Response Of Grain Yield Research Articles

Yield Response of African Rice Genotypes to Mycorrhizal Fungi and Rhizobium Inoculation

Aims: A short term field study was conducted to investigate the yield performance of selected African rice genotypes inoculated with biofertilizers. 
 Study Design: A randomized complete block design laid out in a split-plot arrangement was used to evaluate response of yield components and grain yield of some selected African rice genotypes will be to mycorrhizal fungi and rhizobium inoculation.
 Place and Duration of Study: The study was conducted at the Teaching and Research farm of the Federal university of technology, Akure Ondo state, Nigeria during the 2013 planting season.
 Methodology: The study was laid out in a split plot arrangement in Randomized Complete Block Design (RCBD), with mycorrhizal fungi, rhizobium inoculation and control in the main plot, while genotypes (N-U-1, N-U-8, WAB 56-104, OFADA GR and MOROBEREKAN) were in the sub-plot and treatments were replicated thrice. There were three main blocks, each block consist of 15 sub-plots with a size measurement of 2m x 1m and inter sub-plot spacing of 0.5m in between plots. A total of 50 plants were raised per sub plot. Transplanted seedlings were planted with the soil slurry containing rhizobium and mycorrhizal fungi inoculum into planting holes in the field at two seedlings per stand, according to their respective plot at a spacing of 25cm x 25cm. Yield component data collected include; number of days to 90% maturity, number of days to 50% flowering; plant height at maturity, number of primary tillers per plot, number of grains per panicle, number of panicles, number of filled and unfilled spikelet, weight of 1000 filled grains and grain yield per plot. 
 Results: Result showed significant (P<0.05) single and interactive effect of rhizobium and mycorrhizal fungi inoculation on rice yield and yield components. 61.4% increase in grain yield was observed in rhizobium inoculated genotypes when compared to 37.4% increase in mycorrhized genotypes and the un-inoculated control. WAB56–104 and N-U-8 had the best interactive response amongst genotypes inoculated with rhizobium while genotypes WAB56-104 and MOROBEREKAN responded better amongst mycorrhized genotypes in relation to yield components.
 Conclusion: The results from this study indicate that African rice genotypes differ in grain yield response and host specifity when inoculated with mycorrhizal fungi and rhizobium inoculums. However, inoculating specific African rice genotypes with mycorrhizal fungi and rhizobium can positively influence their grain yield and yield component development and this could play an important role in improving African rice productivity.

Dense planting with reducing nitrogen rate increased grain yield and nitrogen use efficiency in two hybrid rice varieties across two light conditions

Dense planting with reducing nitrogen rate (DPRN) is a sustainable strategy to improve rice yield and nitrogen (N) use efficiency. Nevertheless, the feasibility of such strategy under low light stress condition has not been examined in detail. Two field experiments and a micro-plot experiment were conducted to evaluate the performance of DPRN and sparse planting with high N rate (SPHN) under two light conditions (L0, natural light intensity and L1, 30% of L0) with two contrasting hybrid rice varieties (Yliangyou 1 and Luoyou 9348) in 2014 and 2015. In field experiments, L1 resulted in sharp decline in grain filling, 1000-grain weight, biomass, harvest index, N uptake, N use efficiency for grain production and partial factor productivity of applied N fertilizer, and consequently 41.2–53.4% grain yield loss for two varieties in comparison with L0. Interestingly, 8.6–13.5% higher grain yield, and better performance of yield components and N use efficiency were observed from DPRN than SPHN across two light conditions. In micro-plot experiment, responses of grain dry weight and yield-attributing traits to light intensity and crop managements were similar to those in field experiments. No difference was observed in N uptake from fertilizer, N recovery rate, N retention rate and N loss rate between L0 and L1, while DPRN increased N recovery rate by 14.8% and N retention rate by 35.1%, and consequently decreased N loss rate by 29.4% across two light conditions compared with SPHN. The differences in responses of grain yield and related parameters to low light stress (L1) between the two cultivars were small. These results suggest that DPRN is also feasible to increase grain yield and N use efficiency for hybrid rice varieties grown under two light conditions.

