Lack of undergraduate research experience and impact on PhD applications I am currently a second year (final semester) undergraduate enrolled in Nagoya University's G30 program. After I graduate, I intend pursue a PhD in the chemical sciences, and I am looking to apply to universities in the United States and the UK. So far, I have been doing well academically--I'm at the top of my class and have cumulative GPA of 4.08/4.3. 

Unfortunately, till date I haven't been able to secure any research experience whatsoever in my university, and not for lack of trying. I have approached research groups in my departments whose work I found interesting, but have been turned down by all of them. The rules prevent them from taking on undergraduates students who are not in their 4th year, and they have stuck by them adamantly. 

I do get to work on a research project in my fourth year as part of my graduation requirement, however, I do find it disheartening that I can't start early. 

Regardless, I am still approaching people, looking for a break and also looking into other avenues outside of university. 

However, what if nothing works out--would one year of research experience be sufficient? Personally, I don't think it is enough to prepare me well for graduate school. Moreover, I am concerned about how an admissions committee will view this lack of of research experience? 

Additionally, in the UK, most universities that I am interested in encourage applicants to get in touch with faculty/potential advisors before the make a formal application. By my estimate, I ought to be doing this sometime during my third (early 6th semester) year, and thus would have had probably little to no experience conducting research in a laboratory. How can I overcome this potential handicap, and get them to take me seriously?
Keep going at it!

If local colleagues only take students from 4th year onwards, there must be good reasons - like fairness, openness, transparency, risk assessment... Look forward to your 4th year and beyond :)

Also, how typical is your 'lack of experience'? If all students of your 'class' share this, you will not stand out negatively, and PhD recruiters will expect you by default to have limited experience. Then of course if you manage to acquire relevant experience, that will make you stand out from the crowd.

Your question 'what if not...?' seems to go far beyond your original point and your main ambition. 

Take it as a game and keep the flame alive. Keep looking for opportunities, and you are bound to find one that will fit your circumstances.

Another way to go at it could be to approach higher education institutions where you would be interested in applying, and ask them what their expectations are in terms of lab work experience.

This way you will have a clear vision of the standard you have to meet to have a good chance of being offered a place, and potentially a scholarship. 
You will not have to second-guess what they want any more, and you can focus on achieving what they look for, and more.