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Fusarium oxysporum f. sp. cepae is a soil-borne fungal pathogen that causes basal rot disease of onion (Allium cepa L.) resulting in significant yield losses of the crop. The present study was conducted to assess the disease management potential of Coronopus didymus (L.) Sm., and its effect on onion plant physiology. In laboratory bioassays, different concentrations ranging from 1% to 7% of methanolic extracts of leaves, stems and roots of C. didymus reduced fungal biomass by 60-84%, 51-85% and 73-87%, respectively. In a pot trial, dry leaf biomass of C. didymus was mixed in the soil at 1%, 2% and 3% in combination with F. oxysporum f. sp. cepae and their effect on disease development, plant growth and various physiological parameters was studied in comparison with a negative control (without any addition of pathogen or plant material) and a positive control inoculated only with the fungus. The highest disease incidence (47%) was recorded in positive control. Application of 2% and 3% dry leaf biomass of C. didymus as soil amendment significantly reduced disease incidence to 13% and 3%, respectively. Similarly, plant mortality was reduced to 0% due to 2% as well 3% dry leaf biomass treatments. The highest chlorophyll, sugar and protein content were recorded in treatment where F. oxysporum f. sp. cepae was inoculated with 1% dry leaf biomass incorporation. On the other hand, the highest phenolic content and peroxidase activity were recorded due to combined application of the pathogen and 3% dry biomass incorporation. Present study concludes that soil amendment with 2% leaf dry biomass of C. didymus can effectively manage the basal rot of onion without any adverse effect on plant growth. [ABSTRACT FROM AUTHOR]

Basal rot is a highly destructive disease of onion (Allium cepa L.) that is caused by the fungus Fusarium oxysporum Schlechtend: Fr. f. sp. cepae (Hans.) Snyder and Hansen. This study was carried out to examine the potential of Chenopodium album L. leaves for the control of this disease. In a pot trial, incorporation of dry leaf biomass of C. album at 3% (w/w) significantly reduced disease incidence and mortality by 63% and 89%, respectively. In laboratory bioassays, methanolic leaf extract was successively fractionated using four organic solvents viz. n-hexane, chloroform, ethyl acetate and n-butanol. Different concentrations (3.125, 6.25, …, 200 mg mL[sup -1]) of these fractions were examined against the selected pathogen in malt extract broth. Chloroform fraction exhibited the best antifungal activity resulting in 96-100% reduction in the fungal biomass. Through thin layer chromatography (TLC), two unidentified compounds A (R[sub f] 0.17) and B (R[sub f] 0.44) were isolated from this fraction. Antifungal activity of these compounds was compared with a commercial fungicide Mancozeb. Minimum inhibitory concentrations (MIC) of compounds A and B were 62.5 and 250 µg mL[sup -1], respectively after 24 h as compared to 7.81 µg mL[sup -1] MIC of the reference compound. The results of the present study conclude that antifungal compounds in chloroform fraction of methanolic leaf extract and soil amendment with dry leaf biomass of C. album can be used as alternatives to chemical fungicides for the management of basal rot disease of onion. © 2015 Friends Science Publishers [ABSTRACT FROM AUTHOR]

A field trial was conducted to investigate the herbicidal potential of culture filtrates of four Drechslera spp. viz. D. australiensis (Bugnicourt) Subramanian and Jain., D. biseptata (Sacc. and Roum.) Richardson and Fraser, D. hawaiiensis M.B. Ellis and D. holmii (Luttr.) Subramanian and Jain, against toothed dock (Rumex dentatus L.), a problematic dicotyledonous weed of wheat (Triticum aestivum L.). These culture filtrates were used either alone or in combination with half dose of a commercial herbicide Bromoxynil+MCPA (2-methyl-4-chlorophenoxyacetic acid). Herbicidal application either alone or in combination with fungal culture filtrates completely controlled the weed growth. All the four fungal culture filtrates when used alone significantly reduced the weed biomass by 30-58% over weedy check. Consequently, grain yield in wheat was increased by 6-22%. Culture filtrates of D. australiensis and D. hawaiiensis exhibited the highest herbicidal activity resulting in 58 and 57% reduction in weed biomass over weedy check. Application of culture filtrates of D. australiensis and D. hawaiiensis resulted in Rs. 11632 (28%) and Rs. 10413 (25%) more profit than conventional weedy check, respectively. However, the highest net profit of Rs. 70100 was obtained in hand weeding treatment followed by Rs. 69128 in half dose of herbicide, which was Rs. 28444 (68%) and Rs. 27472 (66%) higher than weedy check, respectively. It is concluded that culture filtrates of D. australiensis and D. hawaiiensis contain herbicidal metabolites and can be used as alternatives to herbicides for the management of R. dentatus in organic wheat production. [ABSTRACT FROM AUTHOR]