Effect of Dense Planting of Hybrid Rice on Grain Yield and Solar Radiation Use in Southeastern China

Core Ideas Hybrid rice grain yield was evaluated under dense planting. Grain yield was greater in hybrid cultivars than in inbred cultivars under dense planting conditions. The yield performance under dense planting was significantly affected by the weather condition. ABSTRACTDense planting has been recommended as a promising practice for achieving greater grain yield. However, whether this practice is suitable for hybrid rice (Oryza sativa L.) is unknown. To evaluate the response of grain yield and canopy structure traits to planting density in hybrid cultivars, field experiments were conducted with inbred‐indica (Huanghuazhan), inbred‐japonica (Xiushui09), hybrid‐indica (Tianyouhuazhan), and hybrid‐japonica (Chunyou84 or Yongyou12) cultivars at five planting densities (40, 26.7, 20, 16.7, and 13.3 hills m−2, designated as D1, D2, D3, D4, and D5) in 2015 and 2016. Results showed that hybrid cultivars had 16.6 to 48.9% greater grain yield compared with inbred cultivars under the dense planting condition (D1 and D2), except for Tianyouhuazhan in 2015. The grain yield increased with increasing plant density in hybrid cultivars (except for Tianyouhuazhan in 2015), with the increase rates of 76.6, 108.0, and 138.6 kg Δhill−1 ha−1 for hybrid‐japonica‐Chunyou84 (2015), hybrid‐indica‐Tianyouhuazhan (2016), and hybrid‐japonca‐Yongyou12 (2016), respectively. However, the yield performance was significantly affected by the climate condition under dense planting. The grain yield of hybrid cultivars in 2015 averaged 8.3 t ha−1, which was 36.3% lower than that in 2016 under dense planting (D1 and D2). We speculate that unfavorable climate would suppress the yield performance more under the dense planting conditions. Furthermore, results showed that greater plant density leads to an increase in plant radiation use efficiency, except for indica‐hybird‐Tianyouhuazhan. This might be attributed to the upright top leaves when the planting density increased, which resulted in smaller leaf angles and extinction coefficient of the canopy.

Index selection for multiple traits in upland rice progenies.

The success of any breeding program depends on the ability of the breeder to select genetically superior progenies formultiple traits simultaneously, and an alternative is the use of selection indexes. In this study, the selection indexesof Smith-Hazel, Base Index, Sum of Ranks, and Index Z were used to select superior upland rice progenies for fourimportant agronomic traits. Five commercial cultivars and 191 progenies F2:4 of upland rice were evaluated for days forflowering, plant height, blast resistance, and grain yield in four environments. The genetic correlation between pairs oftraits, the response of selection in each trait and the correlated response considering the selection for number of days toflowering and the response in grain yield were obtained, using an intensity of selection of 20%. The predicted responseto selection of each trait was expressive, but the indirect selection response was not effective. The most efficient selectionwas obtained by Z Index, which showed the highest response considering all traits simultaneously and was also easyto implement and to interpret graphically interpretation. Therefore, the Z Index can greatly increase the efficiency ofselection for multiple traits in upland rice breeding programs.

ElevatedCO2modulates the effects of drought and heat stress on plant water relations and grain yield in wheat

AbstractTo investigate the interactive effects of drought, heat and elevated atmosphericCO2concentration ([CO2]) on plant water relations and grain yield in wheat, two wheat cultivars with different drought tolerance (Gladius and Paragon) were grown under ambient and elevated [CO2], and were exposed to post‐anthesis drought and heat stress. The stomatal conductance, plant water relation parameters, abscisic acid concentration in leaf and spike, and grain yield components were examined. Both stress treatments and elevated [CO2] reduced the stomatal conductance, which resulted in lower leaf relative water content and leaf water potential. Drought induced a significant increase in leaf and spike abscisic acid concentrations, while elevated [CO2] showed no effect. At maturity, post‐anthesis drought and heat stress significantly decreased the grain yield by 21.3%–65.2%, while elevated [CO2] increased the grain yield by 20.8% in wheat, which was due to the changes of grain number per spike and thousand grain weight. This study suggested that the responses of plant water status and grain yield to extreme climatic events (heat and drought) can be influenced by the atmosphericCO2concentration.

