This experiment aimed to investigate the status of tomato plants in terms of sink or source-limitation of 2 cultivars of greenhouse tomato (Solanum lycopersicum L.), i.e., ‘Grandella’ and ‘Isabella’ under the greenhouse conditions of Iran and to improve the yield and plant growth by manipulating the sink-source balance. To this end, 4 treatments were applied: leaves were not pruned and fruits were pruned to one per truss (1F/3L), leaves were not pruned and fruits were pruned to two per truss (2F/3L), leaves were not pruned and fruits were pruned to three per truss (3F/3L) and no leaf and fruit pruning (control). The results showed that truss pruning reduced the sink demand and consequently, increased the amount of available assimilate for the growth of the remaining fruits or vegetative parts. The negative correlation between the leaf area index and the net assimilation rate and no significant difference in the net assimilation rate between different sink/source ratios showed that the excess leaf area index does not contribute in increasing the assimilate production and hence, total yield. Total fruit weight, harvest index, and the ratio of the ripe fruits to the total fruit led to the highest yield for control plants. No changes in chlorophyll, protein content and nitrate reductase activity were the evidence for the fact that sink/source ratio do not affect light-harvesting and light-utilizing components of photosynthesis. Since the individual weight of fruits increased with decreasing fruit number per trusses, the growth of individual fruits in both cultivars was source-limited and truss pruning can decrease this limitation. Future studies should be carried out to determine the best level of sink/source ratio that in addition to producing an acceptable amount of yield, meets the needs of consumers in the current stressful world by increasing the antioxidant and nutriceutical content of fruits.

该实验的目的是调查的番茄植物在水槽或2个品种温室番茄的源极-限制方面的状态（番茄大号。），即'Grandella' 和 'Isabella' 在伊朗温室条件下，并通过操纵汇源平衡来提高产量和植物生长。为此，进行了 4 次处理：不修剪叶子，将果实修剪为每个桁架一个（1F/3L），不修剪叶子，将果实修剪为每个桁架 2 个（2F/3L），不修剪叶子和水果被修剪成每个桁架三个（3F/3L）并且没有叶子和水果修剪（对照）。结果表明，桁架修剪减少了汇需求，因此增加了剩余水果或营养部分生长的可用同化物量。叶面积指数与净同化率呈负相关，不同汇源比之间的净同化率无显着差异，表明过量叶面积指数无助于增加同化物产量和总产量。总果实重量、收获指数以及成熟果实与总果实的比率导致对照植物的最高产量。叶绿素、蛋白质含量和硝酸还原酶活性没有变化是汇源比不影响光合作用的光收集和光利用成分这一事实的证据。由于果实的个体重量随着每个桁架果实数量的减少而增加，因此两个品种中个体果实的生长都是受源限制的，桁架修剪可以减少这种限制。