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Growth Chamber Experiment (growth + chamber_experiment)
Selected AbstractsIntensity and Importance of Competition for a Grass (Festuca rubra) and a Legume (Trifolium pratense) Vary with Environmental ChangesJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 12 2008Junyan Zhang Abstract How plant competition varies across environmental gradients has been a long debate among ecologists. We conducted a growth chamber experiment to determine the intensity and importance of competition for plants grown in changed environmental conditions. Festuca rubra and Trifolium pratense were grown in monoculture and in two- and/or three-species mixtures under three environmental treatments. The measured competitive variations in terms of growth (height and biomass) were species-dependent. Competition intensity for Festuca increased with decreased productivity, whilst competition importance displayed a humpback response. However, significant response was detected in neither competition intensity nor importance for Trifolium. Intensity and importance of competition followed different response patterns, suggesting that they may not be correlated along an environmental gradient. The biological and physiological variables of plants play an important role to determine the interspecific competition associated with competition intensity and importance. However, the competitive feature can be modified by multiple environmental changes which may increase or hinder how competitive a plant is. [source] Photosynthesis light curves: a method for screening water deficit resistance in the model legume Medicago truncatulaANNALS OF APPLIED BIOLOGY, Issue 3 2009C. Nunes Abstract The photosynthetic performance of two transgenic Medicago truncatula lines engineered for water deficit (WD) resistance and a non-transformed line was assessed in a growth chamber experiment in well-watered, WD and stress recovery conditions. Direct gas exchange measurements showed that the transgenic plants had lower photosynthetic rates under well-hydrated conditions when compared to the non-transformed line. Photosynthesis light curves confirmed this difference but more importantly showed a progressive change in photosynthetic behaviour with intensity of dehydration. Dehydration led to sharp decreases of maximum photosynthesis (Amax), photosynthetic apparent quantum yield (,) and apparent light compensation point. The recovery rates showed that all plant lines had a similar capacity to regain control photosynthetic values. Furthermore, results suggested that light was more limiting for photosynthesis than atmospheric CO2 concentration. The results are discussed in terms of the use of photosynthesis light response curves as a non-destructive and expeditious approach to select M. truncatula transformants with improved WD resistance. [source] New media for the semiselective isolation and enumeration of Xanthomonas campestris pv. mangiferaeindicae, the causal agent of mango bacterial black spotJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2005O. Pruvost Abstract Aims:, Mango bacterial black spot, caused by Xanthomonas campestris pv. mangiferaeindicae, is a potentially severe disease in several tropical and subtropical areas. Data describing the life cycle of the pathogen are needed for improving integrated pest management strategies. Because of the important bacterial microflora associated with mango leaves, isolation of the pathogen is often difficult using nonselective agar media. Methods and Results:, A previously developed medium, BVGA, failed to inhibit several Gram-negative saprophytic bacteria, especially those belonging to Enterobacteriaceae. Two new semiselective media were developed. The selectivity of KC and NCTM3 media was achieved using cephalexin 40 mg l,1, kasugamycin 20 mg l,1 and neomycin 1 mg l,1, cephalexin 100 mg l,1, trimethoprime 5 mg l,1, pivmecillinam 100 mg l,1 respectively. Plating efficiencies ranged from 76 to 104% and from 78 to 132% for KC and NCTM3 respectively. Conclusions:, The new media allowed the growth of X. campestris pv. mangiferaeindicae whatever its country of isolation. The pathogen was repeatedly isolated with these media from asymptomatic leaves sampled in growth chamber experiments. Significance and Impact of the Study:, This work provides a description of new semiselective media, which should be valuable tools to study the ecology and epidemiology of X. campestris pv. mangiferaeindicae. [source] Local adaptation at the range peripheries of Sitka spruceJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2010M. MIMURA Abstract High-dispersal rates in heterogeneous environments and historical rapid range expansion can hamper local adaptation; however, we often see clinal variation in high-dispersal tree species. To understand the mechanisms of the species' distribution, we investigated local adaptation and adaptive plasticity in a range-wide context in Sitka spruce, a wind-pollinated tree species that has recently expanded its range after glaciations. Phenotypic traits were observed using growth chamber experiments that mimicked temperature and photoperiodic regimes from the limits of the species realized niche. Bud phenology exhibited parallel reaction norms among populations; however, putatively adaptive plasticity and strong divergent selection were seen in bud burst and bud set timing respectively. Natural selection appears to have favoured genotypes that maximize growth rate during available frost-free periods in each environment. We conclude that Sitka spruce has developed local adaptation and adaptive plasticity throughout its range in response to current climatic conditions despite generally high pollen flow and recent range expansion. [source] | ||||||||||