Contrasting responses of grain yield to reducing nitrogen application rate in double- and single-season rice

Reducing N rate without sacrificing grain yield is crucial for sustainable rice production in China. In this study, field experiments were conducted in 2016 and 2017 to determine whether the response of grain yield to reducing N rate varied between double-season rice (DSR) and single-season rice (SSR). Three N rates were applied for each rice crop, i.e. 150 kg ha−1 (N150, the locally recommended N rate), 90 kg ha−1 (N90), and 0 kg ha−1 (N0). Grain yield was lower under N90 than under N150 in DSR by 11–18%, whereas the difference was not significant in SSR. Grain yield under N0 was 36–63% lower in DSR than in SSR. There was a significant relationship between percentage change in grain yield comparing N90 to N150 with grain yield under N0. Furthermore, it was observed that grain yield under N0 was not significantly associated with growth duration but was closely associated with daily grain yield under N0, and the relationships of daily grain yield under N0 with seasonal average daily mean temperature and solar radiation were not significant. These results indicate that response of grain yield to reducing N rate was more sensitive in DSR compared to SSR due to lower soil N productivity. Growth duration and climatic conditions did not explain the difference in soil N productivity between DSR and SSR. The findings of this study should encourage more research into comparing the inherent traits of plants, especially the morphology and physiology of the root system, between DSR and SSR.

Agronomic Response of Corn (Zea maysL.) Hybrids to Plant Populations

Field studies were conducted in 2016 and 2017 under rain-fed conditions in south-central Louisiana, (a) to determine the effects of plant density levels on plant height, ear height, stalk diameter, lodging, corn grain yield, test weight, and photosynthetically active radiation with modern corn hybrids in central Louisiana and (b) to test the hypothesis that the response of grain yield to plant population density would depend on the reproductive plasticity (flex, semiflex, or fixed ear) of the hybrids evaluated. Rainfall was above average while air temperatures were below average during the growing season in both years. Grain yield showed a hybrid response in one of two years (fixed ear greater than semiflex ear) while yields increased as plant populations increased. Test weights were less with the fixed ear hybrid and the effect of plant populations was inconsistent with increased populations resulting in greater test weight in one of two years. Lodging increased as plant populations increased with the fixed ear hybrid resulting in greater lodging in one of two years. There was a hybrid by plant population interaction for ear height and seed weight. The effect of plant populations is an important factor for corn yield; however, yield gains associated with higher plant populations may be dependent on the genetic predisposition of corn hybrids (regardless of the reproductive plasticity) to tolerate various environmental conditions and stresses associated with higher populations.

Quantifying extreme climatic conditions for maize production using RZWQM in Siping, Northeast China

Climate change has a great influence on agricultural production, especially under extreme climatic conditions. In this study, Root Zone Water Quality Model (RZWQM) was used to predict grain yields of maize in the Siping region, Jilin Province, Northeast China during the period from 1951 to 2015; and the response of grain yield to main climatic variables was qualitatively analyzed, especially in three special years of 1954, 2000 and 2009. Results showed that 1°C increase for minimum, maximum and mean air temperatures may produce 1224 kg/hm2, 1860 kg/hm2 and 1540 kg/hm2 more grain yields, respectively, and seasonal rainfall amount of less than 450 mm, especially at the flowering and grain filling stages, greatly reduced grain yields. In the years of 1954, 2000 and 2009, grain yields were reduced by 41%, 47% and 40% compared to their mean value, respectively, correspondingly because of extra low temperature (lower by 2.1°C-2.3°C), less rainfall at the grain filling stage (36 mm) and extra high temperature (higher by 1.7°C-1.8°C), and less seasonal rainfall (252 mm). To reduce extreme climate’s effects on grain yield, it is suggested that supplementary irrigation at the flowering and grain filling stages should be provided when rainfall is much less at this stage and also appropriate maize species based on the longtime weather forecast should be selected. Keywords: climate change, RZWQM, extra low and high temperatures, seasonal rainfall distribution, maize yield response, Northeast China DOI: 10.25165/j.ijabe.20191202.3388 Citation: Liu H J, Liu Y, Zhang L W, Zhang Z J, Gao Z Z. Quantifying extreme climatic conditions for maize production using RZWQM in Siping, Northeast China. Int J Agric & Biol Eng, 2019; 12(2): 111–122.