Rumex dentatus L. is a very common weed of wheat (Triticum aestivum L.) in Pakistan. Present laboratory and pot trials were carried out to evaluate metabolites of Drechslera holmii, Drechslera biseptata and Drechslera australiensis as natural herbicides against R. dentatus. Fungal metabolites were prepared in M1D medium. In laboratory bioassays, original and 50% diluted metabolites of different Drechslera spp. significantly reduced seed germination, shoot biomass and root biomass of R. dentatus seedlings by 5-56%, 15-83% and 68-88%, and that of wheat seedlings by 8-20%, 16-38% and 28-38%, respectively. Metabolites of D. biseptata and D. australiensis exhibited greater herbicidal activity than metabolites of D. holmii. In foliar spray repeated pot trials, original metabolites of the three Drechslera spp. significantly reduced shoot biomass of one- and two-week old plants of R. dentatus by 54-60% and 27-46%, respectively. By contrast, the effect of metabolites of all the three Drechslera spp. was non-significant on growth of wheat plants. Metabolites of D. australiensis showed the highest herbicidal activity in pot trials. It is concluded that metabolites of Pakistani Drechslera spp. possess herbicidal potential. [ABSTRACT FROM AUTHOR]

One hundred and ten pea (Pisum sativum L.) germplasm lines were screened under artificial disease conditions for their resistance against Pseudomonas syringe pv pisi, the cause of bacterial blight disease. Different strains corresponding to the two races of P. syringae pv pisi (race 2 and 3) were used for inoculation. The race 2 showed more virulence behaviour than race 3 on pea. Thirty pea lines (27.3%) were found resistant to race 2, while 49 lines (44.5%) to that of race 3. Twenty pea lines were selected among the genetic stock for Simple Sequences Repeat (SSR) analysis. Based on SSR analysis, two major groups A and B were identified. In the group A, there were four genotypes viz. ATC909, ATC613, ATC912 and ATC1641, whereas all other genotypes were placed in group B. The resistant genotypes reported in the present study are suggested for used in breeding program to develop disease resistant pea cultivars. [ABSTRACT FROM AUTHOR]

Antifungal potential of different parts of Chenopodium album L. was examined against Fusarium oxysporum Schlechtend. f. sp. cepae (Hans.) Snyder and Hansen, the cause of basal rot disease of onion (Allium cepa L.). In screening bioassays, the effect of different concentrations (0.5, 1.0, ...3.0%) of methanolic leaf, stem, root and inflorescence extracts of C. album was investigated. Extracts of different parts of the test plant species showed variable antifungal activity. The highest antifungal activity was exhibited by inflorescence extract. Different concentrations of this extract suppressed fungal growth by 24-80%. Methanolic inflorescence extract was successively extracted with n-hexane, chloroform, ethyl acetate and n-butanol. The highest antifungal activity was shown by ethyl acetate fraction resulting in 68-100% reduction in fungal biomass. From ethyl acetate fraction, three unknown compounds viz. A, B and C were isolated through thin layer chromatography (TLC). TLC fraction A exhibited the highest antifungal activity with minimum inhibitory concentration (MIC) of 250 µg mL-1. Thus, antifungal constituents of ethyl acetate fraction of methanolic inflorescence extract of C. album can be used as natural fungicides for the management of basal plate rot of onion. [ABSTRACT FROM AUTHOR]

Laboratory and pot trials were conducted to investigate the herbicidal potential of metabolites of Trichoderma spp. viz. T. pseudokoningii, T. harzianum, T. viride and T. reesei against parthenium (Parthenium hysterophorus L.) weed. Fungal metabolites were prepared in malt extract broth and M-I-D medium. In laboratory bioassays, parthenium seed were sown on filter papers in Petri plates (9-cm diameter) and 3 mL of original and 50% diluted metabolites of the test Trichoderma spp. were applied. Metabolites of all the four fungal species showed herbicidal action. The highest herbicidal activity was observed due to metabolites of T. harzianum. Fungal metabolites prepared in M-1-D medium generally showed greater inhibitory potential against seed germination and seedlings root/shoot growth as compared to the metabolites prepared in the other medium. For foliar spray bioassays, pot grown parthenium seedling at 1- and 2-week growth stages were sprayed with original fungal metabolites. Foliar spray was carried out three times with five days of intervals. In these pot trials, metabolites of all the four fungal species reduced shoot and root growth significantly in 1-week old parthenium plants. Metabolites prepared in M-1- D medium showed greater herbicidal effect than those formed in malt extract broth. It is concluded that metabolites of Trichoderma species, particularly prepared in M-1-D medium can be exploited for the management of parthenium weed. [ABSTRACT FROM AUTHOR]

