Response Of Grain Yield Research Articles

Responses of Phosphorus Use Efficiency, Grain Yield, and Quality to Phosphorus Application Amount of Weak-Gluten Wheat

Phosphorus (P) is one of the most widely occurring nutrients for development and growth of wheat. In this study, the effects of P application amount on grain yield, protein content, and phosphorus use efficiency (PUE) were studied by agronomic management of P fertilizer on spring weak-gluten wheat (Triticum aestivum L.) grown under field conditions for 2 yr. The experiments were performed at five levels of P2O5 application amount, including 0, 72, 108, 144, and 180 kg ha−1. As a result, with increase in P fertilizer, grain yield, and P agricultural efficiency (AEP) increased in a quadratic equitation, but partial factor productivity of P (PFPP) decreased in a logarithmic eq. When 108 kg ha−1 P2O5 was applied, the grain yield reached the highest level, but the protein content in gain was lower than 11.5%, a threshold for the protein content to evaluate weak-gluten wheat suitable for production of cake and biscuit. Yangmai 13 and Ningmai 9 could tolerate to higher P level of soils than Yangmai 9 that had more loss in grain yield when P fertilizer was over-applied. AEP had a concomitant relationship with grain yield and was a better descriptor for P use efficiency in the wheat. A high P use efficiency resulted in leaf area index (LAI), increased chlorophyll content and photosynthetic rate, and stable acid phophatase (APase) activity to accumulate more dry matter after anthesis, which explained that the optimum P fertilizer increased grain yield and improved grain quality of weak-gluten wheat.

Effects of integrated agronomic management practices on yield and nitrogen efficiency of summer maize in North China

Excessive nitrogen (N) fertilizer application, outdated fertilization techniques, and non-optimal planting patterns are current cultivation problems with summer maize (Zea mays L.) among smallholders in North China. To try to solve those problems, this study examined four integrated agronomic management treatments-MT (FP: traditional farming practices; OPT-1: an optimized combination of cropping systems and fertilizer treatment; HY: treatment based on high-yield studies; and OPT-2: further optimized combination of cropping systems and fertilizer treatment) and four N application rate treatments-NT (0, 129.0, 184.5, and 300.0kgha−1). Maize grain yield and N efficiency were determined under each treatment. Grain yield, yield components, individual/population dry matter weight, N partial factor productivity (PFPN), N use efficiency (NUE), and agronomic efficiency of N (AEN) were measured. Results from the NT revealed no significant increase in grain yield in response to N applied above 184.5kgha−1 and increased yield was achieved by the MT. In MT, the change in sowing method from relay intercropping to direct seeding was effective in avoiding maize rough dwarf virus and in encouraging mechanized production; individual and population dry matter accumulation from the tasseling stage (VT) to physiological maturity stage (R6) increased in response to delayed sowing date and harvesting time; grain yield increased significantly from more ears per hectare due to increased planting density; and high N efficiency was achieved after optimizing fertilization patterns. In this study, OPT-2 obtained 67.0%, 104.0%, and 53.5% higher grain yield, PFPN, and NUE, respectively, compared to FP, achieving high yield and high N efficiency. Furthermore, the low AEN value suggests that further reduction in the N application rate of OPT-2 may be possible.

Agronomic Responses of Corn Hybrids to Row Width and Plant Density

Increased corn (Zea mays L.) seed costs and hybrids with greater stress tolerance than in the past make it important to know if the optimum plant density for corn grain yield differs with hybrid relative maturity (RM) or row width. In 2009 and 2010 at two locations in southern Minnesota, agronomic responses of corn to plant densities ranging from 40,700 to 108,700 plants ha−1 were evaluated for 95‐, 101‐, and 105‐d RM hybrids in 51‐ and 76‐cm row widths. Stalk diameter, intercepted photosynthetically active radiation (IPAR) and leaf area index (LAI) at silking, root and stalk lodging, grain yield, and yield components did not differ with row width, and the response of these variables to plant density was not affected by hybrid or row width. Yield of the 105‐d RM hybrid was 13% higher than that of the 95‐d RM hybrid due to greater kernel number despite lower kernel weight, but was similar to the 101‐d RM hybrid. There was a quadratic‐plateau response of grain yield to plant density, with the plateau occurring at 84,500 plants ha−1. Net return was not affected by row width, hybrid, or 23 of 25 scenarios for seed cost and grain price. The economically optimum plant density was 62,200 plants ha−1 for US$350 per 80,000 seeds and US$120 Mg−1, and 87,000 plants ha−1 for US$150 per 80,000 seeds and US$280 Mg−1. These results demonstrate that grain yield can be maximized with mid‐ and late‐RM hybrids and plant densities ≥84,500 plants ha−1 in either 51‐ or 76‐cm rows.

Sensitivity of crop yield and N losses in winter wheat to changes in mean and variability of temperature and precipitation in Denmark using the FASSET model

Sensitivity of wheat yield and soil nitrogen (N) losses to stepwise changes in means and variances of climatic variables were determined using the FASSET model. The LARS-WG was used to generate climate scenarios using observed climate data (1961–90) from two sites in Denmark, which differed in climate and soil conditions. Scenarios involved changes to (i) mean temperature alone, (ii) mean and variability of temperature, (iii) winter and summer precipitation amounts and (iv) duration of dry and wet series. The model predicted lower grain yield and N uptake in response to increases in mean temperatures, caused by early maturity, with little change in variability. This, however, increased soil mineral N causing increased N losses. On sandy loam, larger temperature variability lowered grain yields and increased N losses coupled with higher variability at all the mean temperature ranges. On coarse sand, grain yields either remained unaltered or were slightly reduced when larger temperature variability was introduced to increase in mean temperatures of up to +2°C above baseline. However, introducing variability to further increase in mean temperatures lowered yields without any change in variability. Larger temperature variability did not affect soil mineral N and N2O emissions, but increased N leaching on coarse sand. Large response in grain yield, N uptake and soil N cycling, and in their variability was predicted when summer precipitation was varied, whereas only N leaching responded to changes in winter precipitation. Doubling the duration of dry series lowered grain yield and N removed by grain, but increased N leaching, whereas doubling the duration of wet series showed opposite effect. Predicted responses to changes in precipitation patterns were larger on coarse sand than on sandy loam. This study illustrates the importance of considering effects of changes to mean climatic factors, climatic variability and soil types on both crop yield and soil N losses.

Modelled yield and water use efficiency of maize in response to crop management and Southern Oscillation Index in a soil-climate transect in Argentina

Maize responses to individual management factors have been widely investigated but studies of higher-order interactions involving multiple factors are rare. This paper investigates the responses of grain yield and water use efficiency of rainfed maize to sowing date, stubble condition, hybrids of contrasting cycle length, soil depth and their interactions, and how these responses are affected by El Niño – Southern Oscillation (ENSO) phenomenon. Grain yield and water balance were modelled with CropSyst using 33 years of weather data for eight locations in an east–west transect in the Southern Pampas of Argentina. Modelled grain yield decreased westward, in parallel with decreasing rainfall. Southern Oscillation Index (SOI) discriminated crop season rainfall and grain yield, with lower rainfall and grain yield for SOI phase Consistently Positive (CP) and higher rainfall and grain yield for SOI phase Consistently Negative (CN). Differences in grain yield between stubble and bare soil were constant across location. High available water, as related to soil depth, increased grain yield across the transect. The effect of sowing date and stubble varied with SOI phase; for CN, highest grain yields were obtained with early sowing whereas for CP grain yield showed no correlation with sowing date. Yield differences between bare soil and stubble conditions were higher under CP than under CN, reflecting the positive effect of stubble in years with rainfall below average. Water use efficiency (WUE=yield per unit evapotranspiration) averaged 19.0kgha−1mm−1 for soils with stubble and 16.5kgha−1mm−1 for bare soil. We conclude that SOI provides an agronomically meaningful predictor of seasonal conditions that can be used to estimate crop production and manage risk by adjusting key management practices.

