Genotypic Variation in Phytoremediation Potential of Indian Mustard Exposed to Nickel Stress: A Hydroponic Study

Ten Indian mustard (Brassica juncea L.) genotypes were screened for their nickel (Ni) phytoremediation potential under controlled environmental conditions. All ten genotypes were grown hydroponically in aqueous solution containing Ni concentrations (as nickel chloride) ranging from 0 to 50 μM and changes in plant growth, biomass and total Ni uptake were evaluated. Of the ten genotypes (viz. Agrini, BTO, Kranti, Pusa Basant, Pusa Jai Kisan, Pusa Bahar, Pusa Bold, Vardhan, Varuna, and Vaibhav), Pusa Jai Kisan was the most Ni tolerant genotype accumulating up to 1.7 μg Ni g^?1 dry weight (DW) in its aerial parts. Thus Pusa Jai Kisan had the greatest potential to become a viable candidate in the development of practical phytoremediation technologies for Ni contaminated sites.     

Ethylene Supplementation Increases PSII Efficiency and Alleviates Chromium-Inhibited Photosynthesis Through Increased Nitrogen and Sulfur Assimilation in Mustard

Journal of Plant Growth Regulation - The effect of chromium (Cr) toxicity on four cultivars of mustard (Brassica juncea), Varuna, Pusa Bold, Rohini and SS2, was studied to select the cultivar with...     

Fitness parameters of Plutella xylostella (L.) (Lepidoptera; Plutellidae) at four constant temperatures by using age-stage,two-sex life tables

Different temperature zones have significant impact on the population dynamics of Plutella xylostella. Effective management of P. xylostella requires the knowledge of temperature tolerance by different life stages. In the current study, fitness parameters of diamondback moth were reported by using age-stage, two-sex life table traits at four constant temperatures (15, 20, 25 and 30 °C). The life cycle of P. xylostella was significantly longer at 15 °C. The 20 °C level of temperature was found optimal for fecundity, gross reproductive rate (51.74 offspring) and net reproductive rate (44.35 offspring per individual). The adult pre-oviposition period was statistically at par at all four level of temperatures. However, the survival was maximum at 20 °C as compared to other three temperature ranges. Based on the current study, it was concluded that temperature has a great role in population build-up of P. xylostella and effective management tactics should be applied to prevent significant damage to cabbage and other cruciferous crops when the temperature in the field is near 20 °C.     

Influence of host plant Brassica species) and temperature on population increase of the cabbage whitefly Aleyrodes brassicae

Laboratory studies on the influence of host plant species on population growth of the cabbage whitefly Aleyrodes brassicae Walk. showed that greatest longevity occurred on mustard and lowest on turnip. Leaf age did not affect survival. At 20 or 25 °C the survival curves from mustard plants were shortened Slobodkin's type I whereas those from purple sprouts and turnip were typical of Slobodkin's type II. At 15 °C the survival curves from young leaves of all host plants were of Slobodkin's type I but those from mature leaves were of Slobodkin's type III except that of mustard which was of type I. Young leaves induced higher fecundities than mature leaves. Fecundity was highest on mustard followed by purple sprouts and turnip. This affected population rate such that, for example, daily r_m values on young leaves of mustard, purple sprouts, and turnip at 25 °C were 0.206, O.172, and 0.147, respectively.     

Temperature and host plant effects on development and fecundity of Brevicoryne brassicae (L.) (Homoptera: Aphididae)

The development, survival and reproduction of the cabbage aphid, Brevicoryne brassicae (L.) were evaluated at three constant temperatures (20, 25 and 30°C) on cabbage, cauliflower, red cabbage, turnip and radish. The development periods of immature stages ranged from 10.7 d at 20°C to 7.60 d at 30°C for red cabbage. Total percentages of survivorship of immature stages varied from 39.40 and 82.50 within the temperature range of 25–30°C on radish. The average progeny per female was 31.15, 28.95 and 23.77 at 20, 25 and 30°C on cabbage.     

