Effect of nitrogen doses on disease severity and watermelon yield

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.

Effect of Nitrogen Fertilization on Yield and Quality of Watermelon, Cv. Top Gun

“…Excess N can promote vegetative growth at the expense of flowering and fruiting, thereby decreasing the SS content (MOUSINHO et al, 2003), which reduces the resistance to transport and storage (PRADO, 2008). High plant N content also reduces the production of phenolic (fungistatic) compounds and lignin in the leaves, decreasing the resistance to pathogens (SANTOS et al, 2009).…”

The effects of deficit irrigation on nitrogen consumption, yield, and quality in drip irrigated grafted and ungrafted watermelon

“…Plant nutrition is another important parameter to consider for obtaining high yield from watermelon (Santos et al 2009). Andrade Junior et al (2006) reported that the marketable yield of watermelon could be increased by applying nitrogen via fertigation without affecting fruit quality.…”

Irrigation and fertigation frequencies with nitrogen in the watermelon culture

“…For Santos et al (2009), the constant search for a balance in the application of nitrogen (N), together with the scarcity of studies on plant response and the effects on the production of quality fruits, increases the need for more research on the subject. Thus, starting with the assumption that the fractionation of applying water and nitrogen inputs through fertigation improves the utilization of these by the plant and provides higher yields.…”