Pinus patulaand pine hybrid hedge productivity in South Africa: a comparison between two vegetative propagation systems exposed to natural infection byFusarium circinatum

Abstract

In response to theFusarium circinatum pine pathogen threat in Southern Africa, research has been conducted on the development of F. circinatumtolerant P. patula and P. patula hybrids. The objective of this study was to investigate the propagation potential of these taxa in two vegetative propagation systems, hydroponic sand beds and polythene bags with composted pine bark growing media. Significant differences (p < 0.001) in mortality associated with F. circinatum were observed between the P. patula x P. tecunumanii (LE) hybrid (6%) and P. patula (19-23%). No significant differences in mortality associated with F. circinatum were observed within P. patula x P. tecunumanii (LE) families which ranged from zero to 15 percent. Significant mortality differences (p < 0.001) were observed between P. patula families which ranged from eight to 44 percent. The number of rooted cuttings produced, per hedge established, over the four year period was significantly better (p < 0.001) in the P. patula x P. tecunumanii (LE) hybrid (52) than in P. patula (29-33). Significant differences (p < 0.001) were also observed in the number of rooted cuttings produced per family, with P. patula x P. tecunumanii (LE) families ranging from 35 to 70 cuttings per hedge plant established and P. patula families between 20 and 42 cuttings. Over the four year duration of the trial all taxa showed increased productivity in hedges grown in a hydroponic sand bed system, which received more consistent fertilisation and yielded an average of 55 rooted cuttings per hedge, over those grown in polythene bags with composted pine bark medium which yielded 41 cuttings on average. This study demonstrated that the P. patula x P. tecunumanii (LE) hybrid is a feasible substitute for P. patula in both vegetative propagation systems, as it not only shows improved survival, through increased F. circinatum tolerance, but also improved productivity.

Environmentally friendly methods for controlling pine pitch canker

“…Family variation within hybrids was also high, so selection of the parents is critical, while mass clonal propagation of selected hybrid offspring may result in substantial genetic gains (Roux et al ., ; Mitchell et al ., ). Vegetative propagation of hybrid material proved relatively easy to apply in some pine species, facilitating the massive deployment of resistant material for reforestation (Ford et al ., ).…”

“…This approach is especially required when hybridizing with high-elevation P. tecunumanii origins, for which large family and within-family variation has been observed (Mitchell et al, 2013). In contrast, hybrids with low-elevation origins of P. tecunumanii showed much less variation (Mitchell et al, 2013;Ford et al, 2014).…”

PLANTAS INJERTADAS DE Pinus patula SCHIEDE ex SCHLTDL. et CHAM. PARA PRODUCIÓN DE ESTACAS

“…Aunque se logró multiplicar el material vegetal de los genotipos de interés, es necesario aumentar aún más el número de brotes, ya que en algunos casos las podas no son suficientes para producir la cantidad requerida (Inoti et al, 2017). La fertilización, y particularmente el nitrógeno, en las plantas madre podría ayudar a incrementar el número de brotes, aunque previamente se debe analizar el estado nutricional de la planta para detectar insuficiencias y mejorar su vigor (Cabrera et al, 2022;Ford et al, 2014). La fertilización con nitrógeno en plantas madre de P. taeda y P. radiata aumentó los niveles de carbohidratos, mejorando la producción de brotes (Hernández y Rubilar, 2012;Rowe et al, 2002).…”

“…Estos brotes pueden utilizarse para enraizamiento de estacas, para injertarse o para cultivo in vitro (Read y Bavougian, 2013). El enraizamiento de estacas se ha aplicado operativamente en plantaciones de P. patula en Sudáfrica, P. radiata D. Don en Nueva Zelanda y P. taeda L. en EUA (Ford et al, 2014;Wu, 2019). En México, para P. patula se ha reportado sólo a nivel experimental, con menos de 80 % de enraizamiento (Bautista-Ojeda et al, 2022;Escamilla-Hernández et al, 2020).…”

“…La producción de plantas madre por semilla tiene el inconveniente de que se reproducen individuos genéticamente diferentes al árbol superior seleccionado y requiere preferentemente realizar cruzas controladas con otros progenitores cuya cruza sea comprobada en campo, en ensayos que necesitan hasta de ocho años para evaluarse en P. patula (Ford et al, 2014). Por medio de la propagación serial se evita la variación genética y se pueden clonar a mayor escala los árboles superiores originales (Wendling et al, 2014).…”