Apr09

IRRI agronomy challenge: flag leaves and false smut are good signs

Author // Dr. Leigh Vial Categories // Achim Dobermann's blog

7 April

The crop looks good, albeit a bit variable in maturity. My sons, Digby and Rory, and I walked through it yesterday... the mud has not got any less deep. It is now quite uniform and tiller-number and panicle size have compensated for any differences in plant number.

rice crops

The crop looks good, but has late-maturing patches
like the one in the foreground . 

It presents a fairly even field of grain... Achim got the fertilizer somewhere near right. The rats have done no more, and the stem borers have claimed maybe 0.5% of panicles. We’ll ask Nancy for an informed opinion. Two things please me:

First, the panicles are generally nestled in amongst vigourous flag leaves. The photosynthetic machine continues to operate late in the plant’s life. This is particularly important considering we are finally getting decent swaths of sunshine after a particularly cloudy dry season. The energy is important to feed the main panicles, but also a significant number of later panicles further down. There is up to another 1 ton per hectare in them, I reckon. In my history (admittedly in temperate rice), a flaggy crop is a crop that is nearing its yield potential.

Second, there is a smattering of false smut in the crop. The conventional Filipino farmers’ wisdom is that a bit of false smut is a good sign; the crop has achieved somewhere near its potential.

The main crop is typically nearing the end of the milky-grain stage. There is quite a difference in maturity along each panicle as one would always expect. Looking across the field, there are some patches just approaching flowering now, a good 2 weeks behind the main crop; the later sowing did not catch up quite as expected. Choosing the harvest time will be interesting, especially if we are aiming for quality grain. If we wait for the late patches, the main early crop will be too dry and hence not mill well. Then again, there are those later panicles nestled further down the canopy even in the early crop. We will have to wait a little for them anyway.

The question now is, when to drain?

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About the Author

Dr. Leigh Vial

Dr. Leigh Vial

Dr. Leigh Vial is former head of IRRI's Experiment Station. Read more.