Production cycle and characterization of Italian zucchini genotypes by the logistic model

Abstract

This study aimed to identify the productive cycle response of Italian zucchini genotypes grown under field conditions in two growing seasons using the nonlinear logistic model and its critical points. Two randomized block experiments were conducted, with three genotypes (Caserta, PX13067051, and Tronco) and two growing seasons (spring-summer and summer-fall), with eight replicates and each experimental unit consisting of 7 plants. The logistic nonlinear model was adjusted for the fruit mass variable, as a function of the accumulated thermal sum, and the critical points were estimated by the partial derivatives of the adjusted function. Adjustment by bootstrap resampling was performed to address the violation of assumptions. The results of intrinsic and parametric nonlinearity confirm the quality of the model fit. This experiment demonstrated that the zucchini genotypes evaluated were more productive in the spring-summer growing season, using the parameters and critical points obtained from the logistic nonlinear model. Genotypes PX13067051 and Caserta showed superior productivity to the Tronco genotype, and also fruited earlier and at a higher rate of production. The logistic growth model and its critical points characterized the production cycle of the zucchini genotypes in different growing seasons and allowed inferences to be made to differentiate the genotypes and the growing seasons.

Repeatability coefficient for the determination of the optimal number of harvests for the selection of zucchini hybrids

“…It is important to consider that the zucchini production cycle can extend up to 90 days, with multiple harvests at regular intervals of two to three days (Lúcio et al, 2021). That is, it is possible to carry out between 20 and 30 harvests, depending on the cultivar and environmental conditions.…”

“…Furthermore, zucchini production has great nutritional and economic relevance in the country, especially for family farming (Souza et al, 2017;Tejada et al, 2020). Since the crop requires a high demand for labor, especially in the fruit harvesting (Lúcio et al, 2021), and genetic breeding research usually requires a high number of evaluations and harvests (Lúcio et al, 2021), research costs can be changed as needed (Cruz et al, 2012). Thus, in the selection of superior genotypes, it is necessary to define the ideal minimum number of harvests during the crop production cycle, to speed up the genetic progress and reduce research costs (Martuscello et al, 2015;Cavalcante et al, 2018).…”