To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Herbicide resistance is an increasing issue in many weed species, including rigid ryegrass (Lolium rigidum Gaudin); a major weed of winter cropping systems in southern Australia. Recently, this weed has also been found in summer crops in the south eastern region of Australia. Effective control of this herbicide resistant weed across south eastern Australia requires alternative management strategies. These strategies can be informed from analyses on the interaction of germinable seeds with their regional environment and by identifying the differences between populations of varying herbicide resistance levels. In this study, we explore how various environmental factors differentially affect the seed germination and seedling emergence of three L. rigidum populations, including one glyphosate-resistant population (GR), one glyphosate-susceptible population (GS) and one population of unknown resistance status (CC04). Germination was greater than 90% for all populations at each temperature regime except 15/5 C. Populations germinated at a lower rate under 15/5 C, ranging from 74 to 87%. Salt stress had a similar effect on the germination of all populations, with 0% germination occurring at 250 mM salt stress. Population GS had greater tolerance to osmotic stress with 65% germination at −0.4 MPa compared to 47% and 43% germination for CC04 and GR, respectively; however, germination was inhibited at −0.8 and −1.6 MPa for all populations. All populations had lower germination when placed in complete darkness as opposed to alternating light/dark. Germination in darkness was lower for CC04 (69%) than GR (83%) and GS (83%). Seedling emergence declined with increasing burial depth but retained 37% emergence at 8 cm when averaged over the populations. These results indicate that L. rigidum Gaud. can survive under a range of environmental variables and the extent of survival differs based on population, however, there was no difference based on herbicide resistance status.
African mustard (Brassica tournefortii Gouan) is a problematic winter annual weed in Australia. Germination ecology of B. tournefortii may change in response to the maternal environments or habitats in which the plants grow. A study was conducted to evaluate the effect of environmental factors on germination and emergence of four populations of B. tournefortii that were collected from different fields. Averaged over populations, germination was stimulated by dark and was higher at 25/15 C (92%) compared with 15/5 C (76%) and 35/25 C (45%). Averaged over light/dark regimes, at the lowest temperature regime (15/5 C), population A had higher germination than population D; however, at the highest temperature regime (35/25 C), population D had higher germination than population A. Populations B and C had higher germination in the temperature range of 25/15 C and 30/20 C compared with 15/5 C, 20/10 C, and 35/25 C. Seeds germinated at a wide range of alternating day/night temperatures (15/5 to 35/25 C), suggesting that seeds can germinate throughout the year if other optimum conditions are available. Population A was more tolerant to water and salt stress than population D. The sodium chloride concentration and osmotic potential required to inhibit 50% germination of population A were 68 mM and −0.60 MPa, respectively. Averaged over populations, seeds placed at 1-cm soil depth had the highest emergence (54%), and burial depth of 8 cm resulted in 28% seedling emergence. Averaged over populations, wheat residue retention at 6,000 kg ha−1 resulted in greater seedling emergence than the residue amount of 1,000 kg ha−1. The results suggest that B. tournefortii will be favored in no-till systems and that the seedbank of B. tournefortii could be managed by tillage regimes that bury its seeds below 8-cm depths and restrict seedling emergence and growth of new plants.
Weed emergence time and the longevity of weed seeds within the soil play an important role in implementing a timely and effective weed control program. In this study, the seed longevity and emergence pattern of wild oat (Avena fatua L.) and sterile oat [Avena sterilis ssp. ludoviciana (Durieu) Gillet & Magne] were monitored in field conditions. Fresh seeds of A. fatua and A. ludoviciana were placed into nylon bags (50 seeds per bag in three replications for three locations in eastern Australia: Gatton, Narrabri, and St George) and buried at depths of 0, 2, and 10 cm in November 2017. Bags were exhumed at 6-mo intervals over 30 mo to evaluate seed germination, viability, and decay components. The seed decay component of A. fatua and A. ludoviciana followed an exponential pattern. On both the surface and at the 10-cm burial depth, 50% of the seeds of A. fatua and A. ludoviciana had decayed by 6 mo. The seeds of A. fatua persisted longer at 2-cm depth than at other depths, particularly at St George, where 90% of the seeds decayed after the 30-mo study. However, at Gatton and Narrabri, 90% of the seeds of A. fatua at this depth had decayed after 18 mo of burial in the soil. In the emergence pattern experiment (2017 to 2019), the emergence of A. fatua and A. ludoviciana from different burial depths was also studied. The emergence of A. fatua and A. ludoviciana was greater from 2-cm (29% to 36%) and 5-cm (18% to 43%) soil depths compared with the surface (5% to 10%) and 10-cm (3-9%) soil depth. Avena ludoviciana emerged earlier (2,253 growing degree days [GDD]; March 14, 2018) than A. fatua (3,364 GDD; May 23, 2018). Both species exhibited high emergence between May to June 2018, and the last cohort of each species was observed in October 2018. The highest seedling emergence occurred at the start of the winter season (May), which emphasizes the need for early PRE weed control such as tillage, herbicide application, and cover crops to ensure crops are planted in a clean seedbed. The continued emergence of these weeds into the spring season (October) emphasizes the need for extended periods of A. fatua and A. ludoviciana management. The results also suggest that management strategies that can control all emerged seedlings over 2 yr and restrict seed rain in the field could lead to complete control of Avena spp. in the field.
