Yield potential and nitrogen use efficiency of China's super rice

In 1996, a mega project that aimed to develop rice varieties with super-high yield potential （super rice） was launched by the Ministry of Agriculture （MOA） in China using a combination of the ideotype approach and intersubspecific heterosis. Significant progress has been made in the last two decades, with a large number of super rice varieties being approved by the MOA and the national average grain yield being increased from 6.21 t ha^-1 in 1996 to 6.89 t ha^-1 in 2015. The increase in yield potential of super rice was mainly due to the larger sink size which resulted from larger panicles. Moreover, higher photosynthetic capacity and improved root physiological traits before heading contributed to the increase in sink size. However, the poor grain filling of the later-flowering inferior spikelets and the quickly decreased root activity of super rice during grain filling period restrict the achievement of high yield potential of super rice. Furthermore, it is widely accepted that the high yield potential of super rice requires a large amount of N fertilizer input, which has resulted in an increase in N consumption and a decrease in nitrogen use efficiency （NUE）, although it remains unclear whether super rice per se is responsible for the latter. In the present paper, we review the history and success of China＇s Super Rice Breeding Pro- gram, summarize the advances in agronomic and physiological mechanisms underlying the high yield potential of super rice, and examine NUE differences between super rice and ordinary rice varieties. We also provide a brief introduction to the Green Super Rice Project, which aims to diversify breeding targets beyond yield improvement alone to address global concerns around resource use and environmental change. It is hoped that this review will facilitate further improvement of rice production into the future.

Yield potential and stability in super hybrid rice and its production strategies

China＇s Super Hybrid Rice Breeding Program has made significant progress over the past two decades. In this paper, we reviewed our studies on the yield potential and stability in super hybrid rice and discussed the strategies for super hybrid rice production. The results of our studies show that rice yield potential has been increased by 12% in super hybrid cultivars as compared with ordinary hybrid and inbred cultivars. The higher grain yields in super hybrid rice cultivars are attributed to larger panicle size coupled with higher biomass production or higher harvest index. However, grain yields in super hybrid rice cultivars vary widely among locations depending on soil and climatic factors. Therefore, it is important to tailor target yield to local conditions in super hybrid rice production. The target yield for super hybrid rice production can be determined by the average yield method or the regression model method. Improving soil quality is critical to achieving the target yield in super hybrid rice production. Favorable crop rotations such as rice-oilseed rape and novel soil management practices, such as biochar addition, are effective approaches to improve soil quality. It is needed to develop simplified cultivation tech- nologies for super hybrid rice to meet the changes in socioeconomic environments during the period of transition. There are such technologies as no-tillage direct seeding and mechanized transplanting at high hill density with single seedling per hill.

Quantifying the spatial variation in the potential productivity and yield gap of winter wheat in China

Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential for estimating the food production capacity and improving agricultural policies to ensure food security. Gradually descending models and geographic infor- mation system （GIS） technology were employed to characterize the spatial variability of potential yields and yield gaps in winter wheat across the main production region of China. The results showed that during 2000-2010, the average potential yield limited by thermal resource （YGT） was 23.2 Mg ha-1, with larger value in the northern area relative to the southern area. The potential yield limited by the water supply （YGw） generally decreased from north to south, with an average value of 1.9 Mg ha-1 across the entire study region. The highest YGw in the north sub-region （NS） implied that the irrigation and drainage conditions in this sub-region must be improved. The averaged yield loss of winter wheat from nutrient deficiency （YGH） varied between 2.1 and 3.1 Mg ha-1 in the study area, which was greater than the yield loss caused by water limitation. The potential decrease in yield from photo-thermal-water-nutrient-limited production to actual yield （YGo） was over 6.0 Mg ha-1, ranging from 4.9 to 8.3 Mg ha^-1 across the entire study region, and it was more obvious in the southern area than in the northern area. These findings suggest that across the main winter wheat production region, the highest yield gap was induced by thermal resources, followed by other factors, such as the level of farming technology, social policy and economic feasibility. Furthermore, there are opportunities to narrow the yield gaps by making full use of climatic resources and developing a reasonable production plan for winter wheat crops. Thus, meeting the challenges of food security and sustainability in the coming decades is possible but will require considerable changes in water and nutrient management and socio-economic policies.

