Turbulence Measurements in Swirling Flows

Investigation have been conducted to find out the region of high turbulent intensities in a swirling jet passing through a divergent passage. A hot wire anemometer is used to measure the turbulence intensity using a four position method. It has been concluded that the jet spreads with increasing diffuser angle and the region of high turbulent intensity also spreads. The high turbulence intensity region lies around the recirculation zone and it decays rapidly along the main flow direction

Survival and development of Helicoverpa armigera on artificial diet impregnated with lyophilized leaf and pod powder of different chickpea genotypes

Host plant resistance is one of the components for minimizing the damage by the noctuid pod borer, Helicoverpa armigera in chickpea. However, due to variations in H. armigera infestations in space and time, it becomes difficult to evaluate the test material in under natural infestation. Therefore, we evaluated the diet impregnation assay to evaluate chickpea genotypes for resistance to H. armigera. Ten-day old larvae weighed highest on the standard diet, followed by those reared on diets with leaf powder of the susceptible checks, ICC 4918 and ICCC 37. Larval weights were significantly lower in larvae reared on the leaves/pods of ICC 12476, ICC 12477, ICC 12478, ICC 12479 and ICCV 2 as compared to those reared on the susceptible check, ICC 12426. The larvae reared on artificial diet impregnated with lyophilized leaf and/or pod powder of ICC 12475, ICC 12476, ICCV 2, and ICC 12479 also weighed significantly lower than those fed on diets with ICC 12426, and ICC 3137. Of these, larval period was prolonged on fresh leaves/pos of ICC 506, and in diets with pod powder of ICC 3137, ICC 12479, ICCV 2, and ICC 506. Comparatively lower pupal weights were recorded in larvae reared on fresh leaves/pods and on artificial diets with leaf and pod powder of ICC 12476, ICC 12477, ICC 12478, and ICC 506 as compared to those on ICCC7 37; while larval survival, pupation, and adult emergence were lower on the fresh leaves/pod and on artificial diets with leaf and pod powder of ICC 12476, ICC 12477, ICC 12478, and ICC 506 as compared to the insects reared on the susceptible checks, ICC 37 and ICC 4918. Larval survival and development were also adversely affected on the F1 hybrids based on these genotypes as compared the susceptible check, ICCC 37. There was a significant reduction in fecundity of insects reared on the fresh leaves/pods and on artificial diets with leaf and pod powder of ICC 12476, ICC 12477, ICC 12478, ICC 12479, and ICC 506 as compared to the insects reared on ICCV 2, ICC 4918, and ICCC 37. The results indicated that the antibiosis to H. armigera in chickpea is expressed in terms of slower development, and reduced survival and fecundity. Survival and development of H. armigera of fresh leaves/pods and on diets with lyophilized leaf and pod powder of different chickpea genotypes were highly correlated suggesting that diet impregnation assay can be used to assess antibiosis component if resistance to H. armigera in chickpea

Incorporation of lyophilized leaves and pods into artificial diets to assess the antibiosis component of resistance to pod borer Helicoverpa armigera (Lepidoptera: Noctuidae) in chickpea

Host-plant resistance is one of the major components of integrated pest management programmes against the noctuid pod borer Helicoverpa armigera (Hu¨ bner) in chickpea. Survival and development of H. armigera on nine chickpea genotypes were compared using two food substrates, namely fresh leaves and pods, and artificial diets containing lyophilized leaf or pod powder of the same genotypes. Among the genotypes used, six showed different levels of resistance to H. armigera, while three were used as susceptible checks. Using leaves and pods, five of the resistant genotypes yielded lower larval weights compared to one of the susceptible checks used. Significant differences between four of the resistant and two of the susceptible genotypes were also observed when using artificial diets containing leaf or pod powder, but the rankings were different from that on the fresh leaves and pods. On both substrates, four resistant genotypes resulted in lower larval survival, pupation, adult emergence and fecundity when compared to one of the susceptible checks. A similar trend was also observed for larval survival and development when using F1 hybrids based on four of the resistant genotypes. Survival and development of H. armigera on the two food substrates, fresh leaves and pods and artificial diets with lyophilized leaf or pod powder, were highly correlated, suggesting that incorporation of lyophilized leaves or pods into the artificial diet can be used to assess antibiosis to H. armigera in chickpea

Mechanisms of resistance to Helicoverpa armigera and introgression of resistance genes into F1 hybrids in chickpea

The noctuid pod borer, Helicoverpa armigera is a major pest of chickpea, and host plant resistance is an important component for managing this pest. We evaluated a set of diverse chickpea genotypes with different levels of resistance to H. armigera, and their F1 hybrids for oviposition non-preference, antibiosis, and tolerance components of resistance under uniform insect infestation under greenhouse/laboratory conditions. The genotypes ICC 12476, ICC 12477, ICC 12478, ICC 12479, and ICC 506EB were non-preferred for oviposition under no-choice, dual-choice, and multi-choice conditions, and also suffered lower leaf damage in no-choice tests as compared to the susceptible check, ICCC 37. Antibiosis expressed in terms of low larval weights was observed in insects reared on ICC 12476, ICC 12478, and ICC 506EB. Weight gain by the third-instars was also low on ICC 12476, ICC 12477, ICC 12478, ICC 12479, and ICC 506EB at the podding stage. Non-preference for oviposition and antibiosis (poor larval growth) were also expressed in hybrids based on ICC 12477, ICC 12476, ICC 12478, ICC 12479, and ICC 506EB as compared to the hybrids based on the susceptible check, ICCC 37, indicating that oviposition non-preference and antibiosis in the F1 hybrids is influenced by the parent genotype. Loss in grain yield was lower in ICC 12477, ICC 12478, ICC 12479, and ICC 506EB compared to that on ICCC 37. The genotypes ICC 12477, ICC 12478, ICC 12479, and ICC 506EB showing antixenosis, antibiosis, and tolerance mechanism of resistance to H. armigera can be used for developing chickpea cultivars for resistance to this pest

