Weed Diversity Under Different Water Regimes in Irrigated Direct-Seeded Rice Cultivation

This study comprised two sets of experiment. The field trials were conducted at MARDI Bertam Rice Research Station in Seberang Perai, Penang, while the experiments on weed seed viability were done in a glass house and the Weed Biology Laboratory at Universiti Putra Malaysia. This study began in February 2004 and ended in June 2006. All field trials and weed seed viability studies were done in Off Season 2004 and Main Season 2004/2005. The objectives of the study were: a) to investigate the population and status of dominant weeds and their effect on rice yield under different water regime treatments in field condition; b) to determine the total weed seed reserve, species composition of the entire weed seed bank in the soils and their viability after being treated under different water regime treatments in the rice field. Five water regime treatments were used namely; T1 = continuous flooded condition until maturity, T2 = early flooding until 55 DAS (day after sowing) followed by saturated condition until maturity, T3 = early flooding until 30 DAS followed by saturated condition until maturity, T4 = continuous saturated condition until maturity, T5 = continuous field capacity condition throughout the experiment period. Results from field trials indicated that in unweeded plots (no weed control treatment involved), T1 and T2 showed the lowest number of weed m-2 and weed biomass m-2 compared to the other water regime treatments. Plots treated with T1 and T2 significantly suppressed weed population to approximately 18 – 58% and reduced weed biomass to 14 – 57% as compared to the highest in T5 at all sampling dates (30, 60 and 90 DAS) in both Off Season 2004 and Main Season 2004/2005. For weed composition across the water regime treatments, 11 weed species were recorded in Off Season 2004 and 10 weed species in Main Season 2004/2005. Broadleaved weeds mostly Monochoria vaginalis and Limnocharis flava were the most dominant weeds in most of the water regime treatments. The SDR values of broadleaved weeds were 48.7% (T2) > 46.4% (T1) > 44.2% (T3) > 40.7% (T5) > 35.8% (T4) in Off Season 2004. In Main Season 2004/2005, the SDR values for broadleaved weeds increased to 79.5% (T2) > 68.2% (T1) > 62.4% (T3) > 62.2% (T4) > 50.57% (T5). Sedges mainly Fimbristylis miliacea and Cyperus iria were dominant in Off Season 2004 with SDR value more than 34% in all water regime treatments, but decreased to less than 23% in Main Season 2004/2005. For grasses, mostly Echinochloa crus-galli, Echinochloa colona and Leptochloa chinensis, SDR value more than 20% were recorded in T4 and T5 in Off Season 2004 while in Main Season 2004/2005, SDR value between 21 – 34% were observed in T1, T3 and T5.Meanwhile rice plants treated with T1 significantly produced the highest rice grain yield, followed by T2 and T3, while T4 and T5 were the lowest in weeded plots in both planting seasons. However, rice yield in unweeded plots were not significantly different in all water regime treatments. The rice productions in weeded plots were in the range of 22 – 60% higher in Off Season 2004 and 56 – 78% higher in Main Season 2004/2005 than in unweeded plots. Weed control treatment evidently showed stronger influence than water regime treatments. The percentages of reduction in weeded plots from the highest rice yield in T1 to lowest in T5 were 40% in Off Season 2004 and 44.4% in Main Season 2004/2005. Meanwhile the reduction of rice yield in unweeded plots compared to weeded plots was much higher, which recorded the highest of 59.1% (in T1) in Off Season 2004 and 78.3% (in T4) in Main Season 2004/2005. The effect of different water regime treatments on viability of weed seeds in rice field was evaluated. Total weed seed reserves in soils taken from Off Season 2004 rice plots were dominated by broadleaved weeds (90625 seeds m-2) mainly Hedyotis corymbosa, Monochoria vaginalis and Ludwigia hyssopifolia, followed by sedges (34257 seeds m-2), mostly F. miliacea and Cyperus iria, while grasses (20647 seeds m-2), predominantly Leptochloa chinensis recorded the lowest number in all water regime treatments. In soils taken from Main Season 2004/2005 rice plots, sedges (53041 seeds m-2) mainly Fimbristylis miliacea along with broadleaved weeds (54624 seeds m-2), predominantly Monochoria vaginalis and Ceratopteris pteridoides dominated in most of the water regime treatments, while grasses, mainly Leptochloa chinensis and Panicum repens again recorded the lowest number (24935 seeds m-2). 10 weed species, which were not observed in the field trials, were recorded from the same soil in the weed seed bank experiment.Differences in water regime treatments did not significantly reduce the viability of weeds seeds in the soil in Off Season 2004. However, a small reduction in seed viability (approximately 8%) was observed in Main Season 2004/2005. As for the similarity between weed seed bank composition and aboveground weed flora composition, a moderate value (62.07 - 73.33%) was observed in Off Season 2004, while in Main season 2004/2005, the value was slightly lower (51.65 – 64.29%)