Nitrogen Fertilizer and Residue Management in Dryland No‐Till Hard Red Spring Wheat

Core Ideas Nitrogen may enhance wheat grain quality even when wheat yield is not increased. Nitrogen rate and placement had greater effect on grain protein than wheat yield. Side‐banding N resulted in higher grain protein than broadcasting. Residue management had no effect on wheat production. This article summarizes the results from a 1‐yr field experiment conducted at two locations in northcentral Montana. Nutrient and residue management are important aspects of dryland no‐till cropping systems that directly affect wheat (Triticum aestivum L.) production. The objectives were to assess N response of hard red spring wheat grown in dryland no‐till conditions under varied crop residue management. The effects of N application rate (0, 135, and 270 kg N ha−1) and placement (broadcast vs. side‐banded) and residue management (undisturbed vs. removed) on biomass weight and N content, Normalized Difference Vegetative Index (NDVI), grain yield, grain test weight, and protein content of hard red spring wheat were evaluated. At one of two locations, the 135 kg N ha−1 rate resulted in significantly higher yield, compared with unfertilized check, but further increase of N rate to 270 kg N ha−1 did not improve yield. There was no response of grain yield to N application rate at the second location. At one of two locations, the side‐dress N application resulted in higher wheat yield, but no statistically significant differences in yield associated with N placement was observed at the second location. Biomass N content and grain protein content were significantly affected by the N application rate at both locations. The results of this study confirm that even if wheat grain yields are not always increased with N applications, N fertilizer could still be beneficial in terms of improved grain quality (test weight and protein content).

Wheat grain-yield response to lime application: relationships with soil pH and aluminium in Western Australia

Soil acidity, or more specifically aluminium (Al) toxicity, is a major soil limitation to growing wheat (Triticum aestivum L.) in the south of Western Australia (SWA). Application of calcium carbonate (lime) is used to correct Al toxicity by increasing soil pH and decreasing soluble soil Al3+. Soil testing using a 0.01 m calcium chloride (CaCl2) solution can measure both soil pH (pHCaCl2) and soil Al (AlCaCl2) for recommending rates of lime application. This study aimed to determine which combination of soil pHCaCl2 or soil AlCaCl2 and sampling depth best explains the wheat grain-yield increase (response) when lime is applied. A database of 31 historical lime experiments was compiled with wheat as the indicator crop. Wheat response to lime application was presented as relative yield percentage (grain yield for the no-lime treatment divided by the highest grain yield achieved for lime treatments × 100). Soil sampling depths were 0–10, 10–20 and 20–30 cm and various combinations of these depths. For evidence that lime application had altered soil pHCaCl2, we selected the change in the lowest pHCaCl2 value of the three soil layers to a depth of 30 cm as a result of the highest lime application (ΔpHmin). When ΔpHmin <0.3, the lack of grain-yield response to lime suggested that insufficient lime had leached into the 10–30 cm soil layer to remove the soil Al limitation for these observations. Also, under high fallow-season rainfall (228 and 320 mm) and low growing-season rainfall (GSR) (<140 mm), relative yield was lower for the measured level of soil AlCaCl2 than in the other observations. Hence, after excluding observations with ΔpHmin <0.3 or GSR <140 mm (n = 19), soil AlCaCl2 provided a better definition of the relationship between soil test and wheat response (r2 range 0.48–0.74) than did soil pHCaCl2 (highest r2 0.38). The critical value (defined at relative yield = 90%) ranged from 2.5 mg Al kg–1 (for soil Al calculated according to root distribution by depth within the 0–30 cm layer) to 4.5 mg Al kg–1 (calculated from the highest AlCaCl2 value from the three soil layers to 30 cm depth). We conclude that 0.01 m CaCl2 extractable Al in the 0–30 cm layer will give the more accurate definition of the relationship between soil test and wheat response in SWA.

