Abstract
The fact that Brazilian citriculture has focused on few rootstocks poses several phytosanitary risks to the culture and has made genetic improvement programs develop hybrid genotypes to be used as novel alternatives. This study aimed at evaluating the behavior of 42 different rootstocks regarding their emergence percentage and speed in weather conditions experienced in the extreme south of Brazil. Seeds of hybrids developed by the Citrus Genetic Improvement Program (PMG Citros) at the Embrapa Mandioca e Fruticultura (PMG Citros) and cultivars from other citrus growing regions were sown in conical tubes filled with commercial substrate in May 2017. A thoroughly randomized design with 4 replicates, each composed of 45 sampling units, was employed. Emergence percentage and emergence speed of every genotype were evaluated and the ones with the highest emergence percentage of seedlings and the ones with the most precocious emergence were identified. All genotypes completed seedling emergence 98 days after sowing. Seeds of Trifoliata, TSKC × CTSW-041 and TSKC × CTSW-025 had the highest values of seedling emergence whereas the highest emergence speed indexes were exhibited by genotypes Trifoliata and lemon tree ‘Cravo’.
Highlights
Brazilian citriculture is very relevant in the global scenario, mainly the production of sweet oranges [Citrus sinensis (L.) Osbeck]
This study aimed at evaluating the behavior of 42 rootstocks regarding seedling emergence and emergence speed index in weather conditions experienced in the extreme south of Brazil, so as to find new alternative rootstocks for citriculture in the region
The period of seedling emergence took place at the beginning of winter; the need to raise the temperature in the greenhouse to 25 °C
Summary
Brazilian citriculture is very relevant in the global scenario, mainly the production of sweet oranges [Citrus sinensis (L.) Osbeck]. The citrus chain in Rio Grande do Sul state comprises about 20 thousand producers; most are families that grow citrus in almost 40 thousand hectares and play an important socio-economic role in the state (Oliveira et al, 2016). Citrus production in Rio Grande do Sul focuses on Trifoliata [Poncirus trifoliata (L.) Raf.], since this rootstock is tolerant to cold and induces the production of high quality fruits (Petry et al, 2015). The agroclimatic zoning of citrus recommends the use of rootstocks which are tolerant to cold in four out of five citrus growing regions in the state. It explains the predominance of Trifoliata as a rootstock (Wrege et al, 2004)
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