In Australia, junglerice and feather fingergrass are problematic weeds in sorghum. The high seed production potential of these weeds increases their seedbank in the soil and makes weed control practices more difficult and expensive, particularly when weeds have evolved resistance to herbicides. A study was conducted to evaluate the seed production and seed retention behavior of junglerice and feather fingergrass at sorghum crop maturity following four transplanting times: 0, 2, 4, and 6 wk after sorghum emergence. Averaged across years, junglerice and feather fingergrass produced 4,060 and 5,740 seeds plant-1, respectively,when they were transplanted with the emergence of a sorghum crop. Seed retention ranged from 42% to 56% for junglerice and 67% to 75% for feather fingergrass when these weeds were transplanted from 0 to 4 wk after crop emergence. A positive correlation (r = 0.75 for junglerice; r = 0.44 for feather fingergrass) was found between seed production and weed biomass in both weeds, indicating that larger plants produced more seeds than smaller plants. However, no correlation was found between weed biomass and seed retention for junglerice. A weak positive correlation (r = 0.44) was found between feather fingergrass biomass and percent seed retention, indicating that seed retention was greater in larger plants compared with smaller plants. Our results suggest that feather fingergrass is a good candidate for harvest weed seed control (HWSC) tactics if crop harvest is timely. There is limited opportunity to use HWSC tactics for targeting junglerice seeds in sorghum crops, because most seeds dispersed before crop maturity. Additional research is required to evaluate seed retention levels of these weeds in other summer crops such as corn and soybean to determine the potential for HWSC for management of these species.
Junglerice [Echinochloa colona (L.) Link] is a problematic weed in the northern grain region of Australia. Two pot experiments (Experiment 1 and Experiment 2) were conducted in a screen house to evaluate the growth and reproductive behavior of two biotypes (A, collected from a cotton (Gossypium hirsutum L.)–fallow; B, collected from a fence near a water channel) of E. colona in response to water stress (100%, 75%, 50%, and 25% water holding capacity [WHC]). Averaged across both biotypes, the plant height, biomass, and seed production of E. colona were reduced at 25% WHC compared with 100% WHC. However, E. colona still produced a considerable amount of seeds at 25% WHC (at least 365 seeds plant−1). Biotype A produced more seeds in the second experiment, while biotype B produced more seeds in the first experiment. In Experiment 2, at 100% WHC, biotype A produced more seeds (17,618 seeds plant−1) than biotype B (4,378 seeds plant−1), and similar observations were noticed for root biomass. Growth and seed production of E. colona at all moisture levels and environmental conditions ensure survival in an unpredictable environment and contribute to the weedy nature of this species. Results indicate that biotype A is more invasive than biotype B under favorable environmental conditions (100% WHC). This study suggests an enhanced competitive ability of some biotypes of E. colona in response to a range of environmental and soil moisture conditions in Australia. Under favorable environmental conditions, biotype A could be more problematic, as it has higher seed production than biotype B. Therefore, it is important to implement sustainable weed control methods for such biotypes in the early stages of crop growth to prevent loss of stored moisture.