Suitable growing zone and yield potential for late-maturity type of Yongyou japonica/indica hybrid rice in the lower reaches of Yangtze River, China

Late-maturity type of Yongyou japonica/indica hybrids series （LMYS） have shown great yield potential, and are being widely planted in the lower reaches of Yangtze River, China. Knowledge about suitable growing zone and evaluation of yield advantage is of practicall importance for LMYS in this region. Fifteen LMYS, two high-yielding inbred japonica check varieties （CK-J） and two high-yielding hybrid indica check varieties （CK-I） were grown at Xinghua （119.57°E, 33.05°N） of Lixiahe region, Yangzhou （119.25°E, 32.30°N）of Yanjiang region, Changshu （120.46°E, 31.41°N）of Taihu Lake region, and Ningbo （121.31°E, 29.45°N） of Ningshao Plain in 2013 and 2014. The results showed that maturity dates of the 15 were later than the secure maturity date at Xinghua and 6, 14 and 15 LMYS were mature before the secure maturity date at Yangzhou, Changshu and Ningbo, respectively. One variety was identified as high-yielding variety among LMYS （HYYS） at Yangzhou, 8 HYYS in 201：3 and 9 HYYS in 2014 at Changshu, 9 HYYS at Ningbo. HYYS here referred to the variety among LMYS that was mature before the secure maturity date and had at least 8% higher grain yield than both CK-J and CK-I at each experimental site. Grain yield of HYYS at each experimental site was about 12.0 t ha-1 or higher, and was significantly higher than CK varieties. High yield of HYYS was mainly attributed to larger sink size due to more spikelets per panicle. Plant height of HYYS was about 140 cm, and was significantly higher than check varieties. Significant positive correlations were recorded between duration from heading to maturity stage and grain yield, and also between whole growth periods and grain yield. HYYS had obvious advantage over check varieties in biomass accumulation and leaf area duration from heading to maturity stage. Comprehensive consideration about safe matudty and yield performance of LMYS at each experimental site, Taihu Lake region （representative site Changshu） and Ningshao Plain （representative site Ningbo） were thought suitable growing zones for LMYS in the lower reaches of Yangtze River. The main factors underlying high yield ofHYYS were larger sink size, higher plant height, longer duration from heading to maturity stage and whole growth periods, and higher biomass accumulation and leaf area duration during grain filling stage.

The Effects of Climate Change on the Planting Boundary and Potential Yield for Different Rice Cropping Systems in Southern China

Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.

Influence of water potential and soil type on conventional japonica super rice yield and soil enzyme activities

We carried out a pool culture experiment to determine the optimal water treatment depth in loam and clay soils during the late growth stage of super rice. Three controlled water depth treatments of 0-5, 0-10 and 0-15 cm below the soil surface were established using alternate wetting and drying irrigation, and the soil water potential （0 to -25 kPa） was measured at 5, 10 and 15 cm. A 2-cm water layer was used as the control. We measured soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and rice yield. The results showed that the 0-5-cm water depth treatment significantly increased root antioxidant enzyme activities in loam soil compared with the control, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield did not differ from those of the control. The 0-10- and 0-15-cm water depth treatments also increased root antioxidant enzyme activities, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield decreased. In clay soil, the soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and yield did not change with the 0-5-cm water treatment, whereas the 0-10- and 0-15-cm water treatments improved these parameters. Therefore,the appropriate depths for soil water during the late growth period of rice with a 0 to -25 kPa water potential were 5 cm in loam and 15 cm in clay soil.

Cultivar selection can increase yield potential and resource use efficiency of spring maize to adapt to climate change in Northeast China

Northeast China (NEC) is one of the major maize production areas in China.Agro-climatic resources have obviously changed,which will seriously affect crop growth and development in this region.It is important to investigate the contribution of climate change adaptation measures to the yield and resource use efficiency to improve our understanding of how we can effectively ensure high yield and high efficiency in the future.In this study,we divided the study area into five accumulated temperature zones (ATZs) based on growing degree days (GDD).Based on the meteorological data,maize data (from agrometeorological stations) and the validated APSIM-Maize Model,we first investigated the spatial distributions and temporal trends of maize potential yield of actual planted cultivars,and revealed the radiation use efficiency (RUE) and heat resource use efficiency (HUE) from 1981 to 2017.Then according to the potential growing seasons and actual growing seasons,we identified the utilization percentages of radiation (P_R) resource and heat resource (P_H) for each ATZ under potential production from 1981 to 2017.Finally,we quantified the contributions of cultivar changings to yield,P_R and P_H of maize.The results showed that during the past 37 years,the estimated mean potential yield of actual planted cultivars was 13 649 kg ha^(–1),ranged from 11 205 to 15 257 kg ha^(–1),and increased by 140 kg ha^(–1) per decade.For potential production,the mean values of RUE and HUE for the actual planted maize cultivars were 1.22 g MJ^(–1) and 8.58 kg (℃ d)^(–1) ha^(–1).RUE showed an increasing tendency,while HUE showed a decreasing tendency.The lengths of the potential growing season and actual growing season were 158 and 123 d,and increased by 2 and 1 d per decade.P_R and P_H under potential production were 82 and 86%,respectively and showed a decreasing tendency during the past 37 years.This indicates that actual planted cultivars failed to make full use of climate resources.However,results from the adaptation assessments indicate that,adoption of cultivars with growing season increased by 2–11 d among ATZs caused increase in yield,P_R and P_H of 0.6–1.7%,1.1–7.6% and 1.5–8.9%,respectively.Therefore,introduction of cultivars with longer growing season can effectively increase the radiation and heat utilization percentages and potential yield.

