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Weeds are a major problem in potato production. Two years of trials were conducted to study the efficacy of herbicides and integrated use of mulch with herbicides in controlling weeds and for improving the growth and yield of autumn potato crop at Ludhiana, north-west India, during autumn 2016 and 2017. Each trial had a randomized complete block design with three replicates. There were 11 treatments including weed-free and weedy controls. Uncontrolled weeds caused a yield reduction of 49.7%. Metribuzin at 350 g/ha pre-emergence resulted in 82.4% weed control efficiency at 30 days after planting but this control was reduced to 23.9% at harvest. In contrast, metribuzin at 350 g/ha applied post-emergence controlled broadleaf weeds and grasses very effectively. Clodinafop at 60 g/ha post-emergence resulted in control of grasses only. The post-emergence application of pre-mix clodinafop plus metribuzin at 260 g/ha provided effective weed control and resulted in more tuber yield and economic returns and was significantly better than an application solely of metribuzin or clodinafop. The integrated weed control treatment of paddy straw mulch (PSM) at 6 t/ha with clodinafop plus metribuzin at 195 g/ha post-emergence resulted in the highest tuber yield with weed control efficiency of 95.3% at harvest. The next best one was an integrated treatment of PSM at 6 t/ha with metribuzin at 275 g/ha pre-emergence.

In the present research work, a novel and green TiO2 as an excellent photocatalyst has been synthesized and a comparative study of its structural, morphological and optical properties has been carried out with that of chemical synthesized. Green TiO2 has been synthesized using Titanium(IV)-iso-propoxide as a precursor and Lagenaria siceraria leaf extract has been used as a reducing and capping agent. Photocatalytic activity results indicate that TiO2 nanoparticles synthesized by green method exhibit excellent percentage removal (98.88%) of RG-19 dye in acidic medium as compared to chemical synthesized TiO2 sample which exhibits only 88.55% removal of dye. Higher apparent rate constant (0.02802 min−1) of photocatalytic reaction for green synthesized TiO2 nanoparticles as compared to that of chemical synthesized with apparent rate constant (0.0154 min−1), leads to the lower incubation time i.e., 60 min for green synthesized and 120 min for chemical synthesized. TiO2 nanoparticles synthesized via green synthesis offer high and fast removal of RG-19 dye as compared to chemical route. This study explores the green chemistry based TiO2 as an efficient photocatalyst with outstanding photocatalytic performance, which may open a new perspective for the preparation of excellent photocatalyst with cost-effective and environmentally friendly alternative to chemical and physical methods.

Cotton is the most important cash crop in North-west India. It is highly sensitive to weed competition during initial growth stages. Lack of selective post-emergence herbicides for broad spectrum weed control has been among major cotton production constraints in the region. Farmers had to rely on non-selective herbicides and or hand-weedings for post-emergence control of weeds. Efficacy of a new pre-mix of pyrithiobac sodium plus quizalofop ethyl for selective post-emergence weed control in cotton was evaluated in a field study conducted over two consecutive cropping seasons at Punjab Agricultural University (PAU), Ludhiana, India. Pyrithiobac sodium plus quizalofop ethyl at 100–125 g ha−1 significantly reduced density and dry biomass of annual grasses and broadleaved weeds in both years; it gave effective control (>88%) of Trianthema portulacastrum L., Dactyloctenium aegyptium, Digitaria sanguinalis and Acrachne racemosa, fair to good control (

Post-emergence herbicides are useful for managing weeds in soybean fields. Use of post-emergence herbicide(s) is increasing in India because of the ease of use and control of broad spectrum of weeds. As soybean is a rainy season crop in India, weed control remains an important concern for soybean farmers. An experiment was laid out at Research Farm of Punjab Agricultural University, Ludhiana to study effect of different herbicides for control of grass weeds in soybean. Treatments comprised of post-emergence application of quizalofop 25, 37.5 and 50 g/ha, fenoxaprop 100 g/ha, weed free and unweeded control. Phyto-toxic evaluation of herbicides was carried out on succeeding wheat crop. Quizalofop 37.5–50 g/ha significantly reduced weed density and biomass of grass weeds compared to weedy check. Quizalofop 50 g/ha gave complete control (100%) of Dactyloctenium aegyptium, Digitaria sanguinalis, Acrachne racemosa and Eragrostis spp. till 40 days and > 85% till 80 days after treatment. Quizalopfop 50 g/ha recorded soybean seed yield and yield attributes similar to that of weed free check; it gave highest B:C (2.61) and net returns ($660/ha) All weed control treatments provided higher soybean seed yield compared to unweeded control. Quizalofop at all doses was safe to succeeding wheat crop.