Agronomic productivity and nitrogen requirements of alternative tillage and crop establishment systems for improved weed control in direct-seeded rice

Weed control is a primary concern in direct-seeded rice, particularly for herbicide-resistant weed species which stand to threaten the long-term sustainability of California rice systems. In a four-year field study we evaluated the potential for improved weed control using no-till stale seedbed practices in water-seeded (WS) and drill-seeded (DS) rice establishment systems. In addition, as the agronomic performance of alternative tillage and crop establishment methods is not well understood, we assessed the productivity of these systems and estimated economic optimum nitrogen (EON) rates based on yield response to nitrogen (N) trials. Establishment system treatments included: water-seeded conventional tillage (WS conventional), water-seeded conventional tillage stale seedbed (WS stale), water-seeded no-till stale seedbed (WS no-till stale), drill-seeded conventional tillage (DS conventional), and drill-seeded no-till stale seedbed (DS no-till stale). Compared to the WS conventional system, WS stale and WS no-till stale treatments significantly reduced sedge weed biomass by 59 and 95%, respectively. Although redstem (Ammannia spp.) was not controlled, alternative WS systems reduced grass weed biomass by more than 99% when present. Within DS systems, no-till stale seedbed practices significantly reduced watergrass (Echinochloa spp.) biomass by 75% in the first two years but did not improve watergrass control during the second half of the study. Grain yields were not different for conventional and alternative rice establishment systems each year when N was applied at 168kgNha−1 and weeds were fully controlled. However, yields were significantly lower for alternative establishment systems compared to the WS conventional system when no N fertilizer was applied, likely as a result of greater soil N losses. The response of grain yield to N rate was significantly different among systems and estimated EON rates indicated that WS stale and WS no-till stale systems required an increase of 30–35kgNha−1 to maximize yields and returns to N compared to the WS conventional system. Results from this experiment demonstrate that alternative tillage and crop establishment systems can lead to improved weed control while remaining viable from an agronomic and economic standpoint in California. Provided N rates are close to optimal and WS and DS establishment methods are selected to target weed species of concern, these findings suggest that no-till stale seedbed practices should be considered as a component of integrated weed management strategies in direct-seeded rice moving forward.

Phosphorus availability and rice grain yield in a paddy soil in response to long-term fertilization

Rice (Oryza sativa L.) is one of the most important crops in the world, and its production is limited by soil phosphorus (P) deficiencies in many parts of the world. Impacts of long-term fertilization regimes on rice productivity and soil P availability is largely unknown. A long-term (26-year) field experiment in a paddy soil of southeastern China was carried out to study the response of rice grain yield and soil P pools to different fertilization regimes including control without fertilization (CK), nitrogen, P, and potassium (NPK) fertilizer (NPK), NPK fertilizer plus cattle manure (NPKM), and NPK fertilizer plus rice straw (NPKS). Application of fertilizers (NPK, NPKM, and NPKS) increased rice grain yield compared with the CK treatment (on average, by 75%, 97%, and 92%, respectively). Soil P was predominately present in the organic form (51–75% of total P) across different treatments. Most soil inorganic P fractions decreased with time due to continuous depletion by rice plants in the nonfertilized treatment (CK), while they generally increased with time in the fertilizer treatments (NPK, NPKM, and NPKS) due to continued supply of P to soil. On the other hand, soil organic P fractions increased continuously with time regardless of treatment, probably due to the retention of stubble and biological immobilization of inorganic P. Positive relationships between the rice grain yield and most inorganic P fractions in the CK treatment indicated the P limitation for rice production due to no P inputs and long-term conversion of inorganic P into organic P.

Agronomic Responses of Corn to Planting Date and Plant Density

Corn (Zea mays L.) grain yield is closely related to plant density and is typically maximized in the northern Corn Belt when planting occurs in late April. However, spring rainfall events often result in wet soil conditions that delay planting. From 2008 to 2010, experiments were conducted at two locations in southern Minnesota to determine whether the agronomic responses of corn to plant density differ with planting date. Six plant densities ranging from 38,400 to 107,900 plants ha−1 were evaluated within three planting dates that occurred on 2‐wk intervals beginning in late April to early May. Yield and net return to seed cost were not affected when planting was delayed 2 wk, but were 15 and 18 to 30% lower when planting was delayed 4 wk, respectively. Yield loss due to late planting was associated with a 7% decrease in kernel weight and no change in kernels per square meter. Responses to plant density for stalk diameter, intercepted photosynthetically active radiation (IPAR) and leaf area index (LAI) at silking, lodging, grain yield and components, and net return to seed cost for 25 economic scenarios did not differ with planting date. There was a quadratic‐plateau response of grain yield to plant density with yield maximized at ≥81,700 plants ha−1. These results from a 102‐d relative maturity hybrid over six site‐years in southern Minnesota show that increased plant density may not be able to offset the yield and economic losses associated with late planting.