Introduction: Although oral rehydration therapy is recommended for children with acute gastroenteritis (AGE) with none to some dehydration, intravenous (IV) rehydration is still commonly administered to these children in high-income countries. IV rehydration is associated with pain, anxiety, and emergency department (ED) revisits in children with AGE. A better understanding of the factors associated with IV rehydration is needed to inform knowledge translation strategies. Methods: This was a planned secondary analysis of the Pediatric Emergency Research Canada (PERC) and Pediatric Emergency Care Applied Research Network (PECARN) randomized, controlled trials of oral probiotics in children with AGE-associated diarrhea. Eligible children were aged 3-48 months and reported > 3 watery stools in a 24-hour period. The primary outcome was administration of IV rehydration at the index ED visit. We used mixed-effects logistic regression model to explore univariable and multivariable relationships between IV rehydration and a priori risk factors. Results: From the parent study sample of 1848 participants, 1846 had data available for analysis: mean (SD) age of 19.1 ± 11.4 months, 45.4% females. 70.2% (1292/1840) vomited within 24 hours of the index ED visit and 34.1% (629/1846) received ondansetron in the ED. 13.0% (240/1846) were administered IV rehydration at the index ED visit, and 3.6% (67/1842) were hospitalized. Multivariable predictors of IV rehydration were Clinical Dehydration Scale (CDS) score [compared to none: mild to moderate (OR: 8.1, CI: 5.5-11.8); severe (OR: 45.9, 95% CI: 20.1-104.7), P < 0.001], ondansetron in the ED (OR: 1.8, CI: 1.2-2.6, P = 0.003), previous healthcare visit for the same illness [compared to no prior visit: prior visit with no IV (OR: 1.9, 95% CI: 1.3-2.9); prior visit with IV (OR: 10.5, 95% CI: 3.2-34.8), P < 0.001], and country [compared to Canada: US (OR: 4.1, CI: 2.3-7.4, P < 0.001]. Significantly more participants returned to the ED with symptoms of AGE within 3 days if IV fluids were administered at the index visit [30/224 (13.4%) versus 88/1453 (6.1%), P < 0.001]. Conclusion: Higher CDS scores, antiemetic use, previous healthcare visits and country were independent predictors of IV rehydration which was also associated with increased ED revisits. Knowledge translation focused on optimizing the use of antiemetics (i.e. for those with dehydration) and reducing the geographic variation in IV rehydration use may improve the ED experience and reduce ED-revisits.
Glyphosate-resistant junglerice [Echinochloa colona (L.) Link] is a problematic weed in mungbean [Vigna radiata (L.) R. Wilczek] crops in Australia. Due to limited herbicide options in mungbean, there is an increased interest in developing integrated management strategies for the sustainable control of E. colona. Pot experiments were conducted in a screenhouse in 2017 and 2018 by growing E. colona plants (glyphosate-resistant [GR] and glyphosate-susceptible [GS] biotypes) alone (1 plant pot−1) and in competition with 4 and 8 mungbean plants pot−1. Both biotypes were developed from a single population using the clone method. The growth and seed production of both GR and GS biotypes were similar in response to mungbean competition. Averaged over biotypes, there was a reduction in the growth and seed production of E. colona as crop plants increased. Compared with the weed plants grown alone, crop interference reduced E. colona height by 17% to 19%, tiller numbers by 69% to 82%, total shoot biomass by 85% to 91%, and inflorescence numbers by 74% to 91%. When E. colona was grown with 8 mungbean plants pot−1, leaf weight ratio increased by 42% compared with plants grown alone. Compared with weed plants grown alone, mungbean interference (4 and 8 plants pot−1) reduced weed seed production by 85% to 95%. These reductions were similar for both biotypes (GR and GS), suggesting that there was no fitness penalty associated with resistance. The results of this study suggest that mungbean interference can reduce E. colona growth and seed production, but it should not be considered as a stand-alone strategy to manage E. colona and similar species in mungbean. These results also highlight the need for integrating crop competition with other management strategies to achieve complete and sustainable management of this weed.
