Premature fruit drop in orange and pear is prevented by . . . . . . .

Auxins are abundantly produced in

$A$: $2, 4-D$ is widely used by farmers in agricultural and horticultural practices.
$R$: Flowering in most plants can be initiated by using high concentration of Auxin.

The pineapple,which under natural conditions is difficult to blossom,has been made to produce fruits throughout the year by the application of:

$A$ substance which accelerates the growth in stem is

In parthenocarpic fruits,the enlargement of the ovary into a fruit is brought about by the auxin . . . . . . .