Grain yield and water use efficiency of two types of winter wheat cultivars under different water regimes

To improve grain yields of winter wheat and water-use efficiency in the water-shortage region of the North China Plain (NCP), field experiments involving three irrigation levels and two types of winter-wheat cultivars (Shijiazhuang 8 and Xifeng 20, with moderate and strongly drought tolerance, respectively) were conducted over three growing seasons with different levels of precipitation. The results showed that irrigation significantly improved the grain yield of both wheat cultivars. The response of grain yield was largest in the dry year, followed by the normal and wet years. Shijiazhuang 8 responded more strongly than Xifeng 20. Compared to aboveground biomass under no irrigation treatment, the aboveground biomass of Shijiazhuang 8 and Xifeng 20 improved by 87.0% and 57.8%, respectively, in a dry year, by 27.2% and 18.3%, respectively, in a normal year, and by 13.7% and 11.7%, respectively, in a humid year when irrigation were applied twice. The total water use (TWU) of the two cultivars also increased upon irrigation. The increase was more pronounced in the dry year than in the normal or humid years. However, there were no significant differences in the TWUs of the two cultivars. The water-use efficiency at grain-yield level (WUEy) of Shijiazhuang 8 increased significantly upon irrigation in the dry year, did not change in the normal year, and showed a clear decline in the humid year, while the WUEy of Xifeng 20 was reduced by irrigation in each of the three growing seasons. The harvest index (HI) was not altered by irrigation but it did vary by growing season. The HI of Shijiazhuang 8 was always higher than that of Xifeng 20. A positive correlation was found between both the WUEy and the water-use efficiency at the aboveground-biomass level (WUEbm) and the HI. This suggests that the changes in WUEy as a result of irrigation are mainly due to changes in the WUEbm and that the differences in WUEy between the two cultivars were due to differences in WUEbm and HI. These results suggest the following. (1) The TWUs in the two cultivars were roughly equal, although their levels of drought tolerance differed. (2) A wheat cultivar with moderate drought tolerance is expected to be more suitable for the semi-arid region of the NCP. The variety with strongly drought tolerance was able to keep its biomass high and to maintain grain yield under serious drought stress. (3) In order to both increase grain yield and WUEy, two irrigations in a dry year, one irrigation in a normal year, and no irrigation in a humid year will give optimal results in the studied region.

Responses of rainwater conservation, precipitation-use efficiency and grain yield of summer maize to a furrow-planting and straw-mulching system in northern China

In the rain-fed areas of northern China, maize ( Zea mays L.) is a main field crop, as it is well adapted to high temperatures and bright sunshine. However, low and variable rainfall and high evapotranspiration rates are common in water-limited environments during the growing season, and often mismatched rainfall events with the critical growth stages, making yield unstable. In this study, the performance of a furrow-planting and straw-mulching system was compared with the conventional flat-planting system in a double-crop culture of winter wheat ( Triticum aestivum L.) and summer maize for two consecutive years (2005–2006 and 2006–2007). The four tested treatments were: conventional flat planting (F), furrow planting between ridges (B), flat planting with wheat straw-mulching (FS), and furrow planting between ridges with wheat-straw mulch (BS). Soil water content and leaf area index (LAI) were measured throughout the growing season each year, and grain yield and precipitation-use efficiency (PUE Y) were determined. On average, ridge tillage combined with furrow planting increased maize yield by 430 kg ha −1 (7.3%) and PUE Y by 10.7% (1.5 kg ha −1 mm −1), compared with the conventional flat planting; furrow planting coupled with straw mulching increased yield by an additional 16.9% and PUE Y by 19.4%, respectively. From jointing to maturity, LAI values of BS were significantly higher than those of F-system (55.6% vs. 26.1% in 2006 and 81.4% vs. 21.7% in 2007). Our data suggest that maize production adopted by furrow planting with straw-covered ridges performed best under seasonal average rainfall below 480 mm, which was associated with better synchronization of seasonal soil water supply and crop needs, leading to improved maize yield and PUE Y.