African turnipweed (Sisymbrium thellungii O. E.Schulz) is an emerging problematic broadleaf weed of the northern grain region of Australia. Laboratory experiments were conducted to evaluate the effects of temperature, light, salinity, pH, seed burial depth, and the amount of wheat crop residue on germination and emergence of two Australian S. thellungii weed populations (population C, cropped area; population F, fence line). Both populations behaved similarly across different environmental conditions, except in the residue study. Although the seeds of both populations of S. thellungii could germinate under complete darkness, germination was best (~95%) under light/dark conditions at the 20/10 C temperature regime. Both populations of S. thellungii germinated over a wide range of day/night temperatures (15/5, 20/10, 25/15, and 30/20 C). Osmotic stress had negative effects on germination, with 54% seeds (averaged over populations) able to germinate at −0.1MPa. Complete germination inhibition for both populations was observed at −0.8MPa osmotic potential. Both populations germinated at sodium chloride (NaCl) concentrations ranging from 50 to 100 mM, beyond which germination was completely inhibited. There were substantial reductions in seed germination, 32% (averaged over populations) under highly acidic conditions (pH 4.0) as compared with the control (water: pH 6.4). Seed germination of both populations on the soil surface was 77%, and no seedlings emerged from a burial depth of 1 cm. The addition of 6 Mg ha−1 of wheat (Triticum aestivum L.) residue reduced the emergence of the C and F populations of S. thellungii by 75% and 64%, respectively, as compared with the control (no residue). Information gathered from this study provides a better understanding of the factors favorable for germination and emergence of S. thellungii, which will aid in developing management strategies in winter crops, especially wheat, barley (Hordeum vulgare L.), and chick pea (Cicer arietinum L.).
Introduction: Hypertensive disorders of pregnancy (HDP), including preeclampsia, can develop or worsen in the early postpartum period, often following discharge from hospital, resulting in severe preventable maternal morbidity and mortality. Due to a lack of routine early out-patient follow-up, many women with postpartum HDP present to the emergency department (ED) with severe hypertension or symptoms of preeclampsia (e.g., headache). In the ED, postpartum HDP can be difficult for clinicians to recognize (due to vague presenting symptom) and manage (due to lower blood pressure targets and concern of medication safety). ED clinicians recognized a need for timely recognition and effective treatments for postpartum HDP in the ED to improve maternal outcomes. As such, as part of a multi-step quality improvement initiative, an interdisciplinary team developed and implemented a postpartum HDP management protocol (consisting of nursing and physician protocols and an electronic order set embedded in the electronic medical record). The aims of this specific project were to assess: 1) the use of this clinical management protocol in the ED; and 2) its impacts on clinical care. Methods: This quality improvement project used electronic medical records to identify: 1) ED visits for postpartum HDP for postpartum women ages 20-50; 2) utilization of the postpartum HDP order set; and 3) clinical care outcomes (consultation and admission). Patient population characteristics and clinical care measures were summarized with descriptive statistics and compared using a before and after design. Changes in the utilization of the protocol were assessed using run charts. Results: 540 women with postpartum HDP were seen in the four Calgary EDs in the 16-month period following protocol implementation compared with 335 women in the preceding 12 months. The protocol was used in 46% of these 540 women, and increased over the 16 month follow-up period. We found an increase in the frequency of consultation of specialists (47% to 52%) and admissions (26% to 29%) amongst these women after protocol implementation. Conclusion: This initial assessment demonstrated good uptake of a postpartum HDP management protocol including referral for consultation and admission to hospital for blood pressure management. Future steps include evaluation of the impacts of this management protocol on important patient outcomes.
Mode changing is a phenomenon where a pulsar’s emission abruptly changes between two or more quasi-stable modes. We have discovered mode changing in the Black Widow Pulsar (PSR B1957+20), a first detection of mode changing in a millisecond pulsar. On average, a mode change occurs every 1.7 seconds. Multiple components across the pulse profile participate in the mode changing, indicating that this is likely caused by a global change in the pulsar’s magnetosphere.
Explicitly covariant dispersion relations for a variety of plasma waves in unmagnetized and magnetized plasmas are derived in a systematic manner from a fully covariant plasma formulation. One needs to invoke relatively little known invariant combinations constructed from the ambient electromagnetic fields and the wave vector to accomplish the program. The implication of this work applied to the self-induced transparency effect is discussed. Some problems arising from the inconsistent use of relativity are pointed out.
To assess cardiac functions in adenotonsillar or tonsillar hypertrophy.
A prospective, interventional, academic centre based study was conducted on 25 children with adenotonsillar or tonsillar hypertrophy. All patients underwent pulsed 2-dimensional Doppler echocardiography, pulse oximetry and 12-lead electrocardiography. These assessments were repeated three months later to determine the impact of adenotonsillectomy.
