Number Of Panicles Research Articles

Morphoagronomic descriptors of rice landraces varieties (Oryza sativa L.) from the state of Maranhão

Rice landrace varieties are adapted to the most diverse environmental conditions, which is clearly important in periods of great climatic and sanitary uncertainties. However, there is a gap in their description in the literature. Maranhão, Brazil, has wide diversity in landrace seeds, with rice varieties that can significantly contribute to the genetic breeding of the species. Based on this information, the objective of the present study was to characterize the landraces rice varieties, through the description of the morphological and agronomic profile. The study analyzed 23 qualitative heredity descriptors and three quantitative descriptors in 21 rice landrace varieties from different locations in the state of Maranhão, according to the methodological procedures recommended by the National Cultivar Protection Service. A randomized block e experimental design was used (DBC), with 21 treatments and four replications. Considering complementing To complement the study, a multicategorical analysis was carried out between the 21 accessions, based on qualitative data obtained from the 22 morphological descriptors, which generated a dendrogram. The results showed that there are differences between the qualitative descriptors. Quantitative descriptors are highly significant, with regard to the number of tillers, with emphasis on the Edinho variety. The Quechi variety was responsible for one of the factors that most influences the rice yield, with the highest number of grains per panicle. The varieties Codozinho, Edinho, Palha Murcha and Pé Roxo, are more productive in number of panicles. The dendrogram formed three clusters with evidence of dissimilarities between the varieties. The results show that the landrace varieties differ in their morphoagronomic characteristics and can be valuable materials in the construction of a new, more sustainable agriculture.

Physiological and Biochemical Basis of Variation in Yield of Rice (Oryza sativa L.) under CA-based Crop Establishment Methods and Nutrient Management in R-W Cropping System

Background: Crop establishment methods and nutrient management practices treatments were continuously practiced in the same plots since 2011-12 as a part of long-term experiment. A field study was conducted during 2019-2020 and 2020-2021 i.e. during 9th and 10th year of study to investigate the effects of CE methods and nutrient management on growth, physiological, biochemical, yield attributes and yield of rice crop. Methods: Field experiments were carried out at the Agricultural Research Farm, Banaras Hindu University, Varanasi, laid out in split plot design replicated thrice with four crop establishment (CE) methods viz., CT (puddled transplanted) rice-CT wheat (CE1),CTDSR rice-CT wheat (CE2), CTDSR- ZT wheat (rice residue retention) (CE3), ZT rice-ZT wheat (residue retention in rice and wheat) (CE4) in main plots and three nutrient management (NM) practices viz., FP (164 kg N, 50 kg P2O5, 32 kg K2O and 4 kg Zn ha-1) (N1), RFD (150 kg N, 60 kg P2O5, 60 kg K2O and 5 kg Zn ha-1) (N2) and SSNM- RWCM recommendation (N3). The rice variety used was ‘Sarju-52’ in the present study. Result: The recorded data revealed that ZT rice–ZT wheat (CE4) recorded significantly higher plant height, tillers hill-1, leaf area, RWC, total chlorophyll content and protein content as compared to other CE methods. Among NM practices, SSNM-RWCM (N3) recorded significantly higher plant height, tillers hill-1, leaf area and protein content, whereas, RWC and total chlorophyll content did not differ significantly over farmer’s practice and recommended fertilizer dose. Improved growth and physio-chemical attributes in ZT rice-ZT wheat (CE4) and SSNM-RWCM (N3) resulted in significantly higher panicles hill-1, fertility percentage and number of filled grains panicle-1 over other CE methods and NM practices. Panicle length, spikelets panicle-1 and test weight showed non-significant differences. Grain yield, straw yield and biological yield were significantly higher in ZT rice-ZT wheat (CE4) among CE methods and SSNM-RWCM (N3) among NM practices. The harvest index showed non-significant differences for CE methods and NM practices both.

Multiple-Criteria Decision Analysis for Effect of Shoot Growth at Difference Combination Nutrient Fertiliser NPK for Harumanis Mango

It is vital to have the correct fertiliser arrangement for effective tree development, fruit yield, and essential fruit quality. The amount of fertiliser suggested with adequate nutrition will be maintained in the soil to supply the needs of the trees as they grow throughout the various growth stages. This study evaluated the effect of different combinations of Nitrogen(N), Phosphorus(P), and Potassium(K) on the vegetative flush physiology of Harumanis mango (Mangifera Indica. L). Single and combinations of N (511g), P(511g), and K(255g) fertilisers were used, which were N, P, NP, and NPK throughout May 2021. The results revealed that the minimum number of mature green leaves and a higher number of healthy panicles were observed in the NPK-treated plants. Moreover, NPK treatment showed the lowest malformation intensity percentage compared to other fertiliser treatments. The data were analysed to obtain the best regrowth pattern of shoots using Multiple-Criteria Decision Analysis (MCDA) techniques. The results on the pattern of regrowth after pruning when federalised with NPK fertiliser showed that the maximum percentage of total vegetative flush was 87.5% and the remaining 12.5% did not reach a satisfactory level according to the MCDA analysis.

