Foliar boron spray for improved yield, oil quality and water use efficiency in water stressed sunflower

Boron (B) is a mineral considered essential for improving sunflower (Helianthus annuus L.) resistance to drought. B supplements (0, 15-, 30- and 45 mg L-1) under well-watered and variable water deficit levels (64 and 53 mm irrigation depths) were evaluated for their effects on growth, oil quality and water use efficiency (WUE) in a field study for two consecutive years (i.e. 2011 and 2012). The duration of 50% inflorescence emergence, 50% flowering and 50% maturity stages were reduced with increasing moisture stress. All B application rates improved sunflower growth compared to no B control treatment. The moisture deficit treatments of 64 and 53 mm irrigation depths significantly (p<0.05) reduced the yield-related components. Achenes/head, achenes weight and achene yield under water stress conditions were considerably improved by foliar application of B at 30 mg L-1. An increase in protein contents and a decrease in oil contents were observed with B foliar application under moisture deficit treatments. Foliar application of B (30 mg L-1) on water stressed plants also resulted in increased WUE. The highest net benefits were achieved with B concentration of 30 mg L-1 under well-watered and mild deficit water level of 64 mm irrigation depth. The highest application rate of B (45 mg L-1) gave the best results at the most severe water deficit level. In conclusion, the B rates of 30 and 41 mg L-1 performed best for improving drought tolerance in terms of higher sunflower productivity under mild and higher water deficit conditions

Boron application in clay-loam soil for improved growth, yield and protein contents of mungbean in water-stresses

Boron is considered important to improve the drought resistance, yield and protein contents of pulses. Two years of field experiment was conducted to evaluate the effect of boron application and water stress given at vegetative and flowering stages on growth, yield and protein contents of mungbean during spring 2014 and 2015. The experiment was laid out in randomized complete block design with split-plot arrangement giving more emphasis to boron. The experiment comprised three water stress levels (normal irrigation, water stress at vegetative stage and water stress at reproductive phase) and four boron levels (0, 2, 4 and 6 kg ha-1). Final seed yield was significantly increased by different levels of boron application both under normal and water stressed conditions. The increase in yield was mainly due to greater plant height, number of pods bearing branches, number of pods per plant, number of seeds per pod and 1000-grain weight. Boron application at 4 kg ha-1 caused 17%, 10% and 4% increase in grain yield under normal irrigation, stress at vegetative stage and water stress at reproductive phase, respectively. Protein contents were also increased (9-16%) at same boron treatment. Most parameters showed a marked decrease at higher dose (6 kg ha-1) of boron. In conclusion, the boron application at rate of 4 kg ha-1 in clay-loam soil performed the best to enhance mungbean growth, yield and seed protein both under normal and water stressed conditions

Interference and estimation of economic threshold level of Alternanthera philoxeroides in maize (Zea mays L.)

Knowledge of economic threshold of emerging invasive weed Alternanthera philoxeroides (alligatorweed) is important to implement timely, efficientand economical weed control method for profitable maize production. Two-year field study consisting  fivedensity levels of A. philoxeroides viz. 0, 1, 2, 4 and 8 plants m-2 was conducted  to estimate the maize grain yield losses at different density levels and to determine  economic threshold level (ETL) of A. philoxeroides . Maximum weed dry biomass (44.28 g m-2), N (9.02 kg ha-1), P (7.91-6.86 kg ha-1) and K (7.99 kg ha-1) were observed at 8 plants m-2 A. philoxeroides density. The same weed density caused highest reduction maize plant height, number of grains per cob, 100 grain weight, grain weight per cob and biological yield of maize. Higher A. philoxeroides density also caused up to 62% reduction in maize grain yield and 21% reduction in grain protein contents as compared to weed free. ETL of A. philoxeroides was estimated to be 0.47 plants m-2, if this weed controlled chemically. Based on current finings complete control of this weed using chemical weed control is suggested to tackle yield losses in grain maize

Influence of field soil drought stress on some key physiological, yield and quality traits of selected newly-developed hexaploid bread wheat (Triticum aestivum L.) cultivars

