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Effects of High Temperatures and Starter Nitrogen on the Growth and Nodulation of Soybean 1
Author(s) -
La Favre A. K.,
Eaglesham A. R. J.
Publication year - 1987
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1987.0011183x002700040028x
Subject(s) - sowing , biology , glycine , nitrogen , horticulture , plant growth , bradyrhizobium japonicum , cycling , symbiosis , maxima , botany , zoology , agronomy , bacteria , rhizobiaceae , chemistry , amino acid , biochemistry , history , organic chemistry , archaeology , art , genetics , performance art , art history
Until recently it was believed that soil temperatures in excess of 30°C are likely to inhibit the establishment of root nodules on soybean [ Glycine max (L.) Merr.]; however, using diurnally cycling thermoperiods rather than constant‐temperature techniques, we previously found that a root temperature of 45°C is required to suppress soybean nodulation. Considering that the level of soil N also affects growth and nodulation, in this work we examine the effects of daily maxima of 30 to 45°C in combination with different levels of N (KNO 3 ) applied at planting, using sand‐cultured ‘Wilkin’. Plant growth, on combined N or symbioticaily fixed N, was severely inhibited by temperature maxima >41°C, but was improved by 36°C maximum for 9 h daily. With 21‐day‐old plants, maxima >36° adversely affected nodulation only in the presence of combined N, and after depletion of N excellent nodulation was obtained. Growth and nodulation at 35 days were less adversely affected by temperature stress when a small (e.g., 90 mg N plant ‐1 ) application of N had been made at planting than under N‐free conditions. The results show that inhibition of nodulation of soybean by high temperature is exacerbated by: (i) the presence of available N, and (ii) the complete absence of applied N.