Introduction to robotics agriculture in pest control: a review

Agriculture is one of the latest industries that uses robotic technologies. Cultivation of crops with high yield and quality can be enhanced when technological sustenance is involved. Pests are nuisance and cannot be completely eliminated, but with effective control and management. damages caused by pests could be minimized below economic threshold. Automation in agriculture is stable and accurate and is mainly incorporated in mechanized farming system. However its numerous application in different agricultural practices is not well noticed. Hence this paper attempts to provide profound awareness on robotic technology in agriculture. Robots could have a specific or multiple functions and, most commonly, they are made up of five basic components; sensors, effectors, actuators, controller and arms. Use of automation in weeding, weed mapping, micro spraying, seeding, irrigation and harvesting are progressions which promote sustainable agriculture and food security. In future, solar robots with battery inverter may be invented

Influence of flooding intensity and duration on rice growth and yield

An experiment was conducted in the glasshouse of the Faculty of Agriculture, Universiti Putra Malaysia (UPM) in 2005 to evaluate the effect of different flooding treatments on rice growth and yield. Five flooding treatmentswere used, namely T1 = continuously flooded condition until maturity, T2 = early flooding until 55 DAS (day after sowing) followed by saturated condition until maturity, T3 = early flooding until 30 DAS followed by saturated condition until maturity, T4 = continuous saturated condition until maturity, T5 = continuous field capacity condition throughout the experiment period. The results showed that the response of rice plant to water soil availability varies with its growing stage. At an early stage of rice plant growth (15 and 30 DAS), flooding treatments were found to not affect the growth of rice plant significantly. However, from 45 DAS onwards, the effect was significantly pronounced. All flooding regimes (T1, T2 and T3) significantly favoured rice plant height and the number of tillers as compared to non-flooded regimes (T4 and T5). The positive correlation was observed between the grain yield and yield components. The significant higher number of tillers, high spikelets/ panicle and high 1000-grain weight had contributed to higher grain yield of rice in T1, T2 and T3 as compared to T4 and T5. Shorter duration of flooding (T2 and T3) was found to give a similar performance to continuous flooding, and thus, these methods might save on water use without reducing yields, while over watering might just increase vegetative growth

Diversity of weed communities under different water regimes in bertam irrigated direct seeded rice field.

Experiments were initiated at MARDI Bertam Rice Research Station in Penang in the dry season of 2004 and main season 2004/2005 to study the effect of different water regimes on diversity of weed species. Plots receiving continuous flooded treatment (T1) and flooding up to panicle initiation (T2) significantly suppressed weed population to approximately 18 – 58% and reduced weed biomass to 14 – 57% as compared to the highest values in continuous field capacity treatment (T5) at all sampling dates (30, 60 and 90 DAS) in both planting seasons. Across water regime treatments the weed composition comprised of 11 weed species in the dry season and 10 weed species in the main season. Broadleaved weeds, especially Monochoria vaginalis and Limnocharis flava were the most dominant weeds in most water regime treatments. The SDR values of broadleaved weeds in the dry season were 48.7, 46.4, 44.2, 40.7 and 35.8% for T2, T1, T3 (flooding for the first month), T5 and T4 (continuous saturation), respectively. In the main season, the SDR values for the broadleaved weeds increased to 79.5, 68.2, 62.4, 62.2, and 50.57% for T2, T1, T3, T4 and T5, respectively. Fimbristylis miliacea and Cyperus iria were dominant in the dry season with SDR values of more than 34% in all water regime treatments, but decreased to less than 23% in the main season. For grasses, comprising of mostly Echinochloa crus-galli, Echinochloa colona and Leptochloa chinensis, SDR values of more than 20% were recorded in T4 and T5 in the dry season, while in the main season SDR values of between 21 – 34% were observed in treatments T1, T3and T5

Carbon and phosphorus mineralization from soils amended with cow dung or rice husk ash