Improving yield and water productivity of rice in sodic soil with saline water through drip irrigation

A field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli, to determine suitable rice varieties and lateral spacing for drip irrigation in sodic soil with saline water. The experiment involved four short duration rice varieties ('ADT 36', 'ADT 45', 'TRY (R) 2', and 'Anna (R) 4' ) and four pre-release rice cultures ('TR13-069', 'TR13-083', 'TR09-27', and 'TR09-30'). Drip systems were installed with lateral spacing of 45 cm and 90 cm, and emitter/dripper spacing of 30 cm. Drippers had a discharge rate of 2.0 liters per hour, and irrigation was scheduled at 100% pan evaporation rate, applied every alternate day. The variety, ''TRY (R) 2'' produced a greater number of panicles (365/m2) and a higher percentage of tillers to panicles conversion (77%) while ''ADT 36'' exhibited a higher number of filled grains (99.5/panicle) and total grains per panicle (117.4). With respect to yield, ''TRY (R) 2'' achieved the highest grain yield of 2991 kg/ha, followed by ''ADT 36'' and ''Anna (R) 4 ''. The drip lateral spacing of 90 cm exhibited significantly higher yield compared to a spacing of 45 cm. The varieties ''ADT 36'' and ''ADT 45'' utilized 550.3 mm of irrigation water and received 283.5 mm of rainfall, while ''Anna (R) 4 '' and ''TRY (R) 2'' used a total of 871.9 mm of water, including 575.2 mm of irrigation water and 296.7 mm of rainfall. Variety ''TRY (R) 2'' demonstrated a higher water productivity of 3.58 kg/ha/mm, followed by ''ADT 36''. Based on these findings, it is recommended to grow the ''TRY (R) 2'' rice variety under drip irrigation with a lateral spacing of 90 cm in sodic soil with saline water conditions, as it showed superior performance in terms of grain yield and water productivity.

Analysis of Erect-Panicle Japonica Rice in Northern China: Yield, Quality Status, and Quality Improvement Directions.

China is the only country that extensively cultivates the indica and japonica rice varieties, with the largest japonica rice production area being in northeast China. A study of the relationship between the yield and quality of japonica rice and the effect of nitrogen fertilizer application on this relationship is important. In this paper, we aimed to assess the current yield and quality of japonica rice in northeast China. We selected erect-panicle varieties as the test materials. Field experiments were conducted using different nitrogen fertilizer levels for two consecutive years to analyze the rice varieties' yield, quality, interrelationship, and nitrogen fertilizer response. The average yield following high- and low-nitrogen treatments exceeded 10,000.00 kg/hm2, with a maximum of 12,285.63 kg/hm2. The high-yield-high-nitrogen treatment group had more panicles, a higher seed-setting rate, and a higher 1000-grain weight than the other groups. The high-yield-low-nitrogen group had a higher number of panicles and seed-setting rate than the other groups. The low-yield-high-nitrogen group had a lower number of whole grains, grain length-to-width ratio, and taste value than the other groups. The low-yield-low-nitrogen group had fewer primary branches than the other groups; excluding the primary branch-setting rate and 1000-grain weight, the values of the other panicle traits of the group were significantly higher than those of the other groups. The high-nitrogen-high-flavor group had lower panicle and spikelet numbers and higher spikelet fertility rates than the other groups. The low-nitrogen-high-flavor group had higher spikelet fertility rates and 1000-grain weight than the other groups. Compared to the other groups, the low-nitrogen-high-flavor group had a higher head rice yield, and the high-nitrogen-high-flavor group had a lower chalkiness rate. The main goal of the breeding and cultivation of high-yield and high-quality erect-panicle japonica rice in northern China is to achieve "dual high, dual low, and one high and one low" conditions, signifying a high yield with high or low nitrogen levels, low protein and amylose contents, high head rice rates, and low chalkiness. This study provides a new technique for enhancing the taste of northern erect-panicle japonica rice to promote the sustainable, high-yield, and high-quality development of japonica rice in northern China.

