Stem elongation and somatic embryogenesis under red light-emitting diode and subsequent growth of tuberous begonias(Begonia × tuberhybrida Voss) plantlets on medium containing cobaltnanoparticles - Bui Van The Vinh· Hoang Thanh Tung· Le The Bien · Hoang Dac Khai · Nguyen Thi Nhu Mai· Vu Quoc Luan·Do Manh Cuong (2023)