Yield vs. Quality trade‐offs for wheat in response to carbon dioxide and ozone

AbstractAlthough it is established that there exist potential trade‐offs between grain yield and grain quality in wheat exposed to elevated carbon dioxide (CO2) and ozone (O3), their underlying causes remain poorly explored. To investigate the processes affecting grain quality under altered CO2 and O3, we analysed 57 experiments with CO2 or O3 exposure in different exposure systems. The study covered 24 cultivars studied in 112 experimental treatments from 11 countries. A significant growth dilution effect on grain protein was found: a change in grain yield of 10% by O3 was associated with a change in grain protein yield of 8.1% (R2 = 0.96), whereas a change in yield effect of 10% by CO2 was linked to a change in grain protein yield effect of 7.5% (R2 = 0.74). Superimposed on this effect, elevated CO2, but not O3, had a significant negative effect on grain protein yield also in the absence of effects on grain yield, indicating that there exists a process by which CO2 restricts grain protein accumulation, which is absent for O3. Grain mass, another quality trait, was more strongly affected by O3 than grain number, whereas the opposite was true for CO2. Harvest index was strongly and negatively influenced by O3, but was unaffected by CO2. We conclude that yield vs. protein trade‐offs for wheat in response to CO2 and O3 are constrained by close relationships between effects on grain biomass and less than proportional effects on grain protein. An important and novel finding was that elevated CO2 has a direct negative effect on grain protein accumulation independent of the yield effect, supporting recent evidence of CO2‐induced impairment of nitrate uptake/assimilation. Finally, our results demonstrated that processes underlying responses of grain yield vs. quality trade‐offs are very different in wheat exposed to elevated O3 compared with elevated CO2.

Root Growth of Barley as Affected by Tillage Systems and Nitrogen Fertilization in a Semiarid Mediterranean Agroecosystem

Conservation tillage systems are being widely adopted in the Mediterranean region. A long‐term field experiment was established in 1996 comparing three N fertilization levels (zero, 0 kg ha−1; medium, 60 kg ha−1; and high, 120 kg ha−1), under three tillage systems (conventional tillage, CT; minimum tillage, MT; and no‐tillage, NT) in a semiarid Mediterranean agroecosystem annually cropped with winter barley (Hordeum vulgare, L., cultivar Hispanic), to study the response of root growth. During four consecutive growing seasons, from 2005 to 2009, root length density (RLD) and soil water content were evaluated. Penetration resistance (PR) and soil bulk density were only evaluated in the fourth and last year of this experiment. In dry years, root growth was similar under NT and MT systems but highly reduced under CT due to reduced water availability, which, in the surface 25 cm of soil was 7% and 18% lower than under MT and NT systems, respectively. However, in a wet year (i.e., 2009), RLD was double under CT than under NT due to reduced soil strength. PR at 5 to 15 cm soil depth under NT was 1MPa greater than under MT or CT. Root growth was not affected by N fertilization, in contrast to the response of grain yield that showed a significant interaction between N fertilization and tillage system. In spite of moderate soil compaction, which may reduce root growth in wet years, long‐term NT adoption does not reduce grain yields for monoculture of barley under semiarid Mediterranean conditions.

Responses of biomass growth and grain yield of midseason rice to the anticipated warming with FATI facility in East China

Crop model projections and historical data analyses have shown that global warming may cause serious decrease in crop productivity, however, many uncertainities remain on the impact quantification due to the unclear understanding of actual crop response. Therefore, we performed a three-year field warming experiment with free air temperature increase (FATI) facility to investigate the actual response of midseason rice growth in East China. There were four treatments (AW: all-day warming; DW: daytime warming; NW: nighttime warming; CK: ambient control) with three replicates. This FATI facility presented a good simulation of the local air temperature pattern with an increase in the daily mean temperature of about 1.1–2.0 °C during rice whole growth duration compared to the ambient control. Warming shortened the pre-heading phase respectively by 3.3 d, 1.7 d and 2.0 d in the AW, DW and NW plots, while the post-heading phase stayed almost unchanged. During the three years, warming slightly decreased the aboveground biomass by an average of 9.1%, 10.3% and 3.3%, and the grain yield by an average of 0.9%, 6.4% and 6.1% in the AW, DW and NW plots, respectively. Warming tended to decrease rice photosynthesis rate and stimulate the nighttime respiration rate. It also enlarged the flag leaf area and increased its chlorophyll content. No significant difference and interaction in the actual response of rice growth were found between the warming regimes. The above evidences suggest that the expected warming less than 2.0 °C may not cause significant decrease in rice productivity in East China.

