Effect of delayed fruit harvest on photosynthesis, transpiration and nutrient remobilization of apple leaves

Abstract

Summary• The aim of the work was to compare autumnal photosynthesis and remobilization processes in apple ( Malus domestica ) trees harvested either at commercial harvest date or 6 wk later (delayed harvest).• Apple leaf photosynthesis, measured by porometry, remained large at 8 -14 µmol CO 2 m − 2 s − 1 and was not limited by stomatal function after the commercial harvest date. The autumnal reduction both in photosynthesis and in vivo RUBISCO activity was less pronounced in apple trees with a delayed harvest. Maximum photochemical efficiency ( F v : F m ) of apple leaves also remained large at 0.80 for 3 wk after the commercial harvest date. The subsequent decreases in both maximum photochemical efficiency ( F v : F m ) and chlorophyll content were delayed by 2 wk in trees harvested 6 wk later.• Long shoot leaves developed red-blue anthocyanin colouration 2 wk after harvest, accompanied by greater leaf carbohydrate content. This was by marked contrast to long shoot leaves of still-fruiting apple trees, which lacked this anthocyanin colouration. Potassium, phosphorus and nitrogen declined more rapidly in the leaves of apple trees harvested at the commercial date, an indication of earlier remobilization.• In conclusion, fruit harvest accelerated leaf senescence, indicated by chlorophyll breakdown and remobilization of nutrients in both spur and long shoot leaves, and, additionally, by commencing anthocyanin synthesis in long shoot leaves.

Coloured hailnets alter light transmission, spectra and phytochrome, as well as vegetative growth, leaf chlorophyll and photosynthesis and reduce flower induction of apple

“…18 lmol CO 2 m -2 s -1 (Fig. 4), because apple leaf photosynthesis was saturated, with respect to light, at 800-1,000 lmol PAR m -2 s -1 (Ebert andCassiera 2000, Tartachnyk andBlanke 2004). Our result resembles those of Widmer (1997), Stampar et al (2002) and Romo-Chacon et al (2007), who obtained no significant differences in photosynthesis on a sunny day in Europe or high light conditions in Mexico, between trees with and without black or white hailnets.…”

Net primary productivity, allocation pattern and carbon use efficiency in an apple orchard assessed by integrating eddy covariance, biometric and continuous soil chamber measurements

“…In a less productive and less vigorous apple genotype, Panzacchi et al (2012) have also found an average NPP value of 785 g C m −2 yr −1 . The presence of a large amount of fruit on an apple tree is known to enhance specific leaf photosynthesis as a consequence of their role as a sink, which allows for a more rapid download of photosynthates from the phloem with respect to apple trees not bearing fruit (Giuliani et al, 1997;Tartachnyk and Blanke, 2004).…”

Potassium: a neglected nutrient in global change

“…Currently available data show the capacity of plants to retain K by resorption. Diverse results have been reported in studies comparing the resorption efficiency (RE) for N, P and K. A number of different REs have been observed by researchers: N = P < K (van den Driessche, 1985;Nieminen & Helmisaari, 1996;Sardans et al, 2005), P < N = K (Ozbucak et al, 2008), N < K = P (Chuyong et al, 2000), N > K > P (Yin et al, 2009), P > K > N ( Salehi et al, 2013), K <N = P (Helmisaari, 1992;Duchesne et al, 2001;Tartachnyk & Blanke, 2004;Hagen-Thorn et al, 2006) and N = P = K (Gallardo et al, 1999;Trémolières et al, 1999). A recent review of a global dataset has observed that the RE for K on a global scale (70.1%) seems to be higher than the RE for N (62.1%) and P (64.9%) (Vergutz et al, 2012), although most of the studies reviewed by these authors did not take into account the role of leaf leaching when calculating RE.…”