The effects of dry cultivation on grain‐filling and chalky grains of upland rice and paddy rice

Effects of Drip Irrigations with Different Irrigation Intervals and Levels on Nutritional Traits of Paddy Cultivars

Rice serves as the primary food source for the majority of the world's population. In terms of irrigation water, the highest volume of irrigation water is utilized in paddy irrigation. Excessive water use causes both waste of limited water resources and various environmental problems. The drip irrigation method with high water use efficiency will reduce both the need for irrigation water and the environmental footprint of paddy production. This study was conducted to investigate the effects of two different irrigation intervals (2 and 4 days) and four irrigation levels (150%, 125%, 100%, and 75% of evaporation from a Class-A pan) on the nutritional traits of three different paddy cultivars (Ronaldo, Baldo, and Osmancık). Increasing irrigation intervals and decreasing irrigation levels reduced the nutritional properties (protein, oil, starch) of the rice grains. In addition, increasing irrigation levels also increased the phytic acid and dietary fiber contents. The highest protein (7.14%) and total starch (87.10%) contents were obtained from the 150% irrigation treatments. The highest amylose content (20.74%) was obtained from the 75% irrigation treatment. In general, it was found that irrigation levels should be applied at 125% and 150% to increase the mineral content of rice grains. Although water deficits decreased the nutritional properties of the paddy cultivars, drip irrigation at an appropriate level did not have any negative effects on nutritional traits.

Energy Deficiency and Misdistribution Leads to Disrupted Formation in Grain Yield and Rice Quality

With the progress of society and the improvement of agricultural scientific technology, the single focus on high yield for rice production has gradually shifted to high quality. Coordinated development of grain yield and rice quality has become a core issue for researchers, and the underlying mechanisms remain to be solved. Two varieties, Zhongzheyou1 (ZZY1) and Zhongzheyou8 (ZZY8), were used as study materials under field conditions. The yield of ZZY1 was higher than that of ZZY8, which was mainly characterized by a higher seed-setting rate and grain weight. The rice quality of ZZY8 was better than that of ZZY1, primarily due to lower chalkiness and a higher head rice rate. The total dry matter weight of ZZY1 was lower than that of ZZY8, but the proportion of panicle dry matter weight or nonstructural carbohydrate to the total in the former was higher than that of the latter. The maximum grain-filling rate, average grain-filling rate, and key enzyme activities of ZZY1 were significantly higher than those of ZZY8, while the active grain-filling period was shorter than that of ZZY8. Furthermore, the ATP/ATPase content and energy charge values in the grains of ZZY1 were higher than those of ZZY8 at the early grain-filling stage. Transcriptome analysis showed that carbohydrate and energy metabolism were the main ways affecting the yield and quality of the two varieties. The energy production of ZZY1 was insufficient to simultaneously supply the needs thus leading to the discordant formation in its grain yield and rice quality formation.

Translocation pattern of heavy metals in soil-rice systems at different growth stages: A case study in the Taihu region, Eastern China

Rice production is crucial for human nutrition and food safety globally. However, it has been a significant sink for potentially harmful metals because of intensive anthropogenic activities. The study was conducted to characterize heavy metal translocation from soil to rice at the filling, doughing and maturing stages, and influencing factors of their accumulation in rice. The distribution and accumulation patterns varied for metal species and growth stages. Cd and Pb accumulation mainly occurred in roots, Cu and Zn were readily transported to stems. Cd, Cu, and Zn accumulation in grains had a descending order of filling > doughing > maturing. Soil heavy metals, TN, EC, and pH exerted important impacts on heavy metals uptake by roots during the period from filling stage to maturing stage. Concentrations of heavy metals in grains were positively correlated with the translocation factors TF_stem-grain (from stem to grain) and TF_leaf-grain (from leaf to grain). Grain Cd exhibited significant correlations with total Cd and DTPA-Cd in the soil at each of the three growth stages. Moreover, Cd in maturing grain could be effectively predicted by soil pH and DTPA-Cd at the filling stage.