Yield vs. quality trade-offs for wheat in response to carbon dioxide and ozone.

Although it is established that there exist potential trade-offs between grain yield and grain quality in wheat exposed to elevated carbon dioxide (CO2 ) and ozone (O3 ), their underlying causes remain poorly explored. To investigate the processes affecting grain quality under altered CO2 and O3 , we analysed 57 experiments with CO2 or O3 exposure in different exposure systems. The study covered 24 cultivars studied in 112 experimental treatments from 11 countries. A significant growth dilution effect on grain protein was found: a change in grain yield of 10% by O3 was associated with a change in grain protein yield of 8.1% (R2 =0.96), while a change in yield effect of 10% by CO2 was linked to a change in grain protein yield effect of 7.5% (R2 =0.74). Superimposed on this effect, elevated CO2 , but not O3 , had a significant negative effect on grain protein yield also in the absence of effects on grain yield, indicating that there exists a process by which CO2 restricts grain protein accumulation, which is absent for O3 . Grain mass, another quality trait, was more strongly affected by O3 than grain number, while the opposite was true for CO2 . Harvest index was strongly and negatively influenced by O3 , but was unaffected by CO2 . We conclude that yield vs. protein trade-offs for wheat in response to CO2 and O3 are constrained by close relationships between effects on grain biomass and less than proportional effects on grain protein. An important and novel finding was that elevated CO2 has a direct negative effect on grain protein accumulation independent of the yield effect, supporting recent evidence of CO2 -induced impairment of nitrate uptake/assimilation. Finally, our results demonstrated that processes underlying responses of grain yield vs. quality trade-offs are very different in wheat exposed to elevated O3 compared to elevated CO2 .

Corn Responses to In‐Furrow Phosphorus and Potassium Starter Fertilizer Applications

Starter N–P or N–P–K fertilizers often are applied to corn (Zea mays L.), but questions arise concerning the usefulness of starter K. This study assessed responses of corn grain yield, early growth, and early P and K concentration and uptake to in‐furrow fluid P–K and K starter fertilizers. Six replicated small‐plot trials evaluated a control receiving no P or K, 3–8–15 (N–P–K) starter at 5 to 7 kg P ha−1 and 10 to 14 kg K ha−1, 0–0–25 (N–P–K) starter at 10 to 14 kg K ha−1; broadcast fertilizer at 49 to 66 kg P ha−1 and 112 to 140 kg K ha−1; and broadcast‐starter combinations. More N (191–224 kg ha−1) was applied uniformly. Eight replicated field‐length strip‐trials evaluated 0–0–25 starter at 10 to 14 kg K ha−1, broadcast fertilizer at 112 kg K ha−1, and broadcast plus starter. More N (168–224 kg ha−1) and P (49–66 kg ha−1) were applied uniformly. The fields encompassed various tillage systems, hybrids, soils, and soil‐test levels. Starter P‐K applied in addition to broadcast P‐K increased growth and P and K uptake compared with broadcast P–K at two trials, but did not increase yield. Starter K applied in addition to broadcast P–K at the small‐plot trials or broadcast K at the strip‐trials did not increase growth compared with broadcast fertilization, decreased K uptake at 2 of the 14 trials, and did not affect yield. Potassium seldom had a starter effect on corn. Starter K may not increase corn early growth or yield unless the soil is deficient in K and broadcast K is not applied.