Expression of resistance to the pod borer Helicoverpa armigera (Lepidoptera: Noctuidae), in relation to high-performance liquid chromatography fingerprints of leaf exudates of chickpea

The noctuid moth Helicoverpa armigera (Hubner) is the most damaging pest of chickpea worldwide. Plant resistance is an important component for the management of this pest. To develop cultivars with resistance to insects, it is important to understand the role of different components associated with resistance to insects. Therefore, we characterized a diverse array of chickpea genotypes for organic acid profiles in the leaf exudates that are associated with resistance to H. armigera. Chickpea leaf exudates contained five major organic acids that were identified as malic, oxalic, acetic, citric and fumaric acids. High-performance liquid chromatography (HPLC) profiles of the leaf exudates of nine chickpea genotypes showed that amounts of malic acid were negatively correlated with leaf feeding by H. armigera larvae at flowering and maturity, and with pod damage. Oxalic acid showed a negative association with leaf damage in the detached leaf assay. Additionally, the amounts of acetic acid were negatively correlated with larval weights and damage rating at the flowering and maturity stages. Citric acid levels were negatively associated with damage rating at the flowering stage. Implications of using the HPLC profiles of organic acids in the leaf exudates of chickpea to breed for resistance to H. armigera are discussed

Nature of Gene Action and Maternal Effects for Pod Borer, Helicoverpa armigera Resistance and Grain Yield in Chickpea, Cicer arietinum

Information on mechanisms and inheritance of resistance is critical to plan an effective strategy to breed for resistance to insect pests. Therefore, we evaluated a diverse array of chickpea genotypes (eight desi and one kabuli) with varying levels of resistance to the pod borer, Helicoverpa armigera to gain an understanding of the nature of gene action and possible maternal effects. The test genotypes were crossed in all possible combinations for a full diallel. The 72 F1s (36 direct and 36 reciprocal crosses) along with the parents were evaluated for resistance to H. armigera under field conditions, and for antibiosis mechanism of resistance (larval survival and larval weight gain) by using detached leaf assay under laboratory conditions, and grain yield under un-protected conditions in the field. Additive gene action governed the inheritance of resistance to H. armigera, while non-additive type of gene action was predominant for inheritance of antibiosis component of resistance (larval survival and larval weight) and grain yield. Greater magnitude of σ2 A(17.39 and 1.42) than σ2 D (3.93 and 1.21) indicated the preponderance of σ2 Ain inheritance of resistance to pod borer, H. armigera under laboratory and field conditions, respectively. There were no maternal effects for inheritance of resistance to pod borer and grain yield. Lines with significant gca effects for pod borer damage and grain yield were identified for further use in the resistance breeding program. The implications of the inheritance pattern of pod borer resistance and grain yield are discussed in the context of strategies to enhance pod borer resistance and grain yield in chickpea

Fitness of Isogenic Colony Morphology Variants of Pseudomonas aeruginosa in Murine Airway Infection

Chronic lung infections with Pseudomonas aeruginosa are associated with the diversification of the persisting clone into niche specialists and morphotypes, a phenomenon called ‘dissociative behaviour’. To explore the potential of P. aeruginosa to change its morphotype by single step loss-of–function mutagenesis, a signature-tagged mini-Tn5 plasposon library of the cystic fibrosis airway isolate TBCF10839 was screened for colony morphology variants under nine different conditions in vitro. Transposon insertion into 1% of the genome changed colony morphology into eight discernable morphotypes. Half of the 55 targets encode features of primary or secondary metabolism whereby quinolone production was frequently affected. In the other half the transposon had inserted into genes of the functional categories transport, regulation or motility/chemotaxis. To mimic dissociative behaviour of isogenic strains in lungs, pools of 25 colony morphology variants were tested for competitive fitness in an acute murine airway infection model. Six of the 55 mutants either grew better or worse in vivo than in vitro, respectively. Metabolic proficiency of the colony morphology variant was a key determinant for survival in murine airways. The most common morphotype of self-destructive autolysis did unexpectedly not impair fitness. Transposon insertions into homologous genes of strain PAO1 did not reproduce the TBCF10839 mutant morphotypes for 16 of 19 examined loci pointing to an important role of the genetic background on colony morphology. Depending on the chosen P. aeruginosa strain, functional genome scans will explore other areas of the evolutionary landscape. Based on our discordant findings of mutant phenotypes in P. aeruginosa strains PAO1, PA14 and TBCF10839, we conclude that the current focus on few reference strains may miss modes of niche adaptation and dissociative behaviour that are relevant for the microevolution of complex traits in the wild

A Note on Measurement of Flame Turbulence

A relatively new method for the measurement of flame turbulence, by measuring negative static pressure, has been employed for the measurement of turbulence in a cold jet and behind a three dimensional flameholder

A solar thermal water pump

The pump employs pentane as the working substance -- an organic fluid with a low boiling point. A flat-plate solar collector generates vapour and its pressure is adequate to pump water from a well. Provision of a separate tank for storing the vapour under pressure improves the performance of the pump. Experiments prove its feasibility and yield useful performance characteristics.