Effect of temperature on life table parameters of Plutella xylostella (Lepidoptera: Plutellidae) on two brassicaceous host plants

Life table parameters of diamondback moth, Plutella xylostella (L.), were studied at seven constant temperatures (10, 15, 20, 25, 28, 30, and 35 °C) on two brassicaceous host plants, cauliflower (Brassica oleracea var. botrytis) and cabbage (Brassica oleracea var. capitata). Survival, longevity and reproduction were examined and used to construct a life table. The survival at immature stages varied from 53.0 to 84.1% on cauliflower and from 58.3 to 86.2% on cabbage at 10–30 °C. P. xylostella did not survive at 35 °C. The female adult longevity ranged from 12.9 days at 30 °C to 30.4 days at 10 °C on cauliflower and 9.7 days at 30 °C to 40.0 days at 15 °C on cabbage. The net reproductive rate (R₀) increased with increasing temperature, while generation time (T) decreased. This caused the intrinsic rate of increase (r_m) to increase from 0.038 to 0.340 on cauliflower and 0.033 to 0.315 on cabbage from 10 to 28 °C. The significant decrease in R₀ caused a decrease in r_m at 30 °C. The r_m values on cauliflower were significantly higher than cabbage at 15, 20, 28 and 30 °C.     

Effects of host stages and temperature on population parameters of Oomyzus sokolowskii, a larval-pupal parasitoid of Plutella xylostella

Oomyzus sokolowskii is alarval-pupal parasitoid of diamondback moth, Plutella xylostella. In a host stage preference test, the parasitoid parasitised all larval and pupal stages, but exhibited a strong preference for larvaeover prepupae or pupae, and did not show a preference among the larval instars. At 25°C, the developmental time, number and sex ratio of offspring per host pupa, and successful parasitism did not differ significantly among parasitoids reared from host larvae of different instars, indicating similar host suitability between larvae of different instars. Mean developmental times from egg to adult at 20, 22.5, 25, 30, 32.5, and 35°C were 26.5,21.0, 16.0, 12.7, 11.9 and 13.4 days, respectively. The favourable temperature range for development, survival, and reproduction of the parasitoid was 20--30°C. However, wasps that developed and emerged at a favourable temperature could parasitise effectively at 32--35°C for 24 hours. Life-fertility table studies at 20, 25, and 30°C showed that each female wasp on average parasitised 3.1, 13.2, 6.8 larvae of diamondback moth and produced 20.5, 92.1, 50.4 offspring, respectively, during her lifetime. The highest intrinsic rate of natural increase (r _m) of 0.263 female/day was reached at 30°C as a result of the short mean generation time at this temperature compared to that at 20 and 25°C, suggesting that the parasitoid had the highest potential for population growth at relatively high temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of temperature on seedling growth under impeding conditions

Studies were carried out under controlled laboratory conditions to evaluate the seedling growth capacities of chickpea (Cicer arietinum L.) varieties Pusa 209 and H208 at constant temperatures of 15, 20, 25 and 28°C (±0.5°C) and of pigeonpea (Cajanus cajan L.) variety Prabhat at 20 and 28°C (±0.5°C). Seedling growth at any given time was found to depend on ‘a’, the growth at no impedance, and ‘b’, the impedance growth factori.e., decrease in growth with increase in impedance, and on temperature. The optimum temperature for chickpea was found to be in the range of 20 to 24°C for better seedling growth characteristics, whereas for pigeonpea, 28°C was found to be more congenial than 20°C. Chickpea varieties differed in their response to temperature. Part of the M. Sc. thesis of first author submitted to the Indian Agricultural Research Institute, New Delhi-110012, India.     

INFLUENCE OF TEMPERATURE ON CERTAIN BIOLOGICAL ATTRIBUTES OF A LADYBEETLE COCCINELLA SEPTEMPUNCTATA LINNAEUS

Influence of temperature on certain biological attributes of an aphidophagous ladybeetle, Coccinella septempunctata Linnaeus, feeding on mustard aphid, Lipaphis erysimi (Kaltenbach), at five different temperatures, viz. 20, 25, 27, 30 and 35°C was investigated. Its developmental period was shortest (11.7 ± 0.09 days) at 35°C and longest (20.6 > 0.35 days) at 20°C. Developmental rate increased with increase in temperature. Hatching percent, larval survival, adult emergence and growth index were maximum at 30°C and minimum at 20°C. Oviposition period and fecundity were highest at 30°C and lowest at 20°C. A positive linear relationship exists between temperature and developmental rate and negative correlation between the duration of immature life stages and temperature. The proportion of developmental period allocated to each immature stage was found to be similar at each temperature regime. Thus, 30°C was found as the most suitable for C. septempunctata amongst the five temperatures tested.     

