Studies on low-volume application of plant growth substances; Part 1: Ethylene production,induced by 1-naphthylacetic acid,as a means of evaluating spray parameters

The evolution of ethylene, induced by 1-naphthylacetic acid (NAA), was studied as a means of evaluating spray parameters using cowpea [Vigna sinensis (Torner) Savi] under defined conditions as a test system. The dose-response curve was linear over the range of 1.4-14 μg per leaf. The marked production of ethylene following treatment with an active auxin, 2,4-D (2,4-dichlorophenoxyacetic acid), and the absence of its production following treatment with an inactive analogue (3,5-dichlorophenoxyacetic acid), established that ethylene production was hormonally induced. The effect of application volumes of 10-100 μ1 and of droplet sizes of 1-10 μ1 were evaluated using a constant dose (5 μg NAA per leaf); NAA was more effective when delivered to the leaf in the larger volumes but in the smaller droplet sizes.