Furthermore, the P1 and P2 secondary axes do not display differences in organogenesis or morphogenesis processes ( Lebon et al., 2004). The secondary axes born by the P0 phytomer (hereafter referred to as P0 secondary axes) develop more strongly than those arising from P1–2 phytomers (hereafter referred to as P1–P2 secondary axes) ( Louarn et al., 2007). This modular structure also modifies the development of the secondary axis.
Phytomers bearing tendrils or clusters are classified as P1 or P2 phytomers. P0 phytomers bear no tendril or clusters. The grapevine shoot is a modular branching system with one primary and many secondary axes organized into structures consisting of three successive phytomers (P0–P1–P2). Grapevine organogenesis also depends on the source–sink relationships ( Wardlaw, 1990) between organs ( Pallas et al., 2008) and the anatomical structure of the shoot ( Jaquinet and Simon, 1971). Moreover, a number of routine practices in viticulture, such as pruning ( Rives, 2000) and irrigation ( Stevens et al., 2008), were empirically developed to optimize yield and cluster quality by modifying axis organogenesis.Īxis organogenesis in grapevine has been shown to be driven by temperature ( Schultz, 1992), photosynthetically active radiation ( Pallas et al., 2010) and soil water content ( Lebon et al., 2006). Axis organogenesis is highly variable, and the number of developing leaves may be ten times higher in optimal conditions than in poor environments ( Pallas et al., 2010). As in other species with an indeterminate pattern of development axis organogenesis in grapevine displays strong phenotypic plasticity in fluctuating environments ( Lebon et al., 2004).
0 kommentar(er)
