Restoration of pseudo-self-compatibility (PSC) in derivatives of a high-PSC × no-PSC cross in Nemesia strumosa Benth
SummaryMean PSC increased following each generation of recurrent selection in F1, F2 and F3Nemesia strumosa families derived from a cross of a 100% PSC plant to an unrelated 0% PSC plant. The first 100% PSC individuals occurred in the F4. Populations derived through sib pollination tended to have higher PSC means than lines derived through self pollination. One F3 family showed a three-fold higher PSC level when pollinated in the green-house than when pollinated in the growth chamber, while another F3 family similarly pollinated showed no change in PSC.
THE INHERITANCE OF MODIFIERS CONFERRING SELF‐FERTILITY IN THE PARTIALLY SELF‐INCOMPATIBLE PERENNIAL, CAMPANULA RAPUNCULOIDES L. (CAMPANULACEAE)
Abstract The role of partial self‐incompatibility in plant breeding system evolution has received little attention. Here, we examine the genetic basis of modifiers conferring self‐fertility in the creeping bellflower, Campanula rapunculoides L. (Campanulaceae), a partially self‐incompatible herb. A survey of 35 individuals from two natural populations indicates that 45% of them are strongly self‐incompatible, 40% intermediately self‐incompatible, and 15% weakly self‐incompatible and that some plants show a strong breakdown in self‐incompatibility over floral age. We generated 101 F1 families by random crossing among 31 parental plants and estimated the heritability of self‐fertility in day 1 and day 4 female‐phase flowers, the genetic correlation between day 1 and day 4 self‐fertility, and the coefficient of additive genetic variance of self‐fertility. We use linear regression and data from additional crosses to examine whether there are significant maternal effects in the expression of self‐fertility. We use Fain's test to determine if a major gene influences self‐fertility and, finding no evidence, use data from additional crosses on an F2 generation to estimate the mean number and dominance of genes conferring self‐fertility. These analyses indicate that the heritability (h2) of self‐fertility is 0.24 in day 1 female‐phase flowers and 0.44 in day 4 flowers, self‐fertility is primarily additive but shows some recessive effects, and self‐fertility is estimated to be controlled by four genetic factors. In addition, we have evidence that there may be maternal effects for self‐fertility, especially for weakly self‐incompatible plants. The significance of these results in the context of mating system evolution is discussed.
Experimental study of water fluxes in a residential area: 2. Road infiltration, runoff and evaporation
Lack of accurate data has led some hydrologists and city planners to assume that urban infiltration is zero and runoff is 100% of the rainfall. These assumptions lead to an over estimation of road runoff volume and an underestimation of direct recharge to groundwater, which is already rising under some UK cities. This study investigates infiltration and runoff processes and quantifies the percentage of rainfall that contributes to storm drainage, and that which infiltrates through different types of road surface. Access tubes were installed for measuring soil water content using a neutron probe in three car parks, a road and a grass site at the Centre for Ecology and Hydrology, Crowmarsh Gifford, Wallingford. Storm drainage was recorded at the exit of the Thamesmead Estate in Crowmarsh Gifford, just before the drain joins the River Thames at Wallingford. Rainfall and water table depth were also recorded. Weekly measurements of soil moisture content indicated that the top 40 cm layer is not influenced by water‐table fluctuations and, therefore, positive changes in soil moisture could be attributed to infiltration of rainfall through the surface. Depending on the nature of the surface, subsurface layers, level of traffic, etc., between 6 and 9% of rainfall was found to infiltrate through the road surfaces studied. The storm drainage generated by road runoff revealed a flow pattern similar to that of the receiving watercourse (River Thames) and increased with the increase of infiltration and soil water content below the road surface. The ratio of runoff to rainfall was 0·7, 0·9 and 0·5 for annual, winter (October–March) and summer (April–September) respectively. As the results of the infiltration indicated that 6 to 9% of annual rainfall infiltrates through the road surface, this means that evaporation represents, 21–24% of annual rainfall, with more evaporation taking place during summer than winter. Copyright © 2003 John Wiley & Sons, Ltd.