Influence of natural and artificial selection on the yield differences among progeny derived from crossing between subspecies in cultivated rice

Extended natural and artificial selection have introduced pronounced differences throughout the genomes, morphological traits, and geographical distributions of the two predominant rice strains, Oryza sativa Xian/indica (XI) and O. sativa Geng/japonica (GJ). However, the unique roles of natural and artificial selection in strain differentiation remain uncharacterized. Therefore, we independently produced advanced inbreeding populations in typical GJ- and XI-cultivated areas, beginning from the F2 generation. We utilized pedigree and bulk-selective methods to characterize artificial and natural selection, respectively. Our examination uncovered preferences between artificial and natural selection. Artificial selection was favored by individuals with increased grain count per panicle but reduced panicle number, while natural selection favored traits like greater panicle number, reduced grains per panicle, and higher thousand-grain weight, especially in the XI cultivation areas. Notably, in the XI regions, natural selection produced a preference for wider grains, indicating that the elongated grains in XI rice may be caused by artificial rather than natural selection. Using de novo assembly of a high-quality parental genome, we observed an increased prevalence of the GJ genotype in GJ areas compared to XI areas, segregation distortion in the advanced inbreeding population could be attributed to loci regulating hybrid sterility. Notably, the semi-dwarf allele sd1-d, linked to the “Green Revolution”, was not favored in either selection paradigm in northern areas, possibly due to its disadvantages on grain yield per plant and NH4+ uptake rate. Our study offers novel perspectives into the contributions of natural and artificial selection to the divergence between XI and GJ subspecies.

Evaluation of annual production and economic benefits of tropical rice-crayfish coculture system in China

CONTEXTIn recent years, the rice-crayfish coculture has shown significant progress as an agricultural technology with significant economic value in the middle and lower reaches of the Yangtze River in China. Nonetheless, as the promotion of the technology expands, the unvarying co-culture method poses challenges in adapting to the diverse environmental conditions across different regions. This has resulted in regional disparities dominated by environmental factors, which have emerged as the primary obstacle to the advancement of rice-crayfish coculture. OBJECTIVEIt is uncertain whether the rice-crayfish coculture model can be implemented in tropical regions due to the higher temperature and stronger solar radiation. Therefore, this study analyzes the feasibility of establishing the rice-crayfish coculture model through estimating the rice and crayfish annual production and the economic and ecological benefits in the tropical region. METHODSThe growth, annual production, and nitrogen partial factor productivity (NPFP) of rice, nitrogen dynamics in the field water, as well as the economic inputs and benefits associated with the rice-crayfish coculture system over two years were evaluated in Hainan province. RESULTS AND CONCLUSIONSIt was found that: 1) Even with a reduction of 33.3% in nitrogen fertilizer application, the annual production of the rice-crayfish coculture system remains equivalent to that of the rice monoculture system. Furthermore, the rice-crayfish coculture can increase the effective panicle number of rice. 2) The rice-crayfish coculture system can provide nutrients to support rice growth without polluting the water environment. The nitrogen fertilizer partial productivity in the rice-crayfish coculture system is significantly higher than that in the rice monoculture system. Crayfish culture introduced additional nitrogen in rice field at early stage, but it did not gain any form of nitrogen content in the field water at the end of the season. 3) In comparison to the rice monoculture system, the tropical rice-crayfish coculture system increased net profit by 152.82% -745.26%. 4) Comprehensive analyses of the growth, yield, and economic benefits showed that SXHN is better than YXYLS, which indicated that suitable varieties were needed for developing rice-crayfish coculture in the tropics. SIGNIFICANCERice-crayfish coculture is an economic and ecological agricultural system. However, rice-crayfish coculture encounters extensive technical challenges across various regions, because of the varied culture conditions. These challenges impede the expansion of the rice-crayfish coculture model. Therefore, this study aimed to evaluate the practicality of the rice-crayfish coculture system in the tropics to facilitate the development of the rice-crayfish coculture model.

Research status and prospect of ratoon rice in China under mechanically harvested condition.

The proportion and area of ratoon rice planting in China have been substantially increased, due to continuous improvement of rice breeding methods and consecutive innovation of cultivation technology, which has developed into one of rice planting modes with significant production efficiency. Combining the experience in research and practice, from the perspective of crop physiology and ecology, we reviewed the current situation and prospects of high-yielding formation and physiological mechanisms of ratoon rice. We focused on four key aspects: screening and breeding of ratoon rice cultivars and the classification; suitable stubble height for mechanically harvested ratoon rice, as well as water and fertilizer management; dry matter production and allocation in ratoon rice and the relationship with yield formation; regenerative activity and vigor of ratoon rice roots and their relationship with rhizosphere micro-ecological characteristics. As for the extending of mechanized low-cut stubbles ratoon rice technique, we should properly regulate the rhizosphere system, coordinate rhizosphere nutrient supply, germination of axillary buds, and tillering regeneration, to achieve the target of "four-high-one-low", that is high regeneration coefficient, high number of regeneration panicle, high harvest index, high yield, high quality, low-carbon and safe, aiming to improve the sustainability of ratoon rice industry.

