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The dose-response curves for IAA and 4-Cl-IAA-induced growth of Zea mays L. coleoptile segments were studied as a function of time. Moreover, some characteristic growth parameters for both auxins were compared. The dose-response curve of growth rate measured after IAA or 4-Cl-IAA application was bell-shaped in all experiments. The optimum concentration was 10⁻⁶ M for 4-Cl-IAA and was found not to depend on the time of the growth measurement. However, in the case of IAA the optimum shifted from 10⁻⁶ M at the time of maximal growth rate to 10⁻⁵ M or even 10⁻⁴ M, when growth measured 3–4 hours after auxin application was analysed. The relative activity of 4-Cl-IAA-induced growth rate (as compared to IAA) increased significantly with increasing time from addition of this auxin to the medium. For both auxins the time needed to reach the maximal growth rate was clearly related to their concentrations. These data provided further evidence that 4-Cl-IAA is much more active auxin than IAA and can also suggest that IAA is more rapidly metabolized in comparison to 4-Cl-IAA.
The objective of this study was to determine the effect of trifluralin on the growth of Scenedesmus acutus in comparison to growth without trifluralin during 5 days. For growth in trifluralin 20-40 |g/L, four days of S. acutus growth occurred compared to growth in the absence of trifluralin. This decrease in growth in S. acutus was correlated with an increased amount of trifluralin concentration. At trifluralin concentra­tion of 60 |g/L, growth was maintaned for three days. S. acutus in the presence of at 80 |g/L trifluralin showed one-day growth. It was concluded that increasing trifluralin concentration decreased growth of S. acutus in a dose-dependent manner.
The aim of the paper was to evaluate the effect of the birth body weight of the piglets on their productivity and survivability up to the age of 10 weeks. The observations covered the piglets born by 11 sows F1 of Polish Large White × Polish Landrace, inseminated by the semen of the boras (Duroc × Pietrain). The piglets were weighed on 1st, 21st, 35th and 70th day of life and the feed intake (per litter) was controlled. Depending on their birth body weight, the piglets were classifi ed into two groups: light (L) <1.5 kg (n = 52), heavy (H) ≥1.5 kg (n = 60). The mean general body weight of the piglets on 1st, 21st, 35th and 70th day was equal to 1.45, 5.09, 7.70 and 14.18 kg, respectively. In the groups, it was as follows: L – 1.17, 4.58, 6.91 and 13.00 kg; H – 1.70, 5.51, 8.29 and 15.12 kg, respectively (L–H, P ≤ 0.001). The deaths of the piglets in groups L and H amounted to 15.4 and 6.7%, respectively. In the situation of a free access of the progeny to mother’s feed and solid feedstuff, the obtained results indicate that the worse productivity, as expressed by lower feed conversion (by 10.5–16%), slower growth rate (by 12–20%) and lowered survivability (by 8.7 percentage points) of the piglets from groups L vs. group H, were the effect of considerably lower body weight of the newborn piglets as compared to their mean body weight
Effect of birth weight of piglets on growth rate and rearing performance up to 8 weeks of age. The aim of the experiment was to determine the effect of the birth weight of piglets on their rearing results up to 56 days of age, as expressed by growth rate and survival. Observations were made on 277 crossbred piglets from 22 litters of F1 sows (Polish Landrace ´Polish Large White) derived from crossbred boars (Duroc ´Pietrain), which were kept and fed the same way. Piglets were reared with mothers for 5 weeks and observed for 8 weeks. At 1, 7, 21 and 56 day of age, piglets were individually weighed. The body weight on day 1 of age served as a basis for dividing the piglets into groups I, II, III and IV (≤1.2; 1.21-1.39; 1.40-1.59; and ≥1.60 kg body weight, respectively). Coefficients of correlation were estimated between body weight on day 1 of age and at 7, 21 and 56 days of age, and daily gains. The mean body weight of the piglets on days 7, 21 and 56 differed between groups I, II, III and IV (P ≤0.01) and depended on the birth weight (r=+0.773, r=+0.567, r=+0.504). In the subsequent rearing periods, daily gains in groups I-IV increased and the differences between the groups showed similar relationships. Differences between groups II and III were small (P>0.05), and those between groups I and IV considerable and highly significant. With the increasing mean body weight at birth, piglet survival increased and was higher in group IV vs I by 13.64 percentage points. The birth weight ≥ 1.60 kg ensured the best growth rate and survival of the piglets.
The colour of light is a very important environmental factor that affects fish physiology. The aim of the present study was to evaluate the effects of different colours of light on weight gain, length, condition factor and specific growth rates of the juvenile rainbow trout Oncorhynchus mykiss. The study employed fertilized eggs that were exposed separately to seven colour lamps including white (573 nm, control), azure (397 nm), blue (459 nm), green (524 nm), yellow (586 nm), orange (611 nm) and red (742 nm). The experiment was conducted for 5 months (from fertilization until the fish reached 2 g wet weight) at the Sheshpir fish farm (west of Fars province), Iran. After yolk sac absorption, the weight and length of randomly sampled fish were measured monthly. The results showed that weight parameters of fish exposed to yellow (0.562 ± 0.13) and white (0.547 ± 0.13) coloured light were higher (p ≤ 0.05) than fish subjected to the other colours. The highest length growth was observed in fish exposed to yellow (3.91 ± 0.16) and white (3.61 ± 0.10) light, respectively. The highest growth rate (4.641 ± 0.29) and condition factor (2.00 ± 0.03) were observed in fish maintained under yellow light.
Length and weight growth rates of 206 bream individuals caught in 1992 and 1995 were back-calculated. Different types (non-linear vs. linear) of a relationship between the scale caudal radius and body length were revealed to prevail in the two years. The 1992 bream grew very rapidly during the first four years of life, the growth rate slowing down later on. On the other hand, the bream growth in 1995 was more uniform over time. No sex- or age-dependent differences in growth rate were found. The Lake Dšbie bream population belongs to the fast growing populations of the species.
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