Effects of three different cultivars of cruciferous plants on the age‐stage,two‐sex life table traits of Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Plutella xylostella is an important pest of cruciferous crops worldwide. However, information regarding the age‐stage, two‐sex life parameters of P. xylostella, which is vital for designing more effective control methods, is currently lacking. The present study reports age‐stage, two‐sex life table parameters for P. xylostella on napa cabbage (Brassica oleracea var. napa), white cabbage (B. oleracea var. capitata), and cauliflower (B. oleracea var. botrytis) under laboratory conditions at 25 ± 2°C, 50–60% relative humidity, and a 16‐h light : 8‐h dark photoperiod. The time for development from an egg to a male or female adult P. xylostella on white cabbage (mean [± SE] 41.15 ± 0.54 and 39.50 ± 0.54 days, respectively) was significantly longer than that on cauliflower and napa cabbage. Furthermore, P. xylostella fecundity on cauliflower (261.90 ± 4.53 eggs female) was significantly highest than on napa cabbage and white cabbage. Intrinsic rate of increase (r) and finite rate of increase (λ) were highest on cauliflower 0.182 day^?1 and 1.199 day^?1 respectively as comparison to napa cabbage and white cabbage. The highest gross reproductive rate (GRR) and net reproductive rates (R₀) of P. xylostella 65.87 and 52.58 respectively on cauliflower then those of other hosts. The findings of the present study indicate that cauliflower is the most suitable cultivar (host) for the development of P. xylostella. Based on these findings, crops like cauliflower can be used as trap crops when napa cabbage and white cabbage are the main crops.     

Influence of larval rearing temperature on the quality of cold‐stored Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae)

Oomyzus sokolowskii, an important parasitoid of Plutella xylostella, has great potential for use in biological control. Storage at suboptimal temperature is valuable for increasing the shelf‐life of insect parasitoids. In this study, O. sokolowskii larvae were reared at 30/25, 25/25 and 25/20°C light/dark (65 ± 5% RH, 16 : 8 h L : D) until pupation. The pupae were then cold‐stored at 4 ± 1°C (60 ± 5% RH, full darkness). The pupae were removed out from the storage at 10, 20, 30 and 40 days after storage (DAS) and maintained at 25 ± 2°C until adults emerged or pupae died. Quality of the emerging adults and their F₁ offspring were assessed. Incidence of parasitism by O. sokolowskii was higher at 30/25°C than at 25/20°C. Cold storage of O. sokolowskii pupae greatly affected the fitness of the parasitoid: adult emergence rates were lower in the 40 DAS treatment than in other treatments; when O. sokolowskii larvae developed at 25/25°C, female proportions of the emerged adults were lower in the 40 DAS treatment than in the 0 and 10 DAS treatments. Larval rearing temperature mildly affected the adult emergence rate, post‐storage developmental time and female proportion with a few exceptions. Number of parasitoids emerged per host pupa, and incidence of parasitism by the females were neither affected by larval rearing temperature nor cold storage duration. Trans‐generational effects on F₁ offspring were evident in adult emergence rate, egg‐adult developmental time and female proportion which were negatively affected by long duration of storage (40 days), but not by larval rearing temperature with a few exceptions. In conclusion, O. sokolowskii pupae could be stored at 4°C for up to 30 days without significant fitness loss.     

