The flowers of cucumber basically belong to dioecious flowers, and there are also complete flowers, female plants and male plants (Figure 4). The pistil of the male flower degenerates, with 5 stamens, 4 of which are paired, 1 solitary. Pollen has a short life span, and loses its activity 4-5 hours after flowering at high temperature, and its activity can be delayed to 48 hours after being applied at low temperature. The female flower has a short style, a trifoliate stigma, a lower ovary and nectaries. Female flowers are fertile from 2 days before flowering to one day after flowering.

Fig. 4 The fruits of female, male and bisexual flowers of cucumber are insect-borne flowers. Female flowers can bear fruit without pollination, that is, they have the characteristics of parthenocarpy, which is beneficial to cultivation in facilities without insect pollination. In order to improve the fruit setting rate and yield, artificial pollination can also be carried out, and the pollination effect is the best after flowering in the morning.

The time, quantity and distribution of male and female flowers of cucumber vary with varieties and environmental conditions. Generally, female flowers appear in early-maturing varieties with more than 3 ~ 4 knots, and in mid-late-maturing varieties with more than 7 ~ 10 knots. Sometimes the female flower can appear in every node, and sometimes it will appear after 2 nodes. When the seedling temperature is low, the node position of the second female flower is also low. The node position of female flowers and the number of individual plants are directly related to the early maturity and high yield of cucumber. When cultivated in winter or early spring, varieties with low node position of female flowers should be selected as far as possible.