Ratoon Rice Research Articles

Improved Yield Prediction of Ratoon Rice Using Unmanned Aerial Vehicle-Based Multi-Temporal Feature Method

Pre-harvest yield prediction of ratoon rice is critical for guiding crop interventions in precision agriculture. However, the unique agronomic practice (i.e., varied stubble height treatment) in rice ratooning could lead to inconsistent rice phenology, which had a significant impact on yield prediction of ratoon rice. Multi-temporal unmanned aerial vehicle (UAV)-based remote sensing can likely monitor ratoon rice productivity and reflect maximum yield potential across growing seasons for improving the yield prediction compared with previous methods. Thus, in this study, we explored the performance of combination of agronomic practice information (API) and single-phase, multi-spectral features [vegetation indices (VIs) and texture (Tex) features] in predicting ratoon rice yield, and developed a new UAV-based method to retrieve yield formation process by using multi-temporal features which were effective in improving yield forecasting accuracy of ratoon rice. The results showed that the integrated use of VIs, Tex and API (VIs & Tex + API) improved the accuracy of yield prediction than single-phase UAV imagery-based feature, with the panicle initiation stage being the best period for yield prediction (R2 as 0.732, RMSE as 0.406, RRMSE as 0.101). More importantly, compared with previous multi-temporal UAV-based methods, our proposed multi- temporal method (multi-temporal model VIs & Tex: R2 as 0.795, RMSE as 0.298, RRMSE as 0.072) can increase R2 by 0.020–0.111 and decrease RMSE by 0.020–0.080 in crop yield forecasting. This study provides an effective method for accurate pre-harvest yield prediction of ratoon rice in precision agriculture, which is of great significance to take timely means for ensuring ratoon rice production and food security.

Exploring a sustainable rice-cropping system to balance grain yield, environmental footprint and economic benefits in the middle and lower reaches of the Yangtze River in China

Environmental degradation and resource scarcity are serious challenges faced by global rice production. Although rice production is crucial to ensure global food security, it is also one of the principal sources of greenhouse gas (GHG) and reactive nitrogen (Nr) emissions. Exploring rice-cropping systems with a low environmental footprint and high grain yield and economic benefits is a crucial strategy to improve the sustainability of rice production. Here, life cycle assessment was used to compare the performance of middle-season rice (MR), double-season rice (DR) and ratoon rice systems (RR) based on farmer-reported data in the middle and lower reaches of the Yangtze River of China. The average annual grain yields of DR, MR, and RR were 13.68, 8.96 and 11.97 t ha−1, respectively. Although RR produced 12.5% lower grain yield, it had 41.2% lower global warming potential (GWP) and 33.8% smaller eutrophication potential (EP) than DR, which resulted in lower greenhouse gas intensity (GHGI) and reactive nitrogen intensity (NrI). The lower GWP and EP in RR were mainly attributed to lower agricultural inputs, smaller CH4 and N2O emissions and less Nr losses. Compared with MR, RR had higher GWP and EP, but significantly higher grain yield (33.6%) in RR contributed to lower GHGI and similar NrI. In all three cropping systems, CH4 emissions and NH3 volatilization had the highest contributions to GWP and EP, respectively. Compared with the other two cropping systems, RR exhibited the highest net economic income (NEI), benefit-cost ratio and eco-efficiency. Overall, our results suggested that RR is a sustainable rice-cropping system that can coordinate grain yield, environmental footprint and economic benefits.

Effects of source-sink regulation and nodal position of the main crop on the sprouting of regenerated buds and grain yield of ratoon rice.

