Competition between weeds and wet season transplanted paddy rice for nitrogen use, growth and yield in the central and northern regions of Laos

Inamura, Tatsuya; Miyagawa, Shuichi; Singvilay, Olayvanh; Sipaseauth, Nivong; Kono, Yasuyuki

doi:10.1046/j.1444-6162.2003.00106.x

Cited by 18 publications

(17 citation statements)

References 8 publications

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“…As the soil moisture content decreases from an optimum level in a drought, the comparative advantage for weed growth over rice increases in key processes, such as germination (i.e. a higher percentage of weed seed emergence compared to rice; Morita & Kabaki (2002)), seedling growth, and resource acquisition (Inamura et al . 2003; Ikeda et al .…”

Section: Discussionmentioning

confidence: 99%

Ecophysiological study on weed seed banks and weeds in Cambodian paddy fields with contrasting water availability

Kamoshita¹,

Ikeda

Yamagishi

et al. 2010

Weed Biology and Management

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Weed infestations are a major cause of yield reduction in rice (Oryza sativa) cultivation, particularly with direct-seeding methods, but the relationship between weed dynamics and water availability in Cambodian paddy fields has not been documented previously.We surveyed the weed abundance and weed seed banks in the soil of paddy fields with inferred differences in their water regime in 22 farm fields in three provinces of Cambodia in the 2005 and 2006 rainy seasons.We studied rain-fed lowland fields in upslope and downslope topographic positions and fields at different distances from the irrigation water source inside an irrigation rehabilitation area.The weed seed banks were estimated by seedling emergence in small containers and weed abundance and vigor were estimated by a simple scoring system.The estimated weed seed bank in the top 5 cm of soil ranged from 52.1 to 167 ¥ 10 3 seeds m -2 (overall mean of 8.5 ¥ 10 3 seeds m -2 ) and contained a high proportion (86%) of sedge species, such as Fimbristylis miliacea L. and Cyperus difformis. Several fields had particularly large seed banks, including one near the reservoir. No clear difference was found in the weed seed banks between the irrigated fields that were located close to (upstream) and distant from (downstream) the water source or between the irrigated and rain-fed lowland fields, but the weed scores were larger in the rain-fed fields and the downstream fields within the irrigated area. A water shortage during the late growing season in 2005 led to a proliferation of weeds in some fields and an associated increase in weed seedbank size in 2006. However, the weed scores in 2006 were more strongly associated with that year's water conditions than with the weed seedbank size.

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Section: Discussionmentioning

confidence: 99%

Ecophysiological study on weed seed banks and weeds in Cambodian paddy fields with contrasting water availability

Kamoshita¹,

Ikeda

Yamagishi

et al. 2010

Weed Biology and Management

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“…However, the NUE of both rice and barnyard grass increased under elevated CO 2 in our experiment (Table 4), which again points to an intensification of demand for N under the different physiological regimes this condition induces. Interestingly, Inamura et al (2003) report that nitrogen accumulated in the above-ground parts of paddy rice correlated negatively and linearly with that in a variety of weeds under ambient conditions. They conclude that removal of weeds might therefore increase the rice yields between 10 and 19%, suggesting that rice is a relatively poor competitor for N under contemporary CO 2 levels.…”

Section: Nutrient Competition Between Rice and Barnyard Grass Under Ementioning

confidence: 96%

Elevated CO2 effects on nutrient competition between a C3 crop (Oryza sativa L.) and a C4 weed (Echinochloa crusgalli L.)

