Grain

(kg a.i./ha) applica- of weeds at m2 panicle yield

iion 60 DAT (qlha)

@AT) (PlmZ)

Hand-weeding 0

HW (twice)

HW + rice weeder

,4-D (Na-salt)

Thiobencarb

Thiobencarb + 2,4-D

Pretilachlor

Pretilachlor

Pyrazosulfuron ethyl

Pyrazosulfuron ethyl

Pyrazosulfuron ethyl

Pyrazosulfuron ethyl

Pyrazosulfuron ethyl +

CD (P = 0.05)

DAT, Days After transplanting

Present address: 'Department of Agronomy, CCS HAU, Hisar 125 004

(Table l), was laid out in randoniized block design with 4 replications. The soil was clay loam. The corp (cv. 'Krishna') was sown on 1 April and transplanted on 24 April 1990, with a spacing of 20 cm x 10 cm. The granular herbicide thiobencarb was applied by broadcasting uniformly in the entire plot, whereas other formulations were sprayed by a knapsack sprayer fitted with flat-fan nozzle, using a spray volume of 500 litresl ha.

The major weed flora of the experimental field consisted of Echinochloa crus-galli (L.) P. Beauv., E colomum (L.) Link., Digitaria spp., Cyperus rotundus L., C. difforrnis, C. iria, L., Eleusine indica Gaertn., Fimbristylis miliacea and Monochoria vaginalis Presl.

The dry matter of weeds at 60 days after transplanting was significantly reduced, whereas panicles/m2 were markedly in-creased by all the treatments compared with

Indian J. Agron. 38 (2) :303-304 (June 1993)

the weedy check. Grain yield was signifi- cantly increased by weed-control treatments except hand-weeding at 20 days after trans- planting, and hand-weeding + rice weeder at 20 and 40 days after transplanting respec- tively. The highest grain yield was recorded with thiobencarb applied @ 0.4 kg a.i./ha + 2 4-D Na-salt @ 0.8 kg a.i./ha 7 days after transplanting, followed by pyrazosulfuron ethyl @ 0.005 kg a.i./ha + oxadiazon @ 0.4 kg a.i./ha at 7 days after transplanting, pyra- zosulfuron ethyl @ 0.01 and 0.005 kg a.i./ha at 7 days after transplanting, anilofos @ 0.6 kg a.i./ha at 7 days after transplanting,, weed-free, pretilachlor @ 1.25 kg a.i./ha and pretilachlor @ 0.75 kg a.i./ha at 3 days after transplanting. Pyrazosulfuron ethyl @ 0.01

kg a.i./ha at 3 days after transplanting, and 2, 4-D Na-salt @ 0.8 kg a.i./ha at 7 days after transplanting, though significantly differed from the highest yielder remained at par with the weed-free treatment.

Effect of nitrogen fertilization on maize (Zea mays) varieties under rainfed condition

Zonal Agricultural Research Station, Chhindwara, Madhya Pradesh 480 001

Received: April 1992

An experimcnt consisting of treatment combinations of 4 varieties ('EH 40084',