Ratoon rice (Oryza sativa L.) is the production of a second season rice that utilizes the dormant buds surviving on the stubble left behind after the harvest of the main crop. However, the sprouting mechanism of regenerated buds at separate nodes is rarely reported. Field experiments were conducted to examine the effects of leaf-cutting and spikelet thinning on the sprouting of regenerated buds at the separate node, the contributions of regenerated panicles at the separate node to the total grain yield in the ratoon crop, and the associated mechanism. The results showed that the contribution of separate node yields to the total grain yield in the ratoon crop was D2 (panicles regenerated from the 2nd node from the top) >D3 (panicles regenerated from the 3rd node from the top) >D4 (panicles regenerated from the lower nodes below the 3rd node), and the contribution of D2 and D3 made up approximately 80% of the total yield in the ratoon crop. In addition, the effect of leaf-cutting treatment and spikelet-thinning treatment on the grain yield of ratoon season was mainly realized by regulating the relative contribution rate of D2 and D4 grain yield to the total yield of ratoon season. Further analysis indicated that the sprouting of regenerated buds at the D2 node was mainly affected by the content of CTK, while D3 was mainly regulated by GAs and CTK, and D4 was mainly regulated by ABA and CTK. However, only the CTK content in stems and buds was positively correlated with single bud length and bud number at each nodes. These results indicated that CTK might be the main signal regulating the sprouting of regenerated buds and the grain yield at separate nodes, which might change the transport of assimilates to stems and buds.

Coupled treatment of wet-dry alternation irrigation and seedling-promoting fertilizer has a beneficial effect on the rhizosphere microbial community profile and regenerating physiology of ratoon rice

Coupled treatment of wet-dry alternation irrigation and seedling-promoting fertilizer has a beneficial effect on the rhizosphere microbial community profile and regenerating physiology of ratoon rice

Strategy of Rice Productivity Increment Through Agronomical Treatment at Two Flooding Types of Tidal Swampland

The research objective is to increase rice productivity using a ratoon system through N fertilizer and growth regulator treatments at two flooding types of tidal swampland. It was conducted from February to August 2020. The experiment design used in this research is Split Plot Design with three replications. The main plot is N fertilizer and rice variety (NV) which consisted of N1V1= N fertilizing, 1/3 dose during planting + 1/3 dose at primordia phase + 1/3 dosis at harvest for Inpari 30 variety; N1V2= N fertilizing, 1/3 dose during planting + 1/3 dose at primordia phase + 1/3 dose at harvest for Hipa 5 Ceva variety; N2V1= N fertilizing, 1/3 dose during planting + 1/3 dose at primordia phase + 1/6 dose at harvest +1/6 dose at 21 days after harvest for Inpari 30 variety; N2V2= N fertilizing, 1/3 dose during planting + 1/3 dose at primordia phase + 1/6 dose at harvest +1/6 dose at 21 days after harvest for Hipa 5 Ceva variety. The subplot is the application of growth regulator GA3 (G) consisting of G0 = without application of GA3; G1 = application of GA3 once in 7 days; G2 = application of GA3 once in 14 days. The research results showed that N fertilizing, 1/3 dose during planting + 1/3 dose at primordia phase + 1/3 dosis at harvest and application of growth regulator GA3 60 ppm with interval of once in 7 days to ratoon rice is capable to increase rice productivity using ratoon rice system at B and C flooding types at tidal swampland. How to Cite: Gribaldi, Nurlaili, Novriani, S. Diana, N. Marlina, 2023. "Strategy of Rice Productivity Increment Through Agronomical Treatment at Two Flooding Types of Tidal Swampland." Journal of Agriculture and Crops, vol. 9, pp. 199-204.

Seasonal incidence and source of the panicle rice mite, Steneotarsonemus spinki Smiley (Acari: Tarsonemidae) in paddy fields of Central Vietnam

The panicle rice mite, Steneotarsonemus spinki Smiley (Acari: Tarsonemidae) is the most important and destructive mite species attacking rice crop in Vietnam. Field surveys were carried out in Thua Thien Hue province, Central Vietnam during 2021-22 to investigate the seasonal incidence of S. spinki on commonly used rice varieties and the importance of ratoon rice plants and weeds found on paddy fields as possible sources of S. spinki to infest rice plants in next crop seasons. The panicle rice mites were recorded at all growth stages of investigated rice varieties grown during summer-autumn and winter-spring rice seasons. Incidences of S. spinki were more during the summer-autumn season than during the winter-spring season. Among the seven investigated rice varieties, TH5 and HAPHAT3 recorded higher infestation by S. spinki. Ratoon rice plants in the fallow season (Sept.-Dec.) were survival habitats and maintenance of the panicle rice mite between the two rice seasons. Seven weed species, including Echinochloa crus-galli (L.) Beauv., Fimbristylis sp., Eleocharis sp. and Eschaemum rugosum Salisb. were found as alternative hosts and important sources of infestation of S. spinki. Therefore, the removal of ratoon and weed plants during the crop-free seasons is good field practice in integrated pest management for S. spinki in Central Vietnam.

