Influence of time of planting on yield and grain quality of bean genotypes grown on an andosol in the western highlands of Cameroon

Determining the best combinations of variety choice and planting date may be crucial for farmers in view of optimising bean yields. A study was conducted to assess the agronomic performance of selected dry bean ( Phaseolus vulgaris L.) lines when planted sequentially under rain fed conditions in the Western Highlands of Cameroon (WHC). Forty two introduced lines and three local checks were used, namely, 15 bush lines, 15 semi climber lines, and 15 climber lines. Three sequential dates of planting were chosen at 15 days intervals starting from 15th of September 2007. Delaying bean planting up to the 15th of October resulted in a 50 to 77% yield reduction. The highest losses were recorded by climber and semi-climber lines which have a relatively longer growth cycle. Consequently, grain quality also deteriorated as the weight of 100 seeds dropped by 11.4, 15.8 and 3.3% for bush, semi- climber and climber lines, respectively. The causative factors were likely soil moisture deficit coupled with insect pests damages to grains during formation and towards maturity. Disease incidence on the crop varieties was mild and scores ranged from resistant (1-3) to tolerant (4-6). In this environment, it is better to plant beans up to 1st October; beyond this date, it may be advisable for farmers to go for a high yielding bush variety. Climber and semi-climber varieties yielded at least 25% higher than bush ones under prevailing environmental conditions.La d\ue9termination des meilleures combinaisons de choix de vari\ue9t\ue9s et dates de semis pourrait \ueatre cruciale pour les fermiers afin d\u2019optimiser les rendements du haricot. Une \ue9tude \ue9tait men\ue9e pour \ue9valuer la performance agronomique des lign\ue9es de haricots secs ( Phaseolus vulgaris L.) s\ue9lectionn\ue9s, plant\ue9s sequentiellement en conditions de pluie. Quarante deux lign\ue9es introduites et trois t\ue9moins locaux \ue9taient utilis\ue9s, \ue0 savoir, 15 lign\ue9es naines, 15 lign\ue9es semi volubiles et 15 lign\ue9es volubiles. Trois dates de semis s\ue9quentielles \ue9taient choisies \ue0 15 jours d\u2019intervalle du 15 Septembre 2007. Le semis retard\ue9 jusqu\u2019au 15 Octobre avait induit une r\ue9duction de rendement allant de 50 \ue0 77%. Les pertes les plus \ue9lev\ue9es \ue9taient enregistr\ue9es par les lign\ue9es volubiles et semi-volubiles qui ont relativement un plus long cycle de croissance. En cons\ue9quence, la qualit\ue9 du grain avait aussi d\ue9t\ue9lior\ue9 par la perte du poids de 100 grains de 11.4, 15.8 et 3.3% pour les lign\ue9es naines, semi-naines et volubiles, respectivement. Les facteurs responsables \ue9taient le d\ue9ficit en humidit\ue9 du sol associ\ue9 aux dommages par des insects aux grains durant la formation et vers la maturit\ue9. L\u2019incidence maladie sur les vari\ue9ti\ue9s de cultures \ue9tait modeste et l\u2019echelle de cotation s\u2019\ue9levait du r\ue9sistant (1-3) au tol\ue9rant (4-6). Dans cet environnement, il vaut mieux de planter les haricots jusqu\u2019au 1er Octobre au-del\ue0 duquel, seules les vari\ue9t\ue9s naines \ue0 haut rendement devraient \ueatre les plus recommand\ue9es aux fermiers. Les vari\ue9t\ue9s volubiles et semi volubiles avaient produit au moins 25% plus que les haricots nains en conditions environmentales pre-cit\ue9es