Horticultura Brasileira (2010) 27, 330-334

Gil R. dos Santos, Manoel D. de Castro Neto, Hudson S.M. de Almeida, Leandro N. Ramos, Renato A. Sarmento, Saulo de O. Lima and Eduardo Andrea L. Erasmo (2010)
Effect of nitrogen doses on disease severity and watermelon yield
Horticultura Brasileira 27 (3), 330-334
Abstract: Nitrogen fertilization is an important step for watermelon (Citrullus lanatus) production due to its influence over yield, fruit quality, and disease severity. Currently, the gummy stem blight (Didymella bryoniae) and the downy mildew (Pseudoperonospora cubensis) can be taken as the most important watermelon diseases, since they impose severe impairment to the crop. Furthermore, studies focusing on plant responses to nitrogen fertilization regarding fruit yield and quality, and disease resistance are rare. Hence, the present study aimed at evaluating the effect of nitrogen doses on fruit yield and quality, and on disease prevalence in watermelon. Two experiments were carried out at the Universidade Federal de Tocantins, employing sprinkler irrigation, in an area previously used to grow watermelon. The experimental design was blocks at random, with five treatments (N doses, applied twice as side-dressing, in kg ha^-1, as follows: T1= control treatment without N, T2= 20, T3= 40, T4= 80, and T5= 120), and four replications. Urea (45% N) was used as the N source. In the first assay, the highest fruit yield and average weight were observed when 40 kg ha^-1 of N were applied. The highest severity of the gummy stem blight was observed when the highest nitrogen doses were applied (80 and 120 kg ha^-1). In the second assay, the highest severity levels of the gummy stem blight, as well as of mildew, were observed again when N doses were the highest (80 and 120 kg ha^-1). The lowest severity levels for both diseases were observed in the control treatment.
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Database assignments for author(s): Renato Almeida Sarmento

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Stagonosporopsis cucurbitacearum	Watermelon/colocynth (Citrullus)	Brazil (NE)
	Pseudoperonospora cubensis	Watermelon/colocynth (Citrullus)	Brazil (NE)