Viable weed seed density and diversity in soil were assessed in an experiment that comprised two types of crop rotation rice-wheat and rice-maize, two crop residue management (without residue and ...with residue), and four tillage techniques: conventional tillage (CT) transplanted puddled rice (TPR) – CT wheat/maize (CTTPR-CT), unpuddled transplanted rice – zero tillage (ZT) wheat/maize (UPTPR-ZT), ZT transplanted rice (ZTTPR) – ZT wheat/maize (ZTTPR-ZT), and ZT dry seeded rice (ZTDSR) - ZT wheat/maize (ZTDSR-ZT). The aim was to investigate the density and community composition of viable weed seed in soil in UPTPR-ZT, ZTTPR-ZT, and ZTDSR-ZT systems with and without crop residue, using the seedling germination method. The soil seed density was assessed in 2013-14 and 2014-15 after 4th and 5th year crop cycles established on a sandy loam soil of Patna, India. Total viable seed density was the highest for Cyperus iria L. irrespective of the treatment in both years. Rice-wheat system recorded 4% higher (mean of two years) seed density over the rice-maize system. Residue management practices did not differ for total viable seed density in both years. The ZTDSR-ZT, UPTPR-ZT, and ZTDSR-ZT systems resulted in significantly higher Shannon-Wiener, Simpson, and evenness indices compared to the CTTPR-CT system. Total viable seed density was the lowest for ZTDSR-ZT compared to the remaining tillage practices in both years. The sequence for Leptochloa chinensis (L.) Nees emergence was ZTTPR-ZT > ZTDSR-ZT > UPTPR-ZT > CTTPR-CT in 2014-15 (P < 0.05), signifying the more dominance of monocotyledons in ZT systems. The density of total aboveground weed density (no. m−2) was higher in ZTDSR-ZT in 2013-14 and lower in 2014-15 compared with remaining tillage techniques at 65 days after sowing. Thus, higher aboveground weed density in ZTDSR-ZT system minimized the soil seed density over time. Complete ZT-based practices (ZTDSR–ZT, ZTTPR–ZT) with crop residue significantly enhanced the grain yield of component crops over the CTTPR–CT. Thus, it implies that exhaustion of soil seedbank in ZTDSR-ZT system after 5 years can reduce the aboveground weed infestation and attain the higher grain yield compared to the CTTPR-CT system.
•Viable weed seed density/diversity in conventional and conservation agriculture (CA) was studied.•The CA system maintained the higher Shannon-Wiener, Simpson, and evenness indices.•Rice–wheat cropping system recorded higher weed seed density over rice-maize.•Weed seed density was lower in CA practice than in conventional tilled puddled transplanted rice (CTTPR).•The CA enhanced rice, wheat, and maize grain yield over CTTPR.
A study was conducted in a cropping system mode for rice–wheat (RW) and rice–maize (RM) with crop residue management without residue (R-) and with residue (R+) under different tillage and crop ...establishment (T&CE) techniques. The T&CE techniques comprised conventional tillage (CT) puddled transplanted rice followed by (fb) CT wheat/maize (CTTPR-CT), unpuddled transplanted rice fb zero-tillage (ZT) wheat/maize (UPTPR-ZT), ZT-transplanted rice fb ZT wheat/maize (ZTTPR-ZT), and ZT dry-seeded rice fb ZT wheat/maize (ZTDSR-ZT). Results after four years revealed that the relative dominance of weeds followed the sequence of Echinochloa colona > Cyperus iria > Caesulia axillaris > Alternanthera philoxeroides > Ammannia baccifera in the rainy season, whereas for the winter season, the sequence was Medicago denticulata > Rumex dentatus > Phalaris minor > Chenopodium murale > Cyperus rotundus, irrespective of the treatments. In the rainy season of 2013, the highest total weed density was recorded in ZTDSR-ZT, which was 43.8%, 56.8%, and 46.7% higher than those in CTTPR-CT, UPTPR-ZT, and ZTTPR-ZT, respectively. However, in 2014, the highest total weed density, which was significant, was recorded in ZTTPR-ZT. The R+ treatment decreased the total narrow-leaved weed density by 7.3% compared to that in the R-treatment in 2014. In the winter season of 2013–14, the sequence of total weed density was ZTTPR-ZT > ZTDSR-ZT > UPTPR-ZT > CTTPR-CT, whereas during 2014–15, the sequence was UPTPR-ZT > ZTTPR-ZT > ZTDSR-ZT > CTTPR-CT. The P. minor density in the RW system was 86.7% and 16.2% higher in 2013 and 2014, respectively, than that in the RM system (P < 0.05). Narrow-leaved weeds represented >65% of the total weed density in ZTDSR-ZT during the rainy season, whereas in the winter season, broad-leaved weeds represented >90% of the total weed density in both years irrespective of the treatments. Shifting from CTTPR-CT to UPTPR-ZT and ZTDSR-ZT systems resulted in significantly higher Shannon, evenness, and richness indices, thus indicating that the reduction in tillage intensity increased the weed diversity. However, the ecological dominance (C) was higher in CTTPR-CT (0.234) than in the remaining T&CE practices. The contribution of narrow-leaved and broad-leaved weeds toward total weed biomass became pronounced in the UPTPR-ZT, ZTDSR-ZT, and ZTTPR-ZT compared to the CTTPR-CT. The intensity of the total weed density was diminished in the ZTTPR-ZT and ZTDSR-ZT during 2014–15 compared to that during 2013–14. The results of the study can contribute to the development of effective weed management strategies under changing tillage regime for higher crop productivity.
