EVALUATION OF NITROGEN MOVEMENT AND UREA-15N FERTILIZER USE EFFICIENCY FOR YOUNG RUBBER TREES - HEVEA BRASILIENSIS BY USING 15N ISOTOPE TECHNIQUE.

Abstract

             Studies on nitrogen movement and nitrogen use efficiency of ¹⁵N-labelled urea (referred to as NUE hereafter) play an crucial role in the young stage of

rubber trees (Hevea brasiliensis). Appropriate nitrogen application rates can significantly contribute to foster the development of the plants, hence shorten the premature stage of the rubber trees. The ¹⁵N-labeled urea (¹⁵N abundance was 10.16%) was applied at three different rates of 1, 2, and 3 gN/pot on one-year-old ‘PB260’ rubber trees. The results showed that the ¹⁵N absorbed in all plant parts such as leaves, stems, and roots increased gradually by time, and was highest at 60 days after treatment (DAT), and then decreased at 90 DAT. The NUE in leaves was much higher than that in either roots or stems in all treatments. The highest NUE (38.46%) was obtained at 60 DAT when PB260 was treated with the rate of 1 gN/pot.