Indica rice restorer lines with large sink potential exhibit improved nutrient transportation to the panicle,which enhances both yield and nitrogen-use efficiency

The yield and nitrogen use efficiency(NUE)of hybrid rice combinations are closely related to restorer line.Therefore,it is essential to evaluate the agronomic characteristics of restorer lines with high yield and high NUE(HYHN).However,it is unclear which restorer lines are HYHN,and neither have the common agronomic traits of the HYHN restorer lines been identified.Aiming to address this issue,we conducted two filed experiments using three nitrogen applications,which screened five HYHN restorer lines from 15 indica restorer lines.Yield,NUE and nutrient transportation of restorer lines with different yields and NUE types were examined.Yield and total nitrogen absorption in aboveground biomass(TNA)increased,whereas NUE for grain production decreased with increasing nitrogen application levels.The HYHN restorer lines had large spikelets and high weight per panicle that were significantly positively correlated with yield and NUE.Therefore,large sink potential may be beneficial for both yield and NUE.We further studied the differences in nutrient transportation to panicles between the HYHN and low yield and low NUE(LYLN)restorer lines and found that the former had a higher nitrogen absorption level and dry matter weight ratios of panicle in maturity.Moreover,the HYHN lines also had a higher root and neck-panicle node bleeding intensity per stem after heading and more developed vascular bundles of neck-panicle nodes and leaves than the LYLN lines,which could contribute to the transportation of nutrients from root to ground and from stem and leaf to spike.Therefore,the advantages of large sink potential of the HYHN restorer lines include large nutrient accumulation in and distribution to the panicles and smooth flow of nutrients along the transportation channels.

Juice, Ethanol, and Grain Yield Potential of Five Sweet Sorghum (<i>Sorghum bicolor</i>[L.] Moench) Cultivars

Sweet sorghum (Sorghum bicolor [L.] Moench) accumulates fermentable sugars in the stem and is increasingly being studied as a potential source of feedstock for bioethanol production. The objective of this study was to evaluate biomass and grain yield in five sweet sorghum cultivars (Dale, M81E, Sugar Drip, Della and Keller) and to determine quality of extractable juice and grain. Randomized complete block experiments were performed in the summer of 2009, 2010, and 2011. Leaf dry weight varied with year and cultivar and averaged 6177 kg·ha-1. Fresh stem weight ranged from 21 to 54 Mg·ha-1 with a mean across years and cultivars of 32.9 Mg·ha-1. Variations in stem weight were correlated with extractable juice volumes that ranged from 10 to 24 m3·ha-1. Juice Brix values fell within a narrow range (14% - 19%) across years and cultivars with an average of 15.6%. In all production years, theoretical sugar and ethanol yield were always numerically higher for Keller and M81E. Grain yield was lowest in Keller (90 kg·ha-1), but ranged from 400 to 1300 kg·ha-1 in other cultivars with a mean of 584 kg·ha-1 across years. However, Keller had the highest starch content with a lower proportion of resistant starch in the grain. Except for Keller, the cultivars tested are potential sources of both fermentable sugars and grain.

