why my image rejected ?

If I'm correct, then the image is a phone picture or a small sensor camera image. Those need special attention, as the quality degrades rapidly if the light conditions are not optimal. 

I assume this image was rejected mainly for Quality & Technical reasons. 

• https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
• https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html

Comparing yours to other Stock inventory, which would you buy as a customer?

https://stock.adobe.com/search?k=rice%20field

This appears to be an unedited snapshot. It is not in sharp focus. The shadows are underexposed and the sky is overexposed.

Along with the other comments, your horizon line needs to b straightened out.

You need to sharpen the image., edit in some sky and remove the blurry birds that are flying. 

Hello,

Sorry, but not quite up to Adobe Stock standard. The overall image is 'flat' - the type of day - overcast - gives a flat look. There is not a lot of contrast or colour in your image.

Perhaps it would be good to read these guides from Adobe to get an idea of what they are looking for in an image.

User guide:
https://helpx.adobe.com/stock/contributor/user-guide.html
Exposure:
https://www.adobe.com/creativecloud/photography/discover/exposure-in-photography.html
Composition:
https://www.adobe.com/creativecloud/photography/discover/photo-composition.html
Learn and support:
https://helpx.adobe.com/support/stock-contributor.html