•The UPTPR–ZT, ZTTPR–ZT, and ZTDSR-ZT were assessed for weed diversity and growth.•Narrow-leaved weeds represented >75% to total weed density during rainy season.•Broad-leaved weeds contributed >90% to total weed density in winter season.•The UPTPR-ZT and ZTDSR-ZT caused higher weed diversity indices over CTTPR-CT.•The weed density was diminished in UPTPR-ZT and ZTDSR-ZT over the years.
Rice mealybug (Brevennia rehi) Mishra, J. S.; Poonia, S. P.; Choudhary, J. S. ...
Current science (Bangalore),
08/2019, Letnik:
117, Številka:
4
Journal Article
Recenzirano
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Remote sensing can be used to map tillage practices at large spatial and temporal scales. However, detecting such management practices in smallholder systems is challenging given that the size of ...fields is smaller than historical readily-available satellite imagery. In this study we used newer, higher-resolution satellite data from Sentinel-1, Sentinel-2, and Planet to map tillage practices in the Eastern Indo-Gangetic Plains in India. We specifically tested the classification performance of single sensor and multiple sensor random forest models, and the impact of spatial, temporal, or spectral resolution on classification accuracy. We found that when considering a single sensor, the model that used Planet imagery (3 m) had the highest classification accuracy (86.55%) while the model that used Sentinel-1 data (10 m) had the lowest classification accuracy (62.28%). When considering sensor combinations, the model that used data from all three sensors achieved the highest classification accuracy (87.71%), though this model was not statistically different from the Planet only model when considering 95% confidence intervals from bootstrap analyses. We also found that high levels of accuracy could be achieved by only using imagery from the sowing period. Considering the impact of spatial, temporal, and spectral resolution on classification accuracy, we found that improved spatial resolution from Planet contributed the most to improved classification accuracy. Overall, it is possible to use readily-available, high spatial resolution satellite data to map tillage practices of smallholder farms, even in heterogeneous systems with small field sizes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Thumba straight vegetable oil is used as a fuel in CI engine.•Engine waste heat is used to reduce the viscosity of thumba oil.•Preheating improves thermal efficiency by 1.27% ...(24.66–25.93%).•Preheating reduces emissions significantly as compared to unheated thumba.•Drastically reduction in emissions as compared to diesel also.
This research is motivated for making the rural areas of developing countries self-reliant in energy production. Rural areas are endowed with enormous amount of vegetation that is used to produce edible and non-edible vegetable oil. In the present study thumba oil which is non-edible vegetable oil, having high viscosity and low volatility has been used as a fuel in CI engine. Viscosity of thumba oil is reduced by blending with diesel fuel along with preheating through waste heat of engine’s exhaust gases instead of transesterification, that requires chemicals and process heat, which is not available in rural area due to logistic problem. Experiment has been conducted with a single cylinder diesel engine to obtain performance and emission characteristics with various blend ratio of heated and unheated thumba oil with diesel. It has been observed that preheated thumba oil B-20 blend (20% thumba oil+80% diesel) gives better performance and less emission as compared to all other blending combinations among all preheated and unheated thumba oil and diesel. Preheating of optimized thumba blend results an improvement in break thermal efficiency by 1.27%. It also gives reduced smoke opacity, CO, HC emissions by 2.6%, 0.2%, and 5PPM respectively.
A two-strain model, comprising of drug-sensitive and drug-resistant strains, is proposed for the dynamics of Human Immunodeficiency Virus (HIV) spread in a community. A treatment model is introduced ...by taking drug adherence into account. The treatment-free model is analyzed for the effect of treatment availability and drug adherence on disease dynamics. The analysis revealed that for the treatment-free model, at least one strain faces competitive exclusion, and co-existence of both strains is not possible. On the contrary, both strains may co-exist in presence of treatment. The analysis carried out was both local, as well as global. A comprehensive bifurcation analysis showed periodic behaviour and all solutions approached a stable limit cycle for a wide range of parametric values. Overall, we concluded that the treatment availability and drug adherence play a significant role in determining the dynamics of HIV spread. Numerical simulations are performed to validate the analytical results using MATLAB.
