Obtaining resistant lettuce progenies to downy mildew

A alface é a hortaliça folhosa mais consumida no Brasil. No entanto, a dificuldade em produzi-la vem aumentando, principalmente pela infestação das áreas de produção por Bremia lactucae, sendo o uso de cultivares com resistência horizontal, a alternativa mais viável no controle da doença. Diante do exposto, o objetivo do presente trabalho foi obter progênies de alface crespa resistentes às raças de míldio SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07. O trabalho de melhoramento consistiu de duas etapas: cruzamento dos parentais para obtenção das progênies de alface crespa resistentes e teste de resistência das progênies às raças de B. lactucae. Os parentais utilizados na obtenção das progênies resistentes foram Argeles e linhagem JAB 4-13-7, visando a obtenção de progênies de alface do tipo crespa, com os fatores de resistência R-18 e R-38. Para tanto, adotou-se o método genealógico, tendo como padrão, para as seleções, a cultivar Hortência e o genótipo JAB 4-13-7. Após a seleção e autofecundação das plantas no campo, efetuou-se o teste de resistência ou suscetibilidade, por meio da inoculação nas progênies oriundas dos cruzamentos, de uma mistura de água destilada + esporângios de B. lactucae das raças SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07 obtidas de isolados coletados nos anos de 2008 a 2010. Quinze dias após a inoculação, as plântulas foram selecionadas, descartando aquelas que possuíam esporulação e pontos necróticos causados por B. lactucae. Pelo método genealógico, selecionaram-se 69 progênies F3 com boas características agronômicas. No entanto, após o teste de resistência ou suscetibilidade, somente 19 apresentaram todas as plantas resistentes ao míldio.Lettuce is the most consumed leafy vegetable in Brazil. Its production, nonetheless, is increasing in difficulties mainly due to the infestation of producing areas with Bremia lactucae. Thus, the use of horizontal resistant cultivars is the most viable alternative in controlling progress of disease. So, the objective of this study was to obtain resistant lettuce progenies to the races of downy mildew: SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07. The breeding consisted of two stages: crossover of parentals to obtain the resistant lettuce progenies and endurance test of the progeny to B. lactucae races. The parentals used to obtain progenies with resistance factor R-18 and R-38 were: JAB 4-13-7 and JAB 4-13-7. The Pedigree method was used for obtaining the progeny, using as default selections the Hortência cultivar and JAB 4-13-7genotype. After selection and selfing of the plants in the field, the resistance or susceptibility test was realized, by inoculation of the progenies from the crosses, with mixture of distilled water + sporangia of B. lactucae races SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07 obtained from isolates collected in the years 2008-2010. Fifteen days after inoculation, the seedlings were selected as resistant or susceptible, discarding those presenting sporulation and necrotic spots caused by B. lactucae. Through the Pedigree method we found 69 progenies F3 with good agronomic characteristics. However, after resistance or susceptibility test, only 19 showed all the plants resistant to downy mildew

Responses of basil cultivars to irrigation water salinity

ABSTRACT The objective of this work was to verify the response of basil cultivars to the salinity of irrigation water during the period from January 15 to March 20, 2013, in a greenhouse, at the Federal Rural University of the Semi-Arid, Mossoró, RN, Brazil. The experimental design was completely randomized, with treatments arranged in 2 x 4 factorial scheme, constituted of two cultivars of basil (‘Verde’ and ‘Roxo’) and four levels of irrigation water salinity (0.5; 2.0; 3.5 and 5.0 dS m-1), with four replicates. The plants were collected at 65 days after transplanting and the following variables were evaluated: stem diameter; plant height; number of stems and leaves; leaf area; dry matter of leaves, stems, roots, and total dry matter. The increase in salinity was detrimental to all variables evaluated in both cultivars, but the cultivar ‘Roxo’ proved to be more tolerant than the cultivar ‘Verde’. Both cultivars are tolerant to irrigation water salinity of up to 1.5 dS m-1