Phenotypic Variability in Resistance to Anthracnose, White, Brown, and Blight Leaf Spot in Cassava Germplasm.

Despite fungal diseases affecting the aerial parts of cassava (Manihot esculenta Crantz) and causing significant yield losses, there is a lack of comprehensive studies assessing resistance in the species' germplasm. This study aimed to evaluate the phenotypic diversity for resistance to anthracnose disease (CAD), blight leaf spot (BliLS), brown leaf spot (BLS), and white leaf spot (WLS) in cassava germplasm and to identify genotypes suitable for breeding purposes. A total of 837 genotypes were evaluated under field conditions across two production cycles (2021 and 2022). Artificial inoculations were carried out in the field, and data on yield and disease severity were collected using a standardized rating scale. The top 25 cassava genotypes were selected based on a selection index for disease resistance and agronomic traits. High environmental variability resulted in low heritabilities (h2) for CAD, WLS, and BLS (h2 = 0.42, 0.34, 0.29, respectively) and moderate heritability for BliLS (h2 = 0.51). While the range of data for disease resistance was narrow, it was considerably wider for yield traits. Cluster analysis revealed that increased yield traits and disease severity were associated with higher scores of the first and second discriminant functions, respectively. Thus, most clusters comprised genotypes with hybrid characteristics for both traits. Overall, there was a strong correlation among aerial diseases, particularly between BLS and BliLS (r = 0.96), while the correlation between CAD and other diseases ranged from r = 0.53 to 0.58. Yield traits showed no significant correlations with disease resistance. Although the mean selection differential for disease resistance was modest (between -2.31% and -3.61%), selection based on yield traits showed promising results, particularly for fresh root yield (82%), dry root yield (39%), shoot yield (49%), and plant vigor (26%). This study contributes to enhancing genetic gains for resistance to major aerial part diseases and improving yield traits in cassava breeding programs.

Maturation and quality of 'BRS Magna' grapes influenced by rootstocks in rainy season

Seasonal variations and production factors can influence the quality of grapes. Considering the Sub-middle region of the São Francisco Valley, Brazil, differentiated by production in rainy and warmer periods of the year, the climatic conditions in each season affect the duration of the phenological phases and quality of the grapes. The objective of this study was to characterize the changes in the quality components during maturation of 'BRS Magna' grapes on different rootstocks, in rainy seasons under tropical conditions, as a support to define the harvest time. The experiment was conducted in Petrolina, Pernambuco, Brazil, from Jan to Apr 2017 (cycle 1) and Dec 2017 to Apr 2018 (cycle 2) evaluating rootstocks and age of the fruits. Bunches were picked from the start of maturation to the harvest: 49, 56, 61, 64 and 68 days after fruit set (DAF) for cycle 1, and 35, 41, 48, 55, 61, and 66 DAF for cycle 2. In cycle 1 'IAC 572' and 'Paulsen 1103' rootstocks provided higher sugar contents in grapes, which was only repeated in cycle 2 for 'Paulsen 1103'. The accumulation of anthocyanins and yellow flavonoids was favored by 'IAC 313' and 'IAC 572' rootstocks in cycle 1, and by 'IAC 313' and 'IAC 766' in cycle 2. A higher content of polyphenols was conferred on 'IAC 572' in cycle 1 and on 'IAC 766' in cycle 2, which also had a greater antioxidant capacity. Although there were differences between rootstocks, harvesting at approximately 64 DAF maximized grape quality for all treatments.(AU)

Yield and physicochemical characteristics of BRS Magna and Isabel Precoce grapes influenced by pruning in the São Francisco river valley / Produtividade e características físico-químicas das uvas ‘BRS Magna e ‘Isabel precoce influenciadas pela poda no Vale do São Francisco

The objective of this study was to evaluate the productive performance and physicochemical characteristics of BRS Magna and Isabel Precoce grapes influenced by two types of pruning. The experiment was carried out during two growing seasons in a commercial vineyard of Petrolina, PE, in the period 2013-2014. Treatments were represented by two cultivars, Isabel Precoce and BRS Magna, and two types of pruning, with selection during plant formation (P1) and without selection (P2) of lateral branches, using a randomized experimental block design, in subdivided plots and four replicates. After pruning P2, the amount of buds kept on vines was greater than after pruning P1, favoring an increase in yield. However, the sizes of bunches and berries, content of soluble solids, and titratable acidity were not influenced by the pruning type. In general, the sizes of bunches and berries in BRS Magna were larger than in the Isabel Precoce cultivar. Conversely, content of soluble solids and titratable acidity varied among cultivars as a function of production cycle and type of pruning; however, within the standards described for both cultivars and accepted by the Brazilian legislation.(AU)

