Selection for resistance to fungal diseases and other desirable traits in kikuyu grass (&lt;i&gt;Cenchrus clandestinus&lt;/i&gt;)

William J Fulkerson,Nathan R Jennings,Peter M Martin,Percy T.W Wong,Karen J Harper,Mark Callow

doi:10.17138/tgft(9)60-69

Abstract

While kikuyu (Cenchrus clandestinus) is an important grass for dairy and beef production in the subtropical region of Australia and the world, the most common cultivar, Whittet, is seriously affected by the fungal diseases, kikuyu yellows (Verrucalvus flavofaciens) and black spot (Bipolaris spp.). Thus resistance to these diseases is a priority in selecting a better kikuyu cultivar, along with higher herbage quality and yield and better winter growth. A study was conducted to identify suitable candidates from kikuyu ecotypes collected along the east coast of Australia plus lines obtained by subjecting Whittet to a mutagenic agent. Initial glasshouse studies identified 19 lines that were resistant to the KY1A strain of kikuyu yellows and 4 of these, with forage quality and yield superior to Whittet, were further evaluated in the field at 2 sites using Whittet as the control. At Site 1, line 12A demonstrated a much higher level of resistance to kikuyu yellows than Whittet, with 85% of plants resisting infection compared with only 15% of Whittet plants. At Site 2, the numbers of 12A and Whittet plants infected were similar. Further tests, using kikuyu yellows inoculum collected from 11 sites along the east coast of Australia, found that only 15% of 12A plants became infected compared with 61% of Whittet plants. Thus, kikuyu line 12A was resistant to most, but not all, strains of the kikuyu yellows pathogen. Annual yield of 12A (19,008 kg DM/ha) was 24% higher than that of Whittet and 12% higher than Acacia, but the difference was significant only for Whittet. During summer, 12A produced 10,212 kg DM/ha (24% higher than Whittet), was more active in early spring, had slightly higher dry organic matter digestibility (66.7 vs. 64.0%) and was resistant to black spot infection.

Highlights

Kikuyu grass (Cenchrus clandestinus) is a C4 summer grass, native to northeastern parts of Africa, predominantly in the Aberdare Mountain region of Kenya, which is inhabited by the Kikuyu tribe; the name, kikuyu
Further tests, using kikuyu yellows inoculum collected from 11 sites along the east coast of Australia, found that only 15% of 12A plants became infected compared with 61% of Whittet plants
The study commenced in March 2015 with the evaluation of 115 kikuyu lines, selected from 1,600 lines held at the Animal Science Precinct, University of Queensland from a previous study on the genetic variation in kikuyu grass (Lowe et al 2010) with those lines originating from 3 different sources:

Summary

Introduction

Kikuyu grass (Cenchrus clandestinus) is a C4 summer grass, native to northeastern parts of Africa, predominantly in the Aberdare Mountain region of Kenya, which is inhabited by the Kikuyu tribe; the name, kikuyu. ’Common’ kikuyu grass, introduced into Australia in 1919, was traditionally established by cuttings until Wilson (1968) identified a seeding line of kikuyu grass at Grafton Research Station in northern NSW. This line was primarily selected for its high level of free seeding and more vigorous growth than Common kikuyu grass, in winter, and was registered as cultivar Whittet in 1970. ‘Crofts’ is claimed to have greater cold tolerance and to be slightly higher yielding than Whittet and was released in 1983

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Conclusion