5 research outputs found
Tissue culture of ornamental cacti
Cacti species are plants that are well adapted to growing in arid and semiarid regions where the main problem is water availability. Cacti have developed a series of adaptations to cope with water scarcity, such as reduced leaf surface via morphological modifications including spines, cereous cuticles, extended root systems and stem tissue modifications to increase water storage, and crassulacean acid metabolism to reduce transpiration and water loss. Furthermore, seeds of these plants very often exhibit dormancy, a phenomenon that helps to prevent germination when the availability of water is reduced. In general, cactus species exhibit a low growth rate that makes their rapid propagation difficult. Cacti are much appreciated as ornamental plants due to their great variety and diversity of forms and their beautiful short-life flowers; however, due to difficulties in propagating them rapidly to meet market demand, they are very often over-collected in their natural habitats, which leads to numerous species being threatened, endangered or becoming extinct. Therefore, plant tissue culture techniques may facilitate their propagation over a shorter time period than conventional techniques used for commercial purposes; or may help to recover populations of endangered or threatened species for their re-introduction in the wild; or may also be of value to the preservation and conservation of the genetic resources of this important family. Herein we present the state-of-the-art of tissue culture techniques used for ornamental cacti and selected suggestions for solving a number of the problems faced by members of the Cactaceae family
Sex-associated variations in coral skeletal oxygen and carbon isotopic composition of <i>Porites panamensis</i> in the southern Gulf of California
Coral δ18O variations are used as a proxy for changes in sea
surface temperature (SST) and seawater isotope composition. Skeletal δ13C of coral is frequently used as a proxy for solar radiation because
most of its variability is controlled by an interrelationship between three
processes: photosynthesis, respiration, and feeding. Coral growth rate is
known to influence the δ18O and δ13C isotope record to a
lesser extent than environmental variables. Recent published data show
differences in growth parameters between female and male coral in the
gonochoric brooding coral Porites panamensis; thus, skeletal
δ18O and δ13C are hypothesized to be different in each
sex. To test this, this study describes changes in the skeletal
δ18O and δ13C record of four female and six male
Porites panamensis coral collected in Bahía de La Paz, Mexico,
whose growth bands spanned 12 years. The isotopic data were compared to SST,
precipitation, photosynthetically active radiation (PAR), chlorophyll a,
and skeletal growth parameters. Porites panamensis is a known
gonochoric brooder whose growth parameters are different in females and
males. Splitting the data by sexes explained 81 and 93 % of the
differences of δ18O, and of δ13C, respectively, in the
isotope record between colonies. Both isotope records were different between
sexes. δ18O was higher in female colonies than in male colonies,
with a 0.31 ‰ difference; δ13C was lower in female
colonies, with a 0.28 ‰ difference. A difference in the skeletal
δ18O could introduce an error in SST estimates of ≈ 1.0
to ≈ 2.6 °C. The δ18O records showed
a seasonal pattern that corresponded to SST, with low correlation
coefficients (−0.45, −0.32), and gentle slopes (0.09,
0.10 ‰ °C−1) of the δ18O–SST relation.
Seasonal variation in coral δ18O represents only 52.37 and
35.66 % of the SST cycle; 29.72 and 38.53 % can be attributed to
δ18O variability in seawater. δ13C data did not
correlate with any of the environmental variables; therefore, variations in
skeletal δ13C appear to be driven mainly by metabolic effects. Our
results support the hypothesis of a sex-associated difference in skeletal
δ18O and δ13C signal, and suggest that environmental
conditions and coral growth parameters affect skeletal isotopic signals
differently in each sex. Although these findings relate to one gonochoric
brooding species, they may have some implications for the more commonly used
gonochoric spawning species such as Porites lutea and
Porites lobata
Revista Temas Agrarios Volumen 26; Suplemento 1 de 2021
1st International and 2nd National Symposium of Agronomic Sciences: The rebirth of the scientific discussion space for the Colombian Agro.1 Simposio Intenacional y 2 Nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano