Promoting Stenospermic Grape Seed Trace Development and Germination with Plant Growth Regulators

Abstract

Plant growth regulators (PGRs) [antigibberellins (mepiquat chloride, uniconazole, ancymidol, daminozide, chlormequat, ethephon, methazole), cytokinins (BAP, kinetin, BTP, 2iP), and ABA] were evaluated at various concentrations and timings for promotion of seed trace development and germination of four stenospermic grape cultivars (Vitis spp.): `Venus', `Mars', `Reliance', and `Saturn'. Data include seed trace number per berry, percent of seed traces with endosperm (sinkers), sinker fresh weight, and percent seed trace germination. Several PGRs effectively increased seed number and percent sinkers over control treatments. PGRs had little effect on seed fresh weight and percent germination. PGRs promoted greater increases in percent sinkers than seed number on all cultivars. The number of viable seeds per sample (seed number × percent sinkers) was increased over controls by up to 802% on `Reliance', 239% on `Saturn', 154% on `Mars', and 153% on `Venus'. A moderate percentage of viable seeds from treatments and controls of `Mars', `Venus', and `Saturn' germinated and established normal seedlings. The very small seed traces of `Reliance' did not germinate from either controls or treatments. The results indicate that PGRs can stimulate seed trace formation in some stenospermic cultivars and therefore may be useful tools in grape breeding programs. Chemical names used: abscisic acid (+/-)cis-trans isomer (ABA); a-cyclopropyl-a-(4-methoxy-phenyl)-5-pyrimidinemethanol (ancymidol); 6-benzylaminopurine (BAP); 6-benzylamino-9-(2 tetra-hydropropanyl)-9H-purine (BTP); (2-chloroethyl) trimethyl-ammonium chloride (chlormequat); succinic acid 2,2 dimethyl-hydrazide (daminozide); (2-chloroethyl) phosphonic acid (ethephon); 6-(dimethyl-allylamino) purine (2iP); 6-furfurylaminopurine (kinetin); N,N-dimethyl-piperidinium chloride (mepiquat chloride); [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione] (methazole); E-1-(4-chlorophenyl)-4,4-di-methyl-2-(1,2,4-triazol-1-yl)-1-pentan-3-ol (uniconazole).