Maize yield, rainwater and nitrogen use efficiency as affected by maize genotypes and nitrogen rates on the Loess Plateau of China

Understanding the responses of grain yield (GY), nitrogen (N) use efficiency (NUE), rainwater use efficiency (WUE) and nitrate-N residue (NR) to different maize genotypes and the relationships of these parameters to N management is essential to determining N application rates and choose maize genotypes in rain-fed areas. A field experiment was conducted by using two maize genotypes of Zhengdan 958 (ZD958) and Wuke 2 (WK2) and three N application rates of 86, 172 and 258 kg N ha−1 with one control treatment in Yangling on the Loess Plateau of China. Grain yield, nitrate-N residue, nitrogen and rainwater use efficiency were evaluated in the 2013, 2014 and 2015 maize growing seasons. The results showed that the increasing application of N rate increased the soil NR, but no difference in soil NR was observed between the two maize genotypes at harvest. The “linear-plus-plateau” model could describe the relationship between N rates and GY, the mean values of optimal N rate and maximum GY were (149.1 vs 107.7 kg ha−1) and (7061.3 vs 6449.8 kg ha−1) in ‘ZD958’ and ‘WK2’, respectively. Nitrogen application can significantly improve WUE. Compared to ‘WK2’, ‘ZD958’ had higher WUE, with mean values of 25.5 and 23.2 kg ha-1 mm-1 in ‘ZD958’ and ‘WK2’, respectively. Nitrogen use efficiency and crop N recovery efficiency decreased sharply as the N rate increased; the mean values of NUE were 9.7 and 8.3 kg kg-1 in ‘ZD958’ and ‘WK2’, respectively. Further analysis shows that, the green leaf area index and leaf N concentration were greater in ‘ZD958’ compared with those of ‘WK2’. The findings suggest that the combination of N application rate of 149.1 kg ha−1 with the maize genotype‘ZD958’958′ would result in the maximum GY, with improve in both WUE and NUE under rain-fed conditions.

Different Response of Grain Yield to Soil Organic Carbon, Nitrogen, and Phosphorus in Red Soil as Based on the Long-Term Fertilization Experiment

Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) are essential nutrients for plant growth. Thus, soil amendments that increase the amounts of these nutrients can improve crop yield in poor growing soils such as Red soils in subtropical China, which were classified as Plinthosols in the WRB (World Reference Base for Soil Resources). It is unknown whether any of the three nutrients are more influential than the others on crop yield. A 30-year-long field experiment was established in 1986 to investigate the response of grain yield to changes in SOC, TN and TP levels, identified by regression equations, due to various fertilizer treatments applied to corn crops grown in red soil. Corn yields varied significantly under four different fertilizer treatments. For most of the experimental years, the two fertilizer treatments of application of manure combined with inorganic nitrogen, phosphorus, and potassium (NPKM) and a higher rate of NPK (HNPK) fertilizer produced significantly higher yields than the control (no addition of fertilizer, CK) by 441–548 and 380–703%, respectively. Differences between yields increased over time, particularly between NPKM and CK treatments. The long-term application of NPKM increased SOC, TN and TP contents more so than the other treatments and contents were greater than those in the CK by 48.6–57.1, 26.4–37 and 81.6–142%, respectively. There were no significant differences between the treatments with the low and high rates of NPK (LNPK and HNPK). Additional results showed that NPKM raised the C : N ratio and lowered the C : P ratio. The relationships between SOC, TN, TP and grain yield were best represented by the Michaelis–Menten equation rather than the simple linear equation. Moreover, the equations estimated different maximum yields of corn; yields estimated by SOC and TP were higher than the yield estimated by TN. Furthermore, The estimated maximum yield that could be attained is at a C : N ratio of 10.22 in red soil. Therefore, SOC and TP are likely the more important nutrients to consider altering in soil management of red soil.

