Influence of nitrogen availability on shoot development in young peach trees [ Prunus persica (L.) Batsch]

Abstract

It is commonly stated that nitrogen (N) influences biomass accumulation in plants. For trees, however, a precise characterisation of shoot response to N and its impact on architecture is lacking. We attempted to study on the phytomer scale the effects of N limitation on shoot growth components, i.e. leaf emergence rate, final internode length and branching on the main and secondary axes of 1-year-old peach trees [Prunus persica (L.) Batsch]. Trees were grown on recycled nutrient solutions in which N concentration was restored once a week. We used two hydroponic set-ups in which weekly N availability, i.e. amount of N per tree, differed being either low (N1) or high (N2). Net N availability was defined weekly as the relative amount of N remaining in each set-up before solution replenishment. It declined with time and three periods of contrasting net N availability were identified. During these periods, leaf emergence rate and final internode length were similar on the main axis of N1 and N2 trees, so too was the distribution of secondary axes along the main axis. Secondary axes responded to N limitation by decreasing their growth components according to their position along the main axis. Differences were most important for basal secondary axes. Leaf emergence rate and final internode length responded similarly to N availability depending on axis order and position in the tree. It was concluded that N availability, particularly during the period of maximum growth of axes, influenced the shoot growth components and thus tree architecture.

The effect of autumn N supply on the architecture of young peach (Prunus persica L.) trees

“…Fruit number and potential size (proportional to the number of cells at the end of the first period of growth, Genard and Bruchou 1993), were also determined at the same period. At whole tree level, plant response (summarised in Table 6 for vegetative growth) to the N applied in autumn reflected partly those specificities, when compared to what has been observed by Lobit et al (2001) and Médiène et al (2002). First, growth was regulated more by the number of axes and fruits rather than by variations of growth rate among them.…”

“…Over fertilisation leads to excessive shoot growth that penalises fruit production (Weinbaum et al 1992). The increase of shoot biomass with N fertilisation results from higher sylleptic ramification and increased lengths of the axes, which have longer internodes and contain more phytomers (Lobit et al 2001;Médiène et al 2002). According to these authors, high N treatments increase not only the number of growing flushes, but also their duration by limiting the interval between two successive flushes.…”

Strigolactones as mediators of plant growth responses to environmental conditions

“…19 Nitrogen (N) availability in peach trees affected shoot architecture: secondary axes responded to N limitation by decreasing their growth according to their position along the main axis. 17 However, nutrient supply to pea did not prevent the outgrowth of buds, although it did affect branch length. 9 It is possible that SLs are involved in regulation of shoot branching in response to nutrient status.…”

Members of theLBDFamily of Transcription Factors Repress Anthocyanin Synthesis and Affect Additional Nitrogen Responses inArabidopsis

“…Other typical indicators of low N status observed in the LBD OX plants are high activation (90 to 100%) of NR (Scheible et al, 1997b(Scheible et al, , 1997c and starch accumulation (Scheible et al, 1997a;Peng et al, 2007a). Mimicry of N availability by LBD expression can also be deduced from the alteration of basal shoot branching, an N-dependent growth phenotype (see Supplemental Figure 11 online; Crawford and Forde, 2002;Mé diè ne et al, 2002). Shoot branching has long been known to be influenced by hormones such as cytokinins and auxin (for review, see Ongaro and Leyser, 2008) and recently also by strigolactones (Gomez-Roldan et al, 2008;Umehara et al, 2008).…”