Groundwater Level Effect on Redox Potential, on Cadmium Uptake and Yield of Soybean

In this greenhouse experiment, we investigated the effects of two constant groundwater levels: 10 cm groundwater level (GW-10) and 40 cm groundwater level (GW-40) and one change groundwater level, which was 40-10-40 cm (GW-40-10-40) on Cadmium (Cd) uptake and seed yield of Soybean plant in Cd contaminated soils (1.57 mg·kg-1). The experimental soil layer was made with gravel layer (14 cm), non-polluted soil (15 cm) and polluted soil (25 cm). The redox potential of every soil layer was measured from sowing to harvesting. The soil layer (10 – 40 cm) of GW-10 was always in reduction condition and that of GW-40 was always in oxidation condition. First 50 days of GW 40-10-40 were in oxidation and next 50 days in reduction and final 20 days again returned in oxidation condition. Soybean seed Cd concentration was significantly highest in GW-40-10-40 (1.16 ± 0.13 mg·kg-1) and lowest in GW-40 (0.81 ± 0.12 mg·kg-1). Cd concentration of stem was found significantly higher in GW-40 (1.7 ± 0.2 mg·kg-1) than GW-10 (0.91 ± 0.08 mg·kg-1) and GW-40-10-40 (1.28 ± 0.13 mg·kg-1). There was no significant difference in root Cd concentration among these 3 treatments. Main stem height of soybean plant and 100 seed weight of GW-40 were significantly higher than those of GW-10. The result revealed that, soil redox condition is an important factor for Cd uptake in soybean plant and seed yield of soybean. This study will help to manage the farming process more appropriately with the aim of minimizing uptake of Cd and other toxic metals in grain crops.

Net Primary Productivity and Management Potential of Artificial Pinus tabulaeformis Forest in Shanxi Province

The dynamic variation of net primary productivity of artificial Pinus tabulaeformis forest was studied in Shanxi Province,and potential productivity of artificial forest was predicted to provide reference for improving quality of regional forest stand. The regression equation was established by using the stratification and harvesting method with the relative growth model. Cumulative method and Thornthwaite Memorial model was used to estimate the actual and potential productivity of the forest. The productivity of P. tabulaeformis forest increased with the increase of age and started decrease with the mature period. The actual productivity of P. tabulaeformis forest was 4. 462 t/( ha·year); the contribution rate of trees was 72. 17% of the total productivity,and with the increase of age,the total biomass increased but productivity decreased at late near-mature forest; the contribution rate of herb layer was 21. 16% in the young forest stage,and then decreased gradually. On the contrary,the contribution rate of shrub layer increased gradually,and the contribution rate of the grassland was more than that of the herb layer,so as the key period of structural management; the average potential productivity of forest was 8. 422 t/( ha·year),and the potential space of P. tabulaeformis was at least 32% in Shanxi Province. In conclusion,the potential space of productivity of P. tabulaeformis was at least 32%,and the primary limiting factor of P. tabulaeformis forest productivity in Shanxi Province was rainfall.

Whole Chia Flour as Yield Enhancer, Potential Antioxidant and Input of n-3 Fatty Acid in a Meat Product

In this paper, the effect of the addition of whole chia flour and water at cooked fish burgers on yield, water and fat retention, n-3 fatty acids content and oxidative stability were studied. The results showed that 94% of yield, 92% of water retention and 97% of fat retention were achieved with the addition of 5.92 g of whole chia flour and 15 g of water per 100 g of burger. The n-3 fatty content increased from 704.57 ± 21.66 mg to 1551.71 ± 47.71 mg/100g of cooked burger when the chia flour was added, enhancing nutritional quality indices of lipid. A good oxidative stability, with minimum formation of conjugated dienes, hydroperoxides and thiobarbituric acid reactive substances during 30 days frozen storage was obtained too, probably due to the presence of polyphenolic compounds with antiradical activity and reducing power in the fibrous fraction of the flour chia. The results from the present study highlight remarkable technological applications of whole chia flour as food ingredient in the design of healthier fish meat commodities.

Potential for Green Hydrogen Production from Biomass, Solar and Wind in Togo

Potential of green hydrogen producing from biomass, solar and wind in Togo has been performed. The availability of these three resources has been depicted with maps showing them per cantons in Togo, thus, by using the datasets from ESA Biomass Climate Change Initiative, the global solar atlas and the global wind atlas. The conversions rates used were: for solar resource, 3% of land was allocated for the analysis after removing the exclusions with a conversion rate of 52.5 kWh/kg of hydrogen;for biomass hydrogen, the conversion rate of 13.4 kg BS/kg H2 was assumed. Wind resources at 50 m above ground were not sufficient to evaluate the potential as it is lower than class 3 winds. QGIS version 3.6.4 and R version 4.0.4 were used. Results showed that biomass is the leading resource for producing green hydrogen from renewable energy resources;with good impact in these two cantons: Bassar, Gobe/ Eketo/Gbadi N’Kugna. However, this resource is still decreasing and in some cantons it is null.

