Spray application of Calcium salts: An effective means to improve cracking susceptibility in sweet cherry?

雨裂限制了世界范围内甜樱桃的生产。开裂被认为是由于水果吸收的水分增加导致果皮破裂。因此，开裂取决于两组独立的因素：（1）果皮和花梗的水分运输特性和（2）果皮的机械构造。钙盐的应用（高架喷头，喷雾应用和浸泡试验）对甜樱桃果实的开裂敏感性的影响在过去已经进行了研究。然而，所获得的效果是不一致的。在一些研究中，钙的应用显着减少开裂，在其他钙没有影响。不幸的是，水果的钙含量很少被研究，因此不知道缺乏性能是否仅仅与缺乏通过皮肤的钙吸收有关。通过花梗的吸收在许多水果作物的成熟果实中通常是低的，我们期望甜樱桃也是如此。由于通过角质层的钙阳离子的吸收是低的和高度可变的，缺乏吸收确实是一个可能的解释。然而，目前还没有关于甜樱桃果实钙吸收的研究。本研究的目的是：（1）定量研究果实发育过程中花梗对Ca的吸收、蒸腾作用对Ca吸收的影响以及Ca在果实中的分布;（2）通过对果实表皮节段的双向拉伸试验、组织柱的花色素苷渗漏试验和离体细胞壁的溶胀试验，（3）研究Ca透过果实表皮的渗透性;（4）确定多次施用Ca盐对果实内Ca含量和分布以及裂果敏感性的影响。

Rain-cracking limits the production of sweet cherries world wide. Cracking is thought to result from increased water uptake into the fruit that causes the fruit skin to rupture. Thus, cracking depends on two independent groups of factors: (1) water transport characteristics of skin and pedicel and (2) the mechanical constitution of the fruit skin. The effect of applications of Ca salts (overhead sprinkler, spray application and immersion assays) on cracking susceptibility of sweet cherry fruit has been investigated in the past. The effects obtained, however, were inconsistent. In some studies, Ca applications markedly reduced cracking, in others Ca had no effect. Unfortunately, the Ca-content of the fruit has rarely been investigated and therefore it is not known whether the lack of performance was simply related to a lack of Ca uptake through the skin. Uptake through the pedicel is often low in maturing fruit of many fruit crops and we would expect the same for sweet cherry. Because uptake of the Ca cation through the cuticle is low and highly variable, the lack of uptake is indeed a likely explanation. However, there are no studies on Ca uptake into sweet cherry fruit. The objectives of the present study are to (1) quantify Ca uptake via the pedicel, the effect of fruit transpiration thereon and the Ca distribution within the fruit in the course of development, (2) to determine the effect of Ca on the mechanical properties using biaxial tensile tests of segments of the fruit skin, anthocyanin leakage of tissue cylinders and swelling assays of isolated cell walls, (3) to study Ca penetration through the fruit skin and (4) to establish the effects of multiple applications of Ca salts on the Ca-content and distribution within the fruit and the cracking susceptibility.