Evaluation of Rooting Media Containing Fallen Needles of Japanese Black Pine for Blueberry Cuttings

Abstract

We evaluated the effective use of fallen needles of the Japanese black pine (Pinus thunbergii Parl.) collected at the world heritage site "Miho no Matsubara" as rooting media for blueberry (Vaccinium Spp.) cuttings to develop blueberry cultivation focusing on environmental and regional branding effects. We prepared media containing peat moss with the pine needles (v/v, 1 : 0 (0%), 3 : 1 (25%), 1 : 1 (50%), 1 : 3 (75%) and 0 : 1 (100%)), and compared the effects with those of conventional medium: peat moss and Kanuma pumice (v/v, 1 : 1) as a control. Soil pH in the control and media containing pine needles ranged from 4.4~4.7. The survival rate, shoot length, and root dry weight of the blueberry cuttings in the 25% medium were similar to those with the conventional media. Moreover, the survival rates of 'Brightwell' and 'Misty' in the 0~75% medium, and 'Baldwin' in the 0~50% medium, were similar to those with the conventional media. The shoot length of 'Brightwell' and 'Baldwin' in the 0~75% medium, and the root dry weight except for 'Magnolia' in the 0~75% medium were similar to those with the conventional media. The root dry weight of 'Magnolia' in all examined media showed no significant difference on comparison with the conventional media. The soil EC and total polyphenol content were increased with the addition of pine needles to the media, resulting in extremely high values: 10.2 for EC and 0.83 mg・g -1 for polyphenol in the case of 100% medium. The low survival rate, shoot length, and root dry weight of the blueberry cuttings in the medium with a high percentage of pine needles might be ascribed to these high values. Collectively, we revealed that 25% media can produce a quality (shoot length and root dry weight) of blueberry cuttings with a high survival rate similar to that of the conventional media in all applied cultivars. Moreover, for 'Brightwell', up to 75% pine-containing medium can be used similarly to conventional media.