Flowering dynamics, pollen, and pistil contribution to grain yield in response to high temperature during maize flowering

High temperature (HT) stress during flowering severely threatens crop grain yield, however, little is known about the underlying mechanisms in maize. A HT sensitive maize hybrid was subjected to 32/22 ℃ (maximum/minimum temperature, control), 36/26 ℃, and 40/30 ℃ for 14 consecutive days bracketing flowering (trial 1) and for seven days prior to flowering (trial 2). Maize grain yield did not decrease in the 36/26 ℃ treatment during trial 1 compared to the control treatment, but reduced by 73.6% in the 40/30 ℃ treatment as a result of reduced kernel number rather than kernel weight. High temperature stress advanced tasseling and pollen shedding, extended the anthesis-silking interval, and reduced the number and viability of pollen shed, but had no effects on silking. The shortened duration of pollen shedding was a result of the accelerated flowering speed of the tassel inflorescence. Leaf assimilate can be transferred to the tassel, but cannot be converted into starch in the HT stressed pollen. The damaged pollen morphology and the interrupted sugar to starch physiological process explained the reduced pollen viability. Starch granule number and size in the pollen decreased with the increased temperature. Thus, male organ growth is more sensitive to HT than female organs. Understanding the underlying mechanisms has implications for selecting or breeding HT tolerant maize.

Evaluation and analysis of intraspecific competition in maize: A case study on plant density experiment

Intraspecific competition is a common phenomenon in agricultural production, and maize is one of the most sensitive grass species to intraspecific competition due to its low tillering ability. This study evaluated and analyzed intraspecific competition in maize, and screened competitive indices that could be used to evaluate intraspecific competition in a maize population. A 2-year field experiment was conducted using the maize hybrid Zhongdan 2 at 12 plant densities ranging from 1.5 to 18.0 plants (pl) m−2. The results showed that the response of single-plant grain yield and dry matter at harvest to increased plant density decreased exponentially and that the harvest index decreased linearly. The response of population-level grain yield to plant density was curvilinear, producing a maximum value at the optimum population density. However, the yielddensity equation agreed well with the Steinhart-Hart equation curves, but not with the quadratic equation curves reported by most previous studies. Competitive indices are used to evaluate competition in a plant population or plant species. The present results show that competitive intensity (CI) and absolute severity of competition (ASC) increased with increasing plant density; however, relative yield (RY) and relative reproductive efficiency (RReff) decreased. The different responses of these indices reflect different aspects of competition. According to the analysis of CI, ASC, RY, and RReff, higher CI and ASC values indicate higher intraspecific competition, whereas higher RY and RReff values indirectly reflect lower intraspecific competition. These competitive indices evaluate not only the intraspecific competitive intensity under different plant densities of the same cultivar but also those of different cultivars under the same plant density. However, some overlap exists in the calculations of ASC, CI, and RY, so one could simply select any one of these indices to evaluate intraspecific competition in a maize population. In conclusion, the present study provides a method to evaluate intraspecific competition in maize populations, which may be beneficial for breeding high-yield maize varieties in the future.

