Effect of soil water content threshold on kiwifruit quality at different growth stages with drip irrigation in the humid area of Southern China

Fruit quality as affected by soil water content threshold levels (SWCT) at different growth stages remains largely elusive. Therefore, a drip irrigation experiment was conducted to investigate the effect of SWCT on kiwifruit quality at bud burst to leafing stage (stage I), flowering to fruit set stage (stage II), fruit growth stage (stage III) and fruit maturation stage (stage IV) during 2018 and 2019 in the humid area of southern China, respectively. The results showed that SWCT at stage I mainly affected fruit weight (Fw). I-55% treatment significantly elevated Fw by 11.6%-8.0% (P < 0.05). SWCT at stage II had little effect on fruit quality. SWCT at stage III influenced fruit volume (Fv) and chemical quality. Specifically, Fv was increased by 8.0%-2.2% under III-75% treatment, total soluble solids (TSS), soluble sugar (SS) and solids-acid ratio (SOAR) were increased by 9.4%-10.0% (P < 0.05), 2.4%-5.8% and 7.9%-10.6% (P < 0.05) under III-65% treatment, respectively. SWCT at stage IV impacted fruit firmness (Fn) and chemical quality. IV-60% treatment increased Fn, TSS, SS, VC and SOAR by 5.6%-10.5%, 12.0%-12.6% (P < 0.05), 6.6%-9.1% (P < 0.05), 2.1%-14.0% (P < 0.05), and 8.1%-8.3% (P < 0.05), respec-tively, which was beneficial to the improvement of nutritional value and taste, and also the storage and trans-portation of kiwifruit. Collectively, SWCT of 55% FC (field capacity) at stage I or 65% FC at stage III or 60% FC at stage IV was an effective measure to improve the kiwifruit quality.

Automated summary

The study investigates the effect of soil water content threshold levels on kiwifruit quality at different growth stages. The results suggest that specific threshold levels of soil water content significantly impact fruit weight, volume, and chemical quality. In particular, certain threshold levels enhance the nutritional value, taste, and storage capability of kiwifruits.