Transpiration Rate and Leaf Water Potential as Indices for Cassava Yield in Inland Valley Ecology

Differences in transpiration and leaf water potential （LWP） in relation to cassava yield were investigated along inland valley toposequence in a 4×4 Latin square design. The landrace with the highest transpiration rate and lowest LWP yielded the lowest, while TMS 91/02324 and TMS 91/02327 with intermediate rate and highest LWP yielded the highest, indicating that high transpiration rate associated with low LWP reduced yield. Transpiration was lower in the fringe with deeper water table than valley bottom at deep water table site, while at shallow water table, it was higher in the fringe than valley bottom, suggesting that drought and excess moisture reduced transpiration. LWP and water table depth correlated negatively indicating that shallow water table reduced transpiration by reducing LWP. Transpiration increased and LWP decreased as radiation, leaf temperature and vapour pressure deficit increased and differences in these microclimatic conditions caused differences in the two processes between sites, years and time of day. Under mild water stress, transpiration and LWP were higher in the afternoon than the morning, but the reverse occurred under severe stress. TMS 91/02324 and TMS 91/02327 had the highest LWP under severe stress, indicating their higher drought tolerance than the other cultivars.

A novel Effective Panicle Number per Plant 4 haplotype enhances grain yield by coordinating panicle number and grain number in rice

Increasing effective panicle number per plant(EPN)is one approach to increase yield potential in rice.However,molecular mechanisms underlying EPN remain unclear.In this study,we integrated mapbased cloning and genome-wide association analysis to identify the EPN4 gene,which is allelic to NARROW LEAF1(NAL1).Overexpression lines containing the Teqing allele(TQ)of EPN4 had significantly increased EPN.NIL-EPN4^(TQ) in japonica(geng)cultivar Lemont(LT)exhibited significantly improved EPN but decreased grain number and flag leaf size relative to LT.Haplotype analysis indicated that accessions with EPN4-1 had medium EPN,medium grain number,and medium grain weight,but had the highest grain yield among seven haplotypes,indicating that EPN4-1 is an elite haplotype of EPN4 for positive coordination of the three components of grain yield.Furthermore,accessions carrying the combination of EPN4-1 and haplotype GNP1-6 of GNP1 for grain number per panicle showed higher grain yield than those with other allele combinations.Therefore,pyramiding of EPN4-1 and GNP1-6 could be a preferred approach to obtain high yield potential in breeding.

Spatial distribution of the potential forest biomass availability in Europe

Background: European forests are considered a crucial resource for supplying biomass to a growing bio-economy in Europe. This study aimed to assess the potential availability of forest biomass from European forests and its spatial distribution. We tried to answer the questions(i) how is the potential forest biomass availability spatially distributed across Europe and(ii) where are hotspots of potential forest biomass availability located?Methods: The spatial distribution of woody biomass potentials was assessed for 2020 for stemwood, residues(branches and harvest losses) and stumps for 39 European countries. Using the European Forest Information SCENario(EFISCEN) model and international forest statistics, we estimated the theoretical amount of biomass that could be available based on the current and future development of the forest age-structure, growing stock and increment and forest management regimes. We combined these estimates with a set of environmental(site productivity, soil and water protection and biodiversity protection) and technical(recovery rate, soil bearing capacity) constraints, which reduced the amount of woody biomass that could potentially be available. We mapped the potential biomass availability at the level of administrative units and at the 10 km × 10 km grid level to gain insight into the spatial distribution of the woody biomass potentials.Results: According to our results, the total availability of forest biomass ranges between 357 and 551 Tg dry matter per year. The largest potential supply of woody biomass per unit of land can be found in northern Europe(southern Finland and Sweden, Estonia and Latvia), central Europe(Austria, Czech Republic, and southern Germany),Slovenia, southwest France and Portugal. However, large parts of these potentials are already used to produce materials and energy. The distribution of biomass potentials that are currently unused only partially coincides with regions that currently have high levels of wood production.Conclusions: Our study shows how the forest biomass potentials are spatially distributed across the European continent, thereby providing insight into where policies could focus on an increase of the supply of woody biomass from forests. Future research on potential biomass availability from European forests should also consider to what extent forest owners would be willing to mobilise additional biomass from their forests and at what costs the estimated potentials could be mobilised.