Drought is one of the commonly occurring environmental stresses, limiting crop production in many countries. Selection of cultivar is the most effective and economical means for alleviating the adverse effects of drought stress on crops. The present study aimed to investigate the growth, some physiological processes, yield and quality of some newly-developed wheat cultivars (AARI-2011, AAS-2011, Faisalabad-2008, Millat-2011 and Punjab-2011) under field drought stress conditions. The cultivars were sown in a field under normal irrigation and drought-induced conditions. Maximum net photosynthetic rate was recorded in cv. AAS-2011 at growth stage of 67 days after wheat emergence under normal irrigation and cv. Faisalabad-2008 at 67 days after wheat emergence under drought condition. Leaf stomatal conductance and transpiration rate were maximum in cv. Faisalabad-2008 under drought conditions. The adverse effects of drought stress were observed more on cv. Millat-2011 than Faisalabad-2008, with respect to net photosynthetic rate and transpiration. Drought exerted a significant adverse effect on leaf stomatal conductance at 74 days after wheat emergence which was recorded as 230 mmol m-2 s-1. Among the cultivars, AAS-2011 recorded maximum yield traits and grain yield under normal irrigation condition and Faisalabad-2008 under drought condition. Cultivar Millat-2011 was the most susceptible to drought and Faisalabad-2008 the most resistant to drought. Faisalabad-2008 maintained the quality at the most under drought stress conditions. It is concluded that Fasialabad-2008 should be grown under field drought conditions to achieve maximal yield and quality of wheat

Management tactics for handling Parthenium hysterophorus in non-native environment through phytotoxic compounds of local species

Parthenium hysterophorus L. is an invasive, ubiquitous and infamous herbaceous weed causing suppression of natural vegetation and crop plants. The identification of phytotoxins in local weed species (Datura stramonium, Achyranthes aspera, Chenopodium album, Calotropis procera, C. murale and Melilotus indica) was done through high performance liquid chromatography (HPLC) to check their herbicidal potential against P. hysterophorus. Additionally, filter paper petri plate based and soil filled pot experiments were conducted in laboratory and wire house to evaluate the pre- and post-emergence herbicidal potential of plant water extract of D. stramonium alone and in combination with A. aspera, C. album C. procera, C. murale and M. indica at 2.5, 5 and 10% (w/v) concentrations against germination and seedling growth of P. hysterophorus. The phytotoxins detected in extracts of these plant species were quercetin, gallic, chlorogenic, p-coumaric, m-coumaric, sinapinic, caffeic, benzoic and syringic acids with variable concentrations. Total highest concentration of phytotoxins (61.37 mg L-1) was found in A. aspera while the lowest concentration (7.69 mg L-1) was found in C. album aqueous extract. Significant reduction in germination and seedling growth of P. hysterophorus was shown by all extract combinations that increased in direct proportion to their concentrations. The 10% water extract of D. stramonium in combination with C. procera and A. aspera proved to be the best as they resulted maximum reductions in germination percentage (100 and 95%), shoot length (67 and 62%), and shoot dry weight (67 and 78%) of P. hysterophorus, respectively. (C) 2019 Friends Science Publisher

Weeds Cause Losses in Field Crops through Allelopathy

A large number of weeds are known to be associated with crops and causing economic losses. Weeds interfere with crops through competition and allelopathy. They produce secondary metabolites known as allelochemicals, which belong to numerous chemical classes such as phenolics, alkaloids, fatty acids, indoles, terpens etc. However, phenolics are the predominant class of allelochemicals. The allelochemicals release from weed plants takes place through leaf leachates, decomposition of plant residues, volatilization and root exudates. Weeds leave huge quantities of their residues in field and affect the associated, as well as succeeding crops, in various cropping systems. Liberation of allelochemicals from weeds affects the germination, stand establishment, growth, yield and physiology of crop plants. They cause substantial reduction in germination and growth of the crop plants by altering various physiological processes such as enzyme activity, protein synthesis, photosynthesis, respiration, cell division and enlargement, which ultimately leads to a significant reduction in crop yield. In crux, allelopathic weeds represent a potential threat for crop plants and cause economic losses

Allelopathy for Weed Management

A large number of plant and weed species produce secondary metabolites knownas allelochemicals, and the process is known as allelopathy. Allelochemicals canbe used to control weeds in agricultural systems by using allelopathic crops forintercropping, crop rotation, or mulching. A few important examples of cropspecies with high allelopathic potential may include (but not limited to) wheat,rice, sorghum, rye, barley, and sunflower. The naturally produced allelochemicalsin these crops could be manipulated to suppress weeds and witness an environment-friendly and sustainable agricultural production system

Can hormesis of plant-released phytotoxins be used to boost and sustain crop production?

