Effects of Benzylaminopurine on Shoot and Root Development and Growth of Rice (cv. North Rose) Grown Hydroponically with Different Nitrogen Forms

Abstract

Summary: In spite of a large number of reports on the effects of cytokinin application on growth of wheat, barley and other crops, the impact of it on rice growth has rarely been investigated. The objective of this study was to examine the effects of benzylaminopurine (BA) on shoot and root development and growth of rice plants. Rice (Oryza sativa L. cv. North Rose) was grown in hydroponics under all NH4+, all NO3– and an equal mixture of both forms. From the 6th leaf stage on, 100μ M BA was sprayed to the shoot once every two days for a total of 5 times. BA spray inhibited the development and growth of plant age, plant length, leaf blade length and the root as a whole with the exception that the length of adventitious roots was increased by BA in NH4+-N-grown plants. BA spray also decreased the dry-matter production of both the shoot and root. Single NH4+-N inhibited the shoot and root development and growth compared with N03""-containing N sources. BA counteracted to some extent the inhibitory effect of NH4+-N on plant length, average adventitious root length and the longest adventitious root length. We concluded that 100μM BA spray basically inhibited the shoot and root growth and development of rice (cv. North Rose) grown in hydroponics, but the effects on shoot development are temporary and the treated plants attain or exceed the development of the control plants while the inhibited development of the root did not recover within the experiment period.