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Article Sponsored by RedSun Hortitech | Philip Lee, CompleteLee Nuts Consulting

The first and probably most important decision which every farmer must take when planning a new macadamia orchard:

Which cultivar should I plant? Or, more appropriately, which cultivars should I plant, given the knowledge that there is about half a ton of Nut-In-Shell (NIS) per hectare yield benefit from cross-pollination if we plant two cultivars together in one block.

It is also wise to plant at least 4 cultivars in any new orchard, both to ensure that we do not have all our eggs in one basket if we plant an entire farm to only one cultivar and to attempt to spread the harvest over a period of months using a combination of early, middle and late season maturing cultivars.


The question is, where do we find reliable, independent data on cultivar performance in the local area where the development is planned, to make this important decision based on facts. Ideally these data are found from cultivar trials, like the one illustrated in Figure 1. This cultivar trial was one of three planted in the 1993/94 season at Merensky school outside Tzaneen, and at the ITSC research stations at Levubu and Burgershall, funded by the SAMAC research programme.

In all 3 trials, Beaumont (HAES 695) was among the top two yielding cultivars, and this was probably the driving force behind the popularity of Beaumont, presently comprising about half of the close to 20 million macadamia trees planted in South Africa to date.

As Figure 1 shows, both cultivar 695 and 814 produced yields in this fully irrigated trial in excess of 2 tons kernel per hectare from tree age 8 to tree age 10. It is therefore surprising that cultivar 814 was not planted at the same rate as cultivar 695. Indeed, the accumulated yield of 814 from age 5 in 1998 to age 11 in 2004, was 11 200kg of Sound kernel, accumulated yield of 695 was 11 140kg of Sound kernel, while the lowest producing cultivar 800 had accumulated yield of only 1 950kg Sound kernel from tree age 5 to 11.


These data also highlight the importance of canopy management in maintaining consistent high yields from macadamia orchards. There was no tree training nor pruning carried out in this trial up to tree age 11. The yield decline in all cultivars in this trial in 2004 was primarily caused by the dense canopies of all the trees (planted at 8m by 4m, 312 trees/ha) which had grown to heights in excess of 8m by tree age 11, aggravated by the severe drought of the 2003/04 season in the Tzaneen area.


Even more important for the future of the macadamia industry is the potential for plant improvement indicated by the large difference between the highest and lowest yielding cultivars in this trial. With the highest yielding cultivars 695 and 814 producing five times more nuts over the first seven productive years in the life of the trees than the lowest yielding cultivar 800, imagine the improvements in both yield and quality that are yet to be discovered by unlocking the full genetic potential of macadamias through dedicated plant breeding programmes.

After all, all of the cultivars in this trial came from first generation selections from individual seeds, so we can say that the cultivars which we presently grow and which make up over 90% of world production, are only one step away from the wild trees which still grow in the few patches of indigenous forest on the eastern seaboard of Australia.   

Figure 2. Three year old tree of cultivar MCT1

Fortunately, many of these wild trees have been identified in their natural habitat and preserved by the Australian Macadamia Trust, which has used this genetic diversity in their breeding programme and released the first new cultivar, MCT1 shown in Figure 2, under plant breeders’ rights protection, to the global macadamia industry. More cultivars can be expected from the MCT breeding programme in coming years which will no doubt provide even better yield and quality attributes.

Figure 2

Until more improved macadamia cultivars do become available, new growers will need to use every available source of information on yield and quality performance for their specific local area, whether from the nursery supplying them with trees or the factory that will buy their nuts or from SAMAC cultivar trials, to make an educated decision regarding cultivar choice. Being a member of the Protea family macadamias will adapt to individual niche environments.

The cultivars that performed best in Tzaneen will not necessarily do the same in Empangeni. But if one plants cultivar 800 in Tzaneen, no amount of fertilizer, irrigation or any other cultural management input is going to make it yield anywhere close to cultivar 695 (or 814).