Friday, 21 December 2012

Quality seed?

Key check no. 2: Sow recommended varieties of certified seed.

A "key check" seems to imply that this step should be one of the top ten most important steps to getting it right and getting a good crop. But no one else in the group is taking this one seriously, it seems.

Why is it supposed to be important to use certified seed? The main reasons listed in various documents linked to the Rice KnowledgeBank are: varietal purity, freedom from insect damage and disease, high viability, freedom from weed seeds. Certified seed, by definition, maintains at least at minimum quality standard in these areas. The default among IRRI agronomy-types (and RiceSurvivor participants) is to get seed from a previous field experiments, from another agronomist's field experiment, or from a friendly plant breeder (this last option is a distant third, because breeders aren't usually interested in released varieties). I believe this default option to be similar to a farmer using seed produced on her own farm during the previous season, which is exactly contrary to the official "key check" recommendation.

Producing certified seeds includes the following steps: 1) starting with some level of high-quality seed (e.g. breeder's seed, foundation seed, registered seed, or certified seed); 2) growing it well; 3) "roguing" it at least twice (flowering, harvest) to eliminate off-type plants; 4) harvesting and threshing with unusual care taken regarding moisture content and the time of each operation and with appropriate threshing technique; 5) thorough cleaning to remove chaff, straw, empty grains, weed seeds, dirt; 6) immediate drying and appropriate storage. I guess that a typical IRRI agronomy experiment would usually include steps 2 and 5, would sometimes include optimum conditions in step 4 and 6, and would not usually include steps 1 and 3.

We obtained "registered seed" from PhilRice. I don't know where the other teams ended up getting their seed. I suggest that we all do quick checks of seed quality to get an initial idea of how different our seed sources are. I will make a seed quality survey sheet for each group.

In the short term (i.e. two weeks), maybe we will find that our seed quality is independent of seed source. Maybe not.
In the longer term (i.e. 4 months), maybe we will decide that all of our seed quality was "good enough", and that the many other management decisions were more important than this one. Maybe not.  

1 comment:

  1. Group 2 did consider using certified seed for our plot. However, in the interest of time we decided to use seed from one of my experiments from last season. The seed source for that was certified seed. We felt this was an acceptable compromise that allowed us to establish our seed-bed in time for transplanting.