Decrease of rice plant resistance and induction of hormesis and carboxylesterase titre in brown planthopper, Nilaparvata lugens (Stål) by xenobiotics

The brown planthopper (BPH), Nilaparvata lugens (Stål) is a serious threat to the rice production throughout Asia. The indiscriminate application of various xenobiotics in rice ecosystem is perceived as one of the factors for the frequent outbreak of BPH. The present study has critically analysed the secondary effects of some xenobiotics used in rice field on certain plant and insect parameters that subsequently favour BPH outbreak. Application of 2,4-D, carbendazim, deltamethrin and urea reduced the innate BPH resistance of PTB 33 rice variety due to favourable alterations in rice free amino acid and sucrose content. Similarly, these chemicals also induced hormesis and enhanced feeding in BPH. Alternatively, soil amendment with neem seed powder and Calotropis gigantea leaves improved plant innate resistance and showed no sign of hormesis or enhanced feeding in BPH. In addition, deltamethrin has the ability to stimulate BPH carboxylesterase titre. Native PAGE analysis of esterases from whole body homogenate of BPH revealed at least five esterase isozyme bands, prominent being E1 and E2. However, no difference in BPH esterase banding pattern was observed between different xenobiotic treatments. All these esterase bands are classified under carboxylesterase based on their inhibition by class specific esterase inhibitors.     

Agroforestry as a strategy for carbon sequestration

During the past three decades, agroforestry has become recognized the world over as an integrated approach to sustainable land use because of its production and environmental benefits. Its recent recognition as a greenhouse gas–mitigation strategy under the Kyoto Protocol has earned it added attention as a strategy for biological carbon (C) sequestration. The perceived potential is based on the premise that the greater efficiency of integrated systems in resource (nutrients, light, and water) capture and utilization than single‐species systems will result in greater net C sequestration. Available estimates of C‐sequestration potential of agroforestry systems are derived by combining information on the aboveground, time‐averaged C stocks and the soil C values; but they are generally not rigorous. Methodological difficulties in estimating C stock of biomass and the extent of soil C storage under varying conditions are compounded by the lack of reliable estimates of area under agroforestry. We estimate that the area currently under agroforestry worldwide is 1,023 million ha. Additionally, substantial extent of areas of unproductive crop, grass, and forest lands as well as degraded lands could be brought under agroforestry. The extent of C sequestered in any agroforestry system will depend on a number of site‐specific biological, climatic, soil, and management factors. Furthermore, the profitability of C‐sequestration projects will depend on the price of C in the international market, additional income from the sale of products such as timber, and the cost related to C monitoring. Our knowledge on these issues is unfortunately rudimentary. Until such difficulties are surmounted, the low‐cost environmental benefit of agroforestry will continue to be underappreciated and underexploited.     

Effect of higher levels of dietary selenium on production performance and immune responses in growing Japanese quail

1. The effect of increasing dietary selenium (Se) on production performance and immune responses in growing (0 to 6 weeks) Japanese quail was investigated. 2. One-day-old chicks (240) were randomly selected and divided into 12 groups with 20 chicks in each group (3 dietary treatments x 4 replicates). The basal diet contained 0.2 mg Se/kg and the two experimental diets were supplemented with 0.5 and 1.0 mg Se/kg. 3. Body weight gain, food intake and food conversion ratio and mortality were not affected by Se supplementation. 4. On d 28, antibody responses to inoculated sheep red blood cells were determined. Antibody titres were significantly higher after feeding the two Se-supplemented diets. 5. During week 4, the response to intradermally injected phytohaemagglutinin, an index of the in vivo cell-mediated immune response, was shown to be increased in the groups fed on the Se-supplemented diets. 6. After 6 weeks, the relative weights of the bursa of Fabricius and thymus were greater in the chicks given the Se-supplemented diets but there was no effect on the relative weight of spleen and liver. 7. It is concluded that supplementing the diet with Se has a beneficial effect on immune responses but does not affect production performance in growing Japanese quail.     

