Gucci R, Tustin S, Ravaglia G
Dipartimento di Coltivazione e Difesa delle Specie Legnose, Sez. Coltivazioni Arboree, University of Pisa, Pisa, Italy.
Tree Physiol. 1995 Jan;15(1):35-40. doi: 10.1093/treephys/15.1.35.
Net photosynthetic rates (A) of leaves on 11-year-old, field-grown apple trees (Malus domestica Borkh. cv. Golden Delicious) were measured after removal of fruits at four different stages of development. Defruiting decreased A by 21, 42, 27 and 7% when fruits were growing at 311, 293, 229 and 113 mg(DW) day(-1), respectively. Photosynthesis was inhibited more in the afternoon than in the morning, but it was not affected during the first 8 h after fruit removal. Inhibition of A was positively correlated with crop sink strength, but it was not correlated with fruit relative growth rate or crop load. Defruiting decreased A at saturating irradiances (PPFD > 1000 micro mol m(-2) s(-1)), but did not modify the apparent quantum yield of single leaves. These results suggest that the overall effect of defruiting on carbon fixation is negligible in dense canopies, but it may be significant in sparse canopies and in single shoots.
在四个不同发育阶段摘除果实后，测定了11年生田间种植的苹果树（苹果属 金冠品种）叶片的净光合速率（A）。当果实分别以311、293、229和113毫克（干重）·天⁻¹的速度生长时，疏果使净光合速率分别降低了21%、42%、27%和7%。光合作用在下午比上午受到的抑制更大，但在摘除果实后的最初8小时内未受影响。净光合速率的抑制与作物库强呈正相关，但与果实相对生长速率或作物负载量无关。在饱和光照强度下（光合有效辐射>1000微摩尔·米⁻²·秒⁻¹）疏果降低了净光合速率，但并未改变单叶的表观量子产额。这些结果表明，在郁闭树冠中疏果对碳固定的总体影响可忽略不计，但在稀疏树冠和单枝中可能很显著。