Soil Nitrogen Distribution Affects Nitrogen Utilization and Yield of Drip-Irrigated Rice

The cultivation of drip-irrigated rice has resulted in lower yields. However, the decrease in rice yield under drip irrigation and its relationship with the existing water and N regime have not been fully explained. Research and development of optimized water and N-management techniques are crucial for increasing rice yield under drip irrigation. In this study, two irrigation treatments were set: conventional drip irrigation (DIO) and drip irrigation with water stress (DIS). Each irrigation treatment contained four N rates: urea N 240 kg ha−1 (LN), urea N 300 kg ha−1 (MN), urea N 360 kg ha−1 (HN), and ammonium sulfate N 300 kg ha−1 (AN). The soil’s ammonium and nitrate contents were measured on the 2nd and 28th days after N application at panicle initiation stage. At anthesis, the aboveground and root biomass of rice were measured. In heading and maturity stage the N content of aboveground was measured and the yield, yield components, and NPFP were assessed at maturity stage. The results showed the following: (1) On the second day after N application, the contents of soil NO3−-N and NH4+-N in the 0–10 cm soil layer were highest for both the DIO and DIS. On the 28th day after N application, the soil NO3−-N content was highest at the 20–40 cm depth, while the soil NH4+-N content was still highest at the 0–10 cm depth. (2) The aboveground and root biomass in DIO treatment were significantly higher than in DIS. Furthermore, the root biomass at the 0–10 cm depth was significantly greater than at the 10–50 cm depth for both the DIO and DIS treatments. In the DIO treatment, the root biomass at the 10–50 cm depth was significantly higher with the HN and AN treatments compared to MN. However, in the DIS treatment, the root biomass at the 10–50 cm depth did not show significant differences between the MN, HN, and AN. (3) N accumulation in rice was significantly higher for the DIO treatment compared to the DIS treatment. Under the same irrigation treatment, the N accumulation in rice was highest in the AN and lowest in the LN. The PrNTA and PrNTC in DIS were significantly higher than in DIO, while the PoNAA and PoNAC were significantly lower in DIS. (4) The number of panicles, spikelets per panicle, seed-setting rate, 1000-grain weight, and grain yield were significantly lower in DIS. Under the DIS, these parameters were not significantly different among the MN, HN, and AN. In the DIO, the seed-setting rate, 1000-grain weight, and yield were not significantly different between the HN and AN, but were significantly higher than in the MN and LN. (5) NPFP was significantly higher in the DIO compared to the DIS. Among the different N rates, NPFP was highest with the AN treatment and lowest with the LN. In summary, under drip irrigation, there was a mismatch between soil mineral N and the distribution of rice roots, leading to reduced N accumulation and utilization in rice, ultimately impacting yield formation. Increasing N application and soil ammonium nutrition can improve rice yield under drip irrigation. However, optimizing N fertilizer management may not increase rice yield further when irrigation is further limited.

Performance of Direct-Seeded Upland Rice-Based Intercropping Systems Under Paired Rows in East-West Orientation

Production potential of rice based intercropping systems with legumes in Uganda is little known. Studies were conducted at Ikulwe Station of the National Agricultural Research Organisation to evaluate upland rice-based intercropping systems under paired-rows in the EW direction. A randomized complete block design with 3 replications was adopted during 2022 and 2023 with 8 pure stand and intercropped treatments. Adjustment from conventional planting to paired rows recorded high rice height and significant 1000 seed weights. In 2022 the 2 pure rice treatments produced significantly more tillers and panicles but legume intercrops reduced numbers of rice tillers and panicles. Intercropping significantly reduced the beans height (48%) and soybean pods (41%) during both years and also reduced the pods filling for beans (66%), groundnuts (36%) and soybeans (18.3%) during 2022. Although paired rice did not influence rice yield during both years, lower mean yield for rice (19.8%), beans (35%), groundnuts (33%) and soybeans (30.5%) were recorded. Lower legume intercrop yields were similarly recorded for beans (70%), groundnuts (73%) and soybeans (62%) during 2023. Partial (p) land equivalent ratios (LER) for intercrops were not significant and less than unity, but the one for rice intercropped with beans increased to more than unity (1.06) during 2023. All combined LER for rice-legumes were more than unity and the pLER of sole crops was 1.0. Rice + beans recorded high area time equivalent ratio during the 2 years while high relative equivalent yield and monetary advantage indices were recorded under rice + soybeans. Rice was more aggressive than other crops and intercropped treatments recorded higher Total Rice Grain yield equivalent (TRGYE) than sole rice. Rice + soybeans (2022) and rice + beans (2023) scored higher TRGY. The findings suggest that farmers can intercrop soybean in rice under paired rows in EW orientation for more benefits.

