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Taking steppes towards grass breeding
Readers of a general botanical journal such as this have the advantage of being made aware of the huge, often surprising and always interesting variety of plant life. This variety is even apparent within the very small proportion of plants that are directly exploited by humankind. An example of this is seen in the paper by Huang et al., (Beijing and Fuzhou, China, pp. 295-301). They describe a perennial rhizomatous grass, Leymus chinensis, that is widely distributed in the Asian steppes but, I confess, a species of which I had not heard prior to reading this paper. The authors describe the grass as being very stress-tolerant with ideal qualities for grazing and forage production, and for stabilization of soils in arid areas. Its general usefulness makes it a suitable target for breeding programmes but these are hindered by the grass’s low sexual fecundity (in contrast with its very efficient vegetative propagation). The authors have therefore investigated the breeding biology of this obligate out-breeder in a natural population in inner Mongolia. In this population, in 2002 flowering occurred over a period of 5 d at the end of June. A major peak of pollen release from the hermaphrodite flowers occurred in the late afternoon. The newly released pollen showed a relatively low viability (62 %), as indicated by staining with 1,2,3-triphenyl tetrazolium chloride and the pollen rapidly became inviable after about 3 h. Further, the stigmatic surface also quickly lost its receptivity to pollen so that within about 3 h from anthesis the pistil was effectively non-functional. Even with these limitations approx. 87 % of the pistils were pollinated. However, successful pollination did not lead necessarily to successful seed set which exhibited a maximum of 36 %. The reason for this discrepancy between pollination and seed set was not clear. Further investigation of L. chinensis breeding biology is obviously warranted.
Professor J. A. BryantUniversity of Exeter, UK
j.a.bryant{at}exeter.ac.uk
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