question_answer 36)

  Enlist the steps of controlled cross-pollination. Would emasculation be needed in a cucurbit plant? Give reasons for your answer.

Answer:

                    Steps of controlled cross-pollination are (i) Selection of parents with desired characters. (ii) Emasculation, i.e., if the female parent bears bisexual flowers, before dehiscence anther should be removed by forceps. (iii) Bagging, i.e., emasculated flowers have to be covered with a bag of suitable size, generally made up of butter paper, to prevent contamination of its stigma with unwanted pollen. (iv) When the stigma of bagged flower attains receptivity, mature pollen grains collected from anthers of the male parent are dusted on the stigma (v) The flowers are retagged and the fruits are allowed to develop. Emasculation is not always needed in a cucurbit plant. Emasculation is essential only incase of bisexual flowers to prevent self-pollination. In case of cucurbit plant, female parent produces usually unisexual flowers but may sometimes have bisexual flowers. Note If the female parent produces unisexual flowers, there is no need for emasculation. The female flower buds are bagged before the flowers open. When the stigma becomes receptive, pollination is carried out using the desired pollen and the flower rebagged.