Decomposition of agricultural waste liberates organically-bound nutrient to inorganic form for increased soil fertility and crop productivity. The present investigation delineates carbon and phosphorus mineralization from sandy and clay soils of Peninsular Malaysia amended with cow dung or rice husk ash. Laboratory incubation was conducted for 60 days and a replicate sample of the either soils were incorporated with cow dung or rice husk ash at equivalent rate of 10 t ha -1 under dark condition at 23 o C temperature and field capacity moisture content. The samples containing neither cow dung nor rice husk ash from both soils were included as controls. At fixed intervals, the amount of carbon and phosphorus mineralized from both treatments was determined using standard analytical methods. Temporal increase in carbon mineralization was observed in both the control and amended soils. Sandy soil amended with cow dung or rice husk ash had higher carbon evolution than control while the reverse was obtained from the clay soil. The cumulative carbon evolved from the sandy soil was 82.159, 88.175 and 91.750 µg g -1 for control and soil amended with cow dung and rice husk ash respectively while the respective values for these treatments from the clay soil were 112.336, 96.755 and 90.197 µg g -1 . When the means of carbon evolution from the two soils were compared, clay soil had higher evolution (19.952 µg g -1 ) compared to sandy (17.477 µg g -1 ). Incorporating cow dung or rice husk showed higher extractable phosphorus from both soils compared to control. There was three phases in both carbon and phosphorus mineralization pattern; initial flush, followed by a declined then a phase of slow increase. Sandy soil had higher mean values (29.571 µg g -1 ) of extractable phosphorus than clay (8. 601 µg g -1 ) and this was attributed to acidic nature of clay soil resulting into phosphorus precipitation and adsorption by soil clay and oxides of Fe and Al. The present result showed decomposition potential of cow dung and rice husk ash in these soils

Effect of water regimes on germination of weed seeds in a Malaysian rice field

The effect of different water regime treatments on the viability of weed seeds in direct-seeded rice field was evaluated. Five water regime treatments were used namely, continuous flooding condition until maturity, early flooding until 55 DAS (day after sowing) followed by saturated condition until maturity, early flooding until 30 DAS followed by saturated condition until maturity, continuous saturated condition until maturity, and continuous field capacity condition throughout the experimental period. Total weed seed population in soil sampled from March-May. The results showed that weed population dominated by broadleaved weeds (90625 seeds m-2), mainly Hedyotis corymbosa, Monochoria vaginalis and Ludwigia hyssopifolia, followed by sedges (34257 seeds m-2), mostly F. miliacea and Cyperus iria. The grasses, predominantly Leptochloa chinensis, recorded the lowest number in all water regime treatments (20647 seeds m-2). In soils sampled from September-November, sedges (53041 seeds m-2) mainly Fimbristylis miliacea along with broadleaved weeds (54624 seeds m-2), predominantly Monochoria vaginalis and Ceratopteris pteridoides, dominated in most of the water regime treatments, while grasses, mainly Leptochloa chinensis and Panicum repens, recorded the lowest number (24935 seeds m-2). Ten weed species, which were not observed in the field trials, were recorded from the same soils used in the weed seedbank study. The results showed that differences in water regime treatments did not significantly reduce the viability of weed seeds in the soil. However, a small reduction in seed viability (approximately 8%) was observed in soil samples during the September-November period

Evolution of imidazolinone-resistant weedy rice in Malaysia: the current status

Weedy rice (Oryza sativa f. spontanea or O. sativa complex) has become a severe threat to Malaysian rice (Oryza sativa L.) granaries after the direct-seeding method of rice cultivation was introduced in the late 1980s. Since then, researchers have studied the biology and ecology of weedy rice and espoused the evolutionary theory of the origin of Malaysian weedy rice. This review paper aimed to synthesize the body of knowledge about weedy rice and the evolution of herbicide-resistant (HR) weedy rice in Malaysia. The imidazolinone (IMI) herbicide component of the Clearfield® Production System (CPS) rice package is among the most effective tools for weedy rice control. However, dependence solely on this technology and farmers’ ignorance about the appropriate use of IMI herbicides with the CPS rice package have resulted in the evolution of IMI-resistant (IMI-R) weedy rice. This has reduced the efficacy of IMI herbicides on weedy rice, ultimately nullifying the benefit of CPS rice in affected fields. At present, it is assumed that IMI-R weedy rice populations are widely distributed across the rice granaries in Malaysia. Therefore, it is important that integrated management measures be adopted comprehensively by Malaysian rice growers to curb the spread of IMI-R weedy rice problem in Malaysia, especially in fields planted with CPS rice. This review focuses on the biology of Malaysian weedy rice, the history of the establishment of weedy rice in Malaysian rice fields, the impact of HR rice technology on the evolution of IMI-R weedy rice in Malaysia, the distribution of resistant weedy rice populations across Peninsular Malaysia rice granaries, the weedy rice resistance mechanisms, and weedy rice management. The synthesis of all this information is helpful to researchers, policy makers, the private agricultural industry, advisers to farmers, and proactive farmers themselves with the goal of working toward sustainable rice production

Allelopathic effects of Batawali (Tinospora tuberculata) on germination and seedling growth of plants.

