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THE GROWTH OF TOMATO SEEDLINGS IN RELATION TO THE FORM OF THE NITROGEN SUPPLY
Author(s) -
WOOLHOUSE H. W.,
HARDWICK K.
Publication year - 1966
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1966.tb05975.x
Subject(s) - potassium , phosphorus , nitrogen , chemistry , dry matter , shoot , ammonium , nitrate , ammonia , dry weight , nutrient , agronomy , horticulture , zoology , biology , organic chemistry
S ummary Young tomato plants grown in nutrient solution cultures in which all of the nitrogen supply was in the form of nitrate had a higher relative growth rate than plants grown with ammonium nitrogen. Total phosphorus content expressed on a unit dry weight basis was not significantly different in the two treatments, but inorganic phosphorus content was high and organic phosphorus correspondingly low in ammonium‐grown as compared to nitrate‐grown plants. After 13 days this difference was found only in the shoots, but after 17 days the composition of the roots was similarly affected. Nitrate fed to ammonia‐grown plants resulted in a rapid increase in the dry matter and in organic phosphorus content in the young, incompletely expanded leaves. Total potassium content expressed on a dry weight basis did not differ in the two treatments for the first 10 days but thereafter the concentration in the ammonia‐grown plants fell whilst that in the nitrate grown plants remained approximately constant. The lowered potassium content in ammonia‐grown plants was first apparent in the leaves after 10 days, in the stems later and finally in the roots after 21 days. The causes of this reduced potassium content and its relationship to the lowered phosphate esterification and declining unit leaf rate are discussed.