The reason that one is Chayav for stopping the Yenikah of the Atzitz (by blocking the empty space between the hole and the earth) on Shabos is because he has uprooted the plant that is in the Atzitz. If the Atzitz is merely full of soil, without a plant, he is Patur. Similarly, there is no Telishah on the porcelain of the Atzitz itself.

By the way, most Rishonim are of the opinion that the Halachah of Mechusar Ketzitzah is not dependent on what is considered Ketzitzah on Shabbos. Even if one cuts the paper of the Get which is too wide -- and act which is not a Melachah on Shabbos -- there is a problem of Mechusar Ketzizah.

Dov Zupnik

Albert,

Your question nevertheless remains regarding the following case in the Gemara; why does Abaye permit a Get written on a leaf planted in an Atzitz Nakuv, if the husband blocks the Yenikah of the Atzitz before delivering it to his wife? Since he has done a "Telishah" on the leaf before delivering it, it should be considered Mechusar Ketzitzah!

This is a certainly valid question, if the Gemara is indeed discussing a situation where the husband blocks the Yenikah of the Atzitz before giving it to his wife, as Tosfos proves the Gemara indeed means (Tosfos DH Yatza; see Tiferes Yakov though).

Tosfos implies that not every change in the status of the Get is considered Mechusar Ketzitzah. The Ran makes this more clear. He asks your question explicitly, and answers that even though this is considered Telishah on Shabbos, it is not called Mechusar Ketzitzah since no extra action was done between the writing and delivery of the Get. The very act of delivery that is done with a normal Get simply caused, indirectly, the Telishah of the Atzitz. The Torah does not prohibit something that happens by itself during the normal process of delivering the Get; only an extra action before the delivery of the Get disqualifies the Get.

Be well, Mordecai