Assessing vegetation indices and productivity across nitrogen gradients: a comparative study under transplanted and direct-seeded rice

Nitrogen responses vary under diverse agronomic management practices, influencing vegetation indices (VIs) and productivity across different ecological conditions. However, the proper quantification of these responses under various crop establishment methods with varied nitrogen levels is rarely studied. Therefore, a field experiment was conducted to investigate the impact of varying nitrogen levels on VIs, growth parameters, yield attributes, yield, and economic aspects of transplanted rice (TR) and direct-seeded rice (DSR). The experiment was conducted in the randomized block design consisted seven N levels, which included 0% recommended dose of nitrogen (RDN) or no nitrogen (N0), 33.33% RDN (N1), 66.66% RDN (N2), 100% RDN (N3), 133.33% RDN (N4), 166.66% RDN (N5) and 200% RDN (N6), and replicated thrice. The plots with higher N levels demonstrated increased values of VIs and treatment N3 (120 kg N ha−1), N4 (160 kg N ha−1), N5 (200 kg N ha−1), and N6 (240 kg N ha−1) showed no statistically significant differences in NDVI (normalized difference vegetation index), RVI (ratio vegetation index), NDRE (normalized difference red edge), and GNDVI (green normalized difference vegetation index) values across the various growth stages of rice. The application of treatment N4 resulted in the highest number of panicles m−2 (348.2 in TR, 376.8 in DSR), filled grains panicle−1 (74.55 in TR, 62.43 in DSR), and a 1,000-grain weight of 26.92 g in TR and 26.76 g in DSR. The maximum yield (4.89 t ha−1) was obtained in transplanted rice at treatment N4 and, 8.15% yield reduction was noted in DSR for the same treatment, which was statistically equivalent to N3, but significantly superior to other N levels. Conversely, in DSR with RDN (120 kg N ha−1), the cost–benefit ratio surpassed that of TR by 16.96%, signifying DSR’s adaptability for more profitable rice cultivation in the region. This research provides valuable insights into optimizing nitrogen management practices for TR and DSR, thereby enhancing rice crop performance and economic returns.

Effects of organic nutrient management on aromatic rice (Oryza sativa)-linseed (Linum usitatissimum) sequence

The experiment was conducted during 2019 and 2020 at the Instructional-cum Research (ICR) Farm, Assam Agricultural University, Jorhat, Assam to study the impact of different combinations of organic nutrient sources on aromatic rice (Oryza sativa L.) (rainy-kharif) and their residual effect on linseed (Linum usitatissimum L.) (winter- rabi) crop for developing a double cropping sequence for rice growers of Assam with organic management. The experiment comprised three aromatic rice cultivars, viz. Kola joha, Keteki joha and Chakhao poireiton and five combinations of organic nutrient sources. Out of the organic nutrient sources, application of N @30 kg/ha through vermicompost along with pre-season green manuring of Sesbania bispinosa and root dip treatment of rice seedlings with Azospirillium and phosphorus solubilising bacteria @3.5 kg/ha each (N3) resulted the highest number of panicles/ m2 (216.72 in 2019 and 223.96 in 2020), highest yield of rice (30.26 q/ha in 2019, 32.58 q/ha in 2020 grain yield and 65.99 q/ha in 2019, 68.98 q/ha in 2020 straw yield). The highest seed yield (394.52 kg/ha in 2019, 416.97 kg/ha in 2020) and stover yield (890.09 kg/ha in 2019, 896.63 kg/ha in 2020) of succeeding relay sown linseed were recorded with the N3 treatment. The highest available N (250.10 kg/ha), P2O5 (20.40 kg/ha) and K2O (140.06 kg/ha), organic C (0.65%), soil organic carbon (SOC) stock (13.29 t/ha), soil microbial biomass carbon (SMBC) (183.43 µg/g of soil) in soil were recorded with the N3 treatment after harvest of linseed in 2020. The study affirmed the suitability of rice-linseed cropping sequence for efficient utilization and conservation of resources.

