In Vitro Propagation of Selected Sugarcane ( Saccharum Officinarum L . ) Varieties ( C 86-165 and C 86-12 ) Through Shoot Apical Meristem
Sugarcane (Saccharum officinarum L.) is monocotyledonous crop plant that belongs to the Poaceae family that mostly propagates through conventional methods. However, conventional propagation lacks rapid multiplication procedures to commercialize newly released varieties within a short period of time. Hence, the objective of this work was to optimize in vitro micro propagation protocol for two sugarcane varieties (C 86-165 and C 86-12) using shoot apical meristem explants. The two varieties were cultured on MS medium supplemented with different concentrations of growth regulators on shoot initiation, multiplication and root induction stages. Analysis of variance (ANOVA) revealed that the two varieties showed statistically significant difference in their response to the various hormonal treatments with regard to the parameters measured. For initiation stage vars. C 86-165 and C 86-12 performed best on 1.0 mg/l and 0.5 mg/l of BAP, respectively. On the other hand, multiplication stage was best in MS media enriched with 2.0 mg/l BAP + 0.5 mg/l NAA and 1.5 mg/l BAP + 0.5 NAA as manifested in terms of number of shoots and shoot length per explants after four weeks of culture for vars. C 86-165 and C 86-12, respectively. With regard to root induction, best rooting response in terms of mean root number, mean root length, mean fresh weight and mean dry weight was achieved in 1/2 MS media enriched with 2.0.mg/l NAA and 1.0 mg/l NAA after four weeks of culture for vars. C 86-165 and C 86-12, respectively.
In vitro propagation of six selected sugarcane mutant clones through leaf explants
Six mutant clones of sugarcane with high productivity have been produced through tissue culture techniques combined with mutations using gamma-ray irradiation and Ethyl Methane Sulfonate. The six mutant clones have been tested for stability in the field. They are proven to have high productivity and yields, so that they are very potential to be developed as superior varieties. To support the planting material sufficiency of these clones, an efficient propagation method was needed. Media formulations with different physical properties and composition of growth regulators were tested to obtain high seedling propagation rates. The media formulation for callus induction was Murashige dan Skoog (MS) + 3 mg/l 2,4-D + 3 g/l casein hydrolysate + 3% sucrose and for shoot regeneration was MS + 0,5 mg/l BA + 0,1 mg/l IBA + 100 mg/l PVP and 2% sucrose. Shoot proliferation was carried out on MS liquid (1, ½) + (0.3; 0.5 mg/l) BA + 0.1 mg/l IBA + 1 mg/l Kinetin + (0; 0.5 mg/l) GA3+ sucrose 2%. The results showed that callus induction, callus regeneration, and shoot proliferation of sugarcane mutant clones were influenced by the genotype and medium composition. The fastest callus induction was obtained from the MSP-4 clone (5.82 days), and the longest was MSB-7 (8.82 days). The largest callus diameter was obtained from MSB-6 clone on MS medium containing 1 mg/l BA, 100 mg/l PVP, and 2% sucrose. The highest number of shoots was obtained from the MSB-6 clone, while the least number of shoots conducted from the MSB-8 clone. The MSB-8 clones were more difficult to regenerate compared to the others. The best media formulation for shoot proliferation was ½ MS containing 0.5 mg/l BA, 1 mg/l Kinetin, and 0.1 mg/l IBA, while the best formulation for rooting was ½ MS.
Modelling of Mooney viscosity relaxation in natural rubber
Abstract Better assessment of natural rubber (NR) quality and processability, through the identification of new attributes, is still a major challenge. With this scope, 12 model samples of natural polyisoprene and two of synthetic polyisoprene were characterized in terms of Mooney torque relaxation, using the standardized ISO289 method (ML(1+4)100, explained later in the Section 1 ). The main purpose of this study was to identify a model that gave a better fit for the experimental decay of Mooney torque over time (ML(t)=f(t)) than the usual power law model used before (Y=at−b, [G.M. Bristow, A.G. Sears, The use of novel parameters in the assessment of natural rubber processability, NR Technol. 18 (1987); H.G. Burhin, W. Spreutels, J.M. Campbell, MV2000 Mooney viscometer: Mooney relaxation measurements on raw polymers and compounded rubber stocks, Kautsch. Gummi Kunstst. 43 (1990) 431]). The results showed that a generalized Maxwell model, and the Wu–Abbott empirical model ( Y = 1 − a Ln ( t ) − ( b t / ( c + t ) ) ) [T. Wu, J.A. Abbott, Firmness and force relaxation characteristics of tomatoes stored intact or as slices, Postharvest Biol. Technol. 24 (2002) 59–68], recently used for describing stress relaxation of tomato flesh, allowed a better description of the relaxation curve for the samples studied than the power law or stretched exponential traditionally used. Moreover, the total relaxation time (τm) given by the generalized Maxwell model showed good correlation with the total gel content of the samples studied.