Analyses of covariance were used to relate corn yields to population densities of Pratylenchus hexincisus in South Dakota dryland corn or P. scribneri in irrigated corn. The relationship for P. hexincisus was Y = 5,825 - 0.14X - 0.03X' where Y = yield (kg/ha), X = number of P. hexincisus per gram of dry root at midseason and X' = number at harvest. The relationship for P. scribneri was best des...

There were no signi®cant differences in the percent mortality and weight of earthworms (Lumbricus terrestris) after 40 days in soil planted with Bt (NK4640Bt) or non-Bt corn or after 45 days in soil amended with biomass of Bt or non-Bt corn. The toxin was present in the guts and casts of earthworms in soil planted with Bt corn or amended with biomass of Bt corn, but it was cleared within 2±3 da...

The ability to prevent significant root feeding damage to corn, Zea mays L., by the western corn rootworm, Diabrotica virgifera virgifera LeConte, by crop rotation with soybean, Glycine max (L.) Merr., has been lost in portions of the Corn Belt because this pest has adapted to laying eggs in soybean fields. Cuphea spp. has been proposed as a new broadleaf crop that may provide an undesirable ha...

When amino acids or ammonia are added to plant systems, the effects on the development of nitrate-dependent nitrate reductase activity are variable. In addition, amino acids added singly or as casein hydrolysate may not support a normal growth. A physiologically correct mixture of amino acids, one similar in composition to amino acids released by the endosperm, has been shown to support normal ...

Maize, Zea mays L., is an economically important crop grown throughout the world. Corn rootworm, Diabrotica spp. (Coleoptera: Chrysomelidae), larvae constitute a significant economic threat to maize production in the United States, where yield losses and management costs associated with corn rootworm species exceed $1 billion annually. Furthermore, the introduction of the western corn rootworm,...

Several aryl-carbamoyl dipeptide alcohols increased the uptake of nitrate and ammonium ions into corn root segments by up to 50% and 90%, respectively. The most effective one was N-carbobenzoxy-l-prolyl-l-valinol. Foliar application of this compound to underfertilized corn plants caused an increase in the rate of plant growth in the greenhouse and provided modest (6-10%) corn yield increases in...

It has recently been reported that plasmalemma electron transport may be involved in the generation of H(+) gradients and the uptake of ions into root tissue. We report here on the influence of extracellular NADH and ferricyanide on K(+) ((86)Rb(+)) influx, K(+) ((86)Rb(+)) efflux, net apparent H(+) efflux, and O(2) consumption in 2-centimeter corn (Zea mays [A632 x Oh43]) root segments and int...

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae), are important insect pests in corn, Zea mays L. For more than a decade, growers have been using transgenic plants expressing proteins from the bacterium Bacillus thuringiensis (Bt) to protect corn roots from fee...

Current knowledge about the mechanisms of plant root response to gravity is reviewed. The roles of the columella region and amyloplasts in the root cap are examined. Results of experiments related to gravistimulation in corn roots with and without root caps are explained. The role of auxin, abscisic acid, and calcium also are examined.