Effects of mixed application of biological organic fertilizer and Yellow River sediment on the sink-source relationship of winter wheat in saline-alkaline soil

To study the source and sink characteristics and the transformation of both source and sink of winter wheat in saline-alkali soil, we conducted an experiment in Nanpi County, China, during the winter wheat growing seasons from 2015 to 2018. The positioning monitoring test was employed in the study. The study involved four processes:biological organic fertilizer application (FF), mixing Yellow River sediment (SS), FF and SS combination (SF), and blank (CK) treatment as control. Wheat varietiy 'Xiaoyan 60' was used in the field as the experimental material, and the growth parameters and grain yield of the wheat were monitored during the growth period. The findings revealed that there was a gradual downward trend in the photosynthetic rate (P_n) of flag leaves after anthesis under different treatments. The order of flag leaves P_n was SF > FF > SS > CK from anthesis to 20 d after anthesis. SF, FF, and SS were averagely 55.08%, 27.32%, and 1.88% higher, respectively, than CK. As for the growth process, the leaf area duration showed a single peak curve, with the peak appearing at the boot-anthesis stage. After 30 days of anthesis, there was a rapid decline in leaf area duration, and the photosynthetic potential of the treatments was SF > FF > SS > CK. At the boot-anthesis stage, the photosynthetic potentials of SF, FF, and SS were increased by 29.02%, 18.79%, and 10.62% respectively, compared with CK. Moreover, their total photosynthetic potentials after anthesis were 41.66%, 24.72%, and 13.94% higher, respectively, than that of CK. The source productivity capacity of SF was the highest during the whole growth period, before and after anthesis, at 34.06%, 40.52%, and 28.15% higher respectively, than that of CK. SF had the highest storage indexes, including panicle number, total grain number, maximum potential storage capacity and effective storage capacity; these were averagely 25.69%, 30.00%, 42.06%, and 38.84% higher, respectively, than in CK. The source-sink relationship indexes of SF were all the highest. They were yield, conversion rate of source production capacity after anthesis, grain/leaf ratio, and economic coefficient; these were 41.08%, 9.53%, 8.50%, and 4.01%, higher, respectively, than with CK. In this study, the effective storage capacity showed significantly positive correlation with the total number of spikes and the total number of grain, and these were the key factors affecting winter wheat yield in saline-alkali soil. The way of mixing Yellow River sediment or applying bio-organic fertilizer could improve the photosynthetic performance of wheat, improve the production capacity of the source, and promote the transformation of the source-sink. The best treatment was the SF treatment, which combined SS and FF application. This treatment combines the advantages of both, and was more conducive to the improvement and sustainable development and utilization of coastal saline and alkaline soil.