Root and shoot growth of Atriplex litoralis in relation to nitrogen supply [pot experiment]

Experiments with Atriplex litoralis L. in a natural stand and grown in pots with varied nitrogen supply were carried out on the Swedish west coast in 1978-1980. In the pots, stand density was varied and the plants grown in haline and non-haline soil. In the natural stand on a driftbank, the plants showed only a limited response to extra nitrogen supply given as the only plant nutrient, but the nitrogen content in different plant fractions increased considerably. The effect of nitrogen measured by change in plant weight was much greater if phosphorus and potassium fertilizers were also added. In pots with arable soil without any shortage of P and K, nitrogen clearly increased plant weight and the N content in different plant parts was as high or even higher than in plants from the natural population. This nitrogen effect was similar in pots watered with seawater and fresh water. The plants showed a distinct growth rhythm concerning nitrogen content over the growth period, generally expressed as a decline with time. This rhythm was most accentuated for leaves and flowers plus fruits. In the roots, the content of nitrogen was constant over the whole growth period, approximately 1% in the dry matter, against 3-4% on average in leaves and fruits. The results show that Atriplex litoralis grows well in haline as well as non-haline environments and that nitrogen increases growth irrespective of salinity, provided the general plant nutrient situation is balanced. This suggests that factors other than salinity and nitrogen supply are critical for the very narrow habitat amplitude of A. litoralis and the fact that this species, in contrast to many other annual seashore plants, is not a weed on arable soil. /// Опыты с Atriplex litoralis L. в естественном насаждении и выращенным в горшкак с различным запасом азота, проведены на западном побережье Швеции в 1978-80 гг. В горшках плотность растений варьировала, и растения выращивались в засоленной и незасоленной почве. В естественных насаждениях на дрейфующей отмели растений обнаружили лишь ограниченную реакцию на дополнительную подкормку азотом - единственным элементом питания в удОбрении; но содержание азота в разных частях растений существенно возрастало. Влияние азота, определенное по изменению веса растений, было гораздо больше при добавлении фосфора и калия в удобрении. В горшках с пахотной почвой без недостатка фосфора и калия добавка азота заметно увеличивала вес растений, и содержание азота в разных частях расте