Cutting time & height improve carbon and energy use efficiency of the forage–food dual-purpose ratoon rice cropping

Forage–food dual-purpose ratoon rice cropping (FFRR) is used to balance forage demands with ratoon rice grain yields, that is whole plant (stem and sheath, panicles) cuttings in the main season are used as forage, and rice in the regeneration season is used as food. In this study, the local ratoon rice production system as the control, we were carried out the field experiment of cultivation practices (cutting time and cutting height), and investigated the system productivity, economic benefits, carbon footprints and energy use efficiency. The energy use efficiency, energy productivity and energy profitability increased with cutting time delay, and cutting height decreased. Significant differences of these index were observed among the treatments for cutting time and cutting height (p < 0.05). Carbon efficiency and carbon sustainability index was increase with cutting time delay, and there was significant difference among the treatment of cutting time in 2018 (p < 0.05), the minimum carbon footprint of FFRR was 78.6 kgCO2 t−1 averagely at the cutting time of 30 days after the flowering stage. In 2018, the maximum net income of FFRR was 30,577 CNY hm−2 at a cutting time of 30 days after the flowering stage while the stubble height was 10 cm, and dependent on the forage yield of the main crop; in 2019, the maximum net income of FFRR was 27,326 CNY hm−2 at a cutting time of 10 days after the flowering stage while the stubble height was 10 cm, and dependent on the grain yield of the ratoon crop. Therefore, the optimal cultivation practice of the FFRR (cutting at 30 days after the flowering stage and with a stubble height of 10 cm) showed higher carbon and energy use efficiency, economic benefits of the FFRR were fluctuated with the price of forage of the main crop and rice grain of the ratoon crop.

GF14f gene is negatively associated with yield and grain chalkiness under rice ratooning.

Ratoon rice cropping has been shown to provide new insights into overcoming the current challenges of rice production in southern China. However, the potential mechanisms impacting yield and grain quality under rice ratooning remain unclear. In this study, changes in yield performance and distinct improvements in grain chalkiness in ratoon rice were thoroughly investigated, using physiological, molecular and transcriptomic analysis. Rice ratooning induced an extensive carbon reserve remobilization in combination with an impact on grain filling, starch biosynthesis, and ultimately, an optimization in starch composition and structure in the endosperm. Furthermore, these variations were shown to be associated with a protein-coding gene: GF14f (encoding GF14f isoform of 14-3-3 proteins) and such gene negatively impacts oxidative and environmental resistance in ratoon rice. Our findings suggested that this genetic regulation by GF14f gene was the main cause leading to changes in rice yield and grain chalkiness improvement of ratoon rice, irrespective of seasonal or environmental effects. A further significance was to see how yield performance and grain quality of ratoon rice were able to be achieved at higher levels via suppression of GF14f.

Identification of QTNs, QTN-by-environment interactions, and their candidate genes for grain size traits in main crop and ratoon rice.

