Artificial Transplantation Research Articles

Regulation of 2-acetyl-1-pyrroline and grain quality in early-season indica fragrant rice by nitrogen and silicon fertilization under different plantation methods

Fragrant rice has a high market value, and it is a popular rice type among consumers owing to its pleasant flavor. Plantation methods, nitrogen (N) fertilizers, and silicon (Si) fertilizers can affect the grain yield and fragrance of fragrant rice. However, the core commercial rice production attributes, namely the head rice yield (HRY) and 2-acetyl-1-pyrroline (2-AP) content of fragrant rice, under various nitrogen and silicon (N-Si) fertilization levels and different plantation methods remain unknown. The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars (Yuxiangyouzhan and Xiangyaxiangzhan). They were grown under six N-Si fertilization treatments (combinations of two levels of Si fertilizer, 0 kg Si ha−1 (Si0) and 150 kg Si ha−1 (Si1), and three levels of N fertilizer, 0 kg N ha−1 (N0), 150 kg N ha−1 (N1), and 220 kg N ha−1 (N2)) and three plantation methods (artificial transplanting (AT), mechanical transplanting (MT), and mechanical direct-seeding (MD)). The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars. Compared with the Si0N0 treatment, the N-Si fertilization treatments resulted in higher HRY and 2-AP contents. The rates of brown rice, milled rice, head rice, and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments. The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice, and affected their antioxidant response parameters. The key parameters for the HRY and 2-AP content were assessed by redundancy analysis. Furthermore, the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity, N use efficiency, and grain quality of fragrant rice. Moreover, high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis. The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content, whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.

Optimization of nitrogen–silicon (N-Si) fertilization for grain yield and lodging resistance of early-season indica fragrant rice under different planting methods

In general, nitrogen (N), silicon (Si), and planting method influence fragrant rice yield and lodging resistance. Nevertheless, the response of fragrant rice yield and lodging resistance to N-Si fertilization under different planting methods has not been examined in detail. Field trials were undertaken in the early seasons of 2018 and 2019. Two Si levels i.e., 0 kg Si h m−2 (Si0) and 150 kg Si h m−2 (Si1), three N levels i.e., 0 kg N h m−2(N0), 150 kg N h m−2(N1), and 220 kg N h m−2(N2) as well as three planting methods i.e., artificial transplanting (AT), mechanical transplanting (MT), and mechanical direct-seeding (MD) were set up for two indica fragrant rice cultivars i.e., ‘Yuxiangyouzhan’ (YX) and ‘Xiangyaxiangzhan’ (XY). Results revealed that the N-Si treatments and planting methods significantly affected the grain yield, lodging index, and some related parameters across the two cultivars. The mean fold change (FC) in grain yield for the different planting methods was ranked MD＞MT＞AT, while MT and MD have larger variation of FC in grain yield and lodging index as compared with AT. Besides, under all planting methods, the N1 and N2 treatments significantly increased grain yield and lodging index, while the Si1 treatment significantly reduced lodging index without affecting grain yield. There were also significant Si and N interaction effects on grain yield and lodging resistance, with the Si1N2 treatment producing the best balance of grain yield and lodging resistance. The treatments differed in grain yield and yield-related traits such as yield components, biomass yield and photosynthetic properties, as well as in lodging index and lodging-related traits such as plant height, N and Si content in the stem sheath, and biomass allocation ratio. Overall, this study revealed that the 150 kg Si h m−2 coupled with 220 kg N h m−2 treatment showed the best positive effects on balancing grain yield and lodging resistance under all planting methods. Additionally, fragrant rice planted by mechanical methods requires more stricter N-Si fertilization because mechanical planting methods produce greater variation in the physio-biochemical characteristics that underlie grain yield formation and lodging resistance.

Effects of delaying transplanting on agronomic traits and grain yield of rice under mechanical transplantation pattern.

