Use of alternative plant growth regulators and carbon sources to manipulate Dianthus caryophyllus L. shoot induction in vitro

Abstract

Dianthus caryophyllus L. is an important ornamental resource in global carnation cut flower markets. Any protocols that can increase productivity in vitro are always welcome. Using an as-yet unstudied cultivar ‘Silk Road’, the effects of carbon source as well as plant growth regulators [PGRs; 24-epibrassinolide (24-epiBr), Ribav-Extra® (RE), 6-benzyladenine (BA), and indole-3-acetic acid (IAA)], singly or as combinations between BA and IAA, were assessed on in vitro organogenesis. Internodes served as the initial explants. Fructose (3%) as the carbon source in medium was highly effective, inducing the greatest number of shoots formed per explant and number of internodes/shoot. The longest shoots formed when 4% glucose was used. The optimum concentration of 24-epiBr was 10−3% for shoot growth, shoot multiplication, and number of internodes/shoot. RE at 10−5 and 10−6% stimulated shoot growth and number of internodes/shoot, respectively. The simultaneous use of 8.9 µM BA and 2.9 µM IAA improved the number of shoots/explant, shoot size, and number of internodes/shoot. An effective in vitro internodes-to-plantlet regeneration protocol was devised for D. caryophyllus ‘Silk Road’ using different well-known and unexplored PGRs. These PGRs, especially 24-epiBr and RE, can be used to control hyperhydricity in in vitro carnation cultures.