The rice–wheat cropping system (RWCS) has substantially contributed in making India self-sufficient in food grain production; however, rice residue management is of great concern, threatening the sustainability of this system. Rice residue is invariably disposed of by farmers through open burning. In addition to environmental pollution, residue burning of rice also leads to loss of soil nutrients. One of the alternatives to overcome these problems and sustain the RWCS is managing the rice residues in the field itself. Rice residue retention has variable effects on agricultural pests (namely, weeds, insect pests, diseases, and rodents) in the RWCS. High weed infestation in the RWCS results in high consumption of herbicides, which leads to several ecological problems and evolution of herbicide resistance. The shift from intensive tillage to conservation tillage causes major changes in weed dynamics and herbicide efficacy. Incorporation of rice residue reduces weed density and helps in improving soil physical, chemical, and biological properties. Rice residue retention on the surface or mulching reduces weed density and the biomass of both grass and broadleaf weeds in wheat crop as compared to its removal. Long-term field studies involving the use of rice residue as a component of integrated weed management strategies are needed to be done in the RWCS.

Crops and weeds share the same aboveground/aerial (sunlight, space, atmospheric gases, etc.) and underground/soil (water and nutrients) resources. Competition is a predictable response of organisms living in communities, and is a struggle between two organisms for a limited resource that is essential for their growth. Crop-weed competition causes an alteration in the utilization of various resources and also affects complex interactions between plants and environmental factors. Water, nutrients, light, and space are the major factors for which organisms compete. Light and space are the main aboveground resources, and the effects of competition for these resources can be visually observed. This article focusses on crop-weed interactions for underground resources - nutrients and water. Weeds, being more aggressive, adaptive and persistent than crops, pose a serious threat to crop production as they have the ability to survive under adverse conditions and extract more water and nutrients from the soil; thereby, reducing crop yields. Fertilizer application and inherent soil fertility have a definite influence on weed diversity, emergence, growth, dormancy, persistence, and crop-weed competition. Weed suppression with balanced fertilization through increased competition for light has been regarded as one of the most important determinants of the yield advantage of a crop, and the effect on yield depends upon the interaction of crop and weed flora. The elimination of weeds from crops is the most efficient and practical means of reducing transpiration and thus saving water for crop use. Additional fertilizer and water amounts cannot compensate fully for yield losses due to weed competition, but appropriate fertilizer and water management could be used as an important tool in integrated weed management systems, which may prove helpful for achieving higher net returns.

Herbicide resistance in weeds is a global threat to sustaining food security. In India, herbicide-resistant Phalaris minor was the major problem in wheat for more than two decades, but the continuous use of metsulfuron-methyl (an ALS inhibitor) to control broadleaf weeds has resulted in the evolution of ALS inhibitor-resistant Rumex dentatus L. This review summarizes the current scenario of herbicide resistance in R. dentatus, along with its ecology and management perspectives. Studies have provided valuable insights on the emergence pattern of R. dentatus under different environments in relation to tillage, cropping systems, nutrients, and irrigation. Moreover, R. dentatus has exhibited higher emergence under zero tillage, with high infestation levels in rice-wheat compared to other wheat-based cropping systems (sorghum-wheat). Alternative herbicides for the management of resistant R. dentatus include pendimethalin, 2,4-D, carfentrazone, isoproturon, and metribuzin. Although the pre-emergence application of pendimethalin is highly successful in suppressing R. dentatus, but its efficiency is questionable under lower field soil moisture and heavy residue load conditions. Nevertheless, the biological data may be utilized to control R. dentatus. Therefore, herbicide rotation with suitable spray techniques, collecting weed seeds at differential heights from wheat, crop rotation, alternate tillage practices, and straw retention are recommended for addressing the resistance issue in R. dentatus in North India conditions. Overall, we discuss the current state of herbicide resistance in R. dentatus, the agronomic factors affecting its population, its proliferation in specific cropping systems (rice-wheat), and management strategies for containing an infestation of a resistant population.

