Abstract

Sunn hemp (Crotalaria juncea L.) is an annual cycle legume with high potential for biological nitrogen fixation, being widely used in crop rotation for biomass formation and control of nematodes. The objectives of this study were to determine the sample size for the mean estimation of productive traits of sunn hemp and verify the sample size variability between traits and sowing dates. Two uniformity trials were performed in the agricultural year 2014/2015, with sowing in October (trial 1) and December (trial 2). At the crop flowering stage, 300 plants of each trial were harvested and fresh and dry matter of leaves, stem, root, aerial part, and total weight were evaluated. The normality and randomness tests were performed for each trait and the sample size was calculated for the semi-amplitudes of the confidence interval (estimation errors) of 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20% of the mean estimate. There is sample size variability between productive traits and between sowing dates. The assessment of at least 101 plants is required for mean estimation of productive traits with maximum estimation error of 20% of the mean and 95% confidence level.

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