Genetic background effects on QTL and QTL × environment interaction for yield and its component traits as revealed by reciprocal introgression lines in rice

QTLs for quantitative traits are influenced by genetic background(GB) and environment.Identification of QTL with GB independency and environmental stability is prerequisite for effective marker-assisted selection(MAS). In this study, QTLs and QTL × environment interactions affecting grain yield per plant(GY) and its component traits, filled grain number per panicle(FGN), panicle number per plant(PN) and 1000-grain weight(TGW) across six environments were dissected using two sets of reciprocal introgression lines(ILs) derived from the cross Lemont × Teqing and SNP genotypic data. ANOVA indicated that the differences among genotypes and environments within each set of ILs were highly significant for all traits. A total of 72 distinct QTLs for GY and its component traits including 15 for GY, 25 for FGN, 18 for PN, and 29 for TGW were detected over the six environments. Most QTLs(87.4%) showed significant QTL × environment interactions(QEIs) and appeared to be more or less environment-specific. Among 72 QTLs, 15(20.8%) QTLs and 12(16.7%) QEIs were commonly identified in both backgrounds, indicating QTL especially QEI for yield and its component traits had strong GB effects. Four QTL regions affecting GY and its component traits, including S1269707–S4288071, S16661497–S17511092, and S35861863–S36341768 on chromosome 3, and S4134205–S7643153 on chromosome 5, were detected in both backgrounds and coincided with cloned genes for yield-related traits. These regions can be the targeted in rice breeding for high yield potential through MAS. Application of QTL main effects and their environmental interaction effects in MAS was discussed in detail.

Analysis on Wheat Yield in China Based on the Prediction of Yield Potential

The maximum yield growth range of wheat yield per unit in China is analyzed from three aspects including photosynthesis production potential of wheat,the changing trend of per unit wheat in the previous years and potential of distribution area agricultural crops.In the paper,the potential of using light,the external potential of historical yield evolution tend and AEZ (agricultural ecological zone) are applied to calculate the per unit yield potential of Chinese wheat.The results assume that the maximum growth range of per unit yield in different stages was different:before 1991,the growth range was 10%;before 1996,the growth range was 9%;before 2000,the growth range was 8%.Any variety of wheat and planting technology higher than the above growth range can only be promoted in restricted area and has the statistical error.The results are of reference significance to Chinese wheat production.

Aboveground Woody Biomass, Carbon Stocks Potential in Selected Tropical Forest Patches of Tripura, Northeast India

To estimate woody plant biomass stocks in different patches of forest ecosystems, total 20, 500 × 10 m (0.5 ha) sized line transects were laid in a protected area of Tripura, Northeast India. Overall, 9160 individuals were measured at ≥10 cm diameter at breast height (dbh) in 10 ha sampled area. Estimation of biomass suggested that highest coefficient for allometric relationships between density and biomass in 10 dbh classes was observed in bamboo brakes (R2 = 0.90) than lowest for semi evergreen patch (R2 = 0.48). The stock of carbon (C) was differ significantly along the forest patches (F = 7.01, df = 3.19;p < 0.01). Most of biomass stock (69.38%) was accumulated in lower dbh class (<30 cm) and only 23% of biomass was estimated at higher dbh classes (> 70 cm). Range of biomass stock (37.85 - 85.58 Mg ha-1) was low, compared to other tropical forest ecosystems in India, which implies that the proper management is required to monitor regional ecosystem C pool.

Assessment of Growth, Carbon Stock and Sequestration Potential of Oil Palm Plantations in Mizoram, Northeast India

A study was conducted to assess growth, carbon stock and sequestration potential of oil palm plantations along a chronosequence in Mizoram, Northeast India for which a total of 148 oil palms drawn from different age group plantations (1 to 11 years) were sampled for their biometric parameters and assessment of carbon stock through partial non-destructive methods. All the growth parameters of oil palm (trunk height, crown depth, total height, trunk diameter) and biomass drew from different parts of the palm showed a significant (p belowground biomass (BGB) > standing litter biomass > deadwood biomass > understorey biomass. AGB, BGB and deadwood biomass followed an increasing trend while understorey biomass decreased with age. An 11-year oil palm plantation accumulated 111.96 Mg ha-1 biomass with a carbon density of 49.90 Mg C ha-1 and could sequester 3.70 Mg C ha-1 year-1 in 10 years after planting in Mizoram, Northeast India. The findings showed considerable carbon storage with comparative higher values in oil palm plantations than shifting cultivation fallows. This will enable policy and decision makers in framing climate change mitigation and adaptation policies regarding the extension of oil palm plantations in Mizoram.