**7. Conclusion**

Prunus

**74**

of 4–12°C.

**Figure 11.**

**Figure 10.**

factors can influence the date of flowering.

this parameter such as the genetic potential and self-fertility of the cultivar. The difference in yield between cultivars and sites can be explained by several factors including the behavior of the flower pieces depending on environmental conditions. The duration of the stigma's viability is influenced by weather factors. Regarding sour cherries, Nyeki [34] observed that the viability of the stigma was 2–3 days during sunny and hot days (mean daily temperature is 15–22°C). The viability was longer (4–6 days) in cool weather and daily temperatures

*Yield (Kg/tree; Rdt) and Maximum temperature during blooming at BouSalem site.*

*Yield (Kg / tree; Rdt) and Maximum temperature during blooming at Tibar site.*

Low temperatures and rainy weather reduce the receptivity of the stigma. This was reported by Davarynejad [39] for apples and, in 1996, for pear trees. Although temperature is the main driver of phenological development, other ecogeographic

Thus, the cold temperature during blooming reduces the rate of growth of the pollen tube and can shorten the effective pollination period [40]. Caprio and Quamme [41] have shown a negative effect of high temperatures before blooming

Sweet cherry is sensitive to temperature profiles during the blooming period. The low productivity is largely due to the nonoverlap of flowering periods and pollen incompatibility among different cultivars in the same experimental site. Our study is based on a mixture of introduced and local cultivars with different characteristics to diversify Tunisian orchards. While, the introduction of foreigner sweet cherry cultivars in areas with mild winters leads to increased yields.