Response of Growth and Grain Yield of Amaranth (A. hypochondriacus) to Combined Manure and Inorganic Fertiliser Pellets and Non-pellets

Response of Growth and Grain Yield of Amaranth (A. hypochondriacus) to Combined Manure and Inorganic Fertiliser Pellets and Non-pellets

Genotype-specific response of Foeniculum vulgare grain yield and essential oil composition to proline treatment under different irrigation conditions

Drought stress is a major environmental stress which severely affects growth, yield, as well as quality and quantity of crop products. Proline as a multifunction amino acid has a crucial role in ameliorating of drought stress. In order to study the effect of external proline on the response of fennel to drought stress, three fennel genotypes (namely Urmia, Shiraz, and Kerman) were exposed to two irrigation regimes (drought stress and non-stress control) and two levels of foliar-applied proline (0 and 20 mM) in a pot experiment. Drought led to significant decreases in umbels/plant, plant height, 1000-grains weight, harvest index, above-ground dry mass, grain weight and grain and dry mass WUE, root volume, root fresh and dry mass, ratio of shoot/root, grains and stems essential oil weight/plant and significant increases in root length and grains limonene content. Foliar-applied proline led to notable increases in harvest index and grain essential oil weight in the presence of drought. It also led to increases in umbels/plant, 1000-grains weight, harvest index, above-ground dry mass, grain weight and grain and dry mass WUE and ratio of shoot/root in Urmia and Shiraz genotypes. Anethole, limonene, fenchone, estragole and α-pinene were the main essential oil constituents in both grain and stems. Grain fatty acid and phytosterol compositions were not affected by experimental treatments. It may be concluded that drought stress suppresses fennel growth and grain weight, but foliar-applied proline is potent to mitigate the adverse reaction through increasing growth, grain weight/plant, WUE and grains limonene content in genotypes such as Urmia and Shiraz.

Waterlogging and simulated acid rain after anthesis deteriorate starch quality in wheat grain

The synthesis and accumulation of starch is greatly affected by environmental stress. Wheat grown in the downstream area of the Yangtze River is easily subjected to stress of waterlogging and acid rain. In order to probe the effect of waterlogging and acid rain on yield and starch characteristic, we used winter wheat cultivars of Yangmai 16 (more resistant) and Wennong 17 (relatively sensitive) to sole stress of acid rain or waterlogging and to their combinations during grain filling. The responses of grain yield, the physiochemical properties and morphology of starch granules in endosperm to the stresses were investigated. Compared with CT (control), grain yield in Wennong 17 were significantly decreased by both pH 4.0 acid rain and pH 2.5 acid rain, while in Yangmai 16 only by pH 2.5 acid rain. Waterlogging combined with acid rain significantly reduced grain weight and grain yield in both wheat cultivars. Acid rain, waterlogging and their combination depressed activities of ADP glucose pyrophosphorylase and soluble starch synthase (SSS) in grains of both cultivars. Acid rain and waterlogging damaged endosperm cell structure and caused abnormal starch granules. Starch granules at maturity became fragile and failed to keep in shape and some granules were even totally submerged in the protein matrix and other tissue under acid rain and waterlogging. Content of amylopectin and amylopectin/amylose ratio was also decreased, while content of amylose was increased under acid rain and waterlogging. As a result, swelling power and most viscosity parameters decreased, while the pasting temperature increased in both cultivars due to stresses. In sum, acid rain and waterlogging and their combination damaged cell structure and depressed synthesis of amylopectin, and led to the formation of abnormal fragile starch granules, and finally reduced grain weight and then yield, and deteriorated starch quality.

Responses of Grain Yield and Nutrient Accumulation to Water and Foliar Fertilizer Management in Upland and Wetland Rice Varieties

This study evaluated the effects of water and fertilizer managements on grain yield and nutrient accumulation in upland and wetland rice varieties. The two rice varieties representing upland (KH CMU) and wetland (CNT1) ecotypes were grown in different water conditions and fertilizer managements. The interaction between variety and water condition had significantly affected on grain yield and straw dry weight. The water condition and fertilizer management were also affected on grain nutrient concentrations differently between the two varieties. The difference in responses to grain nutrients between the two rice varieties representing their original ecotypes of wetland and lowland is the key factor with respect to the proper management of water and fertilizers in order to maximize in both grain yield and nutrition. This knowledge is useful for the proper management of water and fertilizers for improving grain yield and nutrient accumulation. However, increasing the number of rice varieties in each upland and wetland ecotypes is needed to confirm the responses to water and fertilizer management in the future study.

