ALBERT

Description: SummaryFour experiments are reported in which the effects of a range of physiological ages of seed tubers on growth and yield in seed crops and regrowth of the progeny seed were studied. Increasing the age of seed in Home Guard, Arran Comet, Pentland Javelin and Désirée advanced emergence, tuber initiation and early growth but restricted leaf area index and reduced the number of tubers and seed tuber yield. In these varieties increasing the physiological age of seed shortened the dormancy of the progeny seed and slightly increased sprout lengths at replanting but in Home Guard had no effects on field growth and tuber yield.In a further series of experiments at Tenby seed of five varieties (Home Guard, Red Craigs Royal, Désirée, Maris Piper and Stormont Enterprise) was multiplied over 2 years using husbandry methods designed to produce seed of contrasting ages. Once-grown seed from Tenby which had been planted and harvested early in the season was stored at either 4 or 12 °C and grown again at Tenby before being stored again at either 4 or 12 °C. The seed resulting from this multiplication over 2 years was compared with seed imported from seed-growing areas stored at the two temperatures. The seasons for the two multiplications at Tenby (1975 and 1976) were hot and were followed by an especially cold and late spring yet few differences between seed from Tenby and other areas could be detected. Where seed from different areas entered sprouting temperatures at different times and therefore produced different ages of seed at replanting large effects on yield were found. Storage temperature had large effects on regrowth of tubers in Home Guard, Red Craigs Royal and Stormont Enterprise for storage at 12 °C produced ‘little potato disorder’ in the majority of plants in one storage phase while storage at lower temperature produced full plant stands and yields. The results provided no support for the suggestion that repeated multiplication in warm lowland areas may lead to cumulative deterioration in the performance of seed.

Description: SUMMARYNine experiments are reported in which effects of site of seed production on dormancy, sprout and field growth of progeny tubers were recorded. The experiments used early varieties, Home Guard (four experiments), Red Craigs Royal (three experiments) and Arran Comet (two experiments) and in each, seed crops were grown with similar husbandry at sites differing in altitude and location in western England and Wales. There was no consistent effect of site of seed production on the timing of the end of dormancy, and the maximum effect in any year was 11 ± 1·2 (S.E.) days. The small effects of site on dormancy influenced initial sprout lengths, and this effect usually persisted up to planting in Home Guard and Red Craigs Royal, although the effects were small in magnitude. There was no effect of site of seed production on sprout lengths at planting or on field growth and yields in Arran Comet. In the other two varieties there was no effect of site of seed production on yield at early harvests, but at later harvests seed from cooler upland sites sometimes significantly outyielded lowland seed. There was, therefore, no evidence to support the view that locally produced seed was advantageous for early potato production. The results, together with those of the concurrent series with maincrop varieties reported by Wurr (1979), show that on half the occasions on which yields were measured covering the whole of the harvesting period, site of seed production had no effect on yields. In these experiments with early varieties effects of site occurred only at harvests later than the commercial harvesting of such old seed. It is therefore suggested that site of seed production is a much less important determinant of tuber yield than hitherto suggested, and of little practical significance.

Description: SUMMARYThree experiments, carried out in 3 years (1972–5), which examined the effects of a wide range of rates of nitrogen fertilizer applied to seed crops of Home Guard on seed and progeny crop growth are reported. There was little effect of increasing rate of N application over the range 0–300 kg/ha on seed yield, and the results suggested that very low rates of nitrogen fertilizer (〈 75 kg/ha) were required for maximum seed yield in mid-Wales. Increasing the rate of nitrogen fertilizer above 304 kg/ha delayed growth and decreased yield in seed crops. Although increasing the rate of nitrogen fertilizer in seed crops delayed senescence and increased the nitrogen concentration of tubers, there were few consistent effects on sprouting or growth of progeny crops.Close negatively quadratic relationships were found between the dry-matter content of tubers and their size. The dry-matter content of all sizes of tubers increased during growth, but there were no effects of nitrogen on dry-matter content.