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Biostimulant activity of two protein hydrolyzates in the growth and nitrogen metabolism of maize seedlings
Author(s) -
Ertani Andrea,
Cavani Luciano,
Pizzeghello Diego,
Brandellero Elena,
Altissimo Adriano,
Ciavatta Claudio,
Nardi Serenella
Publication year - 2009
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.200800174
Subject(s) - nitrate reductase , chemistry , glutamine synthetase , nitrogen assimilation , gibberellin , auxin , amino acid , biochemistry , nitrogen cycle , metabolism , nitrate , assimilation (phonology) , nitrogen , glutamine , enzyme , botany , biology , organic chemistry , linguistics , philosophy , gene
Two protein hydrolyzate–based fertilizers (PHFs), one from alfalfa (AH) and one from meat flour (MFH), were studied chemically and biologically. AH and MFH revealed a different degree of hydrolysis and a different amino acid composition. The biostimulant activity was investigated using two specific and sensitive bioassays of auxins and gibberellins. Extracts of AH and MFH elicited a gibberellin‐like activity and a weak auxin‐like one. To improve our understanding of the biostimulant activity, AH and MFH were supplied to maize plants and their effect on growth and nitrate metabolism was studied. Both PHFs increased root and leaf growth and induced morphological changes in root architecture. Besides, the treatments increased nitrate reductase (NR) and glutamine synthetase (GS) activities, suggesting a positive role of the two hydrolyzates in the induction of nitrate conversion into organic nitrogen. Moreover, treatments enhanced GS1 and GS2 isoforms in maize leaves. The latter isoform, amounting to 5‐ to 7‐fold the level of the former, appears to be a superior form in the assimilation of ammonia. The high NR and GS activities together with the high induction of GS isoforms indicate a stimulatory effect of the two PHFs on the assimilation of nitrate. In addition, a role of amino acids and small peptides of the two PHFs is suggested in the regulation of the hormone‐like activity and nitrogen pathway.