Selection of superior families of Pinus massoniana in southern China for large-diameter construction timber

This study addresses the increasing demand for large-diameter production timber,and considers the time and space variability of half-sib families of Pinus massoniana.Height,diameter at breast height(DBH)and timber volume of 440 open-pollinated half-sib progeny families were investigated in 14 progeny trials in different years and production regions.An evaluation of the genetic variation of all half-sib families was carried out during the sustainable rapid growth period and individual volumes were characterized as a major index.ANOVA analysis showed that there was considerable variance in the growth traits of most families in different years and on different sites.The variations caused by temporal and spatial changes of the mating system required three selection methods for analysis.The results show that there were differences among the heritabilities of different growth traits by different halfsib progenies.Average heritability values of height,DBH and volume were 0.33,0.34 and 0.36,respectively.Fortyfive superior families were selected in every progeny test,12 were selected in progeny trials by different years and five in different habitat progeny trials.Three superior families(Gui GC553A,Gui GC414A and Gui GC431A)were selected,although in different years and production regions.The genetic gains of timber volume of these selected r families ranged from 1.20 to 47.00%,which could provide a foundation for superior wood property selection and serve as material for seed improvement and extension in surrounding areas.

Community Based Seed Production-A Sustainable Seed Production Model for Subsistence of Bhutanese Maize Farmers

Bhutanese maize farmers grow different open-pollinated traditional varieties and improved high yielding varieties recommended by the national maize program. All most every maize farmer uses the recycled seeds from their farms for planting in the next season. Farmers traditional or informal seed system was found to be poorly organized and unscientific that has resulted in the deterioration and contamination of seed quality. Bhutanese maize farmers living in remote areas are highly constrained by the inconsistent supply and poor access to good quality maize seed. The formal public seed sectors lack adequate resources to produce and supply good quality seeds. This called for an urgency to identify and adapt an innovative and a sustainable seed production approach to service the subsistence needs of Bhutanese farmers in a cross-pollinated crop, like maize. The community based seed production （CBSP） approach was introduced and evaluated under the Bhutanese maize production system as an alternative farmer based seed production model. A total of seven farmers CBSP groups were formed and promoted as a smallholder seed enterprise. The technical skills of these CBSP group members on maize seed production were improved through practical demonstrations and trainings. The CBSP groups were supplied with high quality source seed of new maize varieties by the national maize program. For long term, the sustainability of CBSP groups were linked to the formal seed sector in the country for marketing the seeds. The CBSP approach has proven to be a successful small scale maize seed production model under highland maize production ecosystem that has improved the production and supply of good quality maize seeds. The Bhutanese experiences with CBSP in maize, its merits for small holder Bhutanese maize farmers and lessons learnt from the CBSP model are discussed in this paper.

Effects of Growth Type,Sowing Date,and Sowing Rate on the Canopy Architecture,Protein Yields,and Oil Yields of Winter Oilseed Rape(Brassica napus L.)

A split-split-plot design was used to evaluate the effects of sowing dates and sowing rates on three winter rape cultivars,including‘PR45D03’,a semi-dwarf hybrid,‘PR46W31’,a traditional hybrid,and‘Californium’,an open-pollinated cultivar.August 25 was the optimal sowing date for maximizing protein and oil yields across all three cultivars.Of the cultivars,the traditional hybrid,‘PR46W31’,produced the highest protein and oil yields on that date.The yields of the semi-dwarf hybrid,‘PR45D03’,were greater than those of the open-pollinated cultivar,‘Californium’,when these were sown later than the optimal date.Protein and oil yields did not differ significantly among different seeding densities.