Performance of true potato seed families. 1. Effect of level of inbreeding

Summary Successive generations of open pollinated (OP) true potato seed (TPS) families represent a low-cost planting material. This study was conducted to determine whether inbreeding occurred during two successive OP generations and, if so, whether it adversely affected the performance of transplant families from true seed. Potato seedling transplants from 4x×2x hybrid, OP₁, OP₂, S₁ and S₂ families were compared for plant vigour, flowering, pollen stainability, OP fruit set, tuber yield and specific gravity. Hybrids were consistently superior, while S₂ families were inferior. The performance of OP₁, OP₂ and S₁ families did not differ significantly for most traits. The accumulation of inbreeding in successive OP generations was limited by reduced OP seed production on selfed plants; thus, a synthetic TPS variety propagated by open pollination may be feasible. Paper no. 3162 from the Department of Genetics, University of Madison.     

The identification and evaluation of hybrid plants among open pollinated tkue seed families

An increase in the proportion ofhybrid vs. selfed plants improves the performance ofopen pollinated (OP) true potato seed (TPS) families. Strategies to increase the proportion ofhybrid seeds were investigated. A marker gene for yellow tuber flesh in a diploid clone, interplanted as the male parent, permitted identification of 4x × 2x hybrids among the OP progeny. Only 5% of the OP progeny were 4x × 2x hybrids. The proportion of 4x × 2x hybrid plants among the OP progeny was increased when the female parent had low male fertility and when only the largest 25% of the seeds were planted. The hybrid 4x × 2x plants were superior for all traits evaluated on the OP seedling transplant families. Traits included vigor, flowering, pollen stainability, OP fruit set, and tuber yield. Effects of the female parent were significant only for vigor and flowering, while seed size did not affect values for any trait consistently: With the limited outcrossing observed, the low seed set obtained when using parents with low male fertility and the work involved in selecting the largest seeds within individual fruits were not justifiable. However, research with OP true seed families asa low cost planting material should be continued, since high yielding OP families have been identified.     

Pollen fertility in relation to open pollinated true seed production in potatoes

The cost and difficulty of producing hybrid true potato seed (TPS) currently limits their use for commercial production. Twelve clones, selected in preliminary trials for low pollen stainability but high fruit and seed set, initially seemed promising for inexpensive production of mostly hybrid open-pollinated (OP) TPS. However, in subsequent tests, pollen stainability of these clones appeared to be highly variable and fruit and seed set were not as high. Bumblebees favored the most fertile clones, especially during periods when pollen stainability was the highest. Amounts of OP fruit and seed set correlated with maximum observed pollen stainability levels of the clones. Most of the OP seeds produced by these clones were probably the result of self-pollination; therefore, other methods must be used to obtain hybrid TPS.     

Recombinant nucleocapsid-based ELISA for detection of IgG antibody to Rift Valley fever virus in African buffalo

Wild ruminants are thought to serve as natural hosts for Rift Valley fever virus (RVFV) but the role of these animals as reservoirs for RVFV during inter-epidemic periods and as amplifiers during epidemics is not well understood. An indirect enzyme-linked immunoassay (I-ELISA) based on the recombinant nucleocapsid protein (rNp) of RVFV was validated for the detection of specific IgG antibodies in African buffalo. Data sets derived from testing buffalo sera from Kenya (n=405) and South Africa (n=618) were dichotomised according to the results of a virus neutralisation test. The assay characteristic performance was analysed using threshold values optimised by the two-graph receiver operating characteristics (TG-ROC) analysis, and by mean plus two, as well as by mean plus three standard deviations derived from I-ELISA PP values in uninfected animals. Among 1023 buffalo sera tested, 77 (7.5%) had detectable virus neutralising antibodies. The assay had high intra- and inter-plate repeatability in routine runs. At a cut-off optimised by the TG-ROC at 95% accuracy level, the diagnostic sensitivity of the I-ELISA was 98.7% and diagnostic specificity 99.36% while estimates for the Youden's index (J) and efficiency (Ef) were 0.98 and 99.31%. When cut-off values determined by traditional statistical approaches were used, the diagnostic sensitivity was 100% but estimates of J, Ef and other combined measures of diagnostic accuracy were lower compared to those based on cut-off value derived from the TG-ROC. Results of the study indicate that the I-ELISA based on the rNp would be useful for seroepidemiological studies of RVFV infections in African buffalo.     