A study was undertaken to explore the effects of methanol extracts (100,50, 25, 12.5 and 6.25 g/l) from the dried powders of aerial parts of Batawali (Tinospora tuberculata) on emergence and initial growth of rice, radish, lettuce and carrot as represented by germination percentage, radical and hypocotyle length. Results indicated that both stem and leaves of Batawali markedly raised the suppression of germination and primary growth of all examined crops when plants were exposed to increasing the methanol extract concentrations from 6.25to 100 g/l of distilled water. The half-inhibitory concentrations that inhibit germination (ECg50), radicle (ECr50) and hypocotyle (ECh50) growth weredetermined for both the extracts. According to these values, an index (Re) was calculated in order to establish a ranking of the most sensitive plants and most effective extract. It was observed that the leaves extract was more active than the stem extract and caused the greatest negative effect on germination and early growth of plants. All tested plants differed in their sensitivity to T. tuberculata extracts. Higher reduction in plant growth parameters was observed in carrot. The tested extracts inhibited mainly the growth of radicle more than the growth of the hypocotyle and germination percentage in all examined crops, except carrot. According to the study, it could be concluded that T. tuberculata extracts had a significant herbicidal activity which depended on the extract concentrations, plant parts and the target crops

Effects of Tinospora tuberculata leaf methanol extract on seedling growth of rice and associated weed species in hydroponic culture

The study was conducted to evaluate the responses of rice and rice weed seedlings (barnyardgrass and weedy rice) at the three-leaf stage to Tinospora tuberculata leaf methanol extract (3.12, 6.25 and 12.5 g L−1) under hydroponic culture. It shows that the leaf methanol extract had various degrees effects depending on target plant species and each tested index (biomass, root length, shoot length, transpiration volume, chlorophyll a, chlorophyll b and carotenoid contents). The effective concentration of the leaf extract capable of reducing 50% of rice growth was higher than those of target weed species. Moreover, the root length was more tolerant to leaf methanol extract in comparison to the other plant parameters measured. A greater reduction was observed in chlorophyll a content compared to chlorophyll b and carotenoid. The results revealed that the reduction of transpiration volume closely coincided with the magnitude of growth inhibition of tested plants. Ultra-fast liquid chromatography analysis revealed 11 of 32 peaks in chemical profile, including benzoic acid, caffeic acid, chlorogenic acid, isoorientin, isovitexin, orientin, p-anisic acid, syringic acid, trans-cinnamic acid, trans-ferulic acid, and vitexin have the same retention time with those peaks of the extract. The amount of compounds was present in the range of between 4 817 and 115.5 mg kg−1 dry weight (DW). The concentration-response bioassay of all 11 individual compounds and their equimolar mixture against the seeds of barnyardgrass revealed their contribution in the allelopahic activity of T. tuberculata leaf extract. The examined compounds and their combination exhibited various degrees of growth inhibitory effects on the early growth of barnyardgrass. Therefore, the specific number, concentration, combination and inhibitory activity of bioactive compounds leads to allelopathy activity of T. tuberculata leaves which could be employable directly as a natural herbicide and its growth inhibitor compounds can be used as a template for producing new herbicides

Comparative phytotoxic effects of aerial and root aqueous extracts of Sida Cordifolia L. on germination and seedling vigour performance of Lettuce, tomato and carrot

A comparative study was conducted to see the effect of Sida cordifolia L. aerial and root extracts on seed germination and seedling vigour performance of Lacttuca sativa (Lettuce), Lycopersicon esculentum (Tomato) and Daucus carota (Carrot). Four treatments were prepared 50, 25, 10 and 0 g/l (control). The result showed a significant decrease in germination and growth in all the treatments and regardless of concentrations lettuce was observed to be more susceptible in all extracts. Leaf extract exhibited the highest phytotoxicity followed by root while shoot extract produced the least effect. Inhibition index showed decrease in growth appeared to be concentration dependent. Liquid chromatography mass spectrum analysis of leaf and root extracts revealed presence of aliphatic acids notably stearic and palmitic which may act as inhibitory agents