Substitution of live feed by formulated diet: effect on the growth and survival of Betta splendens (Regan) fry

The present work evaluates the effectiveness of partial or total replacement of live feed (LF) (Tubifex) together with formulated diet (FD) for Betta splendens. Three hundred Betta splendens fry of uniform size (mean weight 0.19±0.01g) were equally distributed in five treatment groups with three replicates in glass aquaria of 351itre capacity. Fishes were given diets at different ratio of LF and FD viz. T1(C) 100% LF; T2 75% LF, 25% FD; T3 50% LF, 50% FD; T4 25% LF, 75% FD and T5 100% FD and the experiment continued for 105 days. T2 group registered highest (P<0.05) % body weight gain (125.61±0.26) and specific growth rate (2.34±0.02), which was similar to T1 and T3 groups. Lowest FCR was recorded in T2 (2.40±0.11) group, which was similar to Tl, T3 and T4 groups. Highest (P<0.05) PER was observed in T4 (1.00±0.03) group, which was similar to T3 and T5 groups. At the end of experiment, highest % survival was recoded in T1, T2 and T3 groups (96.67±1.67), which was similar to T4 group. From the study, it is concluded that LF can be successfully replaced up to 75% by FD without any adverse effect on the growth and survival of Betta splendens

Drought yield index to select high yielding rice lines under different drought stress severities

BACKGROUND Drought is the most severe abiotic stress reducing rice yield in rainfed drought prone ecosystems. Variation in intensity and severity of drought from season to season and place to place requires cultivation of rice varieties with different level of drought tolerance in different areas. Multi environment evaluation of breeding lines helps breeder to identify appropriate genotypes for areas prone to similar level of drought stress. From a set of 129 advanced rice (Oryza sativa L.) breeding lines evaluated under rainfed drought-prone situations at three locations in eastern India from 2005 to 2007, a subset of 39 genotypes that were tested for two or more years was selected to develop a drought yield index (DYI) and mean yield index (MYI) based on yield under irrigated, moderate and severe reproductive-stage drought stress to help breeders select appropriate genotypes for different environments. RESULTS ARB 8 and IR55419-04 recorded the highest drought yield index (DYI) and are identified as the best drought-tolerant lines. The proposed DYI provides a more effective assessment as it is calculated after accounting for a significant genotype x stress-level interaction across environments. For rainfed areas with variable frequency of drought occurrence, Mean yield index (MYI) along with deviation in performance of genotypes from currently cultivated popular varieties in all situations helps to select genotypes with a superior performance across irrigated, moderate and severe reproductive-stage drought situations. IR74371-70-1-1 and DGI 75 are the two genotypes identified to have shown a superior performance over IR64 and MTU1010 under all situations. CONCLUSION For highly drought-prone areas, a combination of DYI with deviation in performance of genotypes under irrigated situations can enable breeders to select genotypes with no reduction in yield under favorable environments compared with currently cultivated varieties. For rainfed areas with variable frequency of drought stress, use of MYI together with deviation in performance of genotypes under different situations as compared to presently cultivated varieties will help breeders to select genotypes with superior performance under all situations.Anitha Raman, Satish Verulkar B, Nimai Mandal P, Mukund Variar, V Shukla D, J Dwivedi L, B Singh N, O Singh N, Padmini Swain, Ashutosh Mall K, S Robin, R Chandrababu, Abhinav Jain, Tilatoo Ram, Shailaja Hittalmani, Stephan Haefele, Hans-Peter Piepho, and Arvind Kuma

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Epistatic interactions of major effect drought QTLs with genetic background loci determine grain yield of rice under drought stress

Epistatic interactions of QTLs with the genetic background and QTL-QTL interaction plays an important role in the phenotypic performance of introgression lines developed through genomic-assisted breeding (GAB). In this context, NIL pairs developed with various drought QTL (qDTY) combinations in the genetic background of IR64, TDK1-Sub1 and Savitri backgrounds were utilized to study the interactions. Multi-season phenotyping of NIL pairs harboring similar qDTY combinations provided contrasting performance for grain yield under drought (RS) (classified as high and low yielding NILs) but nearly similar performance under non-stress(NS) conditions. Genome wide genotyping data revealed a total of 16, 5 and 6 digenic interactions were detected under RS conditions in low yielding NILs of IR64, TDK1-Sub1 and Savitri respectively while no significant interaction was found in high yielding NILs under RS and NS conditions in any of the genetic backgrounds used in this study. It is evident from this study that existence of epistatic interactions between QTLs with genetic background, QTL-QTL interaction and interactions among background markers loci itself on different chromosomes influences the expression of a complex trait such as grain yield under drought. The generated information will be useful in all the GAB program of across the crops for precise breeding

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Not AvailableA 60 - day feeding trial was conducted to study the effect of dietary microbial levan on growth performance and metabolic responses of Cyprinus carpio fry exposed to sublethal dose (1/10th LC₅₀) of fipronil [(±) - 5 - amino - 1 - (2,6 - dichloro - α,α,α - trifluoro - p - tolyl) - 4 - trifluoromethylsulfinylpyrazole - 3 - carbonitrile]. Two hundred and twenty five fry were randomly distributed in five treatments in triplicates. Four purified diets were prepared with graded levels of microbial levan. Five different treatment groups were levan control L₀P₀ (basal feed + 0 % levan without exposure to pesticide); pesticide control L₀P₁ (basal feed + 0 % levan with exposure to pesticide); L₀.₂₅P₁ (basal feed + 0.25 % levan with exposure to pesticide); L₀.₅₀P₁ (basal feed + 0.50 % levan with exposure to pesticide); and L₀.₇₅P₁ (basal feed + 0.75 % levan with exposure to pesticide). Weight gain% and specific growth rate were significantly higher (p < 0.05) in levan fed groups compared to their non - levan fed counterpart. Highest (p < 0.05) content of ascorbic acid in muscle, liver and brain tissues was observed with higher level of dietary levan. Glucose - 6 - phosphate dehydrogenase activity decreased with the increasing level of dietary levan in the liver and muscle. Aspartate aminotransferase activity exhibited a second order polynomial relationship with the dietary levan, both in liver (Y = - 1.001x² + 5.366x + 5.812, r² = 0.887) and muscle (Y = - 0.566x² + 2.833x + 6.506, r² = 0.858) while alanine aminotransferase activity showed third order polynomial relationship both in liver (Y = 1.195x³ - 12.30x² + 35.23x + 9.874, r² = 0.879) and muscle (Y = 0.527x³ - 8.429x² + 31.80x + 8.718, r² = 0.990). Highest (p < 0.05) superoxide dismutase activity in gill was observed in the group fed with 0.75 % levan supplemented diet. Overall results indicated that dietary microbial levan at 0.75 % in C. carpio fry ameliorated the negative effects of fipronil and augmented the growth.Not Availabl