Effects of plant density and nitrogen splitting on grain yield and nitrogen uptake in rice re-cropping

Rice (Oryza sativa L.) re-cropping has a special place in the crop rotation of rice plants in terms of increasing the efficiency of land productivity. A two-year research (2013–2014) was done with three replications to determine the best planting density and appropriate nitrogen splitting in rice re-cropping at Qaemshahr Agricultural Faculty, Mazandaran, northern Iran. For this purpose, a split plot design in RCBD format was used. Experimental factors consisted of plant density (33.3, 25, and 16 plants per sq m at intervals of 30 × 10, 20 × 20, and 25 × 25 cm2, respectively) as the main factor, and nitrogen splitting (NS1: all as a base, NS2: 1 2 base + 1 2 tillering, NS3: 1 2 base + 1 2 panicle formation, NS4: 1 3 base + 1 3 tillering + 1 3 panicle formation, and NS5: 1 3 base + 1 3 panicle formation + 1 3 end of panicle emergence) as subfactors. The results showed that the grain yield was higher for 2014 than in 2013 by 60.0%, due to increasing the number of panicles per sq m (27.2%) and the weight of 1000 grains (7.2%). The maximum grain yield was achieved at a density of 33.3 plants per sq m along with NS4 treatment. The highest straw nitrogen uptake was observed in 2013 by NS4 treatment. The maximum grain nitrogen concentration, nitrogen harvest index, and grain protein yield were recorded in 2014 along with NS4 treatment. The density of 33.3 plants per sq m and NS of 1 3 base + 1 3 tillering + 1 3 panicle formation are suggested for rice re-cropping.

Effect of sowing date on radiation and temperature use efficiencies of rice in the low-light region of China

Sowing date optimization is an effective measure for adapting to climatic change and has been widely used to optimize the use of solar radiation and temperature resources in rice production. To evaluate the influences of sowing date on radiation and temperature use efficiencies (RUE and TUE, respectively) and grain yield of rice in low-light regions, field experiments with three rice varieties and four sowing dates (S-0, S-10, S-30, and S-40) were conducted at Dayi, Anzhou, Nanbu, and Shehong, in Sichuan, China, in 2018 and 2019. The results showed that the yield, RUE, and TUE of rice were significantly and negatively correlated with delayed sowing dates across the study sites. Generally, delayed sowing dates increased the daily total solar radiation, daily mean temperature, and effective cumulative temperature before heading, but decreased the growth duration and cumulative total solar radiation before heading, which resulted in a reduction in the effective panicle number per unit area. Meanwhile, delayed sowing dates increased the growth duration after heading, but reduced the daily total solar radiation, daily mean temperature, cumulative total solar radiation, and effective cumulative temperature after heading, contributing to a decrease in both the seed setting rate and 1000-grain weight across study sites. Therefore, S-30 and S-40 markedly decreased the rice yield, RUE, and TUE at Anzhou, Nanbu, and Shehong in both years and at Dayi in 2019, compared to S-0 and S-10. Moreover, growth duration, solar radiation, and temperature parameters before and after heading could explain the 73.7 % variation in the relative grain yield, relative RUE, and relative RTUE across the study sites. Ensuring that the daily mean temperature after heading and growth duration before heading are greater than 25.8°C and 113 d, respectively, and the daily total solar radiation and mean temperature before heading and growth duration after heading are lower than 14.7 MJ m–2 d–1, 23.1°C, and 42 d, respectively, by earlier sowing, is required to improve the RGY, RRUE, and RTUE in the low-light regions of China.

Vetiver grass cleans up arsenic contaminated field for subsequent safe cultivation of rice with low arsenic in grains: A two year field study

The presence of high concentrations of arsenic (As) in agricultural soils and its subsequent accumulation in rice crop is a serious issue threatening sustainability of agriculture and human health. In the present work, remediation of As contaminated field in Nadia, West Bengal, India was done through the cultivation of Vetiver (Vetiveria zizanoides L. Nash) and the same field was subsequently used for rice (Oryza sativa L.) cultivation. The results showed that V. zizanoides could reduce As concentrations in the field to bring it lower than the maximum permissible limit (20 mg kg−1) in 11 months' time. The rice plants grown in remediated field showed improvement in growth and photosynthesis parameters as compared to that of contaminated field. Importantly, yield related parameters (filled seed, 1000 grain weight, number of panicles etc.) were also significantly higher in remediated field than that in contaminated field. Arsenic concentration in roots, shoot, husk and grains of rice was found to be significantly lower in remediated field than in contaminated field. Grain As decreased from 0.75 to 0.77 μg g−1 dw in contaminated field to 0.15–0.18 μg g−1 dw. In conclusion, replacing rice for single year with V. zizanoides crop can significantly remediate the field and can be a viable option.

