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Root Elongation and Plant Growth in a Basal Till Compact Soil Treated with 3,5‐Diiodo‐4‐Hydroxybenzoic Acid and Gibberellic Acid 1
Author(s) -
Saini G. R.
Publication year - 1979
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1979.00021962007100060042x
Subject(s) - subsoil , topsoil , agronomy , gibberellic acid , soil water , bulk density , elongation , chemistry , horticulture , environmental science , soil science , biology , materials science , ultimate tensile strength , germination , metallurgy
Soils developed on basal till have very dense compact subsoil, which may extend many meters below the topsoil. To improve their moisture storage and other physical conditions, deep subsoiling is usually practiced. In most instances, the beneficial effect of subsoiling is short‐lived and the operation has to be repeated every few years. The spiralling costs of fossil fuel may make repeated subsoiling operations prohibitive. Therefore, as an alternative management technique, the use of small quantities of 3,5‐diiodo‐4‐hydroxybenzoic acid (DIHB) and gibberellic acid (GA 3 ) in the top‐soil to promote root elongation and enhance crop yields was compared with loosening the sub‐soil and also with incorporating limestone in the subsoil after loosening. A growth chamber study showed that roots of alfalfa ( Medicago saliva L.) ‘Saranac’ penetrated the dense subsoil, bulk density 1.9 g cm −3 , of a poorly drained basal till soil (Fera Luvic Gleysol) when 1,700 g topsoil was treated with 200 ml of 10 −2 M DIHB or with GA 3 . However, the roots in loosened subsoil and to which limestone at 11.2 metric ton/ha had been added and incorporated went deeper. The treatments in order of their superiority were: loosened sub‐soil plus limestone > loosened sub‐soil > top‐soil treated with DIHB > topsoil treated with GA 3 > control. Mean root lengths of the alfalfa plants in the various treatments were 66.3, 61.0, 51.2, 49.0, and 33.2 cm, respectively. Corresponding mean dry weight yields of shoots in each treatment were 7.05, 6.08, 5.59, 4.65, and 3.08 g. Should the spiraling costs of energy make periodic subsoiling operations uneconomical, the use of small quantities of DIHB in the topsoil may provide an alternate management technique for agricultural lands with dense subsoil.