Managing orchard floor for saving water in a late ripening peach cultivar: a preliminary result

Low humidity conditions occurring in Southern Italy till late summer allow the cultivation of late ripening peach cultivars. However, they are highly water demanding thus the increase of water use efficiency not affecting fruit production and quality is crucial. Four different agronomic managements were evaluated on ‘Redcall’ peach: completely tilled (T), mulched with a plastic film reducing soil evaporation and increasing diffuse light (M), mulching with a Leguminosae cover crop flattened after peach fruit set (F), tilled plot supplying the same volume of M that was supposed to be lower than T (S). Water was supplied till the field capacity when soil humidity reached the threshold of the readily available water. During fruit cell expansion S had leaf net photosynthesis (Pn), stomatal conductance (gs), transpiration (Tr) as well as stem water potential (Ψs) lower than T. Interestingly M and F showed the same low Ψs of S at 120 and 135 DAFB, respectively even if their Pn, gs and Tr were higher than S and comparable with T. Under water stress this peach cultivar behaved in a “conservative” way maintaining its Ψs above a safe threshold against embolism through stomata closure, thus reducing Pn. Few days before the harvest F drastically reduced gas exchanges, fruit growth, Ψs and soil water content albeit it received the same water volume of T. The increase of soil evaporation would be attributable to the disruption of the flattened crop as well as to the onset of soil cracking. Fruit production and size were affected by water stress in S and F, while M showed the highest productivity supplying 43% less water. The “conservative” behaviour of peach suggested that in certain conditions Ψs could not represent the real plant water status. Mulching with plastic film could be a promising practice in semi-arid conditions while the flattening practice should be refined since leaf functionality and fruit growth started to decrease only 15 days before the harvest.