Salinity-induced changes in two cultivars of Vigna radiata: responses of antioxidative and proline metabolism

The influence of increasing salinity stress on plant growth, antioxidant enzymes and proline metabolism in two cultivars of Vigna radiata L. (cv. Pusa Bold and cv. CO 4) was investigated. Salt stress was imposed on 30-days-old cultivars with four different concentrations of NaCl (0, 100, 200 and 300 mM). The roots and shoots of CO 4 showed greater reduction in fresh weight, dry weight and water content when compared to Pusa Bold with increasing salt stress. Under salinity stress, the roots and shoots of CO 4 exhibited higher Na⁺: K⁺ ratio than Pusa Bold. The activities of reactive oxygen species (ROS) scavenging enzymes and reduced glutathione (GSH) concentration were found to be higher in the leaves of Pusa Bold than in CO 4, whereas oxidized glutathione (GSSG) concentration was found to be higher in the leaves of CO 4 compared to those in Pusa Bold. Our studies on oxidative damage in two Vigna cultivars showed lower levels of lipid peroxidation and H₂O₂ concentration in Pusa Bold than in CO 4 under salt stress conditions. High accumulation of proline and glycine betaine under salt stress was also observed in Pusa Bold when compared to CO 4. The activities of proline biosynthetic enzymes were significantly high in Pusa Bold. However, under salinity stress, Pusa Bold showed a greater decline in proline dehydrogenase (ProDH) activity compared to CO 4. Our data in this investigation demonstrate that oxidative stress plays a major role in salt-stressed Vigna cultivars and Pusa Bold has efficient antioxidative characteristics which could provide better protection against oxidative damage in leaves under salt-stressed conditions.     

Effect of temperature,cultivars, injury of root and inoculums load of Ralstonia solanacearum to cause bacterial wilt of tomato

Bacterial wilt, caused by Ralstonia solanacearum , is responsible for severe losses in tomato crops in the world. In the present study, the effect of temperature, cultivars of tomato, injury of root system and inoculums load of R. solanacearum to cause bacterial wilt disease under control conditions was undertaken. Three strains UTT-25, HPT-3 and JHT-5 of R. solanacearum were grown at 5–40?°C in vitro to study, the effect of temperature on the growth of bacteria and maximum growth was found at 30?°C after 72?h in all the strains. Twenty-one days old seedlings of two cultivars of tomato i.e. N-5 (moderately resistant) and Pusa Ruby (highly susceptible) were transplanted into the pots and inoculated with R. solanacearum strain UTT-25 (5 × 10⁸?cfu/ml), mechanically injured and uninjured roots of the plant. The plants were allowed to grow at 20, 25, 30 and 35?°C at National Phytotron Facility, IARI, New Delhi to study the effect of temperature on intensity of bacterial wilt disease. Maximum wilt disease intensity was found 98.73 and 95.9 % in injured roots of Pusa Ruby and N-5 cultivars of tomato at 35?°C on 11th days of inoculation, respectively. However, no wilt disease was observed in both the cultivars at 20?°C up to 60?days. For detection of R. solanacearum from asymptomatic tomato plants, hrpB-based sequence primers (Hrp_rs2F and Hrp_rs2R) amplified at 323?bp was used in bio-PCR to detect R. solanacearum from crown, mid part of stem and upper parts of the plant. Another experiment was conducted to find out the inoculum potential of R. solanacearum strain UTT-25 to cause bacterial wilt in susceptible cultivar Pusa Ruby. The bacteria were inoculated at concentration of bacterial suspension 10 to 10¹⁰?cfu/ml in injured and uninjured roots of the plants separately and injured root accelerated wilt incidence and able to cause wilt disease 63.3% by 100?cfu/ml of R. solanacearum, while no disease appeared at 10?cfu/ml on the 11th day of inoculation in injured and uninjured roots of the plant.     

