The relationship between substrate, biometrics and recalcitrance in the germination and vigor testing of Cojoba arborea (L.) Britton & Rose

Abstract

There is little information in the literature on the management of Cojoba arborea seeds as well as a protocol for determining the germination test indicating an ideal substrate for the species. Therefore, the objective of this work was to evaluate suitable substrates for germination and vigor test with C. arborea seeds, aiming at the determination of protocols for the species. Biometric analysis was performed with 33 fruits and 200 seeds collected from 40 parent trees. The germination and vigor tests were analyzed in different substrates: rice straw; sugarcane bagasse; coffee straw; saw dust; commercial substrate; ground; soil + sand (1:1); sand and vermiculite. With the germination data, speed indices and average germination time were calculated. The variables of germination percentage, germination speed index and vigor test were applied analysis of variance (ANOVA) followed by the Tukey test (p < 0.05) to compare the means. The fruits are of the pod type, ranging from 5 to 13 seeds per fruit, with a water content of 56% and about 1,780 units/kg, characterizing them as large and recalcitrant seeds. The highest germination rates were in sand, sugarcane bagasse, commercial substrate and vermiculite. The lowest average germination time and the highest values ​​of germination speed index and seedling dry mass were in sand and vermiculite. The substrates with the ideal physical characteristics for the development of tests to determine the physiological quality of C. arborea seeds were vermiculite and sand.