Residual effects of chloride-containing fertilizers on kiwifruit yield and quality

Objectives Kiwifruit ( Actinidia deliciosa ) is a chlorine-preferring plant, and appropriate amount of chloride-containing fertilizer can increase the yield of kiwifruit. Thus, we studied the effect of Cl^–-containing fertilizer on kiwifruit to understand best application rate of Cl^–-containing fertilizer on the yield of kiwifruit, to provide scientific basis for the rational application of chloride-containing fertilizers in kiwifruit orchard.

Methods We applied Cl^– containing fertilizers to kiwifruit orchard for three consecutive years (2014– 2017). The five application levels of chlorine were: 0 kg/hm² (Cl-0), 170 kg/hm² (Cl-170), 340 kg/hm² (Cl-340), 910 kg/hm² (Cl-910) and 1480 kg/hm² (Cl-1480). The fruit yield, quality and soil Cl^– content in 0–300 cm soil depth were monitored in 2017 and two years after cessation of Cl^–-containing fertilizer application (2018–2019).

Results In 2019, Cl-170, Cl-340, and Cl-910 treatments increased fruit yield by 7.5%, 11.9% and 18.0%, respectively, while the fruit yield in Cl-1480 was similar to that in Cl-0. The Cl^–contents in shoots, leaves and fruits in Cl-170, Cl-340 and Cl-910 were similar to that in Cl-0. The Cl^– contents in fruits and branches in Cl-1480 were significantly higher than those in Cl-0. The Cl^– accumulated in 100–300 cm soil depth, regardless of application levels of Cl^–containing fertilizer and application years. Complete leaching of Cl^– in the soil was detected at two years after cessation of Cl^–-containing fertilizer application.

Conclusions We found Cl-170 was the best chloride-containing fertilizers (170 kg/hm²) that improved the yield and quality of kiwifruit, with relatively low accumulation of chloride ion in soil and plant. Higher rates of chloride-containing fertilizers (Cl 910 and 1480 kg/hm²) resulted in decrease in yield and fruit Vc content, but these adverse effects disappeared immediately after the cessation of fertilizer application. Moreover, the residual effect of chloride-containing fertilizers is good for fruit yield. Thus, application of 170 kg/hm² chloride-containing fertilizers is recommended in kiwifruit orchard.