Responses of some Moroccan watermelon (Citrullus lanatus) landraces to water stress compared with commercial hybrids

The effect of water stress on 9 watermelon genotypes among which five Moroccan landraces and four commercial varieties. Two irrigation levels were imposed to determine variability on drought tolerance of cultivars. T1 treatment (Well irrigated) received full irrigation which plants received sufficient water to maintain soil water content close to pot capacity, while T2 (limited irrigated) treatment received 50 % of T1. The drought tolerance was estimated by the ratio of the value of a trait under the T1 irrigation level and the value of this trait under the T2 irrigation level. Generally, all traits were affected by water stress and the percentage of reduction was highly variable for all characters. The analysis of variance revealed that genotypic differences were highly significant for all parameters. Genotypes-trials interactions were also highly significant for all characters except for Brix. Moderate to high values of broad-sense heritability were observed for all characters except for rind thickness. The values of heritability in limited watered where lower to those obtained in well‐watered conditions and the Brix had the highest heritability in T1 and T2. Under water stress, the average heritability vary between 0.32 and 0.65 obtained respectively for RT and Brix. In well‐watered conditions, it vary between 0.26 (RT) and 0.81 (Brix). The results also show that only local cultivars have maintained their stable potential while modern varieties were affected by water stress. The results from this study can therefore serve as an initial step to plan the conservation of local watermelon genotypes in Morocco.