已知正项等比数列\(\{a_{n}\}\)满足\(a_{7}=a_{6}+2a_{5}.\)若存在两项\(a_{m}\)，\(a_{n}\)使得\( \sqrt {a_{m}a_{n}}=4a_{1}\)，则\( \dfrac {1}{m}+ \dfrac {9}{n}\)的最小值为\((\)　　\()\)