Muhammad Ather Nadeem

Methods to Break Seed Dormancy of Rhynchosia capitata, a Summer Annual Weed

La dormancia seminal de las malezas es un rasgo significativo contribuyente a su tasa de supervivencia, puesto que ayuda a las malezas a evitar herbicidas y otras practicas de desmalezado junto con condiciones ambientales desfavorables. Investigamos los efectos de diferentes tratamientos para romper dormancia sobre la germinacion de Rhynchosia capitata, una maleza anual estival comun en Paquistan. Las semillas se sumergieron en tiourea, KNO3, HCl, HNO3 y H2SO4 y ademas fueron escarificadas mecanicamente (papel lija). Los resultados indicaron que las semillas de R. capitata muestran signos de dormancia fisica principalmente debido a impermeabilidad de su cubierta. Escarificacion mecanica y acida (inmersion de semillas en H2SO4 por 60 y 80 min y en HCl por 12 y 15 h) fueron muy eficientes para romper dormancia y promover germinacion. Las semillas sumergidas en HNO3 por 1 a 5 dias mostraron poco efecto, mientras diversas concentraciones de tiourea y KNO3 fueron inefectivas para romper dormancia seminal en R. capitata.

Glyphosate hormesis in broad-leaved weeds: a challenge for weed management

ABSTRACT Little is known of glyphosate-induced hormesis in weeds and how this might influence weed management. To test the hormetic effect of low doses of glyphosate on broad-leaved weeds, two experiments were conducted, in the laboratory and the screenhouse. The hormetic effects of glyphosate solution in growth media (0, 65, 130, 250, and 500 g acid equivalent (a.e) ha−1) and foliar spray (0, 4, 8, 16, 32, and 64 g a.e. ha−1) were tested on four broad-leaved weeds (Coronopus didymus, Chenopodium album, Rumex dentatus, and Lathyrus aphaca). Glyphosate solution in the range 65–250 g a.e. ha−1 stimulated the germination and seedling growth of all tested weeds. However, at 500 g a.e. ha−1 inhibition of germination and growth was observed. Foliarly applied glyphosate in the range 4–32 g a.e. ha−1 increased root and shoot length, dry biomass, and seed production ability of all four weeds species; however, the stimulatory response was species dependent. These results indicate that glyphosate hormesis could play a significant role in altering crop/weed competition and might influence weed management.

Comparative allelopathic potential of metabolites of two Alternanthera species against germination and seedling growth of rice

A laboratory study was conducted to investigate the allelopathic effect of aqueous extracts of plant parts of Alternanthera philoxeroides and A. sessilis and soil incorporated residues on germination and seedling growth of rice (Oryza sativa). Aqueous extracts prepared from different plant parts of Alternanthera species delayed rice germination. Alternanthera philoxeroides and A. sessilis inhibited rice germination by 9-100% and 4-49%, respectively. Germination of rice seeds was reduced with increasing concentration of aqueous leaf extracts of both weed species. Early seedling growth (root and shoot lengths) and seedling vigor index were significantly reduced by 5% aqueous leaf extract compared with distilled water treated control. Germination, root and shoot lengths, root and shoot dry weights and seedling vigor index of rice were drastically reduced by 3 and 4% in residue infested soil compared with residue free soil. The inhibitory effect of A. philoxeroides in terms of germination and seedling growth of rice was greater than that of A. sessilis. Five percent aqueous leaf extract and 4% residue infested soil of A. philoxeroides caused complete failure of rice seed germination. Alternanthera philoxeroides contained water soluble phenolics, namely 4 hydroxy-3-methoxy benzoic acid (16.19 mg L-1) and m-coumaric acid (1.48 mg L-1), whereas Alternanthera sessilis was rich in chlorogenic acid (17.85 mg L-1), gallic acid (11.03 mg L-1) and vanillic acid (9.88 mg L-1). The study indicates that the allelopathic potential of Alternanthera species may play an important role in enhancing the invasiveness of these species and may suppress rice plants in the vicinity.

Allelopathic effects of Rhynchosia capitata on germination and seedling growth of mungbean

Experiments were conducted to evaluate the allelopathic influence of Rhynchosia capitata on germination and seedling growth of mungbean (Vigna radiate) along with identification of the phytotoxic substances responsible for this activity. Water extracts of root, shoot, leaf, fruit and whole plant were prepared by soaking them in water in a ratio of 1:20 (w/v) for 24 h. All the extracts affected germination and seedling growth of mungbean, but higher inhibition was seen with R. capitata leaf water extracts. A linear decrease in the germination characteristics of mungbean was observed with the decrease in the concentration of leaf extract from 5% to 1%. The soil-incorporated residues (1-4% w/w) of R. capitata stimulated the growth of root and hypocotyl at low concentrations, while it inhibited their growth at higher concentrations. Rhynchosia capitata soil-incorporated residues (4% w/w) significantly reduced the seedling vigour index of mungbean in addition to their significant effect on total germination. A significant amount of water-soluble phenolic acids were found in R. capitata plant extracts. The content of total phenolic acids was higher in the leaf extract compared to that of the stem, fruit or root extracts. Two phenolic acids including vanillic acid and 4‑(hydroxymethyl) benzoic acid were found in R. capitata leaf extracts.