Comparative bioassay of different isolates of Bacillus thuringiensis subsp. kurstaki on the third larval instars of diamondback moth,Plutella xylostella (L.) (Lep.: Plutellidae)

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) is one of the most important pests of cruciferous plants throughout the world. In recent years, this insect has been a serious pest for cabbage fields in Tehran province. Resistance of P. xylostella to all main groups of insecticides has been recorded and it is ranked in the 20 most resistant pest species reported up to now. According to many researchers, to eliminate the problem of pest resistance to chemical pesticides, an integrated pest management programme should be used. In line with this, the uses of microbial control agents (MCAs) are discussed. The bacterium, Bacillus thuringiensis (Bt) is one of microbial control agents of pests. It is characterised by its ability to produce proteic crystalline inclusions during sporulation. Cry1 protein has insecticidal activity and is highly specific to certain insects and not toxic to unrelated insects, plants or vertebrates. In this work, the pathogenicity of some Bt isolates, including Dipel, 20, 29, 79 and 87, was tested against P. xylostella and the lethal concentrations (LC₅₀) of their crystal proteins to P. xylostella third larval instar was determined. The experiment was designed in factorial in randomised complete design with 5 treatments (different concentrations including 10⁴, 10⁵, 10⁶, 10⁷, 10⁸ CFU/ml and 5 replications and with 10 third larval instars. Spore–crystal complex was applied to the surface of natural diets (cabbage leaves) and the mortality of P. xylostella larvae was assessed 120?h after exposure of Bt toxin in each treatment. Results showed that percentage of survival was significantly higher for control treatment. Results also showed that after 5?days, LC₅₀ for isolates of Dipel, 20, 29, 79 and 87 were equal to 1?×?10⁶, 1?×?10⁵, 5?×?10⁵, 4?×?10⁵ and 1?×?10⁴ CFU/ml, respectively. LT₅₀ were equal to 93.71, 48.04, 71, 40.49 and 75.28?h. Of and most the percentage larval mortality relate to attendance 87 and also at least percentage mortality is related to the groom Dipel.     

Effect of K application on leaf carbonic anhydrase and nitrate reductase activities, photosynthetic characteristics, NPK and NO3 contents, growth, and yield of mustard

In a sand culture experiment on mustard (Brassica juncea L. Czern. & Coss) cv. Varuna, all tested characteristics at 60 d stage and yield characteristics at harvest were enhanced by K application as its levels increased from 5 to 10, 15, 20, 25, and 30 mM K, with 20 mM K proving best.     

Interactions between the diamondback moth, Plutella xylostella L. and glasshouse and outdoor-grown cabbage cultivars

Interactions between Brassica cultivars (cvs) and adult and larval stages of Plutella xylostella L. were examined. In six-way choice oviposition experiments, glasshouse-grown Chinese cabbage cv. Tip Top was preferred to five outdoor-grown temperate cabbage cultivars but was similar to four out of five tropical cultivars. Bionomic studies with neonate larvae on temperate cabbage cultivars showed that mean larval duration was longer and percentage survival less on older compared with younger plants but that plant age or cultivar had little effect on pupal weight. The fecundity of P. xylostella reared on outdoor-grown cabbage cultivars varied ten-fold between the poorest and the best cultivar but plant age had little effect on P. xylostella reared on Chinese cabbage. In a glasshouse experiment, survival of P. xylostella on Chinese cabbage was significantly greater compared with field-grown glossy-leaved, normal bloom green cabbage and red cabbage. In bioassays with neonate larvae, when the leaves were placed vertically instead of horizontally a significant level of intrinsic resistance was revealed for glasshouse and field-grown glossy-leaved cabbage but not for Chinese cabbage. Observed differences in host status to P. xylostella are discussed in relation to the potential for partial plant resistance in control programmes.     

Characteristic of parasitism of diamondback moth by two larval parasites

Laboratory and greenhouse studies were conducted to investigate the suitability of 2 hymenopterous parasites,Diadegma eucerophaga Horstmann andApanteles plutellae Kurdjumov for introduction to control diamondback moth (DBM),Plutella xylostella (L.), a destructive pest of crucifers in tropical to subtropical Southeast Asia. Parasitism byD. eucerophaga was high at temperature range of 15°C to 25°C and that ofA. plutellae, at 20°C to 35°C. Both parasites were active in searching for host and oviposited only during photophase. No parasitism was observed during darkness. WhereasA. plutellae could parasitize all instars of DBM larvae,D. eucerophaga parasitized only the first 3 instars and failed to parasitize the 4^th. Parasitism byD. eucerophaga was greater when DBM larvae were feeding on common cabbage (Brassica oleracea var.capitata L.), than on cauliflower (B. oleracea var.italica L.), broccoli (B. oleracea var.botrytis L.) or Chinese cabbage [Brassica campestris L. ssp.pekinensis (Lour) Olsson].A. plutellae parasitism was greater when DBM larvac were feeding on Chinese cabbage than on common cabbage, cauliflower or broccoli. Storage of pupae at 0°C and 4°C to 6°C for up to 2 weeks reduced emergence ofD. eucerophaga adults more than that ofA. plutellae. A non-selective insecticide, deltamethrin, was toxic to adults of both parasites but selective ones such asBacillus thuringiensis, teflubenzuron, and pirimicarb were not. Pupae were more tolerant than adults to insecticides. The insecticide-resistant Luchu strain and susceptible laboratory strain of DBM suffered an equal level of parasitism by both parasites.      

