1. Remobilization of the carbohydrates across parts of the wheat internode to the grain yield during the grain filling of dry land in China
XP DENG1, W CHEN13, GX LI1, AE ENEJI12 JJ ZHANG3
Fig. 1 Changes in WSC content of the top three parts (A, B, C) of the wheat stem during grain filling
1 State Key Lab of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences/ Northwest A&F University, Yangling, Shaanxi , China
2 Department of Soil Science, University of Calabar, Nigeria
3 Division of Science and Engineering, Murdoch University, Murdoch, WA 6150, Australia
In winter wheat (Triticum aestivum L.) and other cereal crops, grain filling is the final stage of growth when photosynthate is remobilized into caryopses. Field experiments were conducted at the Changwu Agricultural Research Station on the semiarid Loess Plateau of China to determine how water soluble carbohydrates (WSC) partitioning across winter wheat stem responds to different nitrogen management and tillage in dryland of China. The different parts of the wheat stem studied were exposed part of the uppermost internode (EXUI), enclosed part of the uppermost internode (ENUI), penultimate internode (PI), lower internode (ERI), and lowest internode (ESTI). Contents of WSC in different parts of the wheat stem were measured during the grain filling period; the mobilized water soluble carbohydrate (MWSC) and mobilization efficiency (ME) were also determined.
Fig. 2 Changes in WSC content of the bottom two parts (A, B) of the wheat stem during grain filling
The results show that the peak value of WSC in the bottom-two-parts (ERI and ESTI) occurred 5 days earlier than in the top-three-parts (EXUI, ENUI and PI). There was no synchrony in the timing of peak WSC in the different parts of the wheat stem. This phenomenon may explain the formation of superior and inferior grains in wheat. Our conclusion is that the different grains had different onset of grain filling and grain weight. We suggest that different internodes of wheat may mobilize the WSC to different kinds (superior or inferior) of grains during the grain filling period. On average, the bottom-two-parts remobilized more WSC to grains than the top-three-parts. In dryland wheat production, application of spilt nitrogen fertilizer ( kg/ha-1) plus ox manure (4.5t/ha-1) under conservation tillage can increase the accumulation of WSC in the source organ.
Table 1. Post-anthesis maximum and minimum water-soluble carbohydrate (WSC) content, mobilized WSC (MWSC), and mobilization efficiency (ME) of ERI under different fertilizer and tillage treatments.
Treatment
Max.
(mg·g-1)
Min.
MWSC (mg·g-1) ME
(%) T1
426±12.8d
25±5.4b
402±15.6d
94±2.3a T2
465±14.0c
33±5.9a
432±10.8c
93±3.7a T3
486±14.6a
22±6.7b
465±11.1a
96±1.9a T4
476±14.3b
38±6.2a
438±13.8b
92±2.2a
Different letters in each column indicate significant differences at p<0.05 according to Duncan’s multiple range test
Table 2. Post-anthesis maximum and minimum water-soluble carbohydrate (WSC) content, mobilized WSC (MWSC), and mobilization efficiency (ME) of the whole wheat stem under different fertilizer and tillage treatments.
Treatments
Max.
(mg·g-1)
Min.
MWSC (mg·g-1) ME
(%) T1
1192±35.8a
197±12.9d
995±29.7d
83±2.6a T2
1255±37.7a
230±14.2b
1025±31.5c
82±2.1a T3
1364±40.9a
204±16.6c
1159±25.6a
85±4.0a T4
1301±39.0a
256±15.2a
1045±19.7b
80±5.1a
Corresponding Author:
Deng Xi-Ping, Research Professor & Deputy Director of
State Key Laboratory of Soil Erosion and Dryland Farming
on the Loess Plateau,
Institute of Soil and Water Conservation,
Chinese Academy of Sciences.
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Different letters in each column indicate significant differences at p<0.05 according to Duncan’s multiple range test
Acknowledgments: This work was supported by National Basic Research Program of China (2009CB118604), International Science & Technology Cooperation Program of China (2010DFA91930) and 111 Project (No.B12007).