O presente trabalho teve como objetivo estudar o desempenho produtivo e características físico-químicas das uvas BRS Magna e Isabel Precoce submetidas a dois tipos de poda. Um experimento foi realizado durante dois ciclos de produção, nos anos de 2013 e 2014, em um vinhedo comercial em Petrolina, PE. Os tratamentos foram representados por duas cultivares copa, Isabel Precoce e BRS Magna, e dois tipos de poda, com seleção de ramos laterais na formação da planta (P1) e sem seleção de ramos laterais (P2), utilizando delineamento experimental em blocos ao acaso em parcelas subdivididas e quatro repetições. A quantidade de gemas mantidas na videira após a poda é mais elevada na poda P2, favorecendo o aumento da produtividade, mas o tamanho dos cachos e das bagas e o teor de sólidos solúveis e acidez titulável não foram influenciados pelo tipo de poda. O tamanho dos cachos e das bagas da cultivar BRS Magna é, de modo geral, maior que os de Isabel Precoce. Por outro lado, o teor de sólidos solúveis e acidez titulável variaram entre as cultivares em função do ciclo de produção e do tipo de poda, estando dentro dos padrões descritos para ambas cultivares e aceitos pela legislação brasileira.(AU)

Yield and physicochemical characteristics of 'BRS Magna' and 'Isabel Precoce' grapes influenced by pruning in the SãoFrancisco river valley / Produtividade e características físico-químicas das uvas 'BRS Magna' e 'Isabel precoce' influenciadas pela poda no Vale do São Francisco

ABSTRACT: The objective of this study was to evaluate the productive performance and physicochemical characteristics of 'BRS Magna' and 'Isabel Precoce' grapes influenced by two types of pruning. The experiment was carried out during two growing seasons in a commercial vineyard of Petrolina, PE, in the period 2013-2014. Treatments were represented by two cultivars, 'Isabel Precoce' and 'BRS Magna', and two types of pruning, with selection during plant formation (P1) and without selection (P2) of lateral branches, using a randomized experimental block design, in subdivided plots and four replicates. After pruning P2, the amount of buds kept on vines was greater than after pruning P1, favoring an increase in yield. However, the sizes of bunches and berries, content of soluble solids, and titratable acidity were not influenced by the pruning type. In general, the sizes of bunches and berries in 'BRS Magna' were larger than in the 'Isabel Precoce' cultivar. Conversely, content of soluble solids and titratable acidity varied among cultivars as a function of production cycle and type of pruning; however, within the standards described for both cultivars and accepted by the Brazilian legislation.

RESUMO: O presente trabalho teve como objetivo estudar o desempenho produtivo e características físico-químicas das uvas 'BRS Magna' e 'Isabel Precoce' submetidas a dois tipos de poda. Um experimento foi realizado durante dois ciclos de produção, nos anos de 2013 e 2014, em um vinhedo comercial em Petrolina, PE. Os tratamentos foram representados por duas cultivares copa, 'Isabel Precoce' e 'BRS Magna', e dois tipos de poda, com seleção de ramos laterais na formação da planta (P1) e sem seleção de ramos laterais (P2), utilizando delineamento experimental em blocos ao acaso em parcelas subdivididas e quatro repetições. A quantidade de gemas mantidas na videira após a poda é mais elevada na poda P2, favorecendo o aumento da produtividade, mas o tamanho dos cachos e das bagas e o teor de sólidos solúveis e acidez titulável não foram influenciados pelo tipo de poda. O tamanho dos cachos e das bagas da cultivar 'BRS Magna' é, de modo geral, maior que os de 'Isabel Precoce'. Por outro lado, o teor de sólidos solúveis e acidez titulável variaram entre as cultivares em função do ciclo de produção e do tipo de poda, estando dentro dos padrões descritos para ambas cultivares e aceitos pela legislação brasileira.