Effects of Salinity and Na+/K+ Ratio on Osmoregulation and Growth Performance of Black Tiger Prawn,Penaeus monodon Fabricius, 1798, Juveniles Reared in Inland Saline Water

A 60‐d growth trial was conducted with the black tiger prawn, Penaeus monodon (ca. 0.8 g juveniles) at CIFE Rohtak Centre to evaluate the effects of salinity and Na⁺/K⁺ ratio of inland saline water on shrimp growth, survival, and osmoregulation. Three different salinities (5, 10, and 15 ppt) and five different Na⁺/K⁺ ratios (25:1, 45:1, 65:1, 85:1, and 27.9:1), for a total of 15 treatments were prepared by ionic manipulation. The medium with Na⁺/K⁺ ratio 27.9 was reconstituted seawater and was used as the reference treatment. At the end of the 60‐d trial both salinity and Na⁺/K⁺ ratio significantly influenced the survival and growth of shrimp in inland saline water (P < 0.05). Final mean individual weight, weight gain (%) (WG [%]) increased with decreasing Na⁺/K⁺ ratios. Survival rates were significantly higher (P < 0.05) for Na⁺/K⁺ ratio 45 and 27.9 at salinities 10 and 15 ppt, respectively. Minimum growth and survival (0–24%) were observed in mediums with Na⁺/K⁺ ratio 85 at all salinities. Serum osmolality and osmoregulatory capacity were similar across all treatments at identical salinities except for sodium to potassium ratio (Na⁺/K⁺) 85. The serum sodium and potassium levels did not show any significant difference (P > 0.05) for mediums with Na⁺/K⁺ ratio 25, 45, 65, and 27.9 at all salinities. Significantly different (P < 0.05) serum sodium levels were observed in mediums with Na⁺/K⁺ ratio 85 at all salinities at the end of the trial. The serum potassium levels were significantly low in treatments with Na⁺/K⁺ ratio 85. There was no significant difference in the serum magnesium levels between treatments and the serum calcium levels were significantly lower for shrimp reared in the reference mediums. Results of this study confirm that P. monodon can be successfully cultured in low salinity waters with Na⁺/K⁺ ratio ranging between 25 and 45:1.     

Oxidative degradation of triazine derivatives in aqueous medium: a radiation and photochemical study

Pulse and steady state radiolysis techniques have been used to determine the bimolecular rate constants and to investigate the spectral nature of the intermediates and the degradation induced by hydroxyl radicals ((*)OH) with 1,3,5-triazine (T), 2,4, 6-trimethoxy-1,3,5-triazine (TMT), and 2,4-dioxohexahydro-1,3, 5-triazine (DHT) in aqueous medium. A competitive kinetic method with KSCN as the (*)OH scavenger was used to determine the rate constants for the reaction of (*)OH with T, TMT, and DHT. The bimolecular rate constants are 3.4 x 10(9), 2.06 x 10(8), and 1.61 x 10(9) dm(3) mol(-)(1) s(-)(1) respectively, for T, TMT, and DHT at pH approximately 6. The transient absorption spectra obtained from the reaction of (*)OH with T, TMT, and DHT have single absorption maxima at 320, 300, and 300 nm, respectively, and were found to undergo a second-order decay. The formation of TOH(*) [C(6)OH-N(5)-yl radical], TMTOH(*) [N(5)OH-C(6)-yl radical], and DHT(*) [C(6)-yl radical] is proposed from the initial attack of (*)OH with T, TMT, and DHT, respectively. A complete degradation of TMT (10(-3) mol dm(-3)) was obtained after absorbed doses of 5 kGy in N(2)O-saturated solutions and 16 kGy in aerated solutions. A similar degradation pattern was obtained with DHT in N(2)O-saturated solutions. Complete degradation was observed with an absorbed dose of 7 kGy. On the basis of the results from both pulse and steady state radiolysis, a possible reaction mechanism involving (*)OH-mediated oxidative degradation is proposed. A complete photodecomposition of DHT was also observed in the presence of ferric perchlorate using ultraviolet light at low pH. Photoinduced electron transfer between Fe(III) and DHT in the Fe(III)-DHT complex and subsequent formation of DHT(*) are proposed to be the major processes that lead to the complete degradation of DHT at pH 3.     

