Patterns of allocation and growth in aquatic Sphagnum species

1995 ◽  
Vol 73 (3) ◽  
pp. 349-359 ◽  
Author(s):  
Steven K. Rice

The hypothesis that aquatic plants have greater allocation to photosynthetic tissues was tested using a common garden experiment with three pairs of ecologically contrasting Sphagnum species (S. portoricense and S. papillosum; S. trinitense and S. recurvum; S. macrophyllum var. floridanum and S. strictum). When submerged, aquatic taxa (the former in each pair) all had greater relative growth rates and greater allocation to photosynthetic tissues, as evidenced by higher whole plant chlorophyll content. The evolution of greater photosynthetic allocation appears to result from changes in two independently evolving systems: allocation to photosynthetic cells rather than nonphotosynthetic hyaline cells, and a shift in biochemical partitioning within photosynthetic cells favoring light-reaction proteins. The former was assessed by comparing photosynthetic cell volume in leaves, and the latter was estimated from chlorophyll to nitrogen ratios. The mechanism whereby greater photosynthetic allocation was achieved differed in each aquatic species. In a second experiment, variation in growth and allocation was assessed for three populations each of S. trinitense and S. recurvum. Nested analysis of variance verified that the differences between S. trinitense and S. recurvum observed in relative growth rate and chlorophyll content in the species-level test were robust given the magnitude of population-level variation. It is concluded that (i) aquatic habitats do select for features that lead to greater relative growth rate in submerged environments, (ii) relative growth rate is functionally correlated with allocation to photosynthetic tissues, (iii) allocations at the cellular and biochemical level evolve independently, and (iv) patterns of allocation represent adaptations to environmental conditions present in the aquatic environment. Key words: Sphagnum, relative growth rate, chlorophyll content, allocation, aquatic plants, adaptation.


1986 ◽  
Vol 64 (1) ◽  
pp. 233-237 ◽  
Author(s):  
Susan R. Singer

Growth is the major parameter used to assess novel phenotypes derived from plant tissue cultures. Any quantitative analysis of growth must have an explicit rational basis. Frequently this criterion is not met. For example, the calculation (W2 − W1)/W1(W1 = initial weight; W2 = final weight) approximates neither linear nor exponential growth. Yet, it is a common method of analysis, as is the related calculation W2/W1. When absolute growth values provide insufficient information, meaningful relative growth rate equations can be utilized. Relative growth rates should be evaluated as ln (W2/W1)/(t2 − t1) for t = time, thereby yielding a constant growth rate for exponentially growing cell lines. Linear growth (root growth, for example) can be approximated by 2(W2 − W1)/((W1 + W2)(t2 − t1)). All methods of analysis we have encountered assume that relative growth at a given instant depends on total mass. The possibility exists that growth may actually be proportional to mass raised to some power less than one. For example, growth could be limited to a thin outer shell of a spherical callus. Then the relative growth rate would equal 3(W21/3 − W11/3)/(t2 − t1). Data can be seriously distorted when inappropriate calculations are used. Such distortions are exacerbated when comparisons are made. In all cases an adequate assessment of growth kinetics for each cell line and each treatment is essential.



Botany ◽  
2012 ◽  
Vol 90 (10) ◽  
pp. 954-965 ◽  
Author(s):  
Yngvar Gauslaa ◽  
Trevor Goward

Overstory Populus has been shown to facilitate establishment by cyano- and cephalolichens on conifer branches within its dripzone; though the mechanisms behind this “dripzone effect” have yet to be elucidated. Here we test the following hypotheses that throughfall from Populus: (i) elevates bark pH; (ii) increases relative growth rate in cephalolichens; and (iii) stimulates their growth through phosphorus (P) fertilization. In southern British Columbia we transplanted the cephalolichen Lobaria pulmonaria (L.) Hoffm. (promoted by dripzones) and the acidophytic chlorolichen Hypogymnia occidentalis L.H. Pike for 14 months to 26 pairs of similar-sized Picea glauca × engelmannii situated within and outside of Populus dripzones. Half of our transplants were fertilized with P. Bark pH was significantly higher on spruce branches within than outside dripzones. Relative growth rate in L. pulmonaria increased with bark pH and was slightly higher within dripzones than outside, consistent with a facilitating effect of Populus on the Lobarion community. By contrast, the addition of P decreased relative thallus area growth in L. pulmonaria and increased relative thallus area growth in H. occidentalis; though a stronger influence on growth could be attributed to variation in canopy cover and tree height. We conclude that cephalolichens in our study area are unlikely to be facilitated by P leached from Populus.