Zeng

Liu

Gilna

et al. 2010

Nutr Cycl Agroecosyst

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Rice (a C 3 crop) and barnyard grass (Echinochloa crusgalli L.) (a C 4 weed) were grown in a 1:1 mixture in a paddy field in ambient condition and with supplemented free air carbon dioxide enrichment (FACE, CO 2 concentration ? 200 lmol mol -1 ), in order to evaluate the impact of rising atmospheric carbon dioxide on nutrient competition between rice crop and weed. Results showed that elevated CO 2 significantly enhanced the biomass, tillers, leaf area index (LAI) and net assimilation rate (NAR) of rice, but reduced those of barnyard grass after elongation. Tissue nitrogen (N) concentrations were decreased in both competitors, but their phosphorus (P) and potassium (K) concentration were increased. The increase in tissue P concentration of rice was greater than that in barnyard grass. Furthermore, the absolute uptake of C, N, P, K by rice were increased while those of barnyard grass decreased. As a result, significant increase of the ratios of rice/ barnyard grass of biomass and absolute nutrient uptake were observed under elevated CO 2 . The results suggest that rising atmospheric CO 2 concentration could alter the competition between rice and barnyard grass in paddy fields in favor of rice. The ability of rice to compete more successfully for nitrogen and phosphorous under elevated CO 2 is likely an important factor underlying this response. More generally, the results suggest that elevated CO 2 may have varying implications on nutrient dynamics between different elements of overall plant biomass and the soil nutrients pool.

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“…The yield level was very similar to that of Inamura et al (2003), who also evaluated the rice yield in the farmers' fields in the study area in Lao PDR in 1999 and2000, suggesting that the improvement in the yield was not obvious for a decade. The grain yield in this study correlated with the total dry matter during the maturing stage (TDW) (Fig.…”

Section: Discussionmentioning

confidence: 54%

“…In particular, poor soil fertility is the fundamental problem in the rice production (Wade et al, 1999;Inthavong et al, 2011), and, therefore, understanding the relationship between the soil fertility and rice growth and production is thought to be very important. Although several studies have investigated the rice production and soil properties in farmers' fields (Inamura et al, 2003;Asai et al, 2009;Saito et al, 2009), information about the growth of rice plants is limited.…”

Section: Introductionmentioning

confidence: 99%

“…The production constraints in the lowland paddy fields in Lao PDR are poor soil fertility, drought, flooding and diseases, contributing to the low rice yield (Schiller et al, 2001). To increase the yield in farmers' fields, improved rice varieties , soil fertility management (Bell and Seng, 2003) and weed management (Inamura et al, 2003) are recommended. In particular, poor soil fertility is the fundamental problem in the rice production (Wade et al, 1999;Inthavong et al, 2011), and, therefore, understanding the relationship between the soil fertility and rice growth and production is thought to be very important.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of the dynamics of the leaf area index (LAI) of rice in farmer's fields in Vientiane Province, Lao PDR

Hirooka

Homma

Maki

et al. 2017

J. Agric. Meteorol.

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Rice is the most important crop in Lao People's Democratic Republic (Lao PDR). The improvement of its productivity is strongly recommended, but information about its growth characteristics in farmers' fields is limited. This study evaluated the dynamics of the leaf area index (LAI) and analyzed the relationship between the rice productivity and soil in farmers' fields in Vientiane province, Lao PDR. Because the LAI in the farmers' fields increased almost linearly, a straight-line regression was used for the analysis. The rice yield in the farmers' fields ranged from 63.8 g m -2 to 411.8 g m -2 and correlated with the LAI during the later growth stage. The variability in the LAI was explained by the LAI growth rate but rarely by the effective accumulated temperatures from the estimated transplanting date. The LAI growth rate was associated with the nitrogen and carbon content in the soil. These results suggest that the rice productivity in farmers' fields is governed by the soil fertility through LAI growth, and that LAI monitoring is an effective tool to evaluate the production.

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Competition between weeds and wet season transplanted paddy rice for nitrogen use, growth and yield in the central and northern regions of Laos

Cited by 18 publications

References 8 publications

Ecophysiological study on weed seed banks and weeds in Cambodian paddy fields with contrasting water availability

Ecophysiological study on weed seed banks and weeds in Cambodian paddy fields with contrasting water availability

Elevated CO2 effects on nutrient competition between a C3 crop (Oryza sativa L.) and a C4 weed (Echinochloa crusgalli L.)

Evaluation of the dynamics of the leaf area index (LAI) of rice in farmer's fields in Vientiane Province, Lao PDR

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