Refuge plants and jajar legowo systems increasing the useful arthropods population and the rice yield

Ecological engineering has become a promising strategy for restoring paddy field biodiversity and enhancing yield. This study aims to evaluate the effectiveness of refuge plants and cropping systems on the population of useful arthropods and rice production. The study was conducted on a paddy field in Central Sulawesi, Indonesia, using a Split Plot Design. The main plots were refuge plants with four treatments, namely rice without refuge crops, rice crops with wild Cosmos (C. caudatus), marigold (Tagetes erecta), and both flower plants as the refuges, whereas two cropping systems, i.e., the jajar legowo system (JLS) of 2:1 and the symmetries system (SS) was set up as a sub-plot. Direct observation and collection of the arthropods were carried out using yellow-pan traps and a sweep net. The parasitoid eggs were reared at the laboratory. In addition, rice growth and yields were measured. The refuge plants and cropping system had no significant effects on the overall arthropods population but changed their diversity and community structure and increased the proportion of useful arthropods as well. Meanwhile, rice production in the JLS (5.16 tons GKG ha−1) was significantly higher than those of the SS (4.10 tons GKG ha−1), and this was in line with the differences in the panicles number in both cropping systems. The study highlighted the importance of the implementation of ecological engineering at the paddy fields by using the flower plants as the refuge and food sources for the beneficial organisms combined by JLS for enhancing the rice yields.

Reduced tillage coupled with straw returning improves grain yield and 2-acetyl-1-pyrroline content in fragrant rice

The practice of conservation tillage or straw returning to the farmland influences the grain yield and quality of rice (Oryza sativa). The key volatile compound responsible for the fragrance in fragrant rice is 2-acetyl-1-pyrroline (2-AP), which is significantly affected by field management measures. The purpose of this study was to investigate the impact of tillage management and straw returning on the grain yield and biosynthesis of 2-AP in fragrant rice. This study was conducted over two years in 2016 and 2017 and utilized two fragrant rice cultivars (Meixiangzhan 2 and Xiangyaxiangzhan) as materials. It consisted of different tillage managements and straw returning treatments, which included three tillage managements: rotary tillage (T0), minimum tillage (T1), and no tillage (T2), and two straw returning treatments: without straw returning (S0) and straw returning (S1). The straw used for the experiment was sourced from the residue of the early season harvested corresponding fragrant rice cultivar. Tillage management and straw returning substantially affected the grain yield, grain quality, and 2-AP content of both fragrant rice cultivars. Compared with the T0S0 treatment, tillage management and straw returning resulted in an improvement in the 2-AP content in 2016 (12.41-116.85%) and 2017 (34.85-103.89%) on average. A higher content of 2-AP was detected in both fragrant rice cultivars in the T2S1 and T1S1 treatments. A structural equation model (SEM) demonstrated that the enzyme activities of fragrance metabolism in the leaves and grain jointly regulated the biosynthesis of precursors of fragrance metabolism in the grain, which further promoted the accumulation of 2-AP. In addition, a principal component analysis indicated that the T1S1 treatment positively correlated with both 2-AP and grain yield. The SEM demonstrated that the enzymes related to nitrogen metabolism, parameters related to photosynthesis, and yield component contributed to the grain yield. The T1S1 treatment resulted in the highest average grain yield of 760.75 g m-2, which can be attributed to an increase in various attributes, such as the leaf area index, SPAD value, nitrogen metabolism, panicle number per m2, and grain number per panicle. The minimum tillage and straw returning (T1S1) treatment is more effective at simultaneously improving both the grain yield and 2-AP content in fragrant rice.

Genome-wide association studies of salinity tolerance in local aman rice.

The present study aimed to identify and characterize new sources of salt tolerance among 94 rice varieties from varied geographic origins. The genotypes were divided into five groups based on their morphological characteristics at both vegetative and reproductive stages using salinity scores from the Standard Evaluation System (SES). The experiment was designed as per CRD (Completely Randomized Design) with 2 sets of salinity treatments for 8 dS/meter and 12 dS/meter, respectively compared with one non-salinized control set. Using a Soil Plant Analysis Development (SPAD) meter, assessments of the apparent chlorophyll content (greenness) of the genotypes were done to comprehend the mechanism underlying their salt tolerance. To evaluate molecular genetic diversity, a panel of 1 K RiCA SNP markers was employed. Utilizing TASSEL 5.0 software, 598 filtered SNPs were used for molecular analysis. Whole-genome association studies (GWAS) were also used to investigate panicle number per plant (pn, tiller number per plant (till), SPAD value (spad), sterility (percent) (str), plant height (ph) and panicle length (pl. It is noteworthy that these characteristics oversee conveying the visible signs of salt damage in rice. Based on genotype data, diversity analysis divided the germplasm groups into four distinct clusters (I, II, III and IV). For the traits studied, thirteen significant marker-trait associations were discovered. According to the phenotypic screening, seven germplasm genotypes namely Koijuri, Asha, Kajal, Kaliboro, Hanumanjata, Akundi and Dular, are highly tolerant to salinity stress. The greenness of these genotypes was found to be more stable over time, indicating that these genotypes are more resistant to stress. Regarding their tolerance levels, the GWAS analysis produced comparable results, supporting that salinity-tolerant genotypes having minor alleles in significant SNP positions showed more greenness during the stress period. The Manhattan plot demonstrated that at the designated significant SNP position, the highly tolerant genotypes shared common alleles. These genotypes could therefore be seen as important genomic resources for accelerating the development and release of rice varieties that are tolerant to salinity.

