Photosynthetic characteristics of the subtending leaf of cotton boll at different fruiting branch nodes and their relationships with lint yield and fiber quality.

Jingran Liu,Binglin Chen,Zhiguo Zhou,Fengjuan Lv,Lei Zhang,Yina Ma,Youhua Wang,Yali Meng,Ji Chen

doi:10.3389/fpls.2015.00747

Abstract

To investigate photosynthetic characteristics of the subtending leaf at the 2–3rd and 10–11th fruiting branch (FBN, FB2–3, and FB10–11), and their relationship with cotton yield and quality, field experiments were conducted using two cotton cultivars, Kemian 1 and Sumian 15. The results showed that with FBN increasing, chlorophyll (Chl) components, Pn and non-photochemical quenching (NPQ) in the subtending leaf significantly declined, while soluble sugar, amino acid and their ratio (CSS/CAA) as well as Fv/Fm increased. These results indicated that (1) non-radiative dissipation of excess light energy at FB2–3 was reduced to improve solar energy utilization efficiency to compensate for lower Pn, (2) higher NPQ at FB10−11 played a role in leaf photo-damage avoidance, (3) boll weight was related to the CSS/CAA ratio rather than carbohydrates content alone, (4) with FBN increasing, lint biomass and lint/seed ratio increased significantly, but lint yield decreased due to lower relative amount of bolls, and (5) the decreases in Pn, sucrose content and CSS/CAA in the subtending leaf at FB2–3 resulted in lower boll weight and fiber strength.

Highlights

Photosynthesis is an integrated and regulated process highly sensitive to any change in environmental conditions, because it needs to balance the light energy absorbed by the photosystems with the energy consumed by the metabolic sinks of a plant (Ensminger et al, 2006)
Source (Subtending Leaf) Strength of Cotton Plants at Different Fruiting Branch Nodes (FBN) Photosynthetic Pigments in the Subtending Leaf The contents of Chl a, Chl b and Chl(a+b) of the two cultivars decreased significantly from 17 days post-anthesis (DPA) to boll opening during the 3 years, and decreased with fruiting branch nodes (FBN) increasing (Figure 2). Compared with those at the 2–3rd fruiting branches (FB2–3), the Chl a and b contents at the 10–11th fruiting branches (FB10–11) increased by 9.7–12.9% and 15.5–21.5% for Kemian 1 and by 6.4–32.4% and 14.4–40.5% for Sumian 15, respectively
The contents of Chl a, Chl b and Chl(a+b) as well as the Chl a/b ratio in the subtending leaf were higher at FB2–3 than at FB10–11, suggesting that light absorption was increased and the light energy utilization was improved in the subtending leaf at FB2–3, which was consistent with the findings of previous studies performed under shading (Sarijeva et al, 2007). φPS actual PS II efficiency (II) as the non-cyclic electron transfer efficiency or light energy capture efficiency, could reflect the actual primary light energy conversion efficiency of the PS II reaction center (Li et al, 2010)

Summary

Introduction

Photosynthesis is an integrated and regulated process highly sensitive to any change in environmental conditions, because it needs to balance the light energy absorbed by the photosystems with the energy consumed by the metabolic sinks of a plant (Ensminger et al, 2006). Environmental stresses decrease the performance of the photosystem (PS), especially that of PS II; Chl fluorescence is considered a valuable tool to detect the influence of stress factors on plant photosynthesis (Singh et al, 2013). Photosynthesis, cotton yield and quality light energy that exceeds the photochemical processes of CO2 fixation can be either dissipated as heat or re-emitted as Chl fluorescence (Maxwell and Johnson, 2000). Previous studies have shown that higher NPQ in the leaves resulted in a stronger deep-oxidation of the large xanthophyll cycle pool (DemmigAdams and Adams, 1996; Anderson, 1999), and could act as a major defense mechanism to reduce the formation of reactive oxygen species in PS II, and subsequently to avoid or mitigate photo-damage to leaves (Liu et al, 2001; Zhao et al, 2007)

Methods

Results

Discussion

Conclusion