A delay in the mechanical transplantation (MT) of rice seedlings frequently occurs in Huanghuai wheat-rice rotation cropping districts of China, due to the late harvest of wheat, the poor weather conditions and the insufficiency of transplanters, missing the optimum transplanting time and causing seedlings to age. To identify how delaying transplanting rice affects the agronomic characteristics including the growth duration, photosynthetic productivity and dry matter remobilization efficiency and the grain yield under mechanical transplanting pattern, an experiment with a split-plot design was conducted over two consecutive years. The main plot includes two types of cultivation: mechanical transplanting and artificial transplanting (AT). The subplot comprises four japonica rice cultivars. The results indicate that the rice jointing, booting, heading and maturity stages were postponed under MT when using AT as a control. The tiller occurrence number, dry matter weight per tiller, accumulative dry matter for the population, leaf area index, crop growth rate, photosynthetic potential, and dry matter remobilization efficiency of the leaf under MT significantly decreased compared to those under AT. In contrast, the reduction rate of the leaf area during the heading-maturity stage was markedly enhanced under MT. The numbers of effective panicles and filled grains per panicle and the grain yield significantly decreased under MT. A significant correlation was observed between the dry matter production, remobilization and distribution characteristics and the grain yield. We infer that, as with rice from old seedlings, the decrease in the tiller occurrence, the photosynthetic productivity and the assimilate remobilization efficiency may be important agronomic traits that are responsible for the reduced grain yield under MT.

Effects of Cultivars, Transplanting Patterns, Environment, and Their Interactions on Grain Quality of Japonica Rice

With the increasing scarcity of rural labor, the rice transplanting pattern is encountering a shift from artificial transplanting (AT) to mechanical transplanting (MT) in numerous rice‐growing districts of China. The shift of transplanting patterns combined with altered growing environment during the grain‐filling stage in different years presumably affects rice quality. Nevertheless, related information is currently limited. This study investigated the effects of cultivars, transplanting patterns, environment, and their interactions on appearance, milling, eating, and nutritional qualities of four japonica rice varieties. The significant interactive effects of cultivars, environment, and transplanting patterns on almost all rice quality parameters (except Thr, Met, and Ile) were observed. Cultivars and environment were the main factors influencing rice appearance and milling and eating qualities. Cultivar was the primary factor affecting rice nutritional quality. Among all treatments, environment showed the strongest effect on percentage of chalky kernel, milled rice yield, peak viscosity, breakdown, setback, consistence, amylose, Glu, Tyr, and Met contents. However, Leu and Phe contents were unaffected by environment but only by cultivars and transplanting patterns. In addition to amylose and protein, Glu and Met contents were also involved in determining rice eating quality. Amino acid contents (except Cys, Tyr, and Met) were significantly negatively correlated with head rice yield, showing the function of amino acids in controlling rice milling quality. Percentage of chalky kernel as well as protein and almost all amino acid contents were significantly negatively correlated with the difference of maximum and minimum temperature (DMMT) and positively correlated with relative humidity (RH), whereas head rice yield did it reversely. Amylose content and setback were significantly negatively related to daily maximum temperature (DMAT), daily minimum temperature (DMIT), daily average temperature (DAT), and effective temperature accumulation (ETA). However, peak viscosity, breakdown, and consistence had contrary performances. According to these results, we can infer that DMMT and RH are important environmental factors affecting rice appearance, milling qualities, and nutritional qualities and that DMAT, DMIT, DAT, and ETA are key environmental factors influencing rice eating quality.

Benefits Comparison Analysis of Different Rice and Wheat Cropping Patterns to Adapt to Climate Change

Based on the input-output survey of farmers and experts in one of the Jiangsu GEF project areas, the Cost-Benefit analysis method and greenhouse gas estimation method recommended by IPCC were applied to evaluate and compare the social, economic and ecological benefits of artificial transplanting (ATR), mechanical transplanting (MTR) and direct seeding (DSR) rice under wheat-rice Double Late mode (late rice harvest and late wheat sowing). Results showed that the MTR and DSR rice achieved obvious social benefits. Farming measures resulted in excessive emission of anthropogenic greenhouse gases. Through the use of ATR rice and wheat rotation mode it is possible to obtain most economic and ecological benefits. The Double Late mode of action had good application prospects, but the key to implementation was the timely exploitation of the recently increased availability of agricultural climate resources. The cropping pattern of combining the wheat-rice Double Late mode with the ATR was a better choice in mitigating and adapting to climate change. CitationHuang, H.-P., S.-M. Ma, E.-D. Lin, et al., 2013: Benefits comparison analysis of different rice and wheat cropping patterns to adapt to climate change. Adv. Clim. Change Res., 4(3), doi: 10.3724/SP.J.1248.2013.182.