There were significant differences in mean arterial oxygen saturation, pulmonary flow acceleration time and mean pulmonary artery pressure post-operatively. Adenotonsillectomy led to significant improvements in pulmonary flow acceleration time and pulmonary flow velocity time index, while tonsillectomy resulted in right ventricular early and late diastolic velocity index improvement.
Upper airway obstruction in children affects cardiac functioning and this can subsequently lead to morbidity and delayed growth. Hence, revision of surgical indications is advocated in adenotonsillar hypertrophy to avoid irreversible damage to cardiopulmonary functions.
Weeds are a significant problem in crop production and their management in
modern agriculture is crucial to avoid yield losses and ensure food
security. Intensive agricultural practices, changing climate, and natural
disasters affect weed dynamics and that requires a change in weed management
protocols. The existing manual control options are no longer viable because
of labor shortages; chemical control options are limited by ecodegradation,
health hazards, and development of herbicide resistance in weeds. We are
therefore reviewing some potential nonconventional weed management
strategies for modern agriculture that are viable, feasible, and efficient.
Improvement in tillage regimes has long been identified as an impressive
weed-control measure. Harvest weed seed control and seed predation have been
shown as potential tools for reducing weed emergence and seed bank reserves.
Development in the field of allelopathy for weed management has led to new
techniques for weed control. The remarkable role of biotechnological
advancements in developing herbicide-resistant crops, bioherbicides, and
harnessing the allelopathic potential of crops is also worth mentioning in a
modern weed management program. Thermal weed management has also been
observed as a useful technique, especially under conservation agriculture
systems. Last, precision weed management has been elaborated with sufficient
details. The role of remote sensing, modeling, and robotics as an integral
part of precision weed management has been highlighted in a realistic
manner. All these strategies are viable for today's agriculture; however,
site-specific selection and the use of right combinations will be the key to
success. No single strategy is perfect, and therefore an integrated approach
may provide better results. Future research is needed to explore the
potential of these strategies and to optimize them on technological and
cultural bases. The adoption of such methods may improve the efficiency of
cropping systems under sustainable and conservation practices.
This article discusses the role of materials science in the growth and processing of silicon that made modern microelectronics possible. The influence of defects on the electronic properties of silicon is explored, followed by the production of electronic-grade silicon and its conversion into macroscopically dislocation-free doped silicon crystals. The intricacies of dopant distributions in as-grown crystals are also discussed. Oxidation, ion implantation, and metallization are essential elements of device processing, and their salient features are emphasized. The electromigration behavior of interconnects and attempts to prevent it are also introduced.
Field experiments were conducted in Punjab, India, in 2011 and 2012 to study
the integrated effect of planting pattern [uniform rows (20-cm spacing) and
paired rows (15-, 25-, and 15-cm spacing)], cultivars (PR-115 and
IET-21214), and weed control treatments (nontreated control, pendimethalin
750 g ai ha−1, bispyribac-sodium 25 g ai ha−1, and
pendimethalin 750 g ha−1 followed by bispyribac-sodium 25 g
ha−1) on weed suppression and rice grain yield in dry-seeded
rice. In the nontreated control, IET-21214 had higher grain yield than
PR-115 in both planting patterns. However, such differences were not
observed within the herbicide treatment. IET-21214 in paired rows, even in
nontreated control, provided grain yield (4.7 t ha−1) similar to
that in uniform rows coupled with the sole application of pendimethalin (4.3
t ha−1) and bispyribac-sodium (5.0 t ha−1). In uniform
rows, sequential application of pendimethalin (PRE) and bispyribac-sodium
(POST) provided the highest grain yield among all the weed control
treatments and this treatment produced grain yield of 5.9 and 6.1 t
ha−1 for PR-115 and IET-21214, respectively. Similarly, in
paired rows, PR-115 in paired rows treated with sequential application of
pendimethalin and bispyribac-sodium had highest grain yield (6.1 t
ha−1) among all the weed control treatments. However,
IET-21214 with the sole application of bispyribac-sodium produced grain
yield similar to the sequential application of pendimethalin and
bispyribac-sodium. At 30 days after sowing, PR-115 in paired rows coupled
with pendimethalin application accrued weed biomass (10.7 g m−2)
similar to the sequential application of pendimethalin and bispyribac-sodium
