Performance of ‘Galia’ melon grown under different soil cation ratios

Abstract

The northeast region of Brazil stands out in the production and export of melon. In this region, where this crop is mostly grown, part of the soil is of limestone origin, as is the irrigation water used. Over successive cultivations, these conditions can lead to soil alkalinization due to the accumulation of basic cations of the exchange complex, such as Ca, Mg, K and Na, in soils that are already rich in bases, thus influencing nutrient availability and, consequently, crop yield. On this basis, this study was developed to identify the cation ratios (K:Mg:Ca) of the soil that best correlate with attributes indicative of ‘Gália’ melon production. Two experiments were carried out in two consecutive years (2017 and 2018), in a randomized-block design with five treatments and five replicates. Treatments consisted of the following cation ratios (K:Mg:Ca) for experiment I, whose soil had a K content of 0.40 cmolc dm-3: T1 (1:3:34), T2 (1:3:21), T3 (1:3:9), T4 (1:0.8:9) and T5 (1:11:34); and experiment II, where the soil had 0.56 cmolc dm-3 of K: T1 (1:1.6:29.8), T2 (1:1.4:13.3), T3 (1:1.4:8.5), T4 (1:0.5:8.5) and T5 (1:4.8:29.8). The following traits were evaluated: chemical analyses of the soil during the flowering phase and at the end of the cycle, nutrient concentration in the diagnostic leaf during the fruiting phase, total yield, marketable yield, average total weight, average marketable weight, total number of fruits and number of marketable fruits per plant. The cation ratios influenced the average total and marketable fruit weights only in experiment I, but not yield. Therefore, when associated with irrigation water from the Açu sandstone aquifer and fertigation, the high absolute K and medium to high Mg contents are sufficient to meet the K and Mg nutrient requirements, dispensing with correction of the cation ratio.