Morpho-physiological traits conferring drought adaptation among cotton genotypes in Cameroon

Back to Content

Author

ROMAIN LOISON

CIRAD – France

Abstract

In Cameroon, water shortage is the major abiotic factor limiting cotton (Gossypiumhirsutum L) yield and lint quality. Understanding cotton physiological responses to water supply and their consequences on growth and development therefore provides insight into the problem of yield stagnation. The underlying strategies for yield maintenance under water deficit in Cameroon have not been well understood. The objective of this paper is to evaluate which ecophysiological traits could confer a good response to drought among a panel of cotton genotypes used in Cameroon. These genotypes were compared in field and  greenhouse trials under potential and water-limited conditions (fraction of soil transpirable water range: 0.39 to  0.83). Water deficit  had  a  negative impact on almost all the plant functions, both under field and controlled environments. The recent cultivar L484 bred for the driest production area responded quite differently from the other cultivars in this study. L484 had the fastest development, thickest leaves with the most chlorophyll and thus maintained the highest level of photosynthesis and transpiration per unit of leaf area in water-limited conditions. In these conditions, L484 had the highest radiation use efficiency and water use efficiency maintenances. However, despite the advances in cotton breeding in Cameroon, no significant improvement between old cultivars and recently released ones were found on biomass, harvest index and cotton yield across water conditions. The lint percentage was the only yield component significantly enhanced, irrespective of water status.

Back to Content

Sixty Years Of Cotton Breeding In Cameroon: Interaction Between Genetic Improvement And Rainfed Cropping Conditions

Back to Content

Author

ROMAIN LOISON

CIRAD – France

Abstract

Seed cotton (Gossypium  hirsutum L) yield in Northern Cameroon has been declining since the 80s despite breeding efforts. We used a set of widely grown cotton cultivars released at  different dates to study genetic improvement under different cropping conditions in Cameroon, and in controlled conditions. The genetic gain was estimated with a linear regression of the variety mean on its year of release (YR). Contrasts between genetic gains observed with different planting dates were estimated and tested. Our results revealed a genetic improvement on fiber yield of 3.3 kg ha-1 year-1 due to increased ginning out-turn. However, there was no genetic improvement on aerial biomass, harvest index or seed cotton yield. At the early stage of development, aerial and root biomass, and potential root extraction ratio of nutrients decreased with YR. So did leaf number and hairiness at the beginning of flowering. Carbon dioxide assimilation was not affected by YR. Neither were crop cycle duration and phyllochron. Although the potential of almost all fiber technological characteristics was improved under favorable water conditions, some (upper half mean length, short fiber index, uniformity index, and strength) were reduced in water-limited conditions. We concluded that cotton breeding efforts in Cameroon have successfully improved cotton fiber yield and the potential of most fiber technological characteristics. However, in water-limited conditions, fiber quality tended to decrease with the YR. There is still some room for seed cotton yield improvement.

Back to Content