Different growing strategies of two winter wheat cultivars under rainfed conditions during dry years in North China Plain

The North China Plain (NCP) is a severe water shortage region, especially during the wheat growing season. Understanding the response of grain yield and water availability in winter wheat cultivars (Triticum aestivum L.) is important to adjust planting structure under groundwater reducible exploitation in rainfed dry years of NCP. Field experiments were conducted at the Luancheng Agroecosystem Experiment Station of the Chinese Academy of Sciences, Hebei, China. Two different drought resistant winter wheat cultivars (Jinmai47 and Shiluan02-1) were grown under rainfed conditions during four years of 2010-2011, 2011-2012, 2012-2013 and 2013-2014. Grain yield and its components, aboveground biomass (AB), dry matter accumulation translocation efficiency, water consumption, water use efficiency at field scale, and photosynthetic characteristics were measured. The results showed that Jinmai47 rapidly accumulated AB by higher tiller and photosynthetic potential comparing with those of Shiluan02-1. Its grain yield was 16.49% higher than that of the drought-sensitive winter wheat variety Shiluan02-1 during the four rainfed years. However, the dry matter remobilization efficiency (DMRE) and contribution of dry matter remobilization from heading stage to maturity stage to grain (CDMRE) of Shiluan02-1 was higher than those of Jinmai47. The average water use efficiency at grain yield level (WUEy), WUE at aboveground biomass level (WUEab), and WUE at grain yield under rainy conditions (WUEr) of Jinmai47 were 11.08%, 16.41%, and 17.21% higher than those of Shiluan02-1. There was a significant difference in the WUEab and WUEr between the two wheat cultivars. The two wheat varieties under drought condition have different growing strategies. Jinmai47 has more tiller number, earlier vigor, and higher AB than Shiluan02-1, helping it to adapt to the fluctuations in the environment. Keywords: winter wheat cultivar, grain yield, rainy treatment, water use efficiency, dry year DOI: 10.25165/j.ijabe.20181105.4344 Citation: Dong B D, Yang H, Qiao Y Z, Zhang M M, Wang Y K, Jin L L, et al. Different growing strategies of two winter wheat cultivars under rainfed conditions during dry years in North China Plain. Int J Agric & Biol Eng, 2018; 11(5): 150–159.

Responses to phosphorus among barley genotypes

Genetic improvement in phosphorus (P) use efficiency (i.e. the ratio of biomass or yield at nil P to that at a given rate of application) is an important goal to improve P recovery and P efficiency of farming systems. Experiments were conducted at three sites in South Australia between 2009 and 2011 to characterise genetic variation in yield with no applied P and in the response to P fertiliser among a diverse range of barley (Hordeum vulgare L.) genotypes. In each experiment, 39–54 genotypes were grown at 0 or 30 kg P/ha. Responses to P were measured near the beginning of stem elongation by using normalised difference vegetation index (NDVI) and by harvesting the grain. Rhizosheath size was also measured on seedlings. Consistent differences in growth and yield at 0 kg P/ha were measured among the genotypes. By contrast, there were large environmental effects on responses to P, but some genotypes showed consistent responses. Measurements of growth, yield and P uptake on a subset of genotypes showed that most of the variation in biomass and yield could be attributed to variation in P-uptake efficiency (net total P uptake per unit available P) rather than to P-utilisation efficiency (biomass or yield per unit total P uptake). The size of the rhizosheath made a small contribution to variation in NDVI but not grain yield, suggesting that rhizosheath size may be of some benefit to early growth but that this does not persist through to yield. Genetic correlations between NDVI and yield were often weak but were generally positive at 0 kg P/ha. Correlations between responses in NDVI and responses in grain yield were low and often negative. The study identified several barley genotypes that showed consistent differences in yield at low P and responses to P; however, selection for P efficiency based solely on responses in vegetative growth may not be appropriate. Variation in P uptake appeared to be more important than P-utilisation efficiency for P efficiency in barley.