Answer to question regarding benefiting from the fragrance of blossoms of an orlah tree:
The Radbaz (Shu"t 1:44) discusses this topic and rules that, if the tree was not planted for its fruits or if only the blossoms are present and the fruit has not yet grown, the fragrance is permitted (i.e. there is no problem of orlah preventing enjoyment of the ...
Another answer (suggested here in the Sefer "Kerem Efraim") is that because the tree was created through a miracle, it was not obligated in Orlah. He brings support from the Radak (Malachim Beis 100:4) who writes that the oil that was miraculously created for the wife of Ovadia did not require Maaser to be separated from it.
He explains that for the first ...
My understanding is that Chizkuni's focus when bringing neta' reva’i into the discussion is ra'avtanut i.e. voracity or gluttony.
He is saying that a reason behind forbidding eating very immature animals together with or in the presence of their parents (shiluach haken, g'di bachaleiv imo, oto v'et b'no) is to teach us to curb our appetites and make us wait ...
Orlah (fruit from trees planted within 3 years) is forbidden for all benefit, see e.g., Mishne Torah Maachalot Assurot 10:9
Whenever anyone plants a fruit tree, it is forbidden to partake of
or benefit from all of the fruit the tree produces for three years
after being planted
For details see e.g., here from aish. Note this applies both in and ...
There is Orla only for a tree that was planted for eating.
See Rash Orla 1.1
פטור מן הערלה. כדדריש בירושלמי (הלכה א) (ויקרא יט) ונטעתם כל עץ מאכל את שהוא למאכל חייב
So, because roses are generally not cultivated for eating, there is no din Orla and you can smell their perfume.
Ruled in SA YD 294.1
הנוטע עץ מאכל מונה לו ג' שנים מעת נטיעתו וכל הפירות ...
As already stated, this site does not replace a Rabbi. But here are some sources.
The Mishan in Mas. Orla (3:10) says:
ספק העורלה--בארץ ישראל אסור, ובסוריה מותר; ובחוצה לארץ יורד ולוקח, ובלבד שלא יראנו לוקט.
If in doubt, then fruit that could be Orla are forbidden in Eretz Yisrael, but permitted in the Diaspora.
That's also have the Shulchan Aruch ...
After CYLORing this, the answer I got is:
If the tree is planted exclusively for beauty - there is no problem to enjoy from the fruits during first 3 years, and even to eat them.
If the tree is planted also for eating the fruits - it is forbidden to enjoy from the fruits, even from observing (להתבונן) their beauty. However, there is no problem just to look ...
Have there been any (scientific) studies that prove the benefits of Orlah?
Well, as you will see from the answer to your second question, it's not about benefits.
You can see from articles like this one that most fruit trees don't bear (real) fruit for the first 3 - 4 years.
You then asked:
What is the reasoning behind Orlah prohibition?
Rambam Maaser Sheni 9:7 (based on Mishna Maaser Sheni 5:1):
מי שהיה לו נטע רבעי בשנת השמיטה, שיד הכול שווה--צריך לציינו בקוזזות אדמה, כדי שיכירו בו, ולא יאכלו ממנו, עד שיפדו. ואם היה בתוך שני עורלה--מציינין אותו בחרסית, כדי שיפרשו ממנו: שאם ציינו בקוזזות אדמה שמא יתפרדו--שאיסור עורלה חמור הוא, שהיא אסורה בהניה. והצנועין היו מניחין את המעות בשנת השמיטה ...
Shulchan Arukh YD 294:9 (based on Kiddushin 39a) rules that doubtful (safek) Orlah in the Diaspora is permitted; only certain (vadai) Orlah is prohibited. Even if you know the fruit came from a orchard with Orlah trees, if you don't know which tree it came from then it is permitted. So any fruit you find in the grocery which was not imported from Israel and ...
Reminds me of this (Sanhedrin 59b -- summarized and text below):
Rabbi Shimeon ben Chalafta was walking on the road when lions met him and roared at him. Thereupon he quoted from Psalms: “The young lions roar for prey and to beg their food from HASHEM,” and two lumps of flesh descended from heaven. They ate one and left the other. This he brought to the ...
According to this answer, it would seem that this is permitted.
The Radbaz (Shu"t
discusses this topic and rules that, if the tree was not planted for
its fruits or if only the blossoms are present and the fruit has not
yet grown, the fragrance is permitted (i.e. there is no problem of
orlah preventing enjoyment of the fragrance):
Since the majority of produce on the market is not Orlah, we can assume that any given fruit etc. it is permissible, using the halachic principle of rov.
(Regarding Reva'i, I'm pretty sure it doesn't apply in the diaspora. The mishna in Kiddushin only mentions Orlah.)
(I'll try to add an explicit source later).