News Update on Seedling Production : Nov 2021

Seed Production, Seed Populations in Soil, and Seedling Production After Fire for Two Congeneric Pairs of Sprouting and Nonsprouting Chaparal Shrubs

A study of seed production, seed storage in the soil, and seedling production after fire was undertaken for a sprouting and a nonsprouting congenerica pair of species of Ceanothus and Arctostaphylos. All species exhibited large fluctuations in annual seed production. There was a significant correlation between fruit production and precipitation in the previous year. It is hypothesized that high carbon gain in years of high precipitation results in high numbers of floral primordia which, in these species, remain dominant until the following year. It was also noted that high fruit production was not dependent upon high precipitation the same year; suggesting that the fruits were utilizing carbon stored from the previous year. All 4 species were capable of producing more seeds in a single season than were stored in the soil. Apparently the soil seed pools do not represent a steady accumulation of seeds in the soil but rather are the result of dynamic fluctuations in seed inputs and outputs. Each species also had more seeds in the soil, by several orders of magnitude, than seedlings after fire in an adjacent burned stand. The sprouting and seeding productive strategies are quite different in the two genera. The information from this study coupled with that from other studies indicate 4 reproductive modes: sprouting and seedling production (C. leucodermis), abundant seedling production (C. greggii), low seedling production but better “equipped” seedlings (A. glauca), and predominantly sprouting (A. glandulosa). [1]

Enhancement of American chestnut somatic seedling production

Somatic embryogenesis holds promise for mass propagation of American chestnut trees bred or genetically engineered for resistance to chestnut blight. However, low germination frequency of chestnut somatic embryos has limited somatic seedling production for this forest tree. We tested the effects of culture regime (semi-solid versus liquid), cold treatment, AC and somatic embryo morphology (i.e., cotyledon number) on germination and conversion of the somatic embryos. Cold treatment for 12 weeks was critical for conversion of chestnut somatic embryos to somatic seedlings, raising conversion frequencies for one line to 47%, compared to 7% with no cold treatment. AC improved germination and conversion frequency for one line to 77% and 59%, respectively, and kept roots from darkening. For two lines that produced embryos with one, two or three-plus cotyledons, cotyledon number did not affect germination or conversion frequency. We also established embryogenic American chestnut suspension cultures and adapted a fractionation/plating system that allowed us to produce populations of relatively synchronous somatic embryos for multiple lines. Embryos derived from suspension cultures of two lines tested had higher conversion frequencies (46% and 48%) than those from cultures maintained on semi-solid medium (7% and 30%). The improvements in manipulation of American chestnut embryogenic cultures described in this study have allowed over a 100-fold increase in somatic seedling production efficiency over what we reported previously and thus constitute a substantial advance toward the application of somatic embryogenesis for mass clonal propagation of the tree. [2]

Acorn predation and seedling production in a low-density population of cork oak (Quercus suber L.)

Prospects for cork oak recruitment were examined in a scrub-dominated area with low tree density in southern Spain by sowing acorns experimentally in a variety of sites. Seeds placed on the ground surface were invariably eaten within a few months by a variety of vertebrate herbivores (cattle, red deer, fallow deer, wild boar and rabbits). Predation reached 100% whether acorns were placed beneath trees or more than 100 m away from trees. Seeds placed under dense heath scrub were also rapidly removed, although their final fates could not be ascertained. Single acorns buried under open or dense scrub experienced the lowest predation (52% and 0%, respectively) and had relatively high emergence rates (38% and 60%, respectively). Heavy shoot browsing occurred in both scrub types, and out of the 49 buried acorns which produced a shoot, only two seedlings were alive 1 year after germination. None survived 2 years after sowing. [3]

Production and Characterization of Polyhydroxyalkanoate (PHA) Using Mango Seed Kernel as an Alternative to Glucose

Aim: To explore the possibility of using Mango (Mangifera indica) seed kernel as an alternative to glucose in the production of biodegradable plastic (polyhydroxyalkanoate) using soil isolated Bacillus megaterium.

