Influence of harvest time and agricultural year in yield components of table cassava cultivars

Agricultural year and harvesting season may interfere with yield and post-harvest performance of table cassava cultivars, with consequences for their commercialization and net profit. The objective of this work was to quantify the effects of harvesting season and agricultural year on yield performance of table cassava cultivars and their correlations. Planting was carried out in September in two consecutive years near Londrina city, PR, in a Clay-textured Oxisols red eutrophric. The experiment followed a randomized complete block design (RCBD) with four replications, consisting of seven harvesting times (8, 10, 12, 14, 16, 18 and 20 months after planting) for each agricultural year. The table cassava cultivars used were: Catarina Amarela, Catarina Branca, Mato Grosso, Pretona, IAPAR 19-Pioneira and IAC 576-70. The following agronomic characteristics were evaluated: number of roots per plant, length, diameter and yield of tuberous roots, as well as the following post-harvest characteristics: net yield and peeling time per kg of each cassava genotype. The cultivars, harvesting time and agricultural year affected the yield and post-harvest characteristics. ‘IAPAR 19-Pioneira’ presented a larger number of roots per plant (9.9) and peeling time (224.8 seconds.kg-1), but lower yield % (66.2%) and diameter of tuberous roots (4.0 cm), regardless of harvest time and year of planting. 'Catarina Amarela', 'Catarina Branca', 'IAC 576-70' and 'Pretona' provided higher yields, diameters and reduced peeling times. The root mean diameter is one of the characteristics that can be used as a selection criterion in a table cassava genetic breeding program: the larger the root mean diameter the larger are tuber root yield and percentage of weight of the tradable part of the roots, and the lower is the time of peeling.