Withania somnifera (L.) Dunal., a medicinal plant of family Solanaceae, was used to examine its antifungal activity against Ascochyta rabiei, the causal organism of highly damaging blight disease of chickpea (Cicer ariatinum L.). In laboratory screening bioassays, different concentrations (0.2, 0.4, 0.6, 0.8, 1.0 g 100 mL-1) of methanolic extracts of stem, root, leaf and fruit of W. somnifera were evaluated for their antifungal activity against the targeted fungal pathogen. The methanolic extracts of fruit and leaf were found highly effective against A. rabiei causing up to 41% and 43% suppression in fungal biomass, respectively. The methanolic extract of fruit was further subjected to fractionation by using n-hexane, chloroform, ethyl acetate and n-butanol in order of increasing polarity. Different concentrations (3.125, 6.25, ..., 200 mg mL-1) of these fractions were used against the test pathogen. Ethyl acetate fraction was found highly effective against A. rabiei exhibiting complete inhibition of fungal growth. Two compounds namely A and B were isolated from this fraction through thin layer chromatography (TLC). These compounds were then appraised to find minimum inhibitory concentration (MIC) against the test fungal pathogen. Compound B was found more effective than A. The MIC values of compounds B and A were 62.5 Hg mL-1 and 1000 Hg mL-1, respectively. It was concluded that antifungal compounds B could be used for the management of A. rabiei. [ABSTRACT FROM AUTHOR]

Pot experiment was designed to assess the effect of southern blight pathogen Sclerotium rolfsii Sacc. on growth, yield, qualitative gene expression and metal uptake in pea (Pisum sativum L.). Soil was spiked with 25, 50, 75 and 100 ppm of Cu(II) and inoculated with S. rolfsii. Growth, biomass and yield of pea plants were significantly declined by 10-70% in treatments inoculated with S. rolfsii, and 10-50% due to different concentrations of Cu(II) alone or combined with the pathogen after 30 and 60 days of growth. Cu(II) uptake capacity of pea plants were increased under combine stress of metal and pathogen as compared to metal alone. Higher metal concentration was recorded in roots than in shoots and pods. Expression of defensin like gene was intense due to combined influence of S. rolfsii and Cu(II) than in plants under pathogenic stress alone. Metallothionein gene was expressed only in Cu(II)-incorporated treatments. The present study concludes that solitary influence of S. rolfsii or Cu was more detrimental to growth and yield of P. sativum as compared to combined stress of both the factors. [ABSTRACT FROM AUTHOR]

A study was performed to investigate the influence of Sclerotium rolfsii (pathogen of southern blight diseases) on germination and growth of pea (Pisum sativum L.) under Cu(II) toxicity stress. Experiments were conducted in petri plates (9-cm diameter) lined with sterilize filter papers inoculated with S. rolfsii (spore suspension 2.0 × 106) and different concentrations of Cu(II) solution viz. 25, 50, 75 and 100 mg L-1. Germination and different growth parameters were declined by 10-70% in treatments inoculated with pathogen alone. There was 10-50% reduction in these parameters either due to effect of metal alone or combined with the pathogen. Root growth showed more susceptibility to both stresses than shoot growth. In another petri plate bioassay, effect of Cu(II) on growth of S. rolfsii was checked, Cu(II) suppressed the growth of fungus by 10-50% at concentrations of 25-100 mg L-1. Further pots and field trials are required to confirm the results of petri plate and recommendation to the farmers. [ABSTRACT FROM AUTHOR]

Genetic diversity was assessed among 38 chickpea (Cicer arietinum L.) genotypes on the basis of random amplified polymorphic DNA (RAPD) in comparison with agro-morphological traits. Evaluation of agro-morphological traits revealed highly significant differences among genotypes. Days to 50% flowering ranged from 92-118, plant height 54.16-87 cm, number of fruit bearing branches 4-17.25, number of pods per plant 7.6-27.4, and grain yield per plant 3.5-9.8 g. Ascochyta blight (caused by Ascochyta rabiei) score of these genotypes was recorded on 1-9 rating scale that varied from 3-9. Cluster analysis showing relationship based on morphological traits (scale: Euclidean distance) placed 35 genotypes into five distinct groups, while three genotypes namely Noor-91, Local Mankera and BR4 did not include in any cluster. RAPD analysis showed that 35 RAPD primers amplified a total of 212 fragments out of which 45 were polymorphic. Polymorphic bands were generated by 21 primers whereas 14 primers were monomorphic. Genetic similarity matrix based on Nei and Li's index revealed similarity coefficients ranging from 92-97% indicating lower level of genetic polymorphism revealed by RAPD primers. Dandrogram constructed on the basis of these coefficients grouped all the genotypes into 2 major and 3 small clusters at 92% similarity level. Two decamers, OPC5 and OPC14 distinguished between three Desi and two Kabuli genotypes. This study showed that the level of genetic variability observed in chickpea for agro-morphological traits was not reflected in DNA polymorphism obtained by RAPD analysis. [ABSTRACT FROM AUTHOR]