Physical rice grain quality as affected by biophysical factors and pre-harvest practices

Document Type: Research Paper

Authors

1 Institute of Agricultural Research for Development (IRAD), Yaoundé, Cameroon

2 Africa Rice Center, Mbe Station, 01 BP 2551, Bouake, Cote d’Ivoire

3 Faculty of Science, University of Yaoundé-I, Yaoundé, Cameroon

4 Faculty of Science, University of Yaoundé-I, Yaoundé, Cameroon.

5 Africa Rice Center, 01 BP 2031, Cotonou, Benin.

Abstract

Varietal purity and proportions of grains with brown spots, fissured grains, chalky grains and
whole grains in a rice sample are important grain quality attributes influencing consumers'
preference and price but little information exist on how these grain quality attributes are affected
by biophysical factors and pre-harvest practices. Several authors have studied in isolation the
effect of biophysical factors and pre-harvest practices on rice grain quality but most of these
studies neither looked at these within the context of agro-ecological zones nor production
systems. The effects of agro-ecological zone (AEZ) (highlands, sub-humid, humid and
semi-arid), production system (irrigated lowland, rain-fed lowland and rain-fed upland) and
pre-harvest practices on grain quality attributes were investigated in 5 African countries using
data collected through on-farm survey. The rice samples were generally characterized by low
varietal purity, high proportion of brown spots, fissured and chalky grains and a low proportion
of whole grains. Also, they had large variations across and within AEZs and production
systems. AEZs and crop establishment method affected varietal purity. AEZ, production system
affected chalkiness. AEZ and type of variety influenced percentage of grains with fissures.
Percentage of whole grains were affected by AEZ, production system and weeding frequency.
While grain quality attributes were strongly affected by biophysical factors, there is also room
for improving grain quality through good pre-harvest practices.

Keywords