Effect of Long-Term Potassium Fertilization on Crop Yield and Potassium Efficiency and Balance Under Wheat-Maize Rotation in China

Sustainable potassium (K) management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale. We analyzed responses of grain yield of wheat ( Triticum aestivum L.) and maize ( Zea mays L.), K efficiency, and partial balance (difference between K input through fertilizer and K output in the aboveground biomass) during 15- (1990-2005) or 18-year (1990-2008) K fertilizations at five distinctive agroecological zones across China. Compared to the inorganic nitrogen (N) and phosphorus (P) fertilization, the inorganic NPK fertilization significantly increased grain yields of wheat (21%) and maize (16%-72%) at Qiyang and Changping, where soils have low exchangeable and non-exchangeable K contents, but not at Ürümqi, Yangling and Zhengzhou, where soils have a high exchangeable and non-exchangeable K and/or low N/K ratio in crop plants. Compared to the inorganic NPK fertilization, the inorganic NPK (30% N) and organic manure (70% N) fertilization (NPKM) increased grain yields of wheat (14%-40%) and maize (9%-61%) at four sites, but not at Zhengzhou. For a productivity of wheat at 2-5 t ha −1 or maize at 3-6 t ha −1, 13-26 or 9-17 kg K ha −1 were required to produce 1.0 t wheat or maize. The NP fertilization resulted in the lowest negative partial K balance and accumulated 52 kg K ha −1 year −1 less than the NPK fertilization, which accumulated 28 kg ha −1 year −1 less K than the NPKM fertilization. A re-evaluation of the site-specific fertilization effects on N/K ratio in crop plants and soil K accumulation under current NPK and NPKM fertilization is urgently needed to increase both crop yield and K use efficiency at different agroecological zones across China.

Constraints to achieving high potential yield of wheat in a temperate, high-rainfall environment in south-eastern Australia

Average wheat yields in the high-rainfall zone (HRZ) of southern Australia are predicted to be around 10 t ha–1, yet most regions fall short through a lack of locally adapted cultivars or abiotic stress that constrains yield. Wheat yields in Tasmania can be variable but have exceeded this potential yield in some field trials and have thus approached that of other traditionally high-yielding HRZ environments such as northern Europe. A contributing factor to high wheat yields in Tasmania is the cool-temperate climate, which tends not to have extremes in temperature (cold, heat) as may be experienced in HRZ environments elsewhere. Hence an understanding of crop growth, development and yield of wheat of locally adapted wheat cultivars in Tasmania may improve our understanding of the basis of yield formation in other HRZ in Australia. This was evaluated by conducting an analysis for adaptive response of grain yield in 10 wheat genotypes to a range of 14 environments that were favourable for wheat production or experienced constraints to growth. Crop growth and yield formation was then examined in detail for all or a subset of these genotypes in three field trials with contrasting environments, two of which included a time of sowing (TOS) treatment. Environment accounted for around 90% of the sum of squares (SS) in the multi-site analysis of yield. Six environment groups were identified using cluster analysis, two of which were clearly separated in response to frost at flowering or putative biotic stress, which constrained yield to 1.8 and 6.8 t ha–1, respectively. Waterlogging was also a significant abiotic stress in one of the TOS field trials. The late-flowering cultivar Tennant had the highest yield in the presence of waterlogging and by avoiding frost at flowering, although it suffered a yield penalty of 35 and 66%, respectively, compared with the average across environments. The highest-yielding genotypes averaged 8 t ha–1 across environments and included Alberic, the breeding line K37.18 and the new release Revenue. In the detailed experiments on crop growth and development, high grain yields of 10 t ha–1 in Mackellar appeared to be due to increased grains ear–1, resistance to barley yellow dwarf virus and possibly higher radiation-use efficiency, although the latter needs to be confirmed. There was little genotype × environment interaction for grain yield, hence wheat breeders can have a relatively high level of confidence that genetic material with high yield potential should rank consistently across Tasmanian environments. Results presented in the paper will be useful in developing management and breeding strategies to increase potential yield across the HRZ of southern Australia.

