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New Zealand Journal ofAgricultural ResearchPublication details, including instructions forauthors and subscription information:http://www.tandfonline.com/loi/tnza20

Improvement of the yieldof the hop plant (Humuluslupulus) by means of shootselectionR. H. J. Roborgh aa Hop Research Station , Department of Scientificand Industrial Research , Riwaka, NelsonPublished online: 15 Feb 2012.

To cite this article: R. H. J. Roborgh (1968) Improvement of the yield of the hop plant(Humulus lupulus) by means of shoot selection, New Zealand Journal of AgriculturalResearch, 11:1, 215-218, DOI: 10.1080/00288233.1968.10431649

To link to this article: http://dx.doi.org/10.1080/00288233.1968.10431649

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215

IMPROVEMENT OF THE YIELD OF THE HOP PLANT (Humulus lupulus) BY MEANS OF SHOOT SELECTION

By R. H. J. ROBORGH*

(Received 13 November 1967)

ABSTRACT

Shoots of the hop of high potential yield are characterised by a stagnation of increase in the lengths of their first four fully elongated internodes.

The shoots which develop from the perennial rootstock of a healthy hop plant in late October differ in their potential yield. When in a hop garden two shoots of each plant (var. Late Cluster) are trained to separate strings to enable individual harvesting, the yield of the lower-producing bine is on an average only 45% or 65% of the crop of the higher-yielding one, the difference in the percentages depending on whether the shoots originate from a cutting or from an established plant (Roborgh 1966).

Shoots of high potential yield appear to be thicker and their leaf development slightly slower when compared with lower-yielding ones (Fig. I); however, these differences are too subtle to be used in practice for selection, where a choice has to be made between the 10 to 30 shoots which are usually present.

Another characteristic of the high-yielding shoots is that their fully elongated internode No.2, 3, or 4 is shorter or only slightly longer than the preceding one, whereas the first four fully-elongated internodes of lower-yielding shoots do not show this stagnation of increase in internode length (Fig. 2).

In order to test if this characteristic of shoots of high potential yield is of practical value for selection, field trials were laid out in an established Late Cluster garden in 1965-6 and in plantations of the three New Nelson varieties in the 1966-7 season.

* Hop Research Station, Department of Scientific and Industrial Research, Riwaka, Nelson.

N.Z. JI agric. Res. (1968), 11: 215-18

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Fig. 2.-Lengths (mm) at the time of selection and training of successive fully elongated internodes of 14 hop shoots (var. Late Cluster). See stagnation of increase in internode length of the five shoots which produced the highest yields

(No. of hops); hines 7E, 66W, 37E, 7W, and 14W.

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218 Improvement of yield of hop plant

Results show that although there was a limited number of plants where shoots of the required characteristic were absent, the plots trained with shoots selected for stagnation of increase in length of their first four internodes yielded for Late Cluster 12.9%* and for the New Nelson varieties 9.2%* more than the controls.

ACKNOWLEDGMENT

The author wishes to thank Miss Cleone Withell for assistance with the trials and in particular for preparation of the figures.

REFERENCE

ROBORGH, R. H. I. 1966: Yield of the hop bine (Humulus lupulus, var. Late Cluster) in relation to rate of elongation and morphology of the shoot. Proc. lXth Conv. lnst. Brew. (Aust. Sect.). pp. 171-9.

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