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  • Author or Editor: Dale T. Lindgren x
  • Journal of the American Society for Horticultural Science x
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Differences in potato leafhopper (Empoasca fubae Harris) injury symptoms were noted in 22 cultivars or lines of dry beans (Phaseolus vulgaris L.) in a 1991 field trial at North Platte, Neb. Seed yield, biomass, and plant injury symptoms were recorded. The same 22 dry bean cultivars or lines were planted in a split-plot design, with main plots protected (sprayed with insecticide) vs. unprotected (not sprayed) and cultivars or lines as subplots in 1992 and 1993. Significant differences were observed between cultivars/lines for leafhopper injury and yield in all 3 years. `Tacaragua' (black-seeded) and pinto `Sierra' were highly resistant to leafhoppers, with no visual leafhopper injury symptoms in all 3 years. Significant negative correlation coefficients between leafhopper injury symptoms and yield were recorded in the protected (4.50) and unprotected (-0.33) plots in 1993 but only in the unprotected (-0.46) plots in 1992. A cultivar x spray interaction response to leafhoppers occurred in 1992 but not in 1993. The degree of leafhopper injury symptoms varied between years.

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Excised roots were used for evaluating methods and in identifying differences in rates of P absorption by 59 lines of Phaseolus vulgaris. Large variations in P absorption rates between lines were noted. Although the P absorption rate was negatively correlated with root dry weight, it was possible to isolate lines with similar excised root dry weights which displayed large differences in P absorption rates. Rates of P absorption by the terminal 3.5 cm root segment satisfactorily expressed P absorption by other portions of the root system. The rate of P absorption by excised roots was influenced by the amount of P in the solution in which plants were cultured prior to root excision. As the pretreatment P level increased from 3 to 31 mg/plant, P absorption by excised roots decreased and as the P level increased from 31 to 62 mg/plant, P absorption by excised roots leveled off. Rates of P absorption by excised roots also varied with the age of the plant. However, relative values between efficient and inefficient lines remained constant at each plant age. Variance for P absorption by excised roots due to environment was high. Narrow sense heritability estimates derived from parent offspring regression in families of efficient × inefficient lines were estimated to be about 40%. Data on P uptake by excised roots did not predict P uptake and translocation in intact plants. A reliable standardized technique for intact plant ion absorption studies is necessary to make accurate comparisons between plants.

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