Analysing seed systems performance: the case of oil palm in Bénin

E. Akpo

Research output: Thesisinternal PhD, WU

Abstract

Key words: Bénin, genetic quality, growth dynamics, innovation, institutions, multistakeholders

process, oil palm, perennials, physiological quality, pot size, seed quality, seed

systems, smallholders, social learning.

 

The seed supply system used by smallholder farmers is characterised by many dysfunctions.

For perennials, including oil palm, there is a knowledge gap regarding these dysfunctions. In

this thesis, we used oil palm as a case to analyse the performance of seed systems. We

conducted social surveys, sampled farmers’ oil palm plots, ran field experiments and

documented the social learning process of stakeholders involved.

To identify major constraints in the seed system, we conducted a diagnostic study

using farmers’ perspective. Jointly with stakeholders the following major constraints were

identified (in order of importance): poor geographic distribution of official nurseries, poor

genetic quality of palms in smallholder plots, high costs of hybrid seedlings, and poor

seedling care in nurseries leading to poor physiological quality. The poor care was

specifically mentioned in the eastern part of the study area.

We investigated the reliability of genetic quality of seedlings supplied to smallholder

farmers as one of the constraints that emerged from the diagnostic study. Main drivers of

reliability in genetic quality over the past decades were analysed. Using event ecology

approach, we document the historical events that may have affected the oil palm seed system.

Proportions of hybrid palms varied with seedling supply source, farmers’ geographic position,

seedling purchase price and year of planting. Socio-institutional mechanisms associated with

observed variation in smallholder plantations were national policy change, local arrangements

for seedling supply to smallholder farmers, and farmers’ personal characteristics. Local

arrangements improved genetic quality in villages located far away from official supply

sources. Villages where local seedling supply initiatives withdrew showed reduced genetic

quality with farmers having fewer tenera in their fields than before. Membership of farmers’

organisation correlated positively with proportion of tenera. Farmer’s use of informal

intermediaries showed negative effects on genetic quality they received.

To evaluate the efficacy of on-going nursery management practices on the seedling

phenotype at planting we conducted joint learning experiments. In two full 3 × 4 × 3 factorial

experiments, bag size (small, medium, large), type of soil substrate ("forest" soil, household

waste substrate, arable soil, and arable soil with animal manure) and fertiliser supply (no

fertilisation, split dose every 15 days, and full dose every 30 days) were tested for their effects

on seedling phenotype. Bag size proved the main factor determining oil palm seedling

phenotype in both the 2011 and 2012 experiment. Although large-sized bags produced largest

seedlings, medium-sized bags filled with a mixture of arable soil and animal manure without

any fertiliser supply sustained seedling growth well and seemed the best balance between

physiological quality and production cost. Growth variables were highly correlated. Height

and root-collar diameter constituted good proxies to estimate seedling biomass differences

between objects in a non-destructive way.

To gain insight into temporal patterns of effects of bag size, substrate, fertiliser supply,

and their interactions on seedling growth, we analysed the dynamics of oil palm seedling

growth using monthly observations. Overall, in both experiments, bag size explained the

largest proportion of experimental error and started to deviate earlier than substrate, fertiliser

supply or their two and three way interactions. Curve fitting showed different growth models

for height, root-collar diameter and number of leaves. The analysis of growth rates showed

that (relative and absolute) growth rates were mainly affected by bag size in both years with

larger F-values than for substrate, fertiliser supply, and interactions. Experimental findings

indicated that pot size matters and cannot be compensated by fertiliser addition and should

therefore be considered carefully for tree seedling production in nurseries.

We analysed the joint experiment as a multi-stakeholder process and contributed to

understand how the way of organising social learning affects stakeholders’ ownership of

process outcomes. Stakeholders’ perceptions of seedling quality and their appreciation of

treatment performance varied with the use they make of planting material. While farmers, as

end-users, put forward seedling vigour when describing quality seedlings, nursery holders

underlined production costs and reported that seedling quality is a compromise with

production costs. Field observations further to the joint experiment indicated changes in

practices among nursery holders, research, and farmers. The level of stakeholders’

involvement increased their participation, ownership of the learning process, and could lead to

sustainable practices.

The research approach developed in this thesis to analyse seed systems performance

contributed to the methodology for seed systems analysis. It also contributed to knowledge of

dysfunctions of seed systems for perennials, tree nursery seedling production and social

learning processes.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Struik, Paul, Promotor
  • Kossou, D.K., Promotor, External person
  • Tossou, R.C., Promotor, External person
  • Crane, Todd, Co-promotor
Award date9 Dec 2013
Place of PublicationWageningen
Publisher
Print ISBNs9789461738097
Publication statusPublished - 2013

Keywords

  • elaeis guineensis
  • oil palms
  • seed production
  • seeds
  • perennial nurseries
  • small farms
  • farmers
  • benin

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