Germination behaviour of seeds from herbicide treated plants of Chenopodium album L.

The carry-over effect of sub-lethal herbicides was investigated on the germination of seeds collected from surviving Chenopodium album plants, which had received 1/8, 1/8 twice, 1/8 three times, 1/4, 1/2, 1/1 doses of either pre-emergence ioxynil or post-emergence bentazone in a previous onion (Allium cepa) crop. Seeds were also collected from surviving C. album plants, which had received 1/4, 1/2, 1/1 of either pre-emergence pendimethalin, propachlor and linuron, or 1/8, 1/8 twice, 1/8 three times, 1/4, 1/2, 1/1 of post-emergence ioxynil or linuron in a previous leek (Allium porrum) crop. Seeds of surviving plants were collected and tested for germination at temperature of 5, 10, 15, 20 and 25 degrees C. The effect of different temperatures on the total number of germinated seeds was significant. Germination was minimum at low temperatures (5 degrees C or 10 degrees C). Herbicides did not show any effect on germination of C. album and resulted in the same final germination percentage as seeds collected from the unsprayed control plots.

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

ABSTRACT 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.

Allelopathic Effects of Winter Legumes on Germination and Seedling Indicators of Various Summer Cereals

Abstract In the present study, the putative allelopathic potential of aqueous extracts (10 % w/v) of three legumes, i.e. alfalfa, berseem and brassica spp., including distilled water treatments as check were evaluated on germination and early seedling growth indicators of rice, sorghum and millet under laboratory conditions. The treatments were compared in completely randomized design with factorial arrangements in four replications. The recorded observations clearly indicated that the germination process and seedling growth of receptor plants were negatively affected in the presence of legume extracts. The extract of Brassica had the strongtest inhibitory effect on germination process in form of increased mean germination time (MGT) and lowered the coefficient of velocity of germination (CVG), germination % age and germination index (GI) as compared to other extracts. Likewise, the lowest root and shoot length, their fresh and dry weight was also noted in petri dishes with Brassica extracts. Among the receptor crops, rice was the most susceptible in term of both seedling growth and germination attributes. The interaction between test crops and legume extracts was found to be significant for most of studied parameters except germination % age, fresh and dry weight of root and shoot. The presence of allelochemicals in the studied legumes entitled them to be used in weed management programme and is also signal for designing specific production technologies able to reduce their effects on succeeding crops.

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.

Estimation of economic threshold level of alligator weed (Alternanthera philoxeroides (Mart.) Griseb.) to Tackle Grain quality and yield Losses in Rice

ABSTRACT Alligator weed (Alternanthera philoxeroides) is the most troublesome invasive weed in transplanted rice ecosystems worldwide. A two-year field study was conducted to estimate economic threshold levels and the season long competitive effect of six alligator weed densities (0, 2, 4, 8, 16, and 32 plants m−2) on yield and quality traits of transplanted rice. A gradual linear incline in dry weight of alligator weed was observed with an increase in its density from 2 to 32 plants m−2. Maximum N (15.93–18.26 kg ha−1), P (15.10–16.46 kg ha−1) and K (16.34–17.81 kg ha−1) uptake by alligator weed was recorded at its density of 32 plants m−2. More micronutrient loss to the tune of 6.53, 47.92, 19.99, and 38.42 mg kg−1 for Cu, Fe, Zn, and Mn, respectively was observed at the same density. Increasing density of alligator weed caused more losses in paddy yield (up to 21.37–23.78%), amylose and rice grain protein contents. According to a nonlinear hyperbolic regression model, maximum paddy yield loss of rice at asymptotic value of alligator weed density was 38.8% during 2011 and 42.4% during 2012. Economic threshold value of alligator weed was estimated 1.5 and 1.3 plants per m2 during 2011 and 2012, respectively.

Periodic Assessment of Dry Matter Production and Nutritional Value of Millet Legumes Mix Fodder

The intercropping of millet with legumes rich in protein was tested at 50, 60 and 70th day of sowing for the dry matter and its nutritional value. The seeds of cluster bean, cowpea and sesbania were inter-seeded on the same day in millet. The preliminary analysis for forage quality of mixture indicated that the practice of intercropping appeared to be more successful for achieving the required nutritional value. Apparently, the successive delay in harvesting produced more dry matter and organic matter yield with the completion of biologic cycle of both the component crops. The significant loss of feeding value with respect to crude protein and ash of mixture was achieved with delayed harvesting. However, its negative impact was much low in millet–cluster bean and millet–cowpea mixture which sustained their protein contents over the sampling period. It is, therefore, suggested that mix cultivation of millet–legume, preferably sesbania, should be popularized among the dairy farmers for getting palatable and proteinaceous fodder.