Nitrogen absorption rate in highland rice cultivars with different types of plants

Abstract

The use of the irrigation by sprinkling in the rice crop is a relatively recent practice in Brazil and the fertilization management, principally nitrogen, is not well defined yet. Studies of the nutrients absorption rate existents for the rice crop were realized at least twenty years ago, utilizing traditional cultivars of upland systems. Thus, with the appearance of improved cultivars for the highland system it is possible that they would assimilate differently the nitrogen and could have your maximum absorption in distinct developmental stadia. The present work aimed to evaluate the accumulation of dry matter, the nitrogen absorption rate and yield index in highland rice cultivars with different plant types. The experimental design used was randomized blocks, with seven repetitions. Treatments were the cultivars Caiapó (traditional), Primavera (intermediate) and Maravilha (modern). It was concluded that: among the stadia of panicle initiation, flowering and grains filling the cultivar Primavera presented the highest values of dry mass accumulation compared with the cultivars Caiapó and Maravilha. Independent of the cultivar it was observed that about 82% of the total nitrogen was absorbed in the period between the profiling and flowering developmental stadia. The cultivar Primavera presented the highest yield index (0.5) and the greatest number of spikelets per panicle, when compared with the cultivars Caiapó and Maravilha, which presented the greatest increase in the potential of grain production for this cultivar. Additional keywords: Oryza sativa L.; dry matter; grain productivity; harvest index.