A great deal of work has been done to explore the hormetic potential of various herbicides to enhance crop growth and yield. However, the growth stimulatory potential of plant-released phytotoxins at low rates to enhance crop yield has not yet been realized, as most of the research has focused on the herbicidal potential of these phytotoxins. However, hormesis of plant-released phytotoxins is a more practical aspect, as these are present at low concentrations in field conditions. These phytotoxins are biodegradable and safe for the environment, and have the potential for crop enhancement both under controlled and field conditions. Low doses of plant-released phytotoxins have been reported to enhance crop growth by up to 50% under controlled conditions, and crop yield by up to 42% under field conditions. In this review, we have discussed hormesis of plant-released phytotoxins with examples. In addition, we discuss the potential for crop enhancement, the influence of different factors on the expression of hormesis, as well as the potential for both undesirable (in weeds) and desirable hormesis (in crop plants). The use of plant-released phytotoxins as growth regulators is also discussed, focusing on sustainable crop production. In future, phytotoxins may be utilized as a crop stimulator to enhance crop yield, especially in organic crop production systems

Evaluation and management of acetyl-CoA carboxylase inhibitor resistant littleseed canarygrass (Phalaris minor) in Pakistan

A field survey was conducted for the sampling of Acetyl-CoA carboxylase (ACCase) inhibitor resistance littleseed canarygrass, a major weed of wheat, from Punjab, Pakistan in 2014 for confirmation of resistance. The surveyed regions encompassed four different cropping systems including rice–wheat, maize–wheat, cotton–wheat and mixed cropping. Dose–response assay was conducted for confirmation of resistance. Efficacy of herbicide mixtures including clodinafop–propargyl, metribuzin, pinoxaden and sulfosulfuron at a range of doses was investigated to manage littleseed canarygrass. Results revealed that all populations were resistant to fenoxaprop except PM-BWL-2. The higher level resistance (6.5) was found in populations collected from rice–wheat cropping system. The tested herbicide mixtures at 75% and 100% of the recommended dose of each mixture component provided the effective control of resistant littleseed canarygrass. Mixtures at 50% provided more than 80% control and reduced growth and seed production potential of surviving plants. The confirmation of ACCase inhibitor resistance as the first case of herbicide resistance in Pakistan, leads us to discourage use of ACCase inhibitor herbicides alone. However, herbicide mixtures at 75% and 100% of the recommended dose are suggested to manage this weed for sustainable wheat production in the surveyed cropping systems

Identification of phytotoxins in different plant parts of Brassica napus and their influence on mung bean

Jabran, Khawar/0000-0001-8512-3330;WOS: 000436879200076PubMed: 29691745Plants in Brassica genus have been found to possess strong allelopathic potential. They may inhibit seed germination and emergence of subsequent crops following them in a rotation system. Series of laboratory and greenhouse experiments were conducted to determine the allelopathic impacts of Brassica napus L. against mung bean. We studied (1) the effects of aqueous extract (5%) of different plant parts (root, stem, leaf, flower, and whole plant) of B. napus, (2) the effects of leaf and flower extracts of B. napus at 0, 1, 2, 3, and 4% concentrations, and (3) the effect of residues of different B. napus plant parts and decomposition periods (0, 7, 14, and 21 days) on germination and seedling growth of mung bean. Various types of phenolics including quercitin, chlorogenic acid, p-coumeric acid, m-coumaric acid, benzoic acid, caffeic acid, syringic acid, vanillic acid, ferulic acid, cinamic acid, and gallic acid were identified in plant parts of B. napus. Among aqueous extracts of various plant parts, leaf and flower were found to have stronger inhibitory effects on germination and seedling growth traits of mung bean, higher concentrations were more toxic. The decomposition period changed the phtotoxic effect of residues, more inhibitory effect was shown at 14 days decomposition while decomposition for 21 days reduced inhibitory effect. The more total water-soluble phenolic was found in 5% (w/v) aqueous extract and 5% (w/w) residues of B. napus flowers at 14 days of decomposition (89.80 and 10.47 mg L-1), respectively. The strong inhibitory effects of B. napus should be managed when followed in rotation