Virulence analysis and genetic diversity of Xanthomonas campestris pv. campestris causing black rot of crucifers

Xanthomonas campestris pv. campestris (Xcc) is a devastating bacterium to cause black rot disease in crucifers. To study the genetic diversity and virulence analysis, 24 isolates of Xcc were collected from cole crops including cauliflower, cabbage, broccoli and knol khol from different agro-climatic regions of India ranging from temperate to subtropical climates. For virulence analysis, 24 isolates of Xcc were tested on 27 cultivars of crucifers including seven species of Brassica spp. (B. campestris, B. carinata, B. juncea, B. napus, B. nigra, B. oleracea and B. rapa), Sinapsis alba, Eruca sativa and Raphanus sativus under field conditions at IARI, New Delhi, during November 2010–March 2011. Maximum disease incidence 85.15% was found in the cultivars of crucifers caused by strains Xcc-C124, Xcc-C6, Xcc-C125, Xcc-C111 and Xcc-C131 after 15 days of inoculation and significantly increased after 30 days. Black rot severity in cultivars of crucifers varied from 0 to 6.9 and 0 to 7.9 out of 9 scale after 15 and 30 days of inoculation, respectively. But, no disease incidence was recorded on all the tested cultivars of B. juncea (Pusa Bold, Varuna, Pusa Mustard-21 and Pusa Vijay) against all the strains of Xcc after 15 days. Genetic diversity of 24 strains of Xcc was studied using REP- and BOX-PCR, indicating the existence of wide range of genetic diversity among the strains. The strains were clustered into two groups at 50% similarity coefficient and designated as Group 1 and Group 2. The majority of the strains (23 strains) were clustered under Group 1 except Xcc-C120, which formed separate group (Group 2). In the present study, genetic diversity and virulence pattern in Indian strains of Xcc were established, which will be helpful in the development of resistant genotypes against this bacterial pathogen.     

Efficacy of entomopathogenic nematode,Steinernema carpocapsae against the diamondback moth,Plutella xylostella (L.) in laboratory condition

In vitro studies were carried out on the diamondback moth, Plutella xylostella larvae using an insect entomopathogenic nematode isolate, Steinernema carpocapsae obtained from the Koppert company, the Netherlands. Larvae of P. xylostella were collected from cabbage farms around Mashhad city of Iran. During the study, the responses of larvae at 25?°C for three periods of 24, 48 and 72?h with different concentrations of 0, 5, 10, 20, 40, 80, 160 and 320 third instar larvae of nematode (infective stage?=?IJs) per insect into 10?cm Petri dishes containing filter paper soaked with 1?ml of nematodes suspension were compared. Maximum mortality caused by S. carpocapsae nematode was 88% at 24?h, and it was 100% at 48 and 72 h. With increasing nematode population level and exposure time (ET in hour), mortality of P. xylostella larvae was increased. Based on probit analysis, LC₅₀ values of S. carpocapsae nematode in three test periods were 45.61, 12.02 and 40.80 IJs per insect, respectively. Initial ANOVA was performed for S. carpocapsae nematode. The effect of both nematode population levels (IJ) and ET on third instar larvae of the diamondback moth, P. xylostella and interaction between IJ and ET were significant. In general, it is recommended to apply this nematode in suitable condition for controlling diamondback moth.