Effects of irrigated rice sowing season and imazapyr + imazapic time of application on rice grain yield and red rice management

Abstract

-Irrigated rice sowing season and red rice competition are among the main factors affecting grain yield. The objective of this work was to evaluate the sowing date of irrigated rice and moments of application of the herbicide imazapyr + imazapic to control red rice management and irrigated rice grain yield. Eight experiments were performed at the following dates (09/30, 10/19, 11/08 and 12/01) for the 2010/2011 harvest season and (09/27, 10/17, 11/08 and 12/05) for the 2011/2012 harvest season. The treatments were: application of the herbicide imazapyr + imazapic at doses of 105+35 g ha -1 in pre-emergence (PRE); 52.5+17.5 g ha -1 in pre-emergence and 52.5+17.5 g ha -1 in post-emergence (PRE + POST); and 105+35 g ha -1 in post-emergence (POST), and a control without application and no weeding. The cultivar Puitá Inta CL was used and a randomized block design with four replicates. A joint analysis of the experiments was carried out. There was less emergence of red rice and higher grain yield of the irrigated rice at the early periods (09/30/10 and 09/27/11), with 10,578 and 8,653 kg ha -1 , respectively. At the end of the season (12/01/10 and 12/05/11), there was greater reduction of the red rice seed bank. Sowing at the beginning of the recommended period provided more irrigated rice grain yield. The application of imazapyr + imazapic at a dose of 52.5+17.5 g ha -1 in PRE + 52.5+17.5 g ha -1 POST, and 105+35 g ha -1 only in PRE and POST was effective in the control of red rice.

Ser-653-Asn substitution in the acetohydroxyacid synthase gene confers resistance in weedy rice to imidazolinone herbicides in Malaysia

“…), which might have triggered the evolution of resistance to imazapyr in weedy rice populations (e.g., population C). Sartori et al [ 42 ] opined that pre-emergence application of imazapic was effective in controlling weedy rice. A similar outcome was reported by Washburn and Barnes [ 43 ], who observed that pre-emergence application of imazapic was more effective in controlling grass weeds than post-emergence application.…”

Ser-653-Asn substitution in the acetohydroxyacid synthase gene confers resistance in weedy rice to imidazolinone herbicides imazapic and imazapyr in Malaysia

“…The IMI-herbicides OnDuty™ WG premix comprise of imazapic (52.5%) and imazapyr (17.5%) as active ingredients. Sartori et al [29] opined that the application of imazapic as pre-emergence was effective in controlling weedy rice. Similar outcome was reported by Washburn and Barnes [30] where pre-emergence application of imazapic was effective to control grass weeds compared to post-emergence application.…”

Sensibilidade de arroz-daninho oriundo de rebrote a imazapyr+ imazapic

“…Galon et al (2012) observaram que imazapyr + imazapic (73,5 + 24,5 g ha -1 ) foi eficiente para o controle de arroz-daninho, em aplicação de pós-emergência em plantas oriundas de sementes. Sartori et al (2013) relataram controle eficiente arroz-daninho com a aplicação de imazapyr + imazapic tanto em aplicação de pré quanto de pós-emergência. Resultados semelhantes também foram descritos por Marchesan et al (2011).…”