Modular growth and clonal propagation of Hippophae rhamnoides subsp, sinensis in response to irrigation intensity

A multipurpose clone plant species, Hippophae rhamniodes has the capacity for indefinite longevity, although under successive drought stress it may often decline or die across large areas. Field trials were con- ducted over 2 years to examine the effects of varied irrigation intensities on modular growth and clonal propagation in a semi-arid area. Irrigation levels included a control, as well as two, four and six times the volume of water that was typically received via local annual average precipitation. Irrigation intensity significantly influenced clonal propagation capacity （number of daughter ramets）, aboveground modular growth （height, base diameter, and crown width）, belowground modular growth included root nodule dry weight, stretching capacity of lateral roots （length of the longest lateral roots, and diameter of first-grade lateral roots）, and branching intensity of lateral roots （number of lateral roots bifurcation grade, number of first- grade lateral roots）. The modular growth and the density of daughter ramets were small under non-irrigation or low irrigation, and became larger with increased irrigation intensity. Beyond a certain threshold, however, further increases in irrigation intensity resulted in a reversion to the development. The optimal irrigation intensities for growth and propagation were 3.48-5.29 times the volume of nominal local annual average precipitation. There were effects of irrigation intensities on the positive significant correlations between aboveground and belowground modular growths, and on clonal propagation capacities. Under various water treatments, H. rhamnoides may adapt to the environment through the regulation of growth and propagation. We concluded that water shortages act to weaken the growth and propagation of H. rhamniodes plantations.

Bioreactor technology for clonal propagation of plants and metabolite production

Plant cell culture in bioreactors is an enabling tool for large scale production of clonal elite plants in agriculture, horticulture, forestry, pharmaceutical sectors, and for biofuel production. Advantages of bioreactors for plant cell culture have resulted in various types of bioreactors differing in design, operating technologies, instrumentations, and construction of culture vessels. In this review, different types of bioreactors for clonal propagation of plants and secondary metabolites production are discussed. Mechanical and biochemical parameters associated with bioreactor design, such as aeration, flow rate, mixing, dissolved oxygen, composition of built-up gas in the headspace, and pH of the medium, are pivotal for cell morphology, growth, and development of cells within tissues, embryos, and organs. The differences in such parameters for different bioreactor designs are described here, and correlated to the plant materials that have been successfully cultured in different types of bioreactors.

Production and quality of eucalyptus mini-cuttings using kaolin-based particle films

Considering the expansion of forest plantations over the Brazilian territory and the imminent increase in air temperatures due to global warming,the search for technologies that ensure high levels of productivity and high quality plants in clonal nurseries is essential.Applying kaolin-based particle films(KBPF)has been used as a physical barrier to reduce the negative effects of excessive solar radiation and adverse temperatures.The effects of KBPF on production and physiological quality of eucalyptus mini-cuttings were evaluated during two different seasons.A randomized block design was used,consisting of five treatments and four replications.Five concentrations(0,3%,5%,7%,and 10%)were tested here and six weekly replicates of each concentration was applied.The different kaolin concentrations and seasonal variations resulted in a quadratic response of the leaf SPAD reading during both daily evaluation periods.KBPF applications resulted in a quadratic response of photochemical efficiency in the morning period,and an increasing specific leaf weight linear response,and during the dry season,the different kaolin concentrations resulted in a bud length quadratic response.The results indicated that the kaolin application maintained the production and yield index statistically equal between weekly KBPF applications,improving photochemical efficiency,leaf thickness,SPAD reading,and bud length.The use of KBPF could reduce the intervals between collections of mini-cuttings and increase nursery yields in environments that present high temperatures.

Effect of Growth Regulators in Production and Rooting of Coffea arabica L.Minicuttings

The plants of C. arabica do not naturally produce a large number of orthotropic sprouts, hindering clonal multiplication by cutting, which would be the simplest technique with a lower cost of production compared to other methods of vegetative propagation. An alternative form, used successfully in the propagation of eucalyptus, is propagation by minicutting, which consists of pruning the shoot apex of the plant, forming the ministumps, which in variable time interval emits the shoots that will be used to make minicutting. In C. arabica plants the number of shoots can be increased with the application of growth regulators and fertilizers. So, the purpose of this work was to verify the effect of growth regulators and foliar fertilizers on the emission and development of orthotropic shoots of C. arabica. The experiment was installed in a randomized complete block design, with ten treatments composed by growth regulators and fertilizers: T1 (Control);T2 (Stimulate + Sturdy + Enervig);T3 (Stimulate + Vitakelp + Biozyme);T4 (Tiba + Sturdy + Enervig);T5 (Tiba + Vitakelp + Biozyme);T6 (Brs + Sturdy + Enervig) T7 (Brs + Vitakelp + Biozyme);T8 (Stimulate);T9 (TIBA);T10 (Brs-Brassinoesteroid), each plot consisting of two plants. Biometric and physiological parameters were evaluated for the ministumps, as well as the biometric parameters of the shoots and plant survival. The results showed that there was no influence of the treatments on the biometric parameters of the ministumps. A greater number of orthotopic sprouts were obtained in treatments with the TIBA growth regulator, as well as a greater plant survival of the minicuttings, after 25 days of transplanting in a greenhouse. It was concluded that TIBA treatments influenced the production and quality of clonal minicuttings of C. arabica.

Unlikely heroes on the long and winding road to potatoinbreeding

Conversion of potato from a tetraploid, heterozygous, vegetatively propagated crop to a diploid F1hybrid, propagated via botanical seed, would constitute a considerable advance for global agriculture,but faces multiple challenges. One such challenge is the difficulty in inbreeding potato, which involvespurging deleterious alleles from its genome. This commentary discusses possible reasons for thisdifficulty and highlights a recent sequence-based effort to classify SNP variation, in potato germplasm,according to its deleterious potential. Tools and strategies connected to this database may facilitatedevelopment of F1 hybrids.