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Effect of pre-storage fungicidal treatment on prevalence of seed-borne fungi and quality of onion (Allium cepa L.) seeds was evaluated under laboratory condition. Seeds were treated separately with five fungicides namely Bavistin 50 WP (Carbendazim) and Dithane M-45 (Mancozeb) @ 2.2 g/kg, Homai (Thiophanate) and Rovral (Iprodione) @ 2.0 g/kg and Provax-200 (Carboxin) @ 3.0 g/kg of seeds before storage. Prevalence of seed-borne fungi, percent seeds germination and vigor index were evaluated just before storage, 75 and 150 days after storage. Fungicides produced significant negative impact on seed-borne fungi and positive impact in maintaining quality during storage. Provax-200, Rovral, Dithane M-45 and Bavistin effectively reduced seed-borne fungi and performed better for germination and vigor of seeds. Seed treatment with Provax-200, Rovral, Bavistin or Dithane M-45 would therefore be suggested as effective fungicides to control seed-borne fungal infection and maintain better germination and vigor of onion seed in storage.The Agriculturists 2017; 15(2) 52-58

The life table of the indigenous Neoseiulus californicus was studied at different temperatures and 65 ± 5% relative humidity under conditions of 16 h light : 8 h dark (LD 16:8). The total developmental period from egg to adult varied from 3.0 to 14.0 days at 15 to 35°C. Survival to adulthood ranges from 86.21 to 93.94%, with the highest rate at 25°C. The lower threshold temperature from egg to adult stages of females and males was 10.84 and 10.72°C, respectively, and the thermal constant was 57.14 degree-days (DD) for females and 56.18 DD for males. Total number of eggs laid by each female was the highest (70.38 eggs) at 25°C, whereas average daily fecundity was the highest (3.69 eggs/female/day) at 30°C. The net reproductive rate was the highest (48.49) at 25°C and lowest (26.18) at 30°C. Mean generation time decreased from 19.04 to 11.47 days with increasing temperature from 20 to 30°C. Both intrinsic rate of natural increase (0.284) and finite rate of increase (1.32) were maximum at 30°C. Adult longevity was the highest (42.75 days for females and 32.60 days for males) at 20°C and lowest (22.70 days for females and 15.30 days for males) at 30°C. Sex ratio was female biased and was the highest (78.08) at 25°C and lowest (70.24) at 30°C. Developmental data of five constant temperatures, temperature thresholds and thermal requirements may be used to predict the occurrence, number of generations and population dynamics of N. californicus as an important biocontrol agent of Tetranychus urticae.

A study was undertaken to determine the generation-wise parasitizing efficiency of mass reared Bracon hebetor on wax moth (Galleria mellonella). Two experiments were conducted to achieve the objectives. In the first experiment, the host larvae and parasitoid were released in the field micro plot during first generation and reared in the laboratory in subsequent generations. In another experiment, all generations were developed in the laboratory. In the first experiment, generation showed significant variation on sex ratio of adult progeny production. The male sex ratio increased with the range of 62.89 to 74.58% and female sex ratio declined ranging from 39 to 25% with the advancement of generations. The percent parasitization and adult progeny production was not influenced appreciably with the progress of generation. In the second experiment parasitization and adult progeny production did not vary significantly in successive generations. However there was a decreasing trend in parasitization from 95 to 55% by Bracon hebetor and adult progeny production by 47.5 to 15.5 adultsfemale-110 larvae-1 over generation. The sex ratio of adult progeny was significantly influenced by inbreed generation in laboratory reared population. Female decrease in sex ratio from first to sixth generation was 39.25 to 16.88%.SAARC J. Agri., 13(2): 1-12 (2015)

Rearing methods for Bracon hebetor (Say) (Hym., Braconidae) were investigated in the series of laboratory experiments designed to enhance the yield of the mass rearing of this parasitoid for biological control of lepidopteran field and stored product pests. In these experiments, the effects of parasitoid and host densities on fertility and sex ratio of B. hebetor were assessed. In parasitoid densities, 50 last-instar greater wax moth (GWM) Galleria mellonella (L.) larvae were placed per container and 1, 2, 4, 8 or10 pairs of B. hebetor (one male and one female) were released in each container. In host density study two pairs B. hebetor were introduce in six different densities (10, 20, 30, 40, 50 and 60) of host, GWM per container. A density of ten male-female pairs of B. hebetor produced a higher number of progeny (205 ± 7.07 adults) on 50 last instar larvae of GWM. Similarly, in a host density experiment, a density of 60 last instars GWM larvae produced a significantly higher number of parasitoid progeny (142.0 ± 8.75 adults), followed by 50 last instar larvae (141.0 ± 8.34 adults) among the tested host densities when two pairs of B. hebetor were used. The sex ratio of progenies was male-biased in all studies and there were no significant effects on sex ratio in various parasitoid and host densities. In mass rearing experiment, total number of emerged parasitoids per 200 wax moth larvae was 1091 ± 82.38 adults with mean parasitism rate of 98 ± 0.8%.

The two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is a cosmopolitan pest of many greenhouse and field crops worldwide. Host plant quality affects the development, survival and fecundity of T. urticae. The life table parameters of T. urticae on three country bean varieties (Lablab purpureus L.), namely IPSA Seam 1, BARI Seam 1 and Kartica, were maintained at 25 ± 2 °C, 65 ± 5 % relative humidity (RH) and a photoperiod of 16:8 (L:D) in a growth chamber. The mean immature development time of T. urticae from egg to adult was significantly longer on IPSA Seam 1 than on the other two varieties. There were significant variations in fecundity and longevity which resulted in large differences on population growth parameters like the intrinsic rate of natural increase (rm), net reproductive rate (Ro), finite rate of increase (λ) and doubling time (tD). Kartica and BARI Seam 1 were the most suitable host for T. urticae with rm = 0.230 and 0.223 (offspring/female/day), respectively. The slow...

Powdery mildew (Oidium erysiphoides f.sp. ziziphi) is the major disease of Indian jujube (Ziziphus mauritiana) in Bangladesh. An experiment was conducted to test the efficacy of six fungicides, two organic oils, and a detergent against the disease. Tested fungicides were Tilt (Propiconazole) @ 0.05%, Folicur (Hexaconazole) @ 0.1%, Bavistin DF (Carbandazim) @ 0.2%, Dithane M-45 (Mancozeb) @ 0.3%, Thiovit 80 WG (Sulpher) @ 0.3%, and Cupravit (Copper) @ 0.3%, the oils were Mustard oil @ 0.5% and Neem oil 0.5%, and the Detergent (Trix) @ 0.5%. The materials were applied as foliar spray for seven times at an interval of 15 days. All of the fungicides and two oils gave significant decrease in severity of powdery mildew and increased fruit yield of Indian jujube irrespective of varieties, locations and over times. Among the treatments, Folicur, Tilt, Thiovit, and Dithane M-45 sprays were found effective than others. The severity index values on two jujube varieties were 3.89-4.50 at Mowna and 4.00-4.53 at Ishurdi in control treatment. The severity indices were reduced to 1.45-1.96 at Mowna and 1.33-2.07 at Ishurdi due to application of Tilt, Folicur, Thiovit, and Dithane M-45, which gave increase in fruit yield over control by 68.88, 63.69, 63.04, and 54.63% in Apple Kul and 83.25, 77.87, 77.39, and 70.36% in BAU Kul, respectively. Most of the treatments were able to reduce number of spotted fruits. The best effective fungicide was found to be Tilt followed by Folicur and Thiovit in reducing disease severity of powdery mildew as well as other fruit diseases like fruit spot and fruit rot and increase fruit yield of Indian jujube. Therefore, Tilt/Folicur may be recommended for jujube growers to control the powdery mildew disease in commercial orchard. DOI: http://dx.doi.org/10.3329/bjar.v38i4.19032 Bangladesh J. Agril. Res. 38(4): 659-672, December 2013

