Influence of duration of aeration on growth and survival of carp fingerlings during high density seed rearing

Impact of varied durations of aeration on growth, survival and production performances of catla (Catla catla), rohu (Labeo rohita), fringe lipped carp (Labeo fimbriatus) and olive barb (Puntius sarana) were evaluated in outdoor concrete tanks (10 m × 5 m × 1.3 m) during fingerlings rearing. At a combined stocking density of 0.5 million fry/ha, provision of night time aeration for 4, 8 and 12 h was evaluated as the three treatments, T-I, T-II and T-III, respectively against control (T-c, without aeration). Overall survival and net biomass of the species increased among the treatments significantly as a function of aeration hours (T-c < T-I < T-II < T-III). Aeration for 8 and 12 h showed significantly higher survival, harvested body weight and SGR in all the carps than those with 4 h (T-I) and no aeration (T-c), suggesting 8–12 h of aeration requirement for fingerlings rearing at such high density. Further, no significant difference between survival levels in T-II and T-III groups suggested 8 h of aeration to be adequate. However, while species-wise performance showed 8–12 h night time aeration to be advantageous for catla and rohu, aeration for 4 h was adequate for fringe lipped carp and olive barb.     

On the constitutive equations of the orthotropic theory of creep

Summary Creep equations have been formulated for the multi-axial state of stress for an orthotropic medium, based on an invariant proposed by Hill for theory of plasticity. Anyone of the numerous creep laws suggested from time to time by different investigators on the basis of experiments can then be used in these equations giving a complete set of equations for the solution of creep problems in orthotropic medium. Two simple applications are also discussed. An example in which principal axes of stress do not coincide with axes of anisotropy tension of a bar is discussed. Another example, that of compression under conditions of plane strain, illustrates variation of stress with time although load is kept constant. It is shown that in this case {ie142-1} relaxes to the final value {ie142-2} after a few times the retardation time.

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Zusammenfassung Gleichungen zur Berechnung von Kriechdehnungen wurden für den mehrachsigen Spannungszustand orthotroper Stoffe aufgestellt, deren Grundlage eine von Hill für die Plastizitätstheorie vorgeschlagene Konstante bildet. Jedes der zahlreichen Kriechgesetze, die von verschiedenen Autoren auf Grund von Versuchen immer wieder vorgeschlagen wurden, kann mit Hilfe dieser Gleichungen Anwendung finden und bildet ein vollständiges Gleichungs-system zur Lösung von Kriechproblemen in orthotropen Stoffen. Desgleichen werden zwei einfache Anwendungsmöglichkeiten erörtert. Ein Beispiel wird dargestellt, in welchem die Haupt-Spannungsachsen nicht mit den Achsen der anisotropen Zugspannung in einem Balken zusammenfallen. Ein weiteres Beispiel mit Druckbelastung veranschaulicht bei Annahme einer ebenen Dehnung die Änderungen des Spannungszustandes mit der Zeit, wenn die Belastung konstant bleibt. Es wird gezeigt, daß sich in diesem Fall {ie142-3} bis zu dem Endwert {ie142-4} ermäßigt nach einer Zeit, die einem Mehrfachen der Retardierungszeit entspricht.

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The second author gratefully aknowledges the grant of a C.S.I.R. fellowship.     

Arbuscular mycorrhizae in micropropagation systems and their potential applications

Over the past few years, micropropagation techniques are being widely used as an important and advantageous tool for rapid propagation of several commercially important varieties of horticultural and forest tree species. Although, this technology has got several successful applications, low survival rates and poor growth while shifting these plantlets to field conditions are the most common problems which hinders its usage for commercial plant production practices. Inoculation of arbuscular mycorrhizal fungi (AMF) to the roots of micropropagated plantlets plays a beneficial role on their post-transplanting performance. This review discusses the multiple roles played by AMF in the establishment of micropropagated plantlets. Different techniques of mycorrhization and the constraints pertaining to the use of these techniques are also discussed.     

