Fertigated Sugarcane Yield and Carbon Isotope Discrimination (Δ13C) Related to Nitrogen Nutrition
2016
Kölln, Oriel Tiago | de Castro Gava, Glauber José | Cantarella, Heitor | Franco, Henrique Coutinho Junqueira | Uribe, Raul Andres Martinez | da Rocha Pannuti, Luiz Eduardo | Trivelin, Paulo Cesar Ocheuze
The aim of this study was to evaluate the response of sugarcane to nitrogen (N) application with drip irrigation and the relation with carbon isotope discrimination (Δ¹³C), aboveground dry matter cane yield and the N balance in consecutive ratoon crops of sugarcane. An experiment was set up in Jaú, SP, Brazil, in which the second and third ratoon crop cycles (2008/2009 and 2009/2010) were evaluated. The experiment included an unfertilized N control in both years (T1), and the following three nitrogen (N) fertilizer rates (in kg ha⁻¹) applied in 2008 and 2009, respectively: 70 and 50 (T2), 140 and 100 (T3), and 210 and 150 (T4). Fertilization with N caused a marked gain in stalk yields by 98 Mg ha⁻¹ in 2 years. The N export with harvest was higher than N application in the control treatment T1 and at the lower rate (T2); this, in addition to the observed linear response to N, indicate the need to increase N fertilization in irrigated sugarcane. The values of Δ¹³C decreased with the increase of N supply showing a significant negative correlation (p < 0.05) with stalk as well as whole plant aboveground dry matter yields. The values of Δ¹³C in top leaves may be used as a tool to characterize the N status of sugarcane plants and its relation to aboveground dry matter and yield.
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