Productivity and mortality, of Fusarium oxysporum f. sp. passiflorae in passionfruit vines brs rubi do cerrado, grafted onto different rootstocks

The use of scions grafted onto passionfruit vines has become an alternative to their cultivation in areas with a history of fusariosis. However, the combinations between the graft and rootstock can influence on the productivity and longevity of the passionfruit farm. The objective was to evaluate the productivity and mortality of the passionfruit cv BRS Rubi do Cerrado grafted onto three species of rootstock in Terra Nova do Norte-MT. The design was a randomized block with 4 treatments BRS Rubi do Cerrado (BRS-RC) seedling plant along with those grafted onto three species of rootstock: Passiflora gibertii, Passiflora alata; Passiflora nitida. The scions were grafted through a cleft graft and the planting performed after 70 days. The evaluation was made of the total number and weight of the fruits, along with productivity and mortality of plants. Results showed that the BRS-RC, grafted onto P. gibertii and P. nitida, presented the best performance for weight of fruits, number of fruits and productivity. The cultivar that was grafted onto different rootstocks presented higher productivity in regards to the seedling plant. The BRS-RC, grafted onto P. nitida, presented a zero-mortality rate over the 16.5 months of cultivation. The rootstocks P. nitida and P. gibertii were superior to those of P. alata in reducing mortality in the passionfruit vine by Fusarium oxysporum f. sp. passiflorae. The confirmation was made of the pathogen Fusarium oxysporum f. passiflorae isolated in the experimental area in scions of the BRS-RC inoculated at 70 days of age.

Perda de nitrogênio pela Brachiaria decumbens após a antese: relação com a umidade do solo / Nitrogen loss through Brachiaria decumbens after anthesis stage: relation with soil moisture

Com o objetivo de avaliar a perda de N por plantas de Brachiaria decumbens no estádio da pós-antese relacionada com a umidade do solo, realizou-se um experimento em casa-de-vegetação, em delineamento inteiramente casualizado, com três tratamentos e seis repetições. Os tratamentos do estudo constaram da colheita de plantas nos seguintes estádios e condições de umidade do solo: (a) A60: estádio de antese e com umidade do solo mantida a 60 por cento da capacidade máxima de retenção de água; (b) PA60: estádio de pós-antese ou maturidade com umidade do solo mantida a 60 por cento da capacidade máxima de retenção de água; e (c) PA20: pós-antese com umidade estabelecida após a antese de 20 por cento da capacidade máxima de retenção de água do solo. As plantas de Brachiaria decumbens, cultivadas em vasos preenchidos com solo arenoso, foram fertilizadas com sulfato de amônio-15N (800mg vaso-1 de N). As plantas dos tratamentos pós-antese (PA60 e PA20) foram colhidas após 17 dias do início do florescimento. O balanço de N do sulfato de amônio (15N) no sistema solo-planta indicou perdas de N, presumivelmente pela parte aérea das plantas de Brachiaria decumbens, no estádio de pós-antese (tratamento PA60), da ordem de 25 por cento em relação ao de antese (A60). A perda de N na pós-antese avaliada no tratamento com déficit hídrico (PA20) foi reduzida comparativamente ao PA60, sendo da ordem de 11 por cento em relação ao tratamento A60.

The objective of this research work was to evaluate the N loss through Brachiaria decumbens in the stage of post-anthesis related to the soil moisture. The experiment was carried out in green-house condition and the experimental design was a completely randomized, with three treatments and six replications. Plants of grass-Brachiaria were cultivated in pots filled out with sandy soil. The soil of each pot was fertilized with ammonium sulfate-15N (800mg vaso-1 of N). The treatments consisted of harvest of plants in the stages and soil moisture conditions, as following: (a) A60: stage of anthesis and with soil moisture maintained to 60 percent of the maximum water retention capacity; (b) PA60: post-anthesis stage or maturity with soil moisture maintained to 60 percent of the maximum retention capacity, and (c) PA20: post-anthesis stage with soil moisture of 20 percent of the maximum water retention capacity established after the anthesis stage. The plants of the treatments post-anthesis (PA60 and PA20) were harvested after 17 days beginning of the flowering stage. The balance of N from ammonium sulfate (15N) in the soil-plant system indicated losses of N, presumably from the aerial part of grass-Brachiaria plants in the post-anthesis stage (treatment PA60). These values were of the order of 25 percent in relation to the anthesis treatment (A60). The N loss in the post-anthesis stage as evaluated in the treatment with water deficits (PA20), it was minimized comparatively to the PA60 and it was of the order of 11 percent in relation to the treatment A60.