Aquidauana Miqueloto

Preparação, caracterização e propriedades de filmes poliméricos com potencial aplicação no recobrimento de sementes

Films of sodium carboxymethyl cellulose, sodium alginate and their mixture were evaluated in terms of interactions between the polymers, morphology, water absorption and application as seed coatings. FTIR analysis suggested that only hydrophobic interactions occurred between the polymers. The coating of bean seeds was confirmed by microscopy, indicating the formation of dense and homogeneous films with 7 μm thickness. The obtained films did not affect the germination capacity of the seeds. In summary, the characteristics and properties of the films formed and the water absorption capacity, indicate that these systems are viable for use in seed coating processes.

Multivariate analysis of mineral content associated with flesh browning disorder in ‘Fuji’ apples produced in Southern Brazil

Flesh browning is a physiological disorder that occurs in ‘Fuji’ apples during storage, which causes considerable postharvest losses of fruit produced in Southern Brazil. This work aimed to assess the mineral attributes [Ca; Mg and K contents and the Mg/Ca; K/Ca and (K + Mg)/Ca ratios] associated with the flesh browning disorder incidence, as well as to identify which of these mineral attributes better discriminate the differences in the degree of susceptibility to flesh browning disorder in ‘Fuji’ apples stored under controlled atmosphere (CA; 1.2 kPa O2 + 2.0 kPa CO2 and 1.2 kPa O2 + < 0.5 kPa CO2; 0.5 ± 0.1 °C and 96 ± 2% RH, during an 8-month period). Apples from 2 orchards in Fraiburgo, Santa Catarina, 3 orchards in Sao Joaquim, Santa Catarina, and 3 orchards in Vacaria, Rio Grande do Sul were used. The fruit with flesh browning disorder has lower levels of Ca and a higher Mg/Ca ratio when compared to the fruit without flesh browning. The Mg and K contents were not related to the physiological disorder. The canonical discriminant analysis (CDA) showed that the isolated Ca content better discriminated the fruit with and without flesh browning disorder. ‘Fuji’ apples with Ca contents < 80 mg∙kg−1 in the flesh present a greater risk of developing this disorder in the Southern Brazil production region.

