Yes, this matter has been narrated in Hadith that by joining two branches together the tree fetches more fruit. So, according to this Hadith, if anyone crosses male and female trees together to get more and better production then it is neither unlawful nor an intervention in the law of nature. It is lawful to consume such food and production.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband