Mr. Ogoshi,

Thank you very much for your fast answer. I am trying the option you have
given me and comparing results.
I appreciate indeed your help.

Carol

----- Original Message -----
From: "Richard Ogoshi" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, November 28, 2001 1:17 PM
Subject: Re: Final Harvest for Maize


> Hello Ms. Hache,
>    Thank you for your inquiry about the seed dry weight calculation.
>    The calculation in the DSSAT manual should give you a fairly accurate
> estimate of the seed dry weight. The equation is
> Seeds wt dry (g/m2) = (ear wt undried x (seed subsample wt dry / ear
> subsample wt undried)) / harvest area
> The ear wt undried is the total ear weight (cob + seed) from the harvested
> area. I think this is one place where there is confusion: Ear weight
refers
> to total ear wt undried that is recorded in the box that states,
"Calculate
> ear number (ears/m2) by dividing number of ears by harvest area (12.06 m2)
> and record. Enter total ear weight (undried)." I should have made this
more
> explicit. The seed subsample wt dry is the seed dry weight from the box
> just above the box with the seed wt dry equation. In this box it states,
> "Dry seed and cob subsamples to constant weight at 70 C (approximately 7
> days). Log seed and cob subsample weights (dry) separately." The ear
> subsample wt undried is the wt recorded three boxes above the box with
seed
> wt dry equation. In this box it states, "Select a subsample of 10
> representative ears for dry weight and seed number determination. Log ear
> subsample weight (undried)."
>    There is more than one way to calculate seed dry weight (g/m2) as you
> have pointed out. However, in your calculation you don't need to include
> the ear weights (total and subsample). All you need to do is use this
> equation:
> Seeds dry wt (g/m2) = (removed seed wt undried x (100 seed wt dried / 100
> seed wt undried)) / harvest area,
> or seeds dry wt (g/m2) = 915.2 x (17.88 / 37.77)/ harvest area = 433.2 g /
> harvest area
> Where removed seed wt undried is the weight of all seed removed from the
10
> plants.
>     Your method is a more direct method of calculating seed dry weight and
> would be preferable over the method in the manual. The manual's method
> assumes that the cob:seed ratio is the same among ears, which may or may
> not be true. However, the manual's method is much less labor intensive,
> especially if there is no sheller available. So, you may choose the method
> depending on the availability of labor and machinery.
>    I hope this helps.
> Sincerely,
> Richard
>
>
> At 03:20 PM 11/27/01 -1000, you wrote:
> >Dear Listers,
> >
> >I am using the equation for calculating Seed wt. dry (g/m2) in "Final
> >Harvest Procedure for Maize" from DSSAT manual. The equation is :
> >
> >
> >Seeds wt dry (g/m2) = ear wt. undried x (seed subsample wt. dry/ear
> >subsample wt. undried)/Harvest area
> >But when I apply the values (as an example) :
> >Ear wt. (undried) :  776.1 g
> >Seed subsample wt. (dry) : 17.88 g (this is the data from the 100 seed
> >wt.dry)
> >Ear subsample wt (undried): 1299.5 g
> >Harvest area : 1 m2
> >
> >The result is 10.68 g of seed/m2.
> >
> >
> >I wonder if "seed subsample wt (dry)" is not the weight of the 100 seeds
we
> >dried in oven, but a ratio of the 100 seeds wt. dry/100 seeds wt.
undried,
> >multiplied by the weight of all the seeds we removed from the cobs (from
the
> >10 representatives ears). Then the equation would be as follows:
> >
> >Seed wt.dry= [ear wt.undried x {removed seeds wt.undried x (100 seed
> >wt.dry/100seed wt.undried)}/ear subsample wt.undried]/Harvest area
> >Then,
> >removed seeds wt. (undried) : would be all the seeds removed from the
cobs;
> >915.2 g
> >100 seed wt. (undried) : 37.77 g
> >
> >
> >The results would be 258.82 g of seed/m2.
> >
> >I hope my way of explanation is understandable. I would appreciate indeed
> >your help in this matter. Looking forward to hear from you,
> >
> >
> >Carolina Hache
> >Graduate student
> >Tokyo University of Agriculture and Technology
> >Agricultural and Environmental Engineering Department
> >
>