QTL for delayed bolting after winter detected in leaf beet (Beta vulgaris L.)

Growing sugar beet (Beta vulgaris L. ssp. vulgaris) as a winter crop in cool temperate climates is expected to increase yield potential. However, this requires bolting resistance after winter. One strategy to achieve complete bolting resistance is to accumulate genes for bolting delay from various genetic resources within the B. vulgaris gene pool. To identify such genes, a QTL mapping was performed in a segregating population derived from a biennial leaf beet with delayed bolting after winter. The population was tested for bolting delay after winter in two different experiments with natural or artificial vernalization. Three QTL for bolting delay were mapped on linkage groups 3, 5 and 9 affecting bolting time by up to 19 days. These QTL could be combined with recently reported bolting QTL to develop a winter sugar beet with complete bolting resistance.     

Nitrate determination in baby food, using the nitrate ion selective electrode.

The nitrate electrode has been utilized in the determination of nitrate content in food products. The AOAC xylenol method was employed for comparative results. A reasonable correlation (r=0.91) was found between the 2 methods in the analysis of 49 samples containing 30-350 ppm nitrate. At the average nitrate content (100 ppm) of these foods, the standard error was 4.3 ppm. The electrode responds directly to the ionic activity of the nitrate ion. It has a linear concentration range of 1-6000 ppm nitrate and can be used over a wide pH range. The electrode does respond to some extent to anions other than nitrate, and some interferences do occur. These interferences are easily controlled by the use of cation exchange resins. The Corning known addition (spiking) method is used on all samples to insure correct electrode response in solutions containing variable background ionic composition. The electrode has the advantage of simplicity, speed, reproducibility, and accuracy. Work time saved using the electrode as opposed to the xylenol method is about 7 hr for the analysis of 20 samples. Error, and the need for repeating analysis, is much less frequent.