Critical Period of Weed Control in Aerobic Rice

Abstract

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.

Competitiveness of Winter Rice Varieties against Weed under Dry Direct Seeded Conditions

“…Weed biomass was strongly and negatively correlated with grain yield, indicating that weed suppressive ability can be combined with yield potential. Anwar et al [9] and McGregor et al [67] also observed a similar relationship. Weed interference negatively and markedly affected all yield components which cumulatively impaired grain yield.…”

“…Yield and weed competitiveness are effectively predicted by early visual vigor. Vigor rating is rapid, non-destructive, less labor-intensive and reliable, and therefore a promising and feasible tool for making decisions on weed competitiveness [9]. In this study, early visual vigor varied widely among varieties, and its strong correlation with other parameters confirms its acceptability.…”

“…Based on reports in earlier studies [9], the present study in- [60], Caton et al [50], Zhao et al [61], Anwar et al [9].…”

“…Growing rice in non-saturated and non-puddled aerobic soil is a promising water-wise technique of rice cultivation under the context of ever-mounting water scarcity [3] [12]. Growing rice under aerobic conditions requires 36% -41% less water than under the conventional method [13].…”

Effect of Nitrogen Levels and Weed Management on Yield Performance of BRRI Hybrid Dhan3 Under AWD Irrigation System

“…Based on summed dominance ratio (SDR), the most dominant weed species could be arranged in the order of Echinochloa crus-galli > Scirpus juncoides > Cynodon dactylon > Cyperus difformis > Marselia minuta > Monochoria vaginalis. Anwar et al (2012) observed similar type of findings in aerobic rice system in different weed management systems.…”