Study Design: Experimental design.

Place and Duration of Study: This research was carried out at Biotechnology and Genetic Engineering Advanced Laboratory, Sheda Science and Technology Complex and Biochemistry Department, Federal University of Technology Minna, Nigeria, between the periods of June 2014 to October 2015.

Methodology: Using fed-batch fermentation technology, polyhydroxyalkanoate (PHA) pellets were produced, extracted and purified via solvent extraction. Polyhydroxyalkanoate produced was quantified using the crotonic acid assay at 235 nm by UV-VIS spectrophotometry. Fourier transform infrared spectrometry (FTIR) was used to characterize the PHA.

Results: Mango seed kernel produced a significantly greater (p<0.05) dry cell weight (DCW) and polyhydroxyalkanoate (PHA) (10.60±0.90 g/L; 64.22±0.55%) compared to glucose (10.19±0.01 g/L; 54.40±5.60%). Optimum conditions for maximum production of polyhydroxyalkanoate (PHA) were pH 7.5; temperature 35°C; substrate concentration of 2 g/100 ml; Bacilli inoculums volume of 2 ml and an incubation period of 72 hours. Fourier transform infrared spectrometry (FTIR) of extracted PHA revealed C-O, C=O, C-H, O-H functional groups at respective wave bands of 1125.5, 1644.37, 2938.65 and 3399.65 cm-1 for extracted mango seed kernel PHA; and 1086.92, 1646, 2937 and 3403.51 cm-1 for extracted glucose PHA.

Conclusion: Mango (Mangifera indica) seed kernel produced higher dry cell weight and polyhydroxyalkanoate than glucose hence, could be a substitute to glucose in PHA production.[4]

Soilless Nursery Media for African Oil Bean (Pentaclethra macrophylla Benth) Seedling Production

African oil bean (Pentaclethra macrophylla) is an important multi-purpose tree crop. However, bottleneck in seedling production to fully domesticate this crop has not been resolved. This study was carried out to compare the effect of three different soilless media on the production of Pentaclethra macrophylla seedlings. The experiment was laid out in a completely randomized design (crd) with 10 replications using potting bags (25 x 23 cm) filled with the treatments namely sawdust + poultry manure (sd+pm) 3:1 volume by volume (v/v), rice hull + poultry manure (rh +pm) 3:1 v/v, and groundnut husk + poultry manure (gh + pm) 3:1 v/v. Top soil served as the control. Germination and plant growth parameters were studied; days to emergence, germination count (%), plant height and number of leaves at 30, 40, 50, 60 and 70 days after planting (dap). Germination count (%) was recorded highest on sd + pm while gh + pm had the least. This study suggests the use of sd + pm for seedling production.[5]


Reference

[1] Keeley, J.E., 1977. Seed production, seed populations in soil, and seedling production after fire for two congeneric pairs of sprouting and nonsprouting chaparal shrubs. Ecology, 58(4), pp.820-829.

[2] Andrade, G.M. and Merkle, S.A., 2005. Enhancement of American chestnut somatic seedling production. Plant Cell Reports, 24(6), pp.326-334.

[3] Herrera, J., 1995. Acorn predation and seedling production in a low-density population of cork oak (Quercus suber L.). Forest Ecology and Management, 76(1-3), pp.197-201.

[4] Nasir-Naeem, K.O., Shittu, K.O. and Kabiru, A.Y., 2016. Production and characterization of polyhydroxyalkanoate (PHA) using mango seed kernel as an alternative to glucose. Biotechnology Journal International, pp.1-11.

[5] Onwubiko, N.C., Ezeigbo, A.E., Cookey, C.O., Nwokeji, E.M., Tom, C.T. and Onyia, V.N., 2018. Soilless Nursery Media for African Oil Bean (Pentaclethra macrophylla Benth) Seedling Production. International Journal of Plant & Soil Science, pp.186-190.

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