2009 ◽  
Vol 34 (2) ◽  
pp. 91-96
Author(s):  
Jesaja A. Pattikawa ◽  
Elizabeth Ferdinandus

Study on growth of mangrove cockle (Anadara antiquata) was conducted in the intertidal area of Passo, Inner Ambon Bay. Three size-classes of 25 individual cockles were cultured in 1 m3 cage. Length increment data was collected every two weeks for seven periods of observation. Relative growth rate, length-weight relationship and condition factor were estimated using formula proposed by Effendie, Pauly and King, respectively. The results showed that the small size had the highest length increment and relative growth rates while the large size had the best condition factor. Length-weight relationship showed isometric growth for all categories.



2009 ◽  
Vol 52 (6) ◽  
pp. 1341-1348 ◽  
Author(s):  
Adriane Schio Silva ◽  
Valdemir Antônio Laura ◽  
Liana Jank

The soil flood tolerance of seven genotypes of Panicum maximum Jacq. (PM11, PM34, PM40 and PM45, and the commercial cultivars Massai, Mombaça and Tanzânia) was evaluated in plants subjected to two conditions: flooded and not flooded, during a period of 14 days. Flooding significantly decreased the total and above ground biomass of PM40 and PM45. For cultivar Tanzânia, flooding decreased these two variables and also root biomass. The root, total and above ground relative growth rates were significantly reduced by flooding in cultivar Tanzânia, while in PM45 only the above ground relative growth rate was reduced. Cultivar Tanzânia showed significant differences for all variables analyzed, thus was not flood tolerant, as well as PM40 and PM45. It could be concluded that Massai, PM34, Mombaça and PM11 were the most flood tolerant genotypes.



2012 ◽  
Vol 610-613 ◽  
pp. 1829-1832
Author(s):  
Xiao Yun Fu ◽  
Xing Yuan He

Two aquatic macrophytes (Monochoria korsakowii and Alisma plantago-aquatica) were grown in monoculture to test the relative growth rate(RGR) and abilities of removing total nitrogen(TN) by the manipulative indoor experiment. A nutrient treatment consisted of two levels of nitrogen[ low (14 mg L-1 N) and high (56 mg L-1 N) ]of nutrient solution. Result revealed that the RGR of the species was significantly different, however nutrients had no significant affect on the RGR. The results showed that TN in wastewater were significantly higher from unvegetated microcosms compared to vegetated. M. korsakowii was shown to be best removal effect with the removal rates of 94.9% and 77.0% at low and high concentrations of TN.



2016 ◽  
Vol 12 (30) ◽  
pp. 55
Author(s):  
Luis L. Travieso ◽  
Adrian P. Leon ◽  
Veronica R. Logegaray ◽  
Diana Frezza ◽  
Angel Chiesa

Horticultural crops have a strong impact on human nutrition. Lettuce is the most important leafy vegetable in Argentina and it is cultivated mainly in green belts, in greenhouses or open field. The aim of this study was to evaluate growth and phytonutrients concentration of leaf lettuce under greenhouse and field production. Crop establishment was made from seedlings produced in a commercial greenhouse. Loose lettuce cv. Brisa was used for field and greenhouse growth. Experimental design with complete random block with 4 replicates per treatment was used. Fresh and dry weights of shoot, number of leaves, color, ascorbic acid, chlorophyll content were measured. Absolute and relative growth rate and commercial yield were calculated. Lettuce grown under greenhouse system showed, as expected, a higher value of fresh and dry weight, number of leaves, leaf area, yield and absolute and relative growth rate. Ascorbic acid value of the leaves decreased during lettuce growth in both production systems. Chlorophyll content was higher in the greenhouse cultivation but the antioxidant capacity was lower in lettuce leaves from greenhouse than the leaves grown on open field.



