The effects of propagation environment and foliar area on the rooting physiology of Cordia alliodora (Ruiz & Pavon) Oken cuttings

Abstract

AbstractmThe effects of propagation microclimate and foliar area on the rooting of Cordia alliodora (Ruiz & Pavon) Oken cuttings were investigated using non-mist propagators with and without shade. Photosynthetic rates (Pn), stomatal conductance (gs) and chlorophyll fluorescence ratio (Fv/Fm) of the cuttings were assessed during propagation. Pronounced differences in microclimate were recorded between treatments, with lower temperatures and vapour pressure deficit (VPD) under shade. During the first 8 days after insertion, Pn varied between 2.21 and 4.96 and 0.47 -2.54 µmol CO2 m -2 s -1 in the shaded and unshaded propagators, respectively. In the unshaded propagator, Fv/ Fm decreased to a minimum of 0.72 2 days after insertion, recovering thereafter. In two separate rooting experiments, rooting percentage was reduced by high irradiance in the 20 and 30 cm 2 leaf area treatments, but not in the 10 cm 2 treatment. Pn decreased with an increase in leaf area in both shaded and unshaded propagators. Fv/Fm also declined with increasing leaf area in the high irradiance treatment. PAR and Pn were positively correlated under shade (r 2 = 0.51) but negatively correlated in the unshaded treatment (r 2 = 0.49); maximum Pn values were recorded at a PAR of 400 µmol m -2 s -1 . No significant differences in gs were found between treatments, values ranging between 130 and 194 mmol H2O m -2 s -1 . Positive correlations were found between rooting percentage and mean Fv/Fm. These results indicate that rooting of C. alliodora cuttings is related to photosynthetic activity during propagation, which is itself influenced both by propagator microclimate and cutting leaf area. Key wordsmPhotosynthesis ? Stomatal conductance ? Chlorophyll fluorescence ? Vegetative propagation ? Cordia alliodora

Cuttings of Wollemi pine tolerate moderate photoinhibition and remain highly capable of root formation

“…Our results showed that cuttings under mist irrigation can be prone to long periods of moderate photoinhibition (F V /F M mostly >0.65) and yet remain highly capable of root production. These findings contrast with results from cuttings of other species placed in unshaded nonmist propagators, in which more severe photoinhibition develops (F V /F M <0.60), and rooting percentages decline with decreasing F V /F M (Mesén et al 1997(Mesén et al , 2001. Photoinhibition could be partially alleviated by lowering irradiance or by applying foliar fertiliser.…”

“…Photoinhibition could be partially alleviated by lowering irradiance or by applying foliar fertiliser. Reduced irradiance in the propagation environment has been used to minimise photoinhibition (Mesén et al 1997) and increase rooting percentages of cuttings from other tree species (Aminah et al 1997a;Mesén et al 1997;Nketiah et al 1998). Cuttings without roots are prone to nutrient leaching and nutrient deficiencies during extended periods under mist irrigation, as uptake of nutrients through the base of cuttings from the propagation medium is generally very low (Blazich 1988;Hartmann et al 1997).…”

“…Photoinhibition can be exacerbated by stressful conditions such as nutrient deficiency (Balachandran and Osmond 1994;Verhoeven et al 1997;Skillman and Osmond 1998;Ramalho et al 2000;Fernandes et al 2002), water stress (Ögren 1990;Blaikie and Chacko 1998), or extreme temperatures (Adams and Demmig-Adams 1994;Marler and Lawton 1994;Binder et al 1997;Close et al 2001). Despite the considerable importance of cuttingsbased propagation systems, and the likelihood of severe physiological stresses while cuttings remain unrooted, little is known about the degree to which cuttings experience photoinhibition or the extent to which it affects root formation and development (Mesén et al 1997(Mesén et al , 2001Bruce et al 2001).…”

“…Requirements for root initiation have generally been considered as those that minimise physiological stresses resulting from high irradiance, temperature and transpiration (Leakey et al 1994;Mesén et al 1997;Lebude et al 2004). Root production requires that cuttings survive physiological stresses after severance from the stock plant, and maintain sufficient nutrient reserves to allow root initiation and early growth.…”

Effects of cutting size and exogenous hormone treatment on rooting of shoot cuttings in Norway spruce [Picea abies (L.) Karst.]

“…The effect of nutrient status on rooting has been studied during adventitious root development in leafy cuttings (Dick and Dewar 1992). The accumulation of starch at the cutting bases in avocado improves its rooting capability (Reuveni and Raviv 1980), although starch-filled cuttings of T. scleroxylon develop very poor rooting due to inhibited post-severance photosynthesis (Leakey and Coutts 1989;Leakey and Storeton-West 1992;Mesén et al 1997Mesén et al , 2001. The third factor is the lower elemental content of N, P, and K in large cuttings (Burgess et al 1990), which is negatively correlated with rooting.…”