Dry-seeded rice has been introduced as an alternative to puddled hand-transplanted rice in the north Indian states of Punjab and Haryana. In dry-seeded rice, weed flora tends to be more diverse and weeds emerge in several flushes during the crop growth cycle and substantial yield reductions due to weed competition are quite common. The efficacy and compatibility of tank mixtures of different herbicides for the control of diverse weed flora in dry-seeded rice was evaluated in field experiments during the summer seasons of 2012 and 2013. The tank mixture of fenoxaprop with ethoxysulfuron improved the control of Echinochloa crus-galli and Echinochloa colona by 43-69% as compared to fenoxaprop alone while the tank-mix of azimsulfuron with fenoxaprop was antagonistic and reduced the control of Leptochloa chinensis by 86% as compared to fenoxaprop alone. Addition of azimsulfuron or ethoxysulfuron to bispyribac did not improve the control of grass weeds as compared to bispyribac alone. Weed control with the mixture of bispyribac and fenoxaprop varied over the two years. In 2012, bispyribac and fenoxaprop mixture was antagonistic for the control of Dactyloctenum aegyptium, Acrachne racemose, and L. chinensis but in 2013, there was no apparent antagonism and the addition of bispyribac to fenoxaprop reduced grass weed biomass as compared to fenoxaprop alone. In 2013, there was a strong negative correlation (r = -0.95, P < 0.001) between weed dry matter at 45 days after sowing and rice grain yield. According to the linear regression, rice crop is likely to produce no grain yield when weed dry matter exceeds 400 g m. Over the two seasons, fenoxaprop-ethoxysulfuron tank-mix produced similar grain yields (5.6-6.2 t ha) to the weed-free check (5.6-7.1 t ha). At the farmer fields, rice grain yield in the plots treated with pendimethalin followed by post-emergence bispyribac or a tank-mix of fenoxaprop + ethoxysulfuron ranged from 6.2 to 7.7 t ha as compared to 5.3-5.6 t ha in the plots treated with pendimethalin alone. The tank mixture of fenoxaprop with bispyribac needs further evaluation as this mixture has the potential to effectively control aerobic and aquatic grasses in dry-seeded rice. Single hand weeding prevented crop yield loss from weeds that escaped herbicide treatments only when it was performed within six weeks of sowing.

Background Hemicelluloses are a diverse group of complex, non-cellulosic polysaccharides, which constitute approximately one-third of the plant cell wall and find use as dietary fibres, food additives and raw materials for biofuels. Genes involved in hemicellulose synthesis have not been extensively studied in small grain cereals. Results In efforts to isolate the sequences for the cellulose synthase-like (Csl) gene family from wheat, we identified 108 genes (hereafter referred to as TaCsl). Each gene was represented by two to three homeoalleles, which are named as TaCslXY_ZA, TaCslXY_ZB, or TaCslXY_ZD, where X denotes the Csl subfamily, Y the gene number and Z the wheat chromosome where it is located. A quarter of these genes were predicted to have 2 to 3 splice variants, resulting in a total of 137 putative translated products. Approximately 45% of TaCsl genes were located on chromosomes 2 and 3. Sequences from the subfamilies C and D were interspersed between the dicots and grasses but those from subfamily A clustered within each group of plants. Proximity of the dicot-specific subfamilies B and G, to the grass-specific subfamilies H and J, respectively, points to their common origin. In silico expression analysis in different tissues revealed that most of the genes were expressed ubiquitously and some were tissue-specific. More than half of the genes had introns in phase 0, one-third in phase 2, and a few in phase 1. Conclusion Detailed characterization of the wheat Csl genes has enhanced the understanding of their structural, functional, and evolutionary features. This information will be helpful in designing experiments for genetic manipulation of hemicellulose synthesis with the goal of developing improved cultivars for biofuel production and increased tolerance against various stresses. Electronic supplementary material The online version of this article (10.1186/s12870-017-1142-z) contains supplementary material, which is available to authorized users.

Plant cell wall formation is a complex, coordinated and developmentally regulated process. Cellulose is the most dominant constituent of plant cell walls. Because of its paracrystalline structure, cellulose is the main determinant of mechanical strength of plant tissues. As the most abundant polysaccharide on earth, it is also the focus of cellulosic biofuel industry. To reduce culm lodging in wheat and for improved ethanol production, delineation of the variation for stem cellulose content could prove useful. We present results on the analysis of the stem cellulose content of 288 diverse wheat accessions and its genome-wide association study (GWAS). Cellulose concentration ranged from 35 to 52% (w/w). Cellulose content was normally distributed in the accessions around a mean and median of 45% (w/w). Genome-wide marker-trait association study using 21,073 SNPs helped identify nine SNPs that were associated (p < 1E-05) with cellulose content. Four strongly associated (p < 8.17E-05) SNP markers were linked to wheat unigenes, which included β-tubulin, Auxin-induced protein 5NG4, and a putative transmembrane protein of unknown function. These genes may be directly or indirectly involved in the formation of cellulose in wheat culms. GWAS results from this study have the potential for genetic manipulation of cellulose content in bread wheat and other small grain cereals to enhance culm strength and improve biofuel production.

