Partial substitution of organic nitrogen with synthetic nitrogen enhances rice yield, grain starch metabolism and related genes expression under the dual cropping system

Abstract

Improving grain filling in the presernt farming systems is crucial where grain filling is a concern due to the extreme use of chemical fertilizers (CF). A field experiment was conducted at the experimental station of Guangxi University, China in 2019 to test the hypothesis that cattle manure (CM) and poultry manure (PM) combined with CF could improve rice grain filling rate, yield, biochemical and qualitative attributes. A total of six treatments, i.e., no fertilizer (T 1 ), 100% CF (T 2 ), 60% CM + 40% CF (T 3 ), 30% CM + 70% CF (T 4 ), 60% PM + 40% CF (T 5 ), and 30% PM + 70% CF (T 6 ) were used in this study. Results showed that the combined treatment T 6 increased starch metabolizing enzymes activity (SMEs), such as ADP-glucose phosphorylase (ADGPase) by 8 and 12%, soluble starch synthase (SSS) by 7 and 10%, granule bound starch synthesis (GBSS) by 7 and 9%, and starch branching enzyme (SBE) by 14 and 21% in the early and late seasons, respectively, compared with T 2 . Similarly, higher rice grain yield, grain filling rate, starch, and amylose content were also recorded in combined treatments. In terms of seasons, higher activity of SMEs , grain starch, and amylose content was noted in the late-season compared to the early season. The increment in these traits was mainly attributed to a lower temperature in the late season during the grain filling period. Furthermore, our results suggested that an increment in starch accumulation and grain filling rate were mainly associated with the enhanced sink capacity by regulating key enzyme activities involved in Suc-to-starch conversion. In-addition, RT-qPCR analysis showed higher expression levels of AGPS2b, SSS1, GBSS1, and GBSE11b genes, which resultantly increased the activities of SMEs during the grain filling period under combined treatments. Linear regression analysis revealed that the activity of ADGPase, SSS, GBSS, and SBE were highly positively correlated with starch and amylose accumulation. Thus, we concluded that a combination of 30% N from PM or CM with 70% N from CF is a promising option in terms of improving rice grain yield and quality. Our study provides a sustainable fertilizer management strategy to enhance rice grain yield and quality at the lowest environmental cost.

Co-incorporation of manure and inorganic fertilizer improves leaf physiological traits, rice production and soil functionality in a paddy field

“…However, organic manure is relatively low in nutrient content, and its release rate is generally too slow to meet plant requirements in a short time period. Thus, the combined application of organic manure and CF has proven to be a promising option in improving and maintaining soil fertility and crop production than the use of either amendments or alone 20 , 22 . Although the advantages of organic manure fertilization are generally recognized, its optimal application ratio with CF remains unclear.…”

Green Labelled Rice Shows a Higher Nutritional and Physiochemical Quality Than Conventional Rice in China

“…A higher amylose content may be associated with fertilizer application. Iqbal et al reported that the use of an organic fertilizer combined with a chemical fertilizer considerably improved the rice amylase content [ 39 ].…”

Synthetic nitrogen coupled with seaweed extract and microbial inoculants improves rice (<em>Oryza sativa</em> L.) production under a dual cropping system

“…The appropriate use of N fertilizer is key for meeting the demand of the growing human population Accepted paper for food and soil for improving soil health and cereals crop quality (Izhar et al 2020a;Iqbal et al, 2020b;Ullah et al, 2020). However, the overuse of chemical N fertilizer can lead to several problems, such as environmental pollution, soil degradation, water contamination, and decreased crop productivity (Cai et al, 2018;Peng et al, 2015).…”