Five brinjal (Solanum melongena L.) genotypes were selected for characterization using Simple Sequence Repeats (SSR) markers. All the genotypes showed considerable variation in respect of morphological, anatomical and biochemical aspects. For study of relatedness, plant genomic DNA was extracted by CTAB based method using 11 randomly selected primers produced from Calgene Inc. USA. The primers developed 22 bands through PCR amplification out of which 15 from 3 primers and were polymorphic. Genetic similarities of SSR profiles were estimated based on Jaccard’s coefficient value. The dendrogram generated two clusters and they were clearly distinct and separated from each other. Cluster-I consisted of genotypes TURBO and BL009; and cluster-II comprised of genotypes EG058, EG075 and ISD006. Genotype TURBO and BL009 were identified as the diverse genotype and showed a maximum of 17% dissimilarity from EG058, EG075 and ISD006. The similarity value ranged from 0.83 to 1.00 which indicated the presence of narrow range of genetic diversity at molecular level but have still a possibility of crossing among the genotypes of two clusters. The banding pattern of different genotypes could be utilized as reference for further comparisons.DOI: http://dx.doi.org/10.3329/bjpbg.v21i1.17041

The efficacy of seed treatment and foliar spray with fungicides in controlling black point incidence of wheat seeds was evaluated in the field. Two seed treating fungicides, namely Vitavax-200 and Homai-80WP were used @ 0.25% of dry seed weight and foliar spray with Tilt-250EC (0.05%) was applied in six different schedules. Untreated and unsprayed controls were also maintained. Seed treatment with either Vitavax-200 or Homai-80WP significantly increased plant population and grain yield, but none of them was found effective in reducing black point incidence. On the other hand, foliar sprays with Tilt-250EC under all the spray schedules except spraying at 70 and 90 DAS significantly minimized the disease severity over unsprayed control. Among the different spray schedules, spraying at 30, 40, 50, 60, 70, 80, and 90 DAS appeared to be most effective, which was similar to spraying at 30, 45, 60, 75, and 90 DAS in reducing black point incidence and increasing grain yield. Economic analysis on yield advantage showed that the highest additional gross margin of Tk. 6120/ha with BCR 2.57 was obtained from five sprays applied at 30, 45, 60, 75, and 90 DAS. Key Words: Seed treatment, foliar spray, black point, wheat. DOI: 10.3329/bjar.v34i3.3968 Bangladesh J. Agril. Res. 34(3) : 425-434, September 2009

An experiment was conducted to determine the effect of different levels of black point infection caused by Bipolaris sorokiniana and other fungal pathogens on some quality characters of wheat grain. Wheat grains were graded on a 0-5 scale based on levels of black point infection. Quality characters of grain viz., protein, fat, dry matter, ash and mineral contents under different grades were determined following standard methods. The dry matter and ash contents of grain decreased while the contents of protein and fat increased with the increasing severity of black point infection. The observations on macro and micro nutrient contents of grain indicated that the amount of nitrogen, phosphorus, calcium, magnesium, sulphur, and boron increased, whereas the contents of potassium, iron, zinc, copper and sodium decreased with the increase of black point infection. However, the reductions in copper content of black point affected grains under different grades of infection were not significant as compared to apparently healthy grains. Key Words: Black point; Bipolaris sorokiniana; grain quality; wheat. DOI: 10.3329/bjar.v34i2.5789Bangladesh J. Agril. Res. 34(2) : 181-187, June 2009

Rhizoctonia solani isolates were collected from soil of different agro-ecological zones of Bangladesh and also from infected plant parts of different crops and grasses. Collected isolates were classified into five different cluster groups on the basis of morphological and cultural characters. Five isolates taking one from each of the five different cluster groups were selected to study their pathogenicity and host range on 35 different crops. Pathogenicity and host range of the isolates were determined by planting the seeds in water agar plate infested with R. solani isolates and incubated at 25°C temperatures. After analyzing the morphological and cultural characters of the isolates, it was found that there was no relations between the isolates with respect to their origin from where they were collected. It indicated that the diversity among the isolates was not correlated with their origin. In case of host range and pathogenicity among the five selected isolates of different cluster groups, the isolate JES-16 was an avirulent isolate. The isolate SYL-30 had narrow host range and a low virulent isolate. The isolates DIN-8 and GAZ-18 possessed wide host range and might be considered as virulent isolates. The isolate GAZ-9 was a highly virulent isolate with a wide host range. Keywords: Rhizoctonia solani; morphological and pathogenic variations; isolates. DOI: 10.3329/bjar.v35i3.6443Bangladesh J. Agril. Res. 35(3) : 375-380

