Influencia Del Nitrogeno En Rabano

Front. Agric. China 2009, 3(2): 122–129 DOI 10.1007/s11703-009-0041-y

RESEARCH ARTICLE

Yulin LIAO*, Xiangmin RONG*, Shengxian ZHENG*, Qiang LIU*, Meirong FAN*, Jianwei PENG Guixian XIE

Influences of nitrogen fertilizer application rates on radish yield, nutrition quality, and nitrogen recovery efficiency

© Higher Education Press and Springer-Verlag 2009

Abstract Radishes (Raphanussativus L.) were grown in plastic pots in a screenhouse to investigate the influences of nitrogen fertilizer application rates (NFAR) on yield, nitrate content, nitrate reductase activity (NR), nutrition quality, and nitrogen recovery efficiency (NRE) at commercial mature stage. Five N-rate treatments, 0.644, 0.819, 0.995, 1.170, and 1.346 g$pot–1, were set up in the screenhouse pot experiments, andnitrogen fertilizer (unlabeled N and 15N-labeled fertilizer) was applied as basal dressing and topdressing, respectively. The results indicated that the fresh and dry weight yields of radish increased with the increase of NFAR at the range of 0.099 to 0.180 g N$kg–1 soil, decreased at 0.207 g N$kg–1 soil, and accordingly there was a significant quadratic relationship between the fresh and dry weightyields of radish and the NFAR. At the high addition of urea-N fertilizer, the nitrate content accumulated in the fleshy roots and leaves due to the decline in NR activity. From 0.644 to 0.819 g N$pot–1 NR increased most rapidly, the highest NR activity occurred at 0.819 g N$pot–1, and the lowest NR activity happened at 1.346 g N$pot–1. Soluble sugar and ascorbic acid initially increased to thehighest value and then decreased, and, contrarily, crude fiber rapidly decreased with the increase of NFAR. Total N uptake (TNU), N derived from fertilizer (Ndff), and N
Received December 3, 2008; accepted December 30, 2008 Yulin LIAO, Xiangmin RONG ( ), Qiang LIU, Meirong FAN, Jianwei PENG, Guixian XIE College of Resources and Environment, Hunan Agricultural University, Changsha 410128, ChinaE-mail: rongxm2005@126.com Yulin LIAO, Shengxian ZHENG ( ) Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China E-mail: sxzheng@ipni.ac.cn Meirong FAN Changsha Environmental Protection Colleges, Changsha 410004, China * These authors contributed equally to this work

derived from soil (Ndfs) in radish increased, except that Ndfs relatively and slightly decreased at the rate of 0.207g N$kg–1soil. The ratio of Ndff to TNU increased, but the ratio of Ndfs to TNU as well as NRE of N fertilizer decreased with the increase of NFAR. Therefore, the appropriate NFAR should be preferably recommended for improving the yields and nutrition qualities of radish and NRE of N fertilizer. Keywords 15N-labeled nitrogen fertilizer, radish, yields, nutrition quality, nitrogen recoveryefficiency

1

Introduction

✉

✉

Nitrogen (N) affects all levels of plant function, from metabolism to resource allocation, growth, and development (Crawford, 1995; Stitt and Krapp, 1999). In modern agricultural production where crops rely on fertilizers to meet their demand for N, more and more N fertilizer is applied in the field to obtain high yield of crop. As a result, inadequate practicesinevitably cause environmental problems (Ji et al., 2006), mainly linked to nitrate (NO3–) loss in the environment. Presently, with the increasing input of chemical fertilizers, N fertilizer use, therefore, is a major issue as it can result in ground and surface water pollution. Common practices such as high rates of N fertilizer application combined with heavy irrigation are presumed to causeground and surface water pollution through NO3– leaching and soil erosion (Gastal and Lemaire, 2002; Wang et al., 2002). Most previous studies have shown that excessive application of N fertilizer not only resulted in the lower yield of crops, but also negatively affected the quality of agricultural produce (Hu et al., 1992; Chen et al., 2004). For instance, excessive application of N fertilizer in...