RESPONSE TO DISCUSSION PAPER ON USE OF NON-CERTIFIED SEED

Thursday, 17 Nov, 2005

The following is a response from Nick Pyke of FAR to the NZFMA's March Discussion Paper on the Use of Non-Certified Seed which growers may find of interest. The discussion paper in question can be viewed by accessing the archives below dated 27th April 2005.

The discussion paper implies that one of the major causes of cultivars producing below quality grain, loss of their original quality characteristics, is due to use of non-certified seed resulting in a decline in cultivar life. It is implied that use of non-certified seed has resulted in the occurrence of poor quality flour of the variety Regency.

From a scientific perspective and reviewing the scientific literature two points are clearly apparent.

1. Chances of loss of genetic purity through out-crossing is minimal

There is no scientific evidence from that reviewed that indicates the quality of grain will change through the use of non-certified seed. There are a number of the characteristics of wheat which preclude a marked shift in the genetic purity of wheat from the use of farm saved seed.

a. Pollen dispersal and survival

Due to the development of GE wheat, a number of studies have been conducted. Wheat is a self pollinating species with out-crossing rates that are less than 1%. A field study in Canada detected less that 6% of the pollen at 20cm from the pollen source. Cultivars with high out-crossing potential have greater degree of spikelet opening and poor pollen quality (Wheat pollen flow and implications for maintaining integrity of non-GM wheat cultivars, Univ Saskatchewan). These are not generally characteristics of New Zealand wheats.

Further US studies indicate that cross pollination is not a major concern. Pollen movement was in the direction of the prevailing wind with a maximum distance of movement of 42cm and then at a level of less than 0.5%. At four of five locations no out-crossing was detected beyond 30m. Most wheat crops of different cultivars in New Zealand have separation distances of at least 30m negating chance of cross-pollination and loss of genetic purity.

Pollen survival in wheat is very short (30-60 minutes) for pollination to occur and to reduce genetic purity; two cultivars need to be flowering at the same time within 30m of each other. Pollen survival is influenced by environmental conditions such as temperature and relative humidity.

In New Zealand high humidity is common at wheat flowering, reducing pollen viability, mobility and increasing male sterility.

b. Stigma receptivity

The floral biology of wheat is such that stigma maturation for pollen receptivity and pollen shed for mature antlers are in phase within a floret.

Stigmas are usually pollinated by pollen shed from the same floret. This minimises the chances of out-crossing and loss of genetic purity.

c. General

Nebraska University Guide 811 states "Genetically there is no reason for a variety to run-out. There are other reasons this could occur such as accidental mixing of varieties and contamination with seed or build up of seed borne diseases".

Good management of farm saved seed lines should ensure limited loss of genetic purity and clean seed lines, with low weed or disease incidence, are produced.
There is no information from UK studies, including communication with the UK Baking Research Institute, suggesting any impact of loss of genetic purity on grain or flour quality (Orson pers. comm. 2005)

2. Influence of environmental variability on grain and flour quality

There is international evidence that shows grain quality is markedly influenced by environmental conditions, particularly during grain fill. Many countries undertake cultivar evaluation and assess grain quality over a large number of sites and seasons. The New Zealand system has in the past not adequately screened the impact of environmental conditions on grain quality as cultivars are developed and evaluated for the following reasons:

Cultivar selection occurs under relatively controlled growing conditions (reasonable soil types and irrigation).
Cultivar evaluation occurs on relatively uniform and good quality soils, usually with irrigation, partly because breeders want cultivars to perform.
Until this year samples of one cultivar from a number of cultivar evaluation sites have been pooled for quality testing. Thus the grain quality characteristics are averaged.
Usually cultivar testing is carried out using above average management from growers or researchers.

Thus when cultivars move into commercial production, which is undertaken on a range of soil types, with a range of farming skills, there is a high level of variability in grain quality. Traditionally this variability has often been blamed, incorrectly, on loss of genetic purity, particularly in farm saved seedlines.

Conclusion

Use of farm saved seedlines is unlikely to markedly impact on grain or flour quality provided good segregation of lines is maintained by growers.
Growing conditions and sites could markedly influence grain and flour quality.
New Zealand cultivar evaluation systems have not been developed to identify the influence of site on quality.
New Zealand wheat industry and particularly end-users should endeavour to understand how environment, regional conditions and growing expertise influences wheat grain and flour quality. This could result in end-users contracting wheat production from sub-regional areas, grown to optimise quality, to minimise variability in quality.

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