Rate Of Dry Matter Accumulation Research Articles

Late‐sown winter wheat requires less nitrogen input but maintains high grain yield

AbstractIncreased attention on the agricultural impacts to environment has revealed excessive N input to be a major concern. Sowing date reportedly impacts crop N uptake, however, few studies have assessed the effects of late sowing with reduced N apply on crop N status and grain yield. We evaluated three treatments: normal sowing (8 October), late sowing (22 October), and optimized late sowing (22 October, with 75% N application) over two wheat (Triticum aestivum L.) growing seasons (2017–2019), and assessed their effects on crop N status, N allocation and use, net photosynthetic rate (Pmax), grain yield, and soil N budget. Compared to normal sowing, optimized late sowing resulted in near‐optimum N status, improved nitrogen use efficiency (NUE), nitrogen utilization efficiency (UTE), and nitrogen uptake efficiency (UPE), while maintaining a high yield. Although aboveground N uptake of late and optimized late sowing at anthesis was lower than that of normal sowing, N distribution was more optimized, mainly manifesting as: unchanged N allocation to the individual plant, but increased N allocation to flag leaf, and steeper green leaf area N in the canopy under optimized late sowing. Optimized N nutrition index and N distribution under late sowing contributed to a higher Pmax, which resulted in a higher dry matter accumulation rate during post‐anthesis, and ultimately a consistent grain yield among the three treatments. Moreover, N input reduction under optimized late sowing decreased the final mineral N in the 0–100‐cm soil layer at harvest and apparent N loss, which reduced environmental pollution and resources waste.

Application of brassinolide alleviates cold stress at the booting stage of rice

The objective of the study was to determine the physiological mechanisms of plants in response to brassinolide (BR) alleviating cold water stress on rice. In this study, physiological responses of rice to exogenous BR and cold water submergence were investigated using the chilling-tolerant cultivar Kongyu 131 (KY131) and the chilling-sensitive cultivar Kenjiandao 6 (KJD6). A total of 2 mg L−1 BR increased activities of superoxide dismutase (SOD) and peroxidase (POD) and the contents of soluble sugar, soluble protein, and chlorophyll, but decreased the malondialdehyde (MDA) content in KY131 and KJD6 under cold water stress. The observed decreases in SOD and POD activities and MDA content recovered quickly after plants were returned to irrigation with water at temperatures of about 23.0°C in 2014. Additionally, the contents of nitrogen (N), phosphorous (P), and potassium (K) were increased by BR treatment under cold water stress. Exposure to BR also raised the percentage of high effective leaf area and leaf area index at the heading stage. Furthermore, it promoted soluble sugar synthesis, increased the rate of dry matter accumulation, and enhanced the export and translocation rates of the stem-sheath. The yield in KJD6 was significantly (P≤0.01 and P≤0.05) higher than that of the control in 2013 and 2014, respectively. The effect of BR treatment on rice leaf SOD and POD activities, MDA, chlorophyll, P, and stem-sheath K contents were more significant in KJD6 than in KY131. In conclusion, exogenous BR effectively reduced the physiological and metabolic damage in rice due to cold stress at the booting stage, promoted functional recovery