Research Article Modified Application of Nitrogen Fertilizer for Increasing Rice Variety Tolerance toward Submergence Stress Gribaldi Gribaldi, 1 Nurlaili Nurlaili, 1 Nurmala Dewi, 1 Ekawati Danial, 1 Firnawati Sakalena, 1 and Rujito A. Suwignyo 2 1 Faculty of Agriculture, University of Baturaja, Jl. Ratu Penghulu No. 02301, Karang Sari, Baturaja, South Sumatra 32115, Indonesia 2 Faculty of Agriculture, Sriwijaya University, Jl. Palembang-Prabumulih KM 32, Ogan Ilir, South Sumatra, Indonesia Correspondence should be addressed to Gribaldi Gribaldi; gribaldi64@yahoo.co.id Received 27 March 2017; Revised 2 June 2017; Accepted 4 June 2017; Published 10 July 2017 Academic Editor: Allen Barker Copyright © 2017 Gribaldi Gribaldi et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tis research was conducted from July to October 2015, using Randomized Block Design with two treatment factors and three replications for each treatment. Te frst factor was rice varieties (V): V1 = IR 64; V2 = Inpara 5. Te second factor was fertilizer (N): N0: without submergence, all N fertilizer was given during planting; N1: all N fertilizer dose was given during planting; and N2: 1/2 dose of N fertilizer was given during planting; the rest was given at 42 days afer planting. Te submergence was during 7–14 days afer planting; N3 = the entire dose of N fertilizer that was given during planting, N4 = 1/2 the dose of N fertilizer that was given during planting, and the rest was given at 42 days afer planting. Te submergence was during 7–14 and 28–35 days afer planting. Te results showed that the management of nitrogen fertilizer application had efect on rice growth and production which experienced dirty water submergence stress; the application of 1/2 dose of N fertilizer given during planting had the best efect on rice growth and production; the longer the submergence period for rice variety, the higher the efect on rice growth and production. 1. Introduction Food crop production, especially rice (Oryza sativa L.), should be increased in annual basis according to the increase of population growth. Te increase of production can be done through productivity improvement at submergence stress prone areas which is considered as the main constraint in rice crop cultivation. Te area of rice production centers which are mostly located in lowland areas would be extremely vul- nerable to the growing possibility of fooding [1]. According to [2], submergence that causes stress on rice crop at South Asia and Southeast Asia areas was estimated of about 15 million hectares per year, whereas food-prone rice feld areas at South Sumatra were 124,465 ha [3]. Submergence stress on crop causes the obstacle of crop growth and production. Estimated yield loss due to food was about 1.1 million tons of unhulled rice per year or equivalent to yield loss of 0.66 million tons of hulled rice [4]. In addition, [5] showed that rice crop which experienced submergence stress can decrease its grain yield with magnitude of 17.5% compared to the rice crop without submergence stress. One solution to overcome this problem is through development of high yield rice varieties that are tolerant to submergence stress. As shown in Table 4, rice productivity in areas planted in this way is low and unstable, averaging < 2.0 t ha -1 in rainfed lowlands and <1.5 t ha -1 in food-prone areas, compared with yields of >5.0 t ha -1 in input-intensive irrigated systems [6, 7]. Tis results in serious crop losses and sometimes leads to severe food shortages in food-afected regions [8]. Rice variety of IR 64 was developed by IRRI in 2006 which was subsequently converted into IR 64 Sub-1 (Inpara 5) variety by transferring Sub-1 gene from FR13A species which is tolerant to submergence condition. Tis variety is able to decrease harvest loss risk during wet season due to unpredictable change of climate [2]. Te decrease of unhulled rice yield due to the submer- gence for rice variety containing Sub-1 gene was lower than Hindawi International Journal of Agronomy Volume 2017, Article ID 9734036, 6 pages https://doi.org/10.1155/2017/9734036