Margin status is one of the most important prognostic factors in oral cancers. Intraoperative frozen section (FS) can be performed to ensure a margin-negative resection, however the method of FS ...assessment is debatable. The aim of this study was to compare the defect-driven (DDA) versus specimen-driven (SDA) approach for intraoperative assessment of tumour margins in oral cancer resections and their impact on loco-regional recurrence and survival. The primary study endpoint was margin status determined from the final histopathological examination report. Secondary endpoints were disease recurrence and survival. This retrospective cohort study compared the two methods of FS in terms of their performance and survival outcomes. All oral squamous cell carcinoma patients who underwent surgery as the primary treatment from January 2018 to February 2019 were included. The involved margin rate was slightly lower with SDA than DDA (7.5% vs 11.8%), however the difference was not statistically significant. The recurrence rate was higher with DDA (19/51, 37.2%) than SDA (14/53, 26.4%), although this was not statistically significant. Local recurrence-free survival (DDA 62% vs SDA 75%; P = 0.653) and overall survival (DDA 76% vs SDA 78%; P = 0.300) at 18 months of follow-up were comparable. There was no significant difference in sensitivity or specificity of intraoperative FS for margin assessment between SDA and DDA. The type of intraoperative FS technique used did not affect loco-regional recurrence or overall survival.
Sunflower (Helianthus annuus L.) has largely failed as a source of extractable honey from present day cultivated hybrids in India since 1999. So, the amount and rhythms of nectar secretion measured ...as dry nectar sugars (DNS) of 6 hybrids and 2 old populations were evaluated. Three day old florets (DOF) produced maximum DNS (0.891 mg/floret) at 1000 h and in the outermost ring of the capitulum (0.917 mg). Per floret production of DNS in populations was 17.7% higher (0.974 mg) than hybrids (0.803 mg). Population HS-1 and Morden produced maximum DNS per floret (1.004 and 0.943 mg) and DK-3849 was the only comparable hybrid (0.993 mg). Noticeable reduction (14.2-37.5%) was recorded in the rest of hybrids, maximum being in HSFH-1183 (37.5%) followed by Pioneer 64A57 (33.1%). Per hectare, DNS production too was higher (10.2%) in populations (174.3 kg) than hybrids (145.8 kg) although hybrid HSFH-848 was most copious (200.0 kg/ha) followed by populations Morden (188.1) and HS-1 (160.6 kg), other 5 hybrids yielding a low DNS of 116.3-142.5 kg/ha. Populations outperformed hybrids in all DNS production factors viz. per floret (0.974 mg), by florets in their life cycle of 3 days (2.921 mg), per capitulum (3137.5 mg) and per hectare basis (174.3 kg). High DNS producing old populations Morden and HS-1 recorded lowest honey bee abundance (0.33 and 0.47 bees/capitulum/minutes
−2
) than hybrids (0.51-0.69 bees) except Pioneer 64A57 which despite the lowest DNS (116.3 kg/ha) recorded maximum abundance (0.69 bees), indicating their preference for pollen. Studies attribute non extraction of honey to lower nectar production by a majority (83.3%) of new hybrids than old populations.
Short‐term (5 years) impact of tillage and residue management practices on physical properties and organic carbon (OC) of a silty clay soil was evaluated in a rice–wheat rotation in the Indo‐Gangetic ...Plains of Bihar. The experiment had three conservation agriculture (CA) practices: one full (direct‐seeded rice (DSR)–no‐tilled wheat (NTW)–no‐tilled mung bean (NTMB); fCA) and two partial (puddled transplanted rice (PTR)–NTW–conventionally tilled mung bean (CTMB); pCA1 and unpuddled transplanted rice (UPTPR)–conventionally tilled potato+maize (CTP + M)–NTMB; pCA2), which were evaluated against full conventional practice (puddled transplanted rice (PTR)–conventionally tilled wheat (CTW); TA). Subsurface compaction reduced and soil aggregation improved under both full and partial CA. Macro‐ and water‐stable aggregates increased to a large extent (26 and 11%, respectively) in full CA and to a lesser extent in partial CA, mostly due to increase in coarse macroaggregate (2–8 mm) contents in the 0–10 and 10–20‐cm depth soil layers. Steady‐state infiltration rate nearly doubled under full CA, with larger pore volume recorded in 10–20 and 20–30‐cm depth soil layers. The CA increased OC associated with all size fractions of aggregates in the surface soil layer (0–10 cm), but a higher amount of C was associated with macroaggregates, indicating relative stabilization of OC in the soil under CA. Change in bulk soil OC was larger in the 0–10‐cm depth soil layer in favour of CA, which also had an 11% increase in OC stock in the 0–30‐cm depth soil layer. Improvement in soil physical condition did not effectively translate into increased rice or wheat yields, but the system productivity increased largely.
Highlights
Conservation agriculture (CA) resulted in 11–12% higher macro‐aggregation compared to conventional practice (CT).
Macro‐ and total pores reduced in the 0–10 cm depth soil layer but increased in the 10–20 cm depth soil layer under CA.
CA resulted in 27–35% higher aggregate‐associated OC content and 11% increase in OC stock at 0–30 cm.
Full/partial CA improved soil physical condition and the productivity of rice–wheat systems in the Indo‐Gangetic Plains.
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