Field evaluation and economics of insecticides against the major pests of okra

Abstract

Bio‐efficacy of 15 insecticides was evaluated against the pest complex of okra in the semi‐arid region of Rajasthan during July‐October, 1984. Five sprays given at intervals of 15 days throughout the crop period indicated that fenvalerate (0.02%) was most effective, followed by permethrin (0.02%), cypermethrin (0.02%), carbaryl (0.10%), monocrotophos (0.04%) and dimethoate (0.03%), against leafhoppers, aphids and fruit borer. The maximm yield of marketable fruits was obtained with fenvalerate, followed by cypermethrin, carbaryl, monocrotophos and dimethoate treatments. Highest net‐profit of Rs. 4890.00 was also recorded with fenvalerate treatment, followed by Rs. 4430.00 with carbaryl, Rs. 4148.00 with permethrin, Rs. 3977.00 with monocrotophos and Rs. 3053.00 with dimethoate treatments. A higher benfit cost ratio was found with carbaryl (1:9.78), followed by dimethoate (1:7.85), monocrotophos (1:5.18), methyl demeton (1:5.07), fenvalerate (1:3.43) and permethrin (1:2.41). These insecticides can also be used against insect pests of other vegetable crops of the season.     

Modulation of cell adhesion and motility in the immune system by Myo1f

Although class I myosins are known to play a wide range of roles, the physiological function of long-tailed class I myosins in vertebrates remains elusive. We demonstrated that one of these proteins, Myo1f, is expressed predominantly in the mammalian immune system. Cells from Myo1f-deficient mice exhibited abnormally increased adhesion and reduced motility, resulting from augmented exocytosis of beta2 integrin-containing granules. Also, the cortical actin that co-localizes with Myo1f was reduced in Myo1f-deficient cells. In vivo, Myo1f-deficient mice showed increased susceptibility to infection by Listeria monocytogenes and an impaired neutrophil response. Thus, Myo1f directs immune cell motility and innate host defense against infection.     

Aflatoxin Accumulation and Associated Traits in QPM Maize Inbreds and their Testcrosses

Preharvest aflatoxin (AF) contamination by Aspergillus flavus Link:Fr is one of the main limitations for maize (Zea mays, L.) production in the southern USA, causing enormous economic losses and posing a risk to animal and human health. The objectives of this study were (1) to estimate aflatoxin accumulation and expression of associated traits in quality protein maize (QPM) inbreds and their testcrosses, (2) to compute their repeatabilities and correlations, and (3) to study the relationship between inbred lines and their testcrosses for aflatoxin accumulation. Forty-eight inbreds and their testcrosses plus checks were grown in one and three locations in south and central Texas, respectively. Aflatoxin concentration was evaluated in the plants following inoculation with A. flavus. Average aflatoxin concentration overall for inbreds was 286.3 ng g⁻¹, and for testcrosses 596.5 ng g⁻¹ at Corpus Christi, TX, 325.1 ng g⁻¹ at Weslaco, TX, and 105.1 ng g⁻¹ at College Station, TX. Flinty orange inbreds developed from CIMMYT Population 69 were the least susceptible to aflatoxin accumulation in both inbreds and testcrosses at all locations. Repeatability for aflatoxin was 0.67 in inbreds at Weslaco, TX and 0.54 in testcrosses across locations. Aflatoxin in testcrosses was positively correlated both phenotycally and genotypically with endosperm texture and kernel integrity, and negatively correlated with grain yield and silking date. Less aflatoxin accumulation was associated with flinty endosperm texture, better kernel integrity, and later maturities. Association between the expression of traits in inbreds and aflatoxin in testcrosses was relatively high for endosperm texture (R ² = 0.62), silking date (R ² = 0.44), kernel integrity (R ² = 0.39), and aflatoxin (R ² = 0.60 for log ng g⁻¹). It seems plausible to select for associated traits having high heritabilities and strong correlation with aflatoxin, in addition to low aflatoxin accumulation in inbreds and hybrids to reduce the risk of aflatoxin contamination.     

Response of wheat and maize to different nitrogen sources: I. Plant growth and biomass accumulation

Maize (Zea mays L., hyhrid Pioneer 3737) and wheat (Triticum aestivum L., cultivar Jantar) were grown hydroponically in nutrient solutions containing 10 mM nitrogen (N) as either the nitrate (NO₃) anion or the ammonium (NH₄) cation or in a 1:1 combination of both. Maize and wheat plants had different responses to the N sources. Maize growth and biomass accumulation were greatest with the equal combination of NO₃ and NH₄, while NO₃ only was more favourable for wheat. The effects of the different N sources were detected on the 14th and 21st day for maize and wheat plants, respectively.