MAIZE GRAIN YIELD RESPONSE TO INTERCROPPING WITH THREE LEGUME FODDER CROPS

Two field trials were carried out at Shandaweel Agriculture Research Station (Sohag Govemorate) during 2008 and 2009 summer seasons to study response of maize grain yield to intercropping with three legume fodder crops under three sowing dates (simultaneous maize and interaopped crops sowing and sowing at 3 and 5 weeks after maize). A split plot design with three replicates was used. The main plots were devoted to the three legume crops, and the sub plots were allocated to sowing dates of legume crops. The data obtained indicate that all studied characters of maize, cowpea; guar and soybean were reduced as compared with solid crops. This reduction was higher in legume crops than maize. The intercropping system resulted in maize plant height espedally when the interaopped crops were planted at the same of maize planting date. Maize grain yield character and its components were significantly affected by intercropped crops and sowing date. The reduction in maize characters was higher when intercropped with guar than with cowpea or soybean, and at simultaneous (Tr) than delay sowing (T2) or (T3).The forage green yield of cowpea, guar and soybean were affected by intercropping system and sowing dates. The forage green yield at late planting dates (3 or S weeks after maize) was more decreased than those sown at the same date of maize. The results also showed that maize grain yield crop was dominant while intercropped crops were dominated , where the highest land equivalent ratio (LER) recorded 1.15 and monetary 776.96 when maize intercropped with soybean, sown at 5 weeks after maize followed by cowpea sown at the same maize planting date .While total actual grain yield loss (AYL) was positive with cowpea in the three sowing dates with range from 0.13 to 0.23 , indicating increase in grain yield by 13 to 23 %compared with solid crop .While AYL was negative with guar at the first and second sowing dates which indicate decreased in yield with this system. It could be conduded that intercropping maize with cowpea at the same date or with soybean at delayed sowing (5 weeks after maize) had favored the growth and yield of both crops.

Effect of Soil Erosion on Soil Properties and Crop Yields on Slopes in the Sichuan Basin, China

Roles of tillage erosion and water erosion in the development of within-field spatial variation of surface soil properties and soil degradation and their contributions to the reduction of crop yields were studied on three linear slopes in the Sichuan Basin, southwestern China. Tillage erosion was found to be the dominant erosion process at upper slope positions of each linear slope and on the whole short slope (20 m). On the long slope (110 m) and medium slope (40 m), water erosion was the dominant erosion process. Soil organic matter and soil nutrients in the tillage layer were significantly related to slope length and 137Cs inventories on the long slope; however, there was no significant correlation among them on the short slope, suggesting that water erosion lowered soil quality by transporting SOM and surface soil nutrients selectively from the upper to lower slope positions, while tillage erosion transported soil materials unselectively. On the medium slope, SOM, total N, and available N in the tillage layer were correlated with slope length and the other properties were distributed evenly on the slope, indicating that water erosion on this slope was still the dominant soil redistribution process. Similar patterns were found for the responses of grain yield, aboveground biomass, and harvest index for slopes. These results indicated that tillage erosion was a major cause for soil degradation and grain yield reduction on the linear slopes because it resulted in displacement of the tillage layer soil required for maintaining soil quality and plant growth.

Responses of physiological parameters, grain yield, and grain quality to foliar application of potassium nitrate in two contrasting winter wheat cultivars under salinity stress

AbstractAn experiment was conducted to test whether foliar application of KNO3 on wheat in the heading stage could reduce salinity‐induced injuries, produce high grain yield, and improve grain quality. Salt‐resistant DK961 and salt‐sensitive JN17 wheat cultivars under 0 or 100 mM–NaCl conditions were foliarly watered with distilled water or a 10 mM–KNO3 solution. The four treatments included: T1 (CK1), 0 mM NaCl + distilled water; T2, 0 mM NaCl + 10 mM KNO3; T3 (CK2), 100 mM NaCl + distilled water; T4, 100 mM NaCl + 10 mM KNO3. The results indicate that there were no differences (p > 0.05) in plant growth, grain yield, and grain quality between T2 and T1 in both cultivars, but these response variables were significantly lower in T3 than in T1. K+ : Na+ ratio, chlorophyll content, photosynthetic capacity, grain yield, flour yield, water absorbance, ash content, dough‐development time and dough‐stability time were significantly higher in T4 than in T3, while protein concentration, wet‐gluten concentration, and antioxidant enzyme activities were lower. Although foliar application of KNO3 on JN17 enhanced plant growth, grain yield, and grain quality, these parameters were still lower in T4 than in T1. Our findings suggest that cultivating the salt‐resistant wheat cultivar combined with foliar application of KNO3 at heading stage may alleviate salinity injuries and produce higher grain yield and better grain quality under saline conditions.