Although grain size is an important quantitative trait affecting rice yield and quality, there are few studies on gene-by-environment interactions (GEIs) in genome-wide association studies, especially, in main crop (MC) and ratoon rice (RR). To address these issues, the phenotypes for grain width (GW), grain length (GL), and thousand grain weight (TGW) of 159 accessions of MC and RR in two environments were used to associate with 2,017,495 SNPs for detecting quantitative trait nucleotides (QTNs) and QTN-by-environment interactions (QEIs) using 3VmrMLM. As a result, 64, 71, 67, 72, 63, and 56 QTNs, and 0, 1, 2, 2, 2, and 1 QEIs were found to be significantly associated with GW in MC (GW-MC), GL-MC, TGW-MC, GW-RR, GL-RR, and TGW-RR, respectively. 3, 4, 7, 2, 2, and 4 genes were found to be truly associated with the above traits, respectively, while 2 genes around the above QEIs were found to be truly associated with GL-RR, and one of the two known genes was differentially expressed under two soil moisture conditions. 10, 7, 1, 8, 4, and 3 candidate genes were found by differential expression and GO annotation analysis to be around the QTNs for the above traits, respectively, in which 6, 3, 1, 2, 0, and 2 candidate genes were found to be significant in haplotype analysis. The gene Os03g0737000 around one QEI for GL-MC was annotated as salt stress related gene and found to be differentially expressed in two cultivars with different grain sizes. Among all the candidate genes around the QTNs in this study, four were key, in which two were reported to be truly associated with seed development, and two (Os02g0626100 for GL-MC and Os02g0538000 for GW-MC) were new. Moreover, 1, 2, and 1 known genes, along with 8 additional candidate genes and 2 candidate GEIs, were found to be around QTNs and QEIs for GW, GL, and TGW, respectively in MC and RR joint analysis, in which 3 additional candidate genes were key and new. Our results provided a solid foundation for genetic improvement and molecular breeding in MC and RR.

English

Rice (Oryza glaberrima) is a staple food for many people in Africa. In West Africa, especially Liberia, it is the main dish and plays a major role in the political stability of the country despite its insufficient production. The objective of the study was to evaluate how varied cutting heights affected rice yields. The experiment was set up in a Randomized Complete Block Design (RCBD) with three treatments and three replications. Each sampling plot received one of the three treatments: farmers&rsquo; practice (T1), 30 cm (T2), or 50 cm (T3). Other agronomic measures like watering, weeding, fertilizer application, and insect and pest control were uniformly applied. The 50 cm cutting height produced the highest grain yield (1.72 t/ha), followed by the 30 cm cutting height (1.12 t/ha), while the farmers&#39; practice yielded only 0.66 t/ha. As the cutting height climbed to 50 cm, all of the selected yield components: productive tiller, panicle height, and number of panicle seeds rose significantly. In general, it can be stated that ratoon rice is more effective at a height of 50 cm and produces higher yields. It could be used as a substitute for traditional rice planting method. Key words: Rice, ratoon, yield, Liberia.

A seven‐year study on the effects of four tillage modes on soil physicochemical properties, microbial biomass, enzymatic activities, and grain yield in a rice–ratoon rice cropping system

AbstractRatoon rice is resource efficient to produce economically sound and environmentally sustainable rice production. However, there is no more information on the relative impact of soil tillage practices on soil physical and chemical properties, microbial biomass, and enzymatic activity, and grain yield in a rice–ratoon rice cropping system remains to be tested. Systematic study of soil under ratooning rice model is a problem to be solved in the development of ratooning rice model. This study primarily investigated the long‐term (from 2014 to 2020) changes in soil bulk density (BD), soil organic carbon (SOC) concentration, total nitrogen (TN) concentration, microbial biomass, β‐glucosidase activity (BG), urease activity (UR), and yield under four treatments: no‐tillage (NT), no plowing tillage + rotatory tillage (RT), plowing tillage in winter + rotatory tillage (PTW), and plowing tillage in spring + rotatory tillage (PTS). NT increased BD by 9.65%–12.97%, and RT increased the 20–40 cm soil layer BD by 8.80% in 2020, compared with the baseline initial value (in 2014). Plowing tillage (PT) time had no significant effect on BD. All tillage methods decreased the SOC concentration in the 0–20 cm soil layer, and only RT increased the TN concentration. PT was the only treatment that increased the SOC and TN concentrations in the 20–40 cm soil layer. Both the main‐season rice yield and the ratoon season rice yield ranked PTW &gt; PTS &gt; NT &gt; RT, in which the main‐season rice yield increased by 28.15% and the ratoon season rice yield increased by 25.19% in PTW. Overall, the PTW treatment had the highest microbial biomass, enzyme activity, and grain yield compared with the other tillage methods. In conclusion, plowing tillage in winter + rotatory tillage is a more suitable tillage method under the mode of ratooning rice.