Groundwater modelling to assess the effect of interceptor drainage and lining

Recharge to the aquifer through seepage from irrigation canals is often quoted as one of the main causes for waterlogging in Pakistan. In the design of drainage systems to control this waterlogging, rules-of-thumb are often used to quantify the seepage from canals. This paper presents the option to use a groundwater model for a more detailed assessment. Groundwater models may assist in evaluating the effect of recharge reducing measures such as interceptor drains along irrigation canals and lining. These measures are commonly aimed at reducing the drainage requirement of adjacent agricultural lands. In this paper an example is given of the application of a numerical groundwater model, aimed at assessing the effect of interceptor drainage and canal lining in the Fordwah Eastern Sadiqia project, being a typical and well-monitored location in Pakistan. The paper also presents references to other conditions. The model was used to obtain a better insight in the key hydraulic parameters, such as the infiltration resistance of the bed and slopes of irrigation canals, the drain entry resistance of interceptor drains and the hydraulic conductivity of soil layers. The model was applied to assess the effectiveness and efficiency of interceptor drains under various conditions. The results of the study show that the net percentage of intercepted seepage is too low to have a significant effect on the drainage requirement of the adjacent agricultural lands. Besides, the operation of the system, with pumping required, is often an added headache for the institution responsible for operation of the system. The marginal effect of interceptor drains and lining on the drainage requirement of adjacent agricultural land does not always justify the large investments involved. It can be concluded that:

Characterization of the anemia of inflammatory disease in cats with abscesses, pyothorax, or fat necrosis

The purpose of this study was to describe the anemia of inflammatory disease (AID) in cats with naturally-occurring inflammatory diseases, such as abscesses (n = 12), pyothorax (n = 6), and fat necrosis (n = 3). Exclusion criteria were positive FeLV/FIV tests, neoplasia, nephro-, hepato- or endocrinopathies, and blood loss anemia. CBC, clinical biochemistry, measurements of serum erythropoietin, iron, total iron-binding capacity (TIBC), ferritin, acute phase proteins, erythrocytic osmotic fragility (OF), and Coombs' tests were performed. A decrease in hematocrit of 1-28% (median, 10%) occurred within 3-16 days (median, 8 days). The anemia was mild (n = 11), moderate (n = 8), or severe (n = 2). In most cases it was normocytic normochromic, non-regenerative (n = 18), or mildly regenerative (n = 3). Sixteen cats had leukocytosis and 5 mild hyperbilirubinemia. The Coombs' test results were negative for 8 cats and positive for 1 cat. OF was increased in 2 out of 14 cats. Hypoalbuminemia (n = 18) and hyperglobulinemia (n = 16) resulted in a lowered albumin/globulin-ratio in 19 cats. Iron and TIBC were low in 2/19 and 6 /19 cats, respectively. The ferritin concentrations were normal in 7 cats and increased in 12 cats. The acute phase proteins alpha1-acid-glycoprotein and haptoglobin were increased in 14/14 and 13/14 cats, respectively. Erythropoietin was normal (n = 4), mildly increased (n = 7) or severely increased (1). Two cats were euthanized due to their underlying disease, 3 cats needed blood transfusions. AID in cats is usually mild to moderate, non-regenerative, and normocytic normochromic. It can be clinically relevant causing severe and transfusion-dependent anemia. AID seems to be multifactorial with evidence of iron sequestration, decreased RBC survival, and insufficient erythropoietin production and bone marrow response. Specific and supportive therapy, including transfusions, can reverse these processes.