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Ultrasonic treatment and optimal cultivation techniques are both conducive to the high yield of super rice in South China. Many previous studies have shown that the increase in intercepted photosynthetically active radiation (IPAR) and radiation use efficiency (RUE) is an important reason for high rice yield. Field experiments were conducted over two years to evaluate the effects of IPAR and RUE on the yield under different treatments (CK: conventional cultivation technique without ultrasonic treatment; T1: conventional cultivation technique with ultrasonic treatment; T2: super rice-specific cultivation technique without ultrasonic treatment and T3: super rice-specific cultivation technique with ultrasonic treatment), with two representative rice varieties, Wufengyou-615 (WFY) and Jingnongsimiao (JNSM) during the late seasons of rice cultivation in South China. The super rice-specific cultivation technique and the ultrasonic treatment could significantly increase the yield, which was significantly (p < 0.01) and positively correlated with panicle number, grain-filling rate, and aboveground total dry weight. The higher grain yield depended more highly on higher RUE in the mid-tillering stage and maturity stage. The results of multiple-regression models also showed that the contributions of IPAR and RUE to yield were significant (p < 0.01). Conclusively, IPAR and RUE contributed a lot to yield progress of super rice in both super rice-specific cultivation techniques with fewer times of topdressing and ultrasonic treatment in South China. It is worth further studying how to reasonably improve the RUE of high-RUE varieties through other means. [ABSTRACT FROM AUTHOR]

Rapeseed–rice rotation is a cropping system that improves the land-use rate. The present study conducted a field experiment with winter planting of rapeseed as treatment (WR) and winter fallow as control (CK) to investigate the effects of winter planting of rapeseed on growth, yield formation, and 2-acetyl-1-pyrroline (2-AP) biosynthesis of fragrant rice in the two subsequent cropping seasons. The results show that WR treatment improved alkali-hydro nitrogen and rapidly available phosphorus contents in soil. Compared with CK, WR treatment significantly increased grain yield and effective panicle number per plant by 21.16–27.26% and 7.33–21.24%, respectively. Higher net photosynthetic rate, leaf area index, and dry matter accumulation of fragrant rice plants were recorded in WR treatment and CK. Furthermore, compared with CK, WR treatment significantly increased grain 2-AP content, which could be explained by increased content of pyrroline-5-carboxylic acid, methylglyoxal, 1-pyrroline, and enhanced activity of proline dehydrogenase. In addition, future studies should be conducted at a molecular level to reveal the regulation mechanism in 2-AP biosynthesis of fragrant rice under conditions of winter planting of rapeseed. [ABSTRACT FROM AUTHOR]

The major challenge in fragrant rice production is to improve both yield and grain quality in fragrant rice. Reducing tillage has been singled out as an effective impact to improve grain yield. However, information on the improvement of grain yield and grain quality and their relationship is sparse. This study aimed to assess the influence of different tillage methods on rice growth during the booting stage under shading conditions. The experiments were conducted with rotary tillage and no-shading (RTNS), rotary tillage and shading (RTS), reduced tillage and no-shading (LTNS), reduced tillage and shading (LTS), no-tillage and no-shading (NTNS) and no-tillage and shading (NTS), using two fragrant rice varieties, Meixiangzhan 2 (MXZ2) and Xiangyaxiangzhan (XYXZ). Grain yield, grain quality, Malondialdehyde (MDA) content and antioxidant activities were all investigated. Our results showed that grain yield of reduced tillage and no-tillage were 27.9% and 27.0% higher than rotary tillage, respectively. In addition, with shading applied, grain yield significantly decreased. Moreover, with the application of a shading treatment, the brown rice rate, chalkiness degree and chalk grain rate decreased, while the milled rice rate, amylose content and protein content increased. The results of this study revealed that shading improves the grain quality of fragrant rice but has a negative impact on its yield while reducing tillage effectively makes up for the yield loss resulting from shading and improves rice quality. [ABSTRACT FROM AUTHOR]