Fine Mapping and Cloning of a qRA2 Affect the Ratooning Ability in Rice (Oryza sativa L.).

Ratooning ability is a key factor that influences the ratoon rice yield in areas where light and temperature are not sufficient for second-season rice. Near-isogenic lines (NILs) are the most powerful tools for the detection and precise mapping of quantitative trait loci (QTLs). In this study, using 176 NILs, we identified a novel QTL for ratooning ability in NIL128. First, we mapped the QTL between the markers Indel12-29 and Indel12-31, which encompass a region of 233 kb. The rice genome annotation indicated the existence of three candidate genes in this region that may be related to ratooning ability. Through gene prediction and cDNA sequencing, we speculated that the target gene of ratooning ability is LOC_Os02g51930 which encodes cytokinin glucosyl transferases (CGTs), hereafter named qRA2. Further analysis showed that qra2 was a 1-bp substitution in the first exon in NIL128, which resulted in the premature termination of qRA2. The results of the knockdown experiment showed that the Jiafuzhan knockdown mutants exhibited the ratooning ability phenotype of NIL128. Interestingly, the qRA2 gene was found to improve ratooning ability without affecting major agronomic traits. These results will help us better understand the genetic basis of rice ratooning ability and provide a valuable gene resource for breeding strong ratoon rice varieties.

Early harvesting and increasing stubble-cutting height enhance ratoon rice yield

Summary To clarify the combined effects of the cutting time and cutting height on ratooning ability and rice grain yield of the ratoon crop in the novel ratoon rice cropping, a field experiment was carried out to investigate the combined effects of harvesting time and the stubble-cutting height of the main crop on the growth duration, ratooning ability and grain yield of the ratoon crop. The growth period was shortened by 3.5 days on average when the harvesting time was 10 days ahead of time. On average, the growth duration was prolonged by 7 days per each decrease of 10 cm stubble height. Early harvesting and increasing stubble-cutting height greatly increased the grain yield of the ratoon crop. The highest grain yield was achieved at 10 days after flowering stage and a stubble height of 30 cm, which were 6916 kg·hm−2 for XLY900 and 7262 kg·hm−2 for YY4149, averaged across years. High rice yield of the ratoon crop was mainly depended on panicle numbers and grain-filling percentage, rather than spikelets per panicle. Increasing cutting height and the cutting time of the main crop ahead maintain more stubble biomass and nitrogen content. A significant positive correlation was observed between stubble nitrogen content and tillers-to-stubble ratio (TSR), as well as a significant positive relation was found between panicle-to-stubble ratio and TSR. Therefore, cutting 10 days after flowering stage of the main crop with 30 cm stubble-cutting height enhances ratooning ability due to higher stubble biomass and nitrogen content, and then increases rice yield of the ratoon crop.

Effects of the configurations with different organic and inorganic fertilizers on grain yield and its related physiological traits of the main and its ratoon rice crops

The determination for properly combined application rate of organic and inorganic fertilizers is the key to coordinating soil nutrient supplies and rice growth demands, thereby obtaining improved economic and ecological returns in rice ratooning. A complete randomized block design (RCBD) trial with different configurations of organic and inorganic nitrogen fertilizers was conducted to determine the optimal substitution rate of organic nitrogen for inorganic nitrogen and its effect on the related physiological attributes and yield performance of the main and ratoon rice crops in 2018−2019. The results showed that 30% organic and 70% inorganic nitrogen in the mixture fertilizer (GM2) could produce the best effect on root activity, nitrogen nutrient uptake and its utilization, as well as the dry matter accumulation and its partitioning. This in turn resulted in improved productive panicles and harvest index, and hence increased grain yield by 10.36% and 15.48% in GM2 regime relative to that in CF treatment. Moreover, the uptake and utilization efficiency, agronomic utilization efficiency and partial productivity of nitrogen fertilizer were 44.37%, 23.82 kg/kg and 48.97 kg/kg, respectively under the optimal GM2 treatment, which were much higher than those in CF treatment by 12.66%, 5.05% and 13.4%, respectively. The results suggested that properly combined application of organic and chemical nitrogen fertilizer could improve soil nutrient supply to guarantee an efficient plant growth and rational dry matter allocation, thereby increasing the harvest index and grain yield in rice ratooning.

