DUAN Qingqing, ZHANG Zikun, CHANG Peipei, ZHANG Luqi, WANG Jingjing, HE Hongjun
To explore the effect of LED supplementary lighting on mineral nutrients absorption and distribution of greenhouse-grown sweet pepper (Capsium annuum L.), Aodaili was chosen as materials to investigate effects of different LED light quality and durations on accumulation and distribution of N, P, K, Ca, Mg, Mn, Zn in sweet pepper plants. The light emitting diode (LED) as light sources were provided with three light qualities (the ratio of red and blue light 2:1, 2R1B; 4:1, 4R1B and 8:1, 8R1B), and three supplemental light durations (2 h, 18:00 - 20:00; 4h, 18:00 - 22:00; 8h, 18:00 - 02:00), and no supplemental light was taken as control (CK). The results showed that the accumulation and distribution of mineral nutrients in sweet pepper were significantly affected by light quality and light duration and interaction existed between them. Compared with CK, supplementary lighting significantly increased the accumulation of N, P, K, Ca, Mg and Mn in whole sweet pepper plants. No differences were found in the N, P, K, Mg and Mn accumulation among 2R1B, 4R1B and 8R1B treatments in the whole sweet pepper plants. While the light durations affected the accumulation of mineral nutrients significantly, treatment of 8 h showed the highest accumulation in N, P, K, Ca, Mg and Mn which increased by 51.82%, 55.56%, 47.55%, 50.00%, 56.76% and 36.23% compared separately with CK, moreover, there were no significant differences existed in N, Ca, Mn accumulation between treatments of 4 and 8 h. In contrast with CK, sweet pepper treated for 2 h decreased N, P, Mg, Mn distribution ratio in fruits, while that treated for 4 h increased accumulation and distribution of N, P, K, Mg, and Mn in fruits. In conclusion,light quality had little effect on accumulation of the mineral elements in sweet pepper, but supplementary lighting of 4 h was optimal for regulating the accumulation and distribution of mineral nutrients in sweet pepper. These results provide theoretical reference for absorption mechanism of mineral nutrients for greenhouse-grown sweet pepper regulated by LED supplemental lighting.