Palmer J W, Giuliani R, Adams H M
HortResearch, Nelson Research Centre, P.O. Box 220, Motueka, New Zealand.
Tree Physiol. 1997 Nov;17(11):741-6. doi: 10.1093/treephys/17.11.741.
Four-year-old apple (Malus x domestica Borkh.) trees cv. 'Braeburn' on M.26 rootstock were thinned at full bloom to establish six crop loads ranging from a heavy crop to a deflowered treatment. At harvest, mean yield per tree varied from 0 to 38 kg and mean fruit weight ranged from 225 g in the heaviest cropping treatment to 385 g in the lightest cropping treatment. Light cropping resulted in a significant advance in fruit maturity as indicated by background color, starch/iodine score and soluble solids. There were small differences in leaf photosynthetic rate among the treatments when shoot growth was active. However, in early January, coincident with cessation of shoot growth and maximum rate of accumulation of fruit weight, leaf assimilation rate was reduced by as much as 65% on the deflowered trees compared to the trees carrying the heaviest crop. Leaf assimilation rate showed a curvilinear response to crop load at this time, with little increase in leaf assimilation when crop load exceeded 12 fruit m(-2) leaf area.
以M.26为砧木的4年生‘布瑞本’苹果（Malus x domestica Borkh.）树在盛花期进行疏花，以建立从重度负载到疏花处理的6种负载量。收获时，单株平均产量从0到38千克不等，平均单果重从最重负载处理的225克到最轻负载处理的385克。如底色、淀粉/碘评分和可溶性固形物所示，轻负载导致果实成熟显著提前。在新梢生长活跃时，各处理间叶片光合速率差异较小。然而，在1月初，与新梢生长停止和果实重量积累速率最大时一致，与负载最重的树相比，疏花树的叶片同化率降低了多达65%。此时，叶片同化率对负载量呈曲线响应，当负载量超过12个果实/平方米叶面积时，叶片同化率几乎没有增加。
