Accumulation of nutrients and agronomic performance of grafted seedless watermelon

Abstract

Chemical fertilizing is one of the main inputs that increase watermelon production costs. Watermelon grafting with compatible rootstocks and a vigorous root system may increase the efficiency of nutrients absorption. This study aimed at determining the accumulation of dry matter and nutrients, as well as the agronomic performance of grafted watermelon. The triploid 'Precious Petite' watermelon was used as graft and the Line BGCIA941 (Citrullus lanatus var. citroides) as rootstock. The experimental design consisted of randomized blocks, in a split-plot, with six replicates. The 'Precious Petite' grafted onto Line BGCIA941, ungrafted 'Precious Petite' and ungrafted Line BGCIA941 were evaluated in the plot, while the subplot corresponded to the sampling time (0, 10, 20, 30, 40, 50, 60 and 70 days after transplanting). 'Precious Petite' grafted onto Line BGCIA 941 accumulated more macro and micronutrients than the ungrafted plants, increasing fruit yield, flesh firmness and rind thickness, but it did not affect the soluble solids contents. The decreasing order for nutrient accumulation in the grafted plants was N > K > Ca > Mg > P > S > Fe > Mn > Zn > B > Cu, whereas for ungrafted 'Precious Petite' it corresponded to N > K > Ca > Mg > P > S > Mn > Fe > B > Zn > Cu.

Growth and accumulation of nutrients of ‘Top Gun’ watermelon

“…The maximum accumulation of S by the fruit was 1.06 g plant -1 , and was characterized by being slow in the first 44 DAS and then increasing in demand until the end of the cycle. The results found agree with those obtained by Grangeiro & Cecílio Filho (2005a), for the Nova hybrid, and Santos et al (2016), for crop BGCIA 941, which reported accumulated sulfur values of 1.75 and 1.70 g plant -1 , respectively. In terms of micronutrient accumulation, manganese was the most accumulated in Top Gun, reaching 404.1 mg plant -1 at 71 DAS (Figure 8).…”

“…According to Marschner (2011), of the total accumulated magnesium in the plant, between 6 and 25% is related to the chlorophyll molecule and, therefore, the macronutrient is expected to accumulate in greater proportion in the leaves . However, the results suggest that there are differences between the cultivars in terms of absorption and redistribution of magnesium, a hypothesis that has already been verified in standards of grafted watermelon (Santos et al, 2016).…”

“…In the Quetzale and Shadow watermelons, Aguiar Neto et al (2016), reported that the greatest nitrogen demand occurred during the period from 45 to 55 DAT and that the fruit contributed with 35% and 41% of the total nitrogen accumulated, respectively. Santos et al (2016) in Precious Petite and BGCIA 941 watermelons found the highest demands for nitrogen, 15.0 and 20.9 g plant -1 , were from 20 to 70 DAS and from 32 to 60 DAS, respectively.…”

“…In addition, although not part of organic compounds, it participates in photosynthesis, enzymatic activation and protein synthesis (Lucena et al, 2011). Santos et al (2016) mention that potassium also has an effect on several parameters concerning the quality of the watermelon such as the color, size, acidity, resistance to transportation and cracking.…”

“…According to Schiavon , calcium is an important element for cucurbitaceae due to its role in flower formation, fruit quality and productivity. In addition, calcium is related to the incidence of apical rot, a common nutritional disorder in watermelon, and it has been verified that applications of this cation generate positive effects on the integrity and functionality of the cell wall, maintaining the consistency of the fruit and increasing the resistance to mechanical damage (Santos et al, 2016 Figure 5 -Accumulation of calcium in stems (Y1), leaves (Y2), fruits (Y3) and plant without root (Y4), of watermelon 'Top Gun'.…”