Test Of Hundreds Established Hybrid Rice Seed Derivatives P-05 And Quantity Of Cemeti Inbrid Rice Derivatives On Product Quality And Quantity

This study aims to determine the combination of treatment of ratoon derived from F1 rice seeds (Hybrid) of Mapan P-05 and ratoon derived from rice seeds (Inbred) whip with various spacings on the quality and quantity of which yield is the best and to know the interaction factors of ratoon derived from Mapan hybrid rice seeds. P-05 and whip inbred rice were the best in terms of yield quality and quantity. Held from December 2021 to June 2022. And planting of ratoons was carried out on November 14, 2021-March 31, 2022. This research was carried out in Sumberharjo Village, Prambanan District, Sleman Regency, Special Region of Yogyakarta. This study used a Completely Randomized Block Design (RAKL) factorial. The first factor is ratoon rice with two varieties and the second factor is the treatment of various spacings of 20x20;25x25;30x30 cm. Data analysis used ANOVA with a level of 5% and 1%, if it had a significant effect, it was followed by a significant difference test (DMRT) with a level of 5%. The results showed that the hybrid variety treatment always showed higher yield quality and quantity than the whip inbred with spacing treatment. 20x20 cm and followed by a spacing of 25x25 cm and 30x30 cm from the Inbred cemeti variety. The combination of hybrid varieties treatment with 20x20 cm spacing gave the heaviest results on the average weight of dry grain harvested per plot, weight of dry grain storage per plot, weight of 1000 grains of grain, weight of dry grain harvested.

Nitrogen response of regenerated tillers varied among node positions in ratoon rice

Rice ratooning produces a ratoon crop (RC) with regenerated tillers in different nodes on the stubble of main crop (MC). It is crucial to apply nitrogen (N) at 15 d after heading and 1–2 d after harvest of MC for promoting bud initiation (N B ) and tiller growth (N T ), respectively to achieve high grain yield of RC. However, limited information is available on the N response of regenerated tillers in different node positions of RC. The hypothesis is that N response varied among node positions of regenerated tillers. [METHODS] Field experiments were conducted in 2019 and 2020 to compare yield performance of regenerated tillers of upper and lower node positions in RC under various combinations of N B and N T treatments and two cutting heights (15 and 45 cm) using a rice variety Huanghuazhan. showed that there was no significant difference in grain yield among N treatments of regenerated tillers in upper node (3rd and 2nd nodes from the top for 15 and 45 cm cutting height, respectively). However, N B and N T significantly increased the grain yield of regenerated tillers in lower nodes by 23.5 %− 52.7 % and 49.3 %− 115.7 %, respectively, which was mainly attributed to increased panicles m −2 for both cutting heights. N application also increased total dry weight and total N uptake of regenerated tillers in lower nodes, but not in upper node. Furthermore, a significant and positive correlation between grain yield and total N uptake was observed for regenerated tillers in lower nodes, but not in upper node. Our results indicate that regenerated tillers in lower nodes were more responsive to N application than those in upper node. [IMPLICATIONS] Therefore, optimization of N management for RC should emphasize on the N response of regenerated tillers in lower nodes for achieving high grain yield of RC. • Nitrogen (N) responses of tillers varied among node positions in ratoon crop. • Nitrogen responses of tillers in lower nodes were higher than in upper node. • Cutting height did not change N responses of tillers in various node positions. • Yield variation of ratoon crop was mainly due to the tillers in lower nodes.