The field efficacy of pre-and post-emergence herbicides for control of mixed weed flora in wheat was evaluated in a field study conducted at Punjab Agricultural University, Ludhiana during Rabi seasons of 2014–15 and 2015–16. The season long growth of weeds reduced wheat yield upto 38.5%. Pendimethalin and metribuzin recorded 65–73 and 73–78% control of Phalaris minor, respectively and their tank-mix application enhanced P. minor control to 78–85%. Pendimethalin and metribuzin recorded 26–33 and 5863% control of Medicago denticulata, respectively and their tank-mix application enhanced control to 77–92% of this weed. Pendimethalin and metribuzin provided control of Rumex dentatus to the extent of 98–100% and 68–92%, respectively, while provided 98–100 and 63–72%, respectively control of C. album. Sequential application of pendimethalin as pre-emergence followed by sulfosulfuron as post-emergence recorded the highest weed control efficiency (96%) and wheat grain yield (4.8 t/ha), and it was at par to pre-emergence pendimethalin + metribuzin, post-emergence pinoxaden + metsulfuron, mesosulfuron + iodosulfuron, sulfosulfuron + metsulfuron and two hand weeding.

A study was planned to evaluate efectiveness of new pre-mix herbicide metsulfuron methyl+chlorimuron ethyl for management of sedges and broadleaf weeds in transplanted rice at research farm of Punjab Agricultural University, Ludhiana for three years. The treatments comprised of metsulfuron methyl+chlorimuron ethyl 3, 4 and 5g/ha, azimsulfuron 20g/ha and metsulfuron 4 g/ha as post emergence and unsprayed control, replicated four times. The results indicated that the density and biomass of sedges and broadleaf weeds was signifcantly less in metsulfuron methyl+chlorimuron ethyl 4 and 5g/ha than 3g/ha, azimsulfuron 20g/ha, metsulfuron 4g/ha and unsprayed control. Application of metsulfuron methyl+chlorimuron ethyl 4g/ha applied in rice recorded signifcantly highest average grain yield of 7.31t/ha. There was a negative linear relationship between weed biomass and grain yield (r=-24.08). Correlation matrix revealed that all the yield attributes showed higher correlation with metsulfuron methyl+chlorimuron ethyl 4g/ha. Post emergence application of metsulfuron methyl+chlorimuron ethyl at 4g/ha resulted in efective control of broadleaf weeds and sedges in transplanted rice.

Seeds of isoproturon resistant Phalaris minor were collected from wheat fields and field experiments were conducted during winter season of 2012 and 2013. The biotype was found resistant to clodinafop-propargyl, fenoxaprop-pethyl and also showed cross resistance to pinoxaden. Mesosulfuron + iodosulfuron and sulfosulfuron provided 65 and 90 per cent control of the weed, respectively. Metribuzin recorded above 90 per cent weed control during both the years. Plants sprayed with metribuzin showed a sharp decrease in chlorophyll fluorescence (Fv/Fm ratio) of about 65 per cent as compared to control after 24 hours of spray even when there were no visible symptoms of herbicide injury. By this time, reduction in Fv/Fm ratio was less than 10 per cent for plants treated with ACCase and ALS inhibitors. At 15 days after spray, Fv/Fm ratio decreased by 11 to 13 and 23 to 30 per cent as compared to control for ACCase and ALS inhibitors, respectively.

A field experiment to study the efficacy of imidazolinone herbicides in greengram was conducted during Kharif seasons of 2012 and 2013. Ten weed control treatments viz. imazethapyr at 50 and 70 g, premix of imazethapyr + imazamox at 60 and 70 g/ha, both applied as post-emergence at 20 days after sowing; pendimethalin 1000 g and premix of pendimethalin + imazethapyr at 800, 900, 1000 g/ha, both applied as pre-emergence, along with two hand weedings and weedy check were evaluated. Imazethapyr alone and its premixes with pendimethalin and imazamox recorded effective control of mixed weed flora and produced significantly higher greengram seed yield than weedy check. Pendimethalin alone did not control Commelina benghalensis and recorded lower seed yield. All the herbicides were safe to crop.