2011 ◽  
Vol 356-360 ◽  
pp. 2278-2281
Author(s):  
Xiao Ming Hang ◽  
Tao Wang ◽  
Meng Zhang ◽  
Ye Qing Sun

Lab-cultured Ulva pertusa were exposed to three selected types of contaminated areas (industry, mariculture and living) and one relatively clean area near Dalian seashore for 1, 3, 5 and 14 days. Relative growth rate, chlorophyll content and activities of two kinds of antioxidant defense enzymes (superoxide dismutase and catalase) were measured and compared with their lab controls at different time points, respectively. No significant change was observed in either relative growth rate or chlorophyll content in 1-day exposed samples, while obvious decreases were observed in relative long-period (3, 7 and 14 days) exposed samples. Antioxidant defense enzymes activities were stimulated to increase after 1-day exposure and decrease after relative long-period exposure. Significant statistical decreases were found in the relative growth rate, chlorophyll content and antioxidant defense enzymes activities of samples from industry pollution area, which indicates a more serious pollution situation in industry area than the other two areas near Dalian seashore. Above results demonstrated the established method would be useful for biological evaluation of multiplex pollution in real situation.



2013 ◽  
Vol 864-867 ◽  
pp. 1486-1489
Author(s):  
Xiao Yun Fu

Two aquatic macrophytes (Lythrum salicaria and Alisma plantago-aquatica) were grown in monoculture to test the relative growth rate (RGR) and abilities of removing total phosphorus (TP) by the manipulative indoor experiment. A nutrient treatment consisted of two levels of phosphorus [ low (3 mg L-1 N) and high (12 mg L-1 N) ] of nutrient solution. Result revealed that nutrients had significant affect on the RGR, however the RGR of the species was non-significant. The results showed that TP in wastewater were significantly higher from unvegetated microcosms compared to vegetated. L. salicaria was shown to be best removal effect with the removal rates of 81.7% and 91.1% at low and high concentrations of TP.



Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 248-251 ◽  
Author(s):  
Thomas O. Ballard ◽  
Michael E. Foley ◽  
Thomas T. Bauman

A study was conducted to evaluate the response of common and giant ragweed to postemergence applications of imazethapyr using relative growth rate parameters. The relative growth rate was the same for untreated common and giant ragweed through the 21 d harvest interval. Relative growth rates of treated common and giant ragweed were 50% lower than the relative growth rates of untreated ragweeds 21 d after treatment. Between 21 and 56 d after treatment, the relative growth rate of common ragweed declined an additional 13%, while the relative growth rate of giant ragweed declined an additional 38%. The sharp continued decline in the relative growth rate of giant ragweed indicated plant death. The moderation and slight increase in the relative growth rate of common ragweed between 21 and 56 d corresponded with the initiation of lateral axillary buds and the regeneration of plant growth. Relative growth rate parameters identified differences in the response of common and giant ragweed to imazethapyr as early as 21 d after treatment. Relative growth rate demonstrated utility by objectively measuring differences in the growth response of these two weeds that are moderately susceptible to imazethapyr under laboratory conditions.



1972 ◽  
Vol 25 (5) ◽  
pp. 905 ◽  
Author(s):  
MG Pitman

Determinations of potassium transport are described for plants growing at varied relative growth rates. These determinations were based on differences in total potassium content of the shoot over a 3.day period for plants growing on culture solution. It is shown that rate of transport from root to shoot is correlated with relative growth rate. The concentration of potassium in the shoot was independent of ratio of root to shoot, and little affected by relative growth rate (potassium was the only available univalent cation).



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