Effect of light and gibberellic acid on coleoptile and first-foliage-leaf growth in durum wheat (Triticum durum Desf.).

A comparison has been made of the relative effectiveness of light quality and quantity and gibberellic acid (GA3) treatment on the elongation growth of the coleoptile and the first foliage leaf in durum wheat (Triticum durum Desf. cvs. Cappelli and Creso). The cultivar Creso is a shortstrawed variety carrying the Gai 1 gene on chromosome 4A, which influences both plant height and insensitivity to applied gibberellins. The main conclusions are as follows: 1) coleoptile elongation growth appears to be modulated via the fluencerate-dependent action of a blue-light receptor and via a low energy response of phytochrome; 2) the inhibition of first-foliage-leaf growth depends on the operation of a single blue-light-responsive photoreceptor; 3) high energy blue light produces the same inhibitory effect on the two wheat cultivars, whereas at relatively low fluences of white and blue light, the cultivar Creso is more sensitive; 4) the insensitivity to applied GA3 exerted by the gene Gai 1 in Creso is independent of light; 5) in Cappelli, the action of light on coleoptiles appears to be independent of the applied GA3, whereas the hormone is able to change the pattern of growth inhibition of the first-foliage-leaf.