coupled with uniform rows (8.1 g m−2). Similarly, IET-21214 with
bispyribac-sodium application provided weed control similar to the
sequential application of pendimethalin and bispyribac-sodium. Our study
implied that grain yield of some cultivars could be improved by exploring
their competitiveness through paired-row planting patterns with less use of
The looming water crisis and shortage of labor during rice transplanting in northwest India have led researchers to develop alternative methods to transition away from puddled transplanted rice. In this context, dry-seeded rice (DSR) is emerging as an efficient production technology to replace puddled transplanted rice. Weeds, however, are the main biological constraints to its success. A study comprising 12 treatments was conducted to evaluate the efficacy of PRE (pendimethalin and pyrazosulfuron) and POST herbicides (bispyribac, penoxsulam, and azimsulfuron) applied either alone or in a sequence for weed control in dry-seeded fine rice cv. ‘Punjab Mehak 1’. Results indicated that the single application of pendimethalin (750 g ai ha−1) PRE, pyrazosulfuron (15 g ai ha−1) PRE, bispyribac-sodium (25 g ai ha−1) POST, penoxsulam (25 g ai ha−1) POST, and azimsulfuron (20 g ai ha−1) POST reduced total weed biomass by 75, 68, 73, 70, and 72%, respectively, compared with the nontreated control at flowering stage of the crop. Azimsulfuron POST and pyrazosulfuron PRE proved effective against purple nutsedge and crowfootgrass, respectively. Chinese sprangletop, large crabgrass, and junglerice were effectively controlled with pendimethalin PRE. POST application of bispyribac-sodium and penoxsulam provided effective control of rice flatsedge. Compared to the nontreated control, grain yield following the single application of pendimethalin PRE, pyrazosulfuron PRE, bispyribac-sodium POST, penoxsulam POST, and azimsulfuron POST increased by 149, 119, 138, 124, and 144%, respectively. The sequential application of herbicides proved better than single applications. The lowest weed biomass was observed with the sequential application of pendimethalin PRE followed by azimsulfuron POST, and rice yielded 228% more than the nontreated control following this treatment. The results of this study are important for farmers growing DSR in making decisions regarding the application of POST herbicides, according to existing weed flora in the field.
Due to the poor positive predictive value of nucleic acid amplification tests (NAATs) for gonorrhoea when applied to a low-prevalence setting, current guidelines recommend the use of supplementary polymerase chain reaction (PCR) targeting a different gene for confirmation of true positives in urogenital specimens. This study sought to standardize and evaluate performance of an in-house opa gene-based PCR assay for gonorrhoea compared to assays targeting the porA pseudogene and 16S rRNA gene. Four hundred samples (300 endocervical, 100 urethral swabs) from patients attending STD clinics in New Delhi, India were used. The sensitivity, specificity, positive predictive value and negative predictive value of the opa-based PCR were 100%, 97·9%, 89·5% and 100%, respectively. In females, the use of NAATs provided enhanced diagnosis of gonorrhoea.
Weeds are a major biotic constraint to aerobic rice production in Asia. Research is needed on the effects of cultural practices on weed management in aerobic rice, including techniques such as planting pattern and competitive cultivars. Field experiments were conducted in Punjab, India, in the wet seasons of 2008 and 2009 to study the growth of weeds and two rice cultivars [PR 115 and Punjab (P.) Mehak 1] in relation to planting pattern (uniform rows [23-cm row spacing] and paired rows [15-, 30-, and 15-cm row spacings]) under aerobic conditions. Junglerice and rice flatsedge were the dominant weed species during the early stages of the crop, while Chinese sprangletop and large crabgrass were the predominant species during flowering stage of the crop. Weed dry matter was not affected by planting pattern of P. Mehak 1; however, for PR 115, weed dry matter was greater in rice grown in uniform rows (244 g m−2) than in paired rows (183 g m−2). Planting patterns did not affect weed-free crop growth and yield, but weeds tended to be more abundant in the uniform planting system, particularly under cultivar PR 115. Consequently, this cultivar grew and yielded better under the paired rows when weeds were present. The cultivar PR 115 had greater yield potential than P. Mehak 1, but growth and productivity of P. Mehak 1 were unaffected by the planting patterns, suggesting better competitive ability against weeds than PR 115. The results imply that yield of some aerobic rice cultivars may be improved by exploring competitiveness of rice cultivars through paired row planting patterns. There is a need to study plasticity changes for cultivars which respond with more competiveness in paired rows. The identified traits could be useful as selection criteria for screening weed-competitive cultivars in paired row pattern.