METHODS OF FRUIT TISSUE SAMPLING TO QUANTIFY CALCIUM AND MAGNESIUM CONTENTS TO SEGREGATE APPLES FOR BITTER PIT INCIDENCE

Susceptibility to bitter pit (BP) has been associated with low Ca content and high Mg/Ca ratio in the fruit, which is highly affected by fruit genotype. This study was carried out to identify the best fruit tissue sampling method to assess Ca and Mg contents to segregate apples for BP occurrence. ‘Fuji’ and ‘Catarina’ apples (with low and high susceptibilities to BP, respectively) were segregated in lots without and with BP symptoms, after four months of cold storage (0±0.5°C/95% RH), and then analyzed for Ca and Mg contents by three fruit tissue sampling methods: peel+flesh, peel, and flesh. For peel+flesh, a wedge-shaped segment was cut longitudinally from the fruit, discarding the core tissue. The fruit calyx-end was used for peel (thickness of 2 mm) and flesh (thickness of 2-8 mm) sampling. For peel+flesh and flesh, Ca content was lower and Mg/Ca ratio was higher in fruit with BP in both cultivars. For peel, only in ‘Fuji’, Ca content was lower and Mg/Ca ratio was higher in fruit with BP. In ‘Catarina’, Mg/Ca ratio in the flesh tissue at the calyx-end increased from 1.83 in fruit without BP to 4.56 in fruit with BP (~2.5-fold increase), while in ‘Fuji’ this ratio increased from 0.96 in fruit without BP to 1.29 in fruit with BP (~1.3-fold increase). Therefore, the high susceptibility to BP in ‘Catarina’ might be explained by its high Mg/Ca ratio in the flesh tissue under the peel, at the calyx-end of the fruit, were the symptoms appeared. Nonetheless, the results show that the Mg/Ca ratio in the flesh at the calyx-end is more suitable to segregate apple fruit for BP susceptibility in both cultivars. INTRODUCTION The incidence of bitter pit (BP) in apples is commonly associated with low calcium (Ca) concentrations in the fruit (Ferguson and Watkins, 1989; Saure, 2005). However, fruit Ca concentration alone may not be informative in relation to BP development. It is believed that a high magnesium (Mg) content exacerbates the potential for apple fruit to initiate the chain of reactions leading to BP symptoms development (Burmeister and Dilley, 1994; Amarante et al., 2013). Due to the ionic similarity between Ca and Mg, these two minerals strongly compete in various cellular processes, such as enzyme activation and membrane stabilization processes (White and Broadley, 2003). Although Mg can replace Ca at the binding sites, Mg cannot replace the role of Ca in the cellular processes, and the competition between these ions may explain the occurrence of physiological disorders related to Ca deficiency in response to high Mg/Ca ratios in fruit tissues (de Freitas et al., 2010). Thus, the quantification of Ca and Mg contents represents an important approach to predict BP development in apple fruit (Amarante et al., 2006, 2013). Calcium and Mg concentrations vary according to the fruit tissue analyzed (Amarante et al., 2006; Miqueloto et al., 2011). Although a few approaches have been developed to predict BP development in apple fruit based on Ca and Mg contents, there are limited studies focused on determining the most appropriate tissue to be sampled for that purpose. The sampling method most used today is the removal of a longitudinal slice, Proc. V International Conference Postharvest Unlimited Eds.: G.A. Manganaris et al. Acta Hort. 1079, ISHS 2015 360 containing peel+flesh tissues (Perring and Wilkinson, 1965; Argenta and Suzuki, 1994), involving different parts of the fruit (proximal, medial and distal), which reduces the ability to predict the occurrence of BP in apples (Amarante et al., 2006, 2013). As BP symptoms mainly occur at the fruit distal end tissue, peel and flesh sampling at that region are possibly the most appropriated methods to quantify Ca and Mg contents related to BP development (Amarante et al., 2013; Miqueloto et al., 2011). This study was carried out to identify the best fruit tissue sampling method to assess Ca and Mg contents in apple cultivars with low (‘Fuji’) and high (‘Catarina’) susceptibility to BP, aiming to segregate apples for BP incidence. MATERIALS AND METHODS ‘Fuji’ and ‘Catarina’ apples were harvested at commercial maturity from a commercial orchard in São Joaquim, State of Santa Catarina, Southern Brazil, in 2012. The orchard was not sprayed with Ca formulations during the growing season to favor BP development. Fruit were left in cold storage (0±0.5°C and 95% RH) for four months. After five days at room temperature (20±4°C and 70-80% RH), fruit of both cultivars were segregated in lots without and with BP. Fruit were gently washed with distilled water, left to dry and then analyzed for Ca and Mg contents in peel+flesh, peel and flesh. A longitudinal wedge-shaped segment (1 cm wide at the equator region), without core tissue, was used for peel+flesh sampling method (Fig. 1A), while the calyx-end was used for peel (thickness of 2 mm) and flesh (thickness of 2-8 mm) sampling methods (Fig. 1B). In the same fruits, samples were removed by the three different methods. In both cultivars, the experiment followed a completely randomized design, with 10 replications, each replication composed of 10 fruit. The fruit samples were digested with a mixture of sulfuric acid and hydrogen peroxide for quantification of Ca and Mg contents (mg kg fresh weight). The digested samples were then analyzed with an inductive coupled plasma spectrophotometer (ICP). Mineral attributes (Ca and Mg contents, and Mg/Ca ratio) quantified in the peel+flesh, peel and flesh were submitted to analysis of variance (p<0.05) to compare fruit without and with BP, for each cultivar, using SAS software (SAS Institute Inc., 2002). RESULTS AND DISCUSSION In ‘Fuji’, only Mg content in the flesh was not statistically different between fruit without and with BP (Table 1). In ‘Catarina’, Mg content in the peel+flesh and peel, and Ca content and Mg/Ca ratio in the peel were not different between fruit without and with BP (Table 1). For peel+flesh and flesh tissues, Ca content was lower and Mg/Ca ratio was higher in fruit with BP, in both cultivars (Table 1). However, in ‘Fuji’ peel tissue Ca content was lower and Mg/Ca ratio was higher in fruit with BP. Calcium and Mg contents at the calyx-end of the fruit were higher in the peel than in the flesh in both cultivars, regardless of BP incidence (Table 1). The results are in agreement with other studies, showing that total Ca and Mg contents are higher in the peel than in the flesh tissue of apples (Lewis and Martin, 1973; Ferguson and Watkins, 1983; Amarante et al., 2006, 2013; Miqueloto et al., 2011). In ‘Fuji’, the total Ca and Mg contents in the flesh corresponded respectively to ~26 and ~43% of those observed in the peel, regardless of BP incidence. In ‘Catarina’, the total Ca and Mg contents in the flesh corresponded respectively to ~13 and ~41% of those observed in the peel, regardless of BP incidence. Therefore, ‘Catarina’ (more susceptible to BP) has a more pronounced reduction of Ca content in the flesh compared to the peel tissue than ‘Fuji’ (less susceptible to BP) at the calyx-end, while for Mg the reduction in content from peel to flesh is similar in the two cultivars. As the decrease of Mg content from peel to the flesh was lower compared to Ca content, the Mg/Ca ratio value was higher in the flesh than in the peel in both cultivars, regardless of BP incidence (Table 1). The Mg/Ca ratio increase from peel to flesh was