Mobilization of seedpiece nitrogen during plant growth from aged potato (Solanum tuberosum L.) seed-tubers
1987
Knowles, N.R.
A study was conducted to characterize patterns of mobilization and translocation of seedpiece nitrogen (N) from single-eye seedcores cut from 5 and 17-month-old potato seed-tubers. Differences in mobilization efficiency were related to age-induced, morphological differences in plant development. Seedcores from older seed-tubers sprouted earlier and produced an average of 6.6 shoots per eye compared to a single shoot from younger seed-tubers. Shoot vigour (d. wt per shoot) from 17-month-old was four-fold lower than that from 5-month-old seed-tubers following 25 d of growth. However, total shoot dry matter from older seedcores was two-fold greater than that from younger seedcores. Differences in vigour per shoot were not explained entirely by differences in shoot number. Rates and absolute amounts of free amino, soluble protein and total-N mobilized from 17-month-old seedcores were greater than from younger seedcores. However, a higher degree of intersprout competition from older seedcores translated into a lower amount of mobilized N available to support growth of individual shoots. Furthermore, before seedcore N became limiting, concentration of foliar N (mg g d. wt−1) from older seedcores was lower compared to that from younger seedcores, indicating a lower sink strength for N per unit increase in dry weight of the multiple shoots. Seedpiece N did not appear to limit shoot growth from younger seedcores. Age-induced loss of vigour on an individual shoot basis may thus be related to decreased sink strength and increased competition among multiple shoots for seedcore N.
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