Semi-minimal-pruned hedge (Smph) as a climate change adaptation strategy: Impact of different yield regulation approaches on vegetative and generative development, maturity progress and grape quality in riesling [* Cross-Reference *]

While saving labor, this training system results in relatively high crop load and a poor leaf area to fruit weight-ratio (LFR), and thus, needs to be able to ripen grapes in a cool to moderate climate. For these reasons the impact of yield regulation strategies, including (i) shoot thinning (Darwin-Rotor), (ii) biotechnological thinning (Gibberellic acid), and (iii) bunch thinning (harvest machine) were trialed in a three year study at Geisenheim, Germany between 2017 and 2019 using Riesling (Vi-tis vinifera L.).

The average yield per vine in SMPH (5.34 ± 1.10 kg) was 61.1% higher with a narrower LFR (14.01 cm2 g−1 ), compared with VSP (3.32 ± 1.02 kg, LFR: 16.99 cm2 g−1 ). The yield was successfully reduced and LFR simultaneously increased with shoot thinning (−33.1%, LFR: 19.04 cm2 g−1 ), biotechnological thinning (−18.3%, LFR: 16.69 cm2 g−1 ) and bunch thinning (−37.3%, LFR: 21.49 cm2 g−1 ). Ripening was delayed in SMPH.