Personnel techniques necessary to maximize bio-barrier integrity at a Martian receiving laboratory

The planning of biological isolation measures for the Mars Surface Sample Return Mission is discussed in terms of personnel and organizational management. Deficiencies in past operation of the Lunar Receiving Laborator are analyzed. It was found that the failure to clearly define relationship among the government agencies involved and to effectively integrate their objectives and responsibilities was a major cause of Laboratory deficiencies. Possible solutions to these problems are presented for application to future missions

Advanced composites wing study program. Volume 1: Executive summary

The effort necessary to achieve a state of production readiness for the design and manufacturing of advanced composite wing structure is outlined. Technical assessment and program options are also reviewed for the wing study results

Drought Tolerance of Interspecific Hybrids between \u3ci\u3eTrifolium repens\u3c/i\u3e and \u3ci\u3eTrifolium ambiguum\u3c/i\u3e

Hybrids between the stolonifeous white clover (Trifolium repens L., 2n=4x=32) and rhizomatous Caucasian clover (T. ambiguum M.Bieb, 2n=4x=32) have been produced. A backcross 2 (BC2) generation with white clover as the recurrent parent combines the growth habit of both parent species with the objective of increasing the persistency of large leaved T. repens varieties under grazing. T. ambiguum is more drought tolerant than T. repens. The drought tolerance of the hybrids in comparison with the parental species was compared in deep soil bins over a four week drought cycle. Soil moisture content, leaf relative water content (RWC), and leaf water potential were measured on plants subjected to drought and those watered normally and maintained at field capacity. T. ambiguum and the backcross hybrids were able to maintain a higher leaf RWC and leaf water potential than T. repens at comparable levels of soil moisture. The dry matter production of the hybrids and parental species was also compared in field plots sown with a perennial ryegrass companion. In the first harvest year, under a cutting regime, the yield of T. repens was highest and T. ambiguum lowest with the hybrids intermediate between the parents, with the BC2 approaching the yield of T. repens. These hybrids will be evaluated over further years and under grazing. The implications of these results for T. repens germplasm improvement programmes are discussed

Introduction of Vegetative and Reproductive Characters into Trifolium Repens by Interspecific Hybridisation

Interspecific hybridization between white clover (Trifolium repens L.) and ball clover (T.nigrescens) and Caucasian clover (T.ambiguum) is a means of improving the reproductive growth and persistency of T.repens. F1 hybrids between T.repens and T.nigrescens were produced without ovule culture and confirmed as true hybrids by chromosome counts, isoenzyme analysis and leaf markers. Their growth habit was generally intermediate between the two parents. After backcrossing to T.repens the BC1 and BC2 hybrids had more of the characteristics associated with T.repens though they retained some of the greater reproductive growth of T.nigrescens. Hybrids between T.repens and T.ambiguum were produced using ovule culture. Two F1 seedlings were produced with a morphology intermediate to the two parents. 35 BC1 seedlings were produced with a similar morphology to the F1 but with less of the T.ambiguum growth habit. The BC2 population showed greater variability in the expression of characters from Caucasian clover and contained only 10% of plants with the combined stoloniferous and rhizomatous habit. The implications for improving the growth of T.repens by interspecific hybridization are discussed

Forage Quality of White Clover (\u3cem\u3eTrifolium Repens\u3c/em\u3e L.) X Caucasian Clover (\u3cem\u3eT.ambiguum\u3c/em\u3e Bieb.) Hybrids Over Three Harvest Years

Interspecific hybrids have been produced from crosses of white clover, a stoloniferous species with Caucasian clover, a rhizomatous species. Using white clover as the recurrent parent first and second generation backcross (BC1 and BC2) plants have been produced that have both rhizomes and stolons and are more drought tolerant than white clover (Marshall et al., 2001). Forage quality of these interspecific hybrids was investigated to determine whether introgression of the rhizomatous trait has any impact on forage quality

Forage Quality of White Clover (\u3cem\u3eTrifolium Repens\u3c/em\u3e L.) X Ball Clover (\u3cem\u3eT.nigrescens Viv.\u3c/em\u3e) Hybrids Over Three Harvest Years

Introgression of reproductive traits from the annual, profusely flowering species ball clover into white clover is one route to improve seed yields in T.repens. The interspecific cross produced F1, backcross 1 (BC1), backcross 2 (BC2) and backcross 3 (BC3) plants with white clover as recurrent parent (Marshall et al., 2002). These hybrids were found to be comparable with white clover for yield and persistency but produced 30% more flowers and their forage quality, relative to white clover was investigated