Mulching affects photosynthetic and chlorophyll a fluorescence characteristics during stage III of peach fruit growth on the rain-fed semiarid Loess Plateau of China

• Soil water content was influenced through mulching treatments in a semiarid peach orchard.
• Both mulching treatments increased the net photosynthetic rate compared to the clean tillage method.
• The performance index (PI) of the photosystem was improved by mulched treatments.
• Fruit yields were increased in mulched treatments.

In this study, we compared the soil water content of plastic film mulched ridge with furrows (PFM) and straw mulched (SM) and unmulched (clean tillage, CT) peach (Prunus persica L.) orchard soil on the rain-fed semiarid Loess Plateau of China during the final stage of rapid fruit growth (stage III) in 2011 and 2012. Analyses were focused on measurements of fast chlorophyll a fluorescence (ChlF), photosynthetic performance, fruit yield and quality. Compared with the CT water management method, PFM and SM significantly increased the soil water content (P < 0.05) by 14.5% and 19.5% in stage III, respectively. Both mulching methods increased the fruit yield (∼28%) with no change in fruit quality compared to the CT method. This result was supported by the analysis of the daily average photosynthetic rate (PN) showed that PN was improved from 11.4 (CT) to 13.1 (PFM) and 12.2 μmol m−2 s−1 (SM); these daily average photosynthetic rates were confirmed by the response curve analysis. Furthermore, the ChlF analyses uncovered major functional differences between the mulched and unmulched leaves at midday: lower connectivity among the photosystem II decreased the number of electron carriers and facilitated the dissipation of excess excitation energy to minimize the potential damage caused by CT drought stress. Nevertheless, the structural integrity and stability of PSII were largely maintained, as reflected by the recovering of the photosynthetic activity after mid-day.