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Kwame Nkrumah University of Science and Technology (2015)

Effect of isolation distances on varietal seed purity for open pollinated varieties of pearl millet [pennisetum glaucum (l.) r. br.] at farmers’ level in Northern Ghana

Abdoulkarim, Liman Souley

Titre : Effect of isolation distances on varietal seed purity for open pollinated varieties of pearl millet [pennisetum glaucum (l.) r. br.] at farmers’ level in Northern Ghana

Auteur : Abdoulkarim, Liman Souley

Université de soutenance : Kwame Nkrumah University of Science and Technology

Grade : Master of Philosophy (Seed Science and Technology), 2015

Résumé
Pearl millet seed supply in West Africa is dominated by the informal system in which small scale farmers produce and supply local seeds of landraces or open pollinated varieties mostly without any quality control during production. Standards for quality control are mostly designed for the formal and commercially oriented system which fails to supply adequate quantity of seeds. To increase agricultural productivity through the use quality planting materials more attention is required on small seed producers to ensure that seed of acceptable quality are produced and used by large scale millet producers. This study aimed at assessing the level of varietal seed purity at farmer‟s level. Two open pollinated varieties of Pearl millet were used, one variety as pollen source characterized by yellow coloured seeds and the other seed parent with grey coloured seeds. After cross pollination, it was expected to produce hybrid of yellow coloured seeds on the seed parents due to xenia effect. The results showed significant differences (p<0.001) in varietal seed purity with regard to the interaction between distance and direction of seed parents from the pollen parents. Closer pollen parents (from 0.4 to 30 m) showed higher significant differences in varietal seed purity compared to distant seed parents (from 40 to 60 m). Seed parents located to the direction of wind from pollen parents produced seeds with significantly lower seed quality compared to those located in the opposite direction. Varietal purity was positively and strongly correlated (p<0.01) with distances from pollen parents. Wind speed and direction showed significant direct effect on varietal seed purity while other climatic parameters such as temperatures, relative humidity and rainfall may have iv some indirect effects. Although it was possible to produce pure seed on some points of the experimental field at 60 m to the South East and to the West, 45 m and above to the South East, 50 m and above to the South, 55 m and above to the South West and North West, it is very challenging for farmers to produce seeds that meet standards. However, some measures can be taken by farmers in order to produce seed with an acceptable level of seed purity. These measures include : plotting the seed field by considering the prevailing wind direction in the area, planting at least 3 weeks after the source pollen is planted, choosing seed parents that are „‟taller‟‟ than the pollen parents, adopt a communal seed grower system where a cluster of farmers grow the same variety. These could not prevent cross-contamination from neighbouring farms with different varieties but rather can minimize the flow of pollen grains in the seed production filed.

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