Jiawen Guo

Growth and metal uptake of energy sugarcane (Saccharum spp.) in different metal mine tailings with soil amendments.

A pot experiment was conducted to investigate the feasibility of growing energy sugarcane (Saccharum spp.) in three different metal mine tailings (Cu, Sn and Pb/Zn tailings) amended with uncontaminated soil at different mixing ratios. The results indicated that sugarcane was highly tolerant to tailing environments. Amendments of 20% soil to Sn tailings and 30% soil to Cu tailings could increase the biomass of cane-stem for use as the raw material for bioethanol production. Heavy metals were mostly retained in roots, which indicated that sugarcane was useful for the stabilization of the tailings. Bagasse and juice, as the most valuable parts to produce bioethanol, only accounted for 0.6%-3% and 0.6%-7% of the total metal content. Our study supported the potential use of sugarcane for tailing phytostabilization and bioenergy production.

Relationship between endogenous ethylene production and natural defoliation traits during the maturation of sugarcane

The relationship between endogenous ethylene production and natural defoliation rate was examined in sugarcane cultivars with different natural defoliation traits. Ethylene production was examined at different positions on leaf sheaths and leaf scars at various sugarcane maturation stages using gas chromatography as an external standard method. During the sugarcane maturation process, ethylene production was greatest in the 2nd leaf sheath scar, followed by the 5th and 10th, in that order. It was also greatest during the early maturation stage, followed by the mid-maturation and harvest stages. Ethylene production of the leaf sheaths and leaf scars differed significantly among the sugarcane cultivars. Cultivars that defoliate easily produced significantly more ethylene than those that do not defoliate easily. The natural defoliation rates was greatest in the harvest stage, followed by mid-maturation and early maturation stage. Correlation analysis indicated that ethylene production was positively correlated with natural defoliation rates, particularly during early- and mid-maturation stages.

Differential Analysis of Endogenous Hormone Levels and Natural Defoliation Traits During Sugarcane (Saccharum spp.) Maturation

The relationship between natural defoliation rate and endogenous ethylene, indole-3-acetic acid (IAA), and abscisic acid (ABA) levels in four sugarcane cultivars possessing different defoliation traits was investigated. Leaf sheath, leaf scar, and leaf blade samples were collected from the 10th leaf position below the fully expanded leaves during sugarcane maturation stage. Ethylene, IAA, and ABA levels were measured using gas chromatograph, liquid chromatograph, and external standard methods. The results showed that during sugarcane maturation, the highest natural defoliation rate was observed in CYZ03-194, followed by CYZ01-1413, CMT02-467, and CYA99-91. Ethylene production and IAA levels in the leaf scars, leaf sheaths, and leaf blades were the highest during the early-to-mid-maturation stage and decreased afterwards. The ABA levels showed a mono-peak curve change and peaked at the late-to-mid-maturation stage. Ethylene production in leaf scars during the early-to-mid- and mid-maturation stages as well as ABA levels in leaf scars at the late-to-mid-maturation stage significantly differed among the cultivars, with the highest levels in CYZ03-194, followed by CYZ01-1413, CMT02-467, and CYA99-91. On the other hand, the IAA levels in leaf scars and leaf sheaths at the early-to-mid-maturation stage were highest in CYA99-91, followed by CMT02-467, CYZ01-1413, and CYZ03-194. Correlation analysis demonstrated a positive correlation between the natural defoliation rate and ethylene production, ABA level, ethylene/IAA ratios, and ABA/IAA ratios, whereas a negative correlation was observed with IAA level during the early-to-mid- and mid-maturation stages.