Mapping the potential northern limits and promotion extent of ratoon rice in China

Ratoon rice has emerged as a promising rice cropping system to improve grain production and reduce labor costs compared with traditional single/double rice in China. However, the potential planting areas of ratoon rice in China remain unclear. This research investigated the potential northern limits and promotion extent of ratoon rice in China by considering its climatic suitability based on the optimized maximum entropy (MaxEnt) model as well as terrain and land use conditions. The MaxEnt model derived by all environmental variables yielded a good performance, with average AUC (area under the curve) and TSS (true skill statistic) over the validation dataset of 0.940 and 0.825, respectively. The comparison with field samples and previous studies revealed the reliability of the derived potential promotion areas. Potential northern limits contained a closed curve surrounding the Sichuan Basin, and the other curve ran from Yunnan Province to Jiangsu Province. Safe promotion areas of ratoon rice in China were 472,003 km2, mainly located in Sichuan, Hubei, Guangxi and Hunan. Risky promotion areas were 74,150 km2, which were dominant in Henan, Anhui and Yunnan. Our study provides crucial information for rice planting pattern adjustment to alleviate national food insecurity caused by the loss of double rice.

Quality Characteristics of Noodles Processed from Rice Grains of the Ratoon Crop

Rice noodles are usually manufactured using rice grains of the main crop. There is limited information available on rice noodles processed from ratoon rice grains. In this study, two-year field experiments were conducted to compare the cooking and texture properties of noodles and the grain chemical properties of ratoon crops with those of main crops from two rice cultivars (Guichao 2 and Zhenguiai) that are widely used for processing noodles. Results showed that the cooked break rate and the cooking loss rate of rice noodles processed from grains of the ratoon crop were similar to those of the main crop in both cultivars; however, changes in texture of cooked rice noodles processed from grains of the ratoon crop compared with the main crop were cultivar-dependent, being significantly softer in Zhenguiai but not in Guichao 2. Hardness and chewiness of cooked rice noodles were significantly negatively correlated with amylopectin content in milled rice grains in Zhenguiai, indicating that amylopectin content is a key chemical property determining the texture differences between rice noodles processed from grains of ratoon and main crops.

Physiological and transcriptomic analysis reveal the regulatory mechanism underlying grain quality improvement induced by rice ratooning.

Ratoon rice cropping has been introduced for increased rice production in southern China and, as a result, has been becoming increasingly popular. However, only a few studies have addressed the regulatory mechanism underlying grain quality improvement induced by rice ratooning. In this study, parameters of rice quality, including head rice yield, chalky grain percentage, grain chalkiness degree, hardness and taste value, were shown to be much improved in the ratooning season rice as compared to its counterparts main and late cropping season rice, indicating that such an improvement was irrespective of seasonal effects. In addition, the nutritional components of grains varied greatly between main-cropping season rice, ratooning season rice and late-cropping season rice and displayed a significant correlation with rice quality. Finally, the regulatory mechanism underlying rice quality improvement revealed that gibberellin-dominated regulation and plant hormone signal transduction jointly contributed to a decrease in formation of chalky grains. This work improves our knowledge on rice quality improvement under rice ratooning, particularly on the regulatory mechanism of plant hormones. © 2022 Society of Chemical Industry.

Study on path planning of mechanized harvesting of ratoon rice in the first season based on the capacitated arc routing problem model.

The stubble crushing caused by the harvester during the first season of ratoon rice harvesting will directly affect the grain yield of the ratoon season. In this work, a harvester path planning method for quadrilateral fields to address the harvester driving path problem of the first season of ratoon rice mechanized harvesting is proposed. This research first analyzes the operational characteristics and requirements of ratoon rice first-season mechanized harvesting, and then models the mechanized harvesting process of ratoon rice in the first season as a capacitated arc routing problem (CARP) considering the fact that the harvester cannot complete the full-coverage harvesting operation at one time due to the limitation of grain bin volume. The genetic algorithm (GA) with strong global search capability is used to solve it, and the selection and variation links of the algorithm are improved. The path planning method proposed in this article can dynamically find the optimal harvester travel route according to the specific conditions of the field and the parameters of harvester implements. The simulation test shows that the CARP method performs better in terms of harvesting path length and crushed area compared to the conventional rectangular detour and foldback reciprocating harvesting paths. The degree of optimization of this method is influenced by various factors such as the width of the cutting table, the turning radius of the harvester, and the size of the grain bin capacity. This research provides a more efficient and flexible path planning method to improve the efficiency of ratoon rice first-season mechanized harvesting operations and optimize the harvester's operating path, which can well meet the operational requirements.