Silicon Fertilizer Addition Can Improve Rice Yield and Lodging Traits under Reduced Nitrogen and Increased Density Conditions

Reducing nitrogen fertilizer application, selecting a reasonable planting density, and adding silicon fertilizer can be used together to decrease excessive nitrogen fertilizer inputs in rice fields, reduce production costs, and ensure stable rice yield. However, the dynamics of the stem and internodes, as well as the changes in the physical and physiological characteristics of rice under a combination of these three strategies, are still unclear. In this study, we aimed to clarify these effects to improve the efficiency of rice production in northeastern China. A 2-year field experiment was conducted using five treatments: a conventional densification treatment (DM), a densification combined with reduced N input (−20%) treatment (DLM), and three densifications combined with reduced N input (−20%) and basal silicon fertilizer treatments (low fertilizer: DLMS1; medium fertilizer: DLMS2; and high fertilizer: DLMS3). This study revealed that the addition of silicon fertilizer improved rice yield compared to that under reduced nitrogen or increased density treatments alone, prevented excessive ineffective tillering after a density increase, and increased the number of productive panicles. Among the treatments, the DLMS3 treatment had the highest yields of 10.53 t/ha and 10.73 t/ha over the 2 years. Reducing nitrogen and increasing density reduced the weight and length of single panicles, while the addition of silicon fertilizer was beneficial for improving stem toughness, improving the physical and physiological characteristics of the plants and panicles, and enhancing plant bending resistance. Among the treatments, DLMS3 had the highest bending resistance, which increased by 440.1 g and 503.8 g compared to the lowest values in the DM treatment in 2020 and 2021, respectively. Nitrogen reduction resulted in the lowest lodging index values, with DLMS3 having the lowest values in both years, which decreased by 19.6% and 22.5% compared to the highest values in DM (2020) and DLM (2021), respectively. This study indicates that the application of 150.0 kg/ha silicon fertilizer in combination with reduced nitrogen and increased density (DLMS3) reduces the lodging index while ensuring rice yield, preventing a tradeoff between yield reduction and lodging due to a density increase or due to nitrogen reduction combined with a density increase and allowing for a reduction in nitrogen fertilizer input, which could ensure a uniform yield and an increase in lodging resistance. These results provide a scientific basis for rice cultivation measures that lead to high yield and lodging resistance while protecting the environment.

Effectiveness of the Drought-tolerant Plant Growth Promoting Rhizobacteria (PGPR) that Supports Paddy Growth in Drought Condition

Drought stress is the primary constraint on plant-based food production, particularly paddy production. Several studies have examined plant resistance to heat and osmotic pressure. This study aimed to isolate bacteria with plant growth-promoting properties that could tolerate high temperatures and improve paddy growth during drought. Five isolates with a high optical density value (OD600) at 30% PEG 6000 (equivalent to -1.03MPa) and able to grow at high temperatures were identified based on the 16S rRNA gene sequences as Achromobacter spanius UKM UR10, Bacillus pumillus UKM UR11, Bacillus cereus UKM R66, and Bacillus altitudinis UKM RB11, which were isolated from the root, where as Bacillus sp. UKM S8 was isolated from rhizosphere soil. These isolates exhibited 1-amino cyclopropane-1-carboxylate (ACC) deaminase activities ranging between 1.01 and 1.12 mmol α-ketobutyrate mg-1 protein h-1, which degraded ACC to α-ketobutyrate and ammonia. Other plant growth promoters assessed include indole acetic acid (IAA; concentration between 9.69 and 13.15µg/ml) and phosphate solubilization (concentrations between 31.74 and 51.30 mg/l) production. Subsequently, the selected plant growth-promoting rhizobacteria (PGPR) were incorporated as a consortium and inoculated on paddy seeds, thus increasing total chlorophyll, proline, and soluble sugar content in paddy subjected to drought-stress conditions. Paddy yield components and performances, such as panicle number, spikelet number, dry grain weight, number of leaves, stalk length, and root length increased significantly. This isolated PGPR exhibits heat resistance, promotes plant growth, and can serve as an inoculant for paddy plants under drought conditions.