A study was undertaken to determine the prevalence of black point and percentages of germination, moisture content and different fungi associated with wheat seeds during storage in different types of container. Seeds of a widely cultivated variety Kanchan were stored in five types of containers viz., ‘dole'(bamboo made), earthen pitcher, tin container, polyethylene bag and refrigerator (10°C) for ten months at room temperature. Samples were taken at monthly interval beginning from the month of April (prior to storage). The seed moisture content and black point severity were found highest in dole resulting in the lowest percentage of seed germination. The highest germination percentage was observed under storage in refrigerator followed by polyethylene bag, tin container and earthen pitcher. The moisture content and black point infection increased and seed germination decreased with the increase of storage period. Prior to storage in April, the seed germination was 95%, which decreased to about 75% at the end often months of storage (in January). Various fungal flora associated with wheat seeds differed in their prevalence depending on the length of storage period and types of container used for storage. The population of field fungi viz., Alternaria alternata, Aiternaria triticina, Bipolaris sorokiniana, Cladosporium cladosporioides, Curvularia lunata, Epicoccum purpurascens and Fusarium spp. decreased while that of storage fungi viz., Aspergillus, Chaetomium, Nigrospora, Penicillium and Rhizopus increased with the progress of storage period. Key Words: Storage, seed quality, wheat. doi:10.3329/bjar.v33i3.1606 Bangladesh J. Agril. Res. 33(3) : 469-477, September 2008

Performance of potato seed tubers of first, second, third, fourth, and fifth generations were evaluated against PVY and PLRV. Potato plants grown from first generation seed tubers were free from PVY infection. Incidence of the virus was the minimal at second generation, which increased afterwards steadily by third, fourth, and fifth generations. Incidence of PLRV was minimal at first generation. It increased gradually with the advancement of generation seed tubers showing the highest incidence at fifth generation. The highest plant growth and tuber yield were recorded at second generation, which was followed by third, fourth, and fifth generations. The highest reduction in plant height, tuber number, and tuber yield were recorded in 5th generation due to infection of PVY and PLRV. Keywords: Generation evaluation; PVY; PLRV; growth; yield; potato DOI: 10.3329/bjar.v35i1.5865Bangladesh J. Agril. Res. 35(1) : 37-50, March 2010

An experiment was conducted to find out variation in isolated Rhizoctonia solani based on radial mycelial growth and sclerotial production. Five isolates of Rhizoctonia solani representing five clusters group were selected and were grown at different levels of temperature and pH on potato dextrose agar (PDA). It was observed that optimum temperature and pH for growth and scierotial production varied among the isolates. The rates of growth and sclerotial formation were not uniform at the same levels of the two growth factors. The maximum mycelial growth of all isolates was found at 30°C. At 35°C, only GAZ-9 and GAZ-18 showed initiation of growth, but the rate was very slow. The optimum temperature for sclerotial production of the isolates GAZ-9, JES- 16, GAZ-18 SYL-26 was 30°C and for the isolate DIN-8 was 25°C. The optimum pH for maximum radial growth was 6 for DIN-8 and 7 for other four isolates. The maximum number of sclerotia was produced by DIN-8, GAZ-9, and SYL-30 at pH 8, 4, and 7, respectively. The optimum pH for sclerotia formation in JES-16 and GAZ-18 was pH 6. Keywords: Rhizoctonia solani; variations; temperature; pH. DOI: http://dx.doi.org/10.3329/bjar.v36i3.9267 BJAR 2011; 36(3): 389-396