Determinants of Shoot Biomass Production in Mulberry: Combined Selection with Leaf Morphological and Physiological Traits.

Xu Cao,Jialing Cheng,Qiudi Shen,Li Liu,Chunqiong Shang,Honglei Yang

doi:10.3390/plants8050118

Abstract

Physiological and morphological traits have a considerable impact on the biomass production of fast-growing trees. To compare cultivar difference in shoot biomass and investigate its relationships with leaf functional traits in mulberry, agronomic traits and 20 physiological and morphological attributes of 3-year-old mulberry trees from eight cultivars growing in a common garden were analyzed. The cultivars Xiang7920, Yu711, and Yunsang2 had higher shoot fresh biomass (SFB), which was closely associated with their rapid leaf expansion rate, large leaf area, and high stable carbon isotope composition (δ13C). Conversely, the cultivars 7307, Husang32, Wupu, Yunguo1, and Liaolu11 were less productive, and this was primarily the result of slower leaf expansion and smaller leaf size. Growth performance was negatively correlated with leaf δ13C and positively correlated with the total nitrogen concentration, indicating that a compromise exists in mulberry between water use efficiency (WUE) (low δ13C) and high nitrogen consumption for rapid growth. Several morphological traits, including the maximum leaf area (LAmax), leaf width and length, petiole width and length, leaf number per shoot, and final shoot height were correlated with SFB. The physiological traits that were also influential factors of shoot biomass were the leaf δ13C, the total nitrogen concentration, and the water content. Among the studied leaf traits, LAmax, leaf δ13C, and concentrations of chlorophyll a and b were identified as the most representative predictor variables for SFB, accounting for 73% of the variability in SFB. In conclusion, a combination of LAmax, leaf δ13C, and chlorophyll should be considered in selection programs for high-yield mulberry cultivars.

Highlights

Fast-growing tree species are arguably the most important feedstock for biomass energy generation.In woody biomass production, most of the attention has been paid to poplar (Populus), willow (Salix), Eucalyptus, and pine (Pinus) [1]
Significant differences were detected among the tested mulberry cultivars in shoot fresh biomass (SFB), leaf fresh biomass of growing shoots, leaf number kilogram, total fresh shootbiomass length, Significant differences were detected among the tested mulberryper cultivars in shoot shoot number per tree, and average shoot length
The spring shoot biomass of mulberry plantations is important for the sericulture industry because there is a huge demand for mulberry leaves for raising silkworm in spring [26]

Summary

Introduction

Fast-growing tree species are arguably the most important feedstock for biomass energy generation. Most of the attention has been paid to poplar (Populus), willow (Salix), Eucalyptus, and pine (Pinus) [1]. With the increased demand for energy and the fast-changing global climate, there is an urgent need to identify new candidate fast-growing woody trees that can produce satisfactory biomass under unfavorable climatic and soil conditions [2]. Morus species are traditionally best known for their predominant role in rearing silkworm (Bombyx mori L.) in the sericulture industry. Mulberry trees have been cultivated perennially in a wide geographical range, from temperate to tropical areas, and their abundance is ascribed to their high adaptability to various agroclimatic conditions [3].

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