Exploitation of the late flowering species <Emphasis Type="Italic">Brassica oleracea</Emphasis> L. for the improvement of earliness in <Emphasis Type="Italic">B. napus</Emphasis> L.: an untraditional approach

The oilseed Brassica rapa flowers and matures earlier than B. oleracea, as well as their amphidiploid B. napus. Therefore, earliness of B. rapa has been investigated as a source of variation for earliness in B. napus breeding programs. Variation for days to flower exists in B. oleracea; however, its earliest flowering variant B. alboglabra flowers 2–3 weeks later than B. napus. We hypothesized that the C genome of B. alboglabra carries alleles for early flowering which are different from the C-genome alleles of B. napus; and these alleles can be used for the improvement of B. napus. To test this, we examined flowering time in pedigree and DH populations from two B. napus × B. alboglabra crosses. A B. napus line with about a week earlier flowering than the B. napus parent was achieved through reconstitution of its C genome following pedigree selection. Introgression of the B. alboglabra allele in the early flowering pedigree lines is also evident from the presence of B. alboglabra-specific SSR alleles in this line. However, application of doubled haploidy failed to generate any line that flowered earlier than the B. napus parent, which is probably due to the difficulty of obtaining large numbers of euploid B. napus DH lines from this interspecific cross. Thus, we demonstrate that a trait of the diploid species, which apparently looks undesirable, might in fact be highly valuable for the improvement of amphidiploids; and knowledge from this research can also be applied for other traits.     

Pseudostem rot caused byCorticium rolfsii,a new disease ofMusa sp. in Tamil Nadu,India

In 1987 a new disease, called pseudostem rot, was observed on 3–5-month-old banana plants(Musa sp.) cv. ’Robusta’. The pathogen was isolated in pure culture and identified asCorticium rolfsii (Sacc.) Curzi, teleomorph ofSclerotium rolfsii Sacc. The teleomorphic stage of the fungus was observed inside the pseudostem sheath. The pathogen produced leaf spot diseases (by basidiospores) on 16 tested host plants from various families.     

First molecular detection of porcine bocavirus in Malaysia

Several strains of porcine bocaviruses have been reported worldwide since their first detection in Sweden in 2009. Subsequently, the virus has been reported to be associated with gastrointestinal and respiratory signs in weaner and grower pigs. Although Malaysia is host to a self-sufficient swine livestock industry, there is no study that describes porcine bocavirus in the country. This report is the first to describe porcine bocavirus (PBoV) in Malaysian swine herds. PBoV was identified in various tissues from sick and runt pigs using the conventional PCR method with primers targeting conserved regions encoding for the nonstructural protein (NS1) gene. Out of 103 samples tested from 17 pigs, 32 samples from 15 pigs were positive for porcine bocavirus. In addition, a higher detection rate was identified from mesenteric lymph nodes (52.9%), followed by tonsil (37.0%), and lungs (33.3%). Pairwise comparison and phylogenetic analyses based on a 658-bp fragment of NS1 gene revealed that the Malaysian PBoV strains are highly similar to PBoV3 isolated in Minnesota, USA. The presence of porcine bocavirus in Malaysia and their phylogenetic bond was marked for the first time by this study. Further studies will establish the molecular epidemiology of PBoV in Malaysia and clarify pathogenicity of the local isolates.     

Impact of Fertility Variation on Gene Diversity and Drift in two Clonal Seed Orchards of Teak (Tectona grandis Linn. f.)

Two 25 year old teak clonal seed orchards comprising 15 (CSO-I) and 20 clones (CSO-II), respectively, selected mostly from moist forests of Western Ghats (latitude 10° N) in southern India, were evaluated for fertility, offspring diversity, and genetic drift. The orchards differed in fertility of clones as well as flower and fruit production per ramet. Fertility was highly skewed in CSO-II, where one clone (originating from higher latitude −17° N, in Eastern Ghats of peninsular India) produced 55% of the fruits and 68% of the flowers in the orchard, in contrast to a similar contribution from four most fertile clones in CSO-I. Fertility variation, measured as `sibling coefficient' (1.7 in CSO-I and 8.3 in CSO-II), was high in CSO-II resulting in high coancestry and low effective population size (3 times lower than CSO-I) in the seed crop. In CSO-I, 58% of the clones contributed effectively to seed production compared to only 12% effective contribution resulting in eight times higher genetic drift in CSO-II. Placing limits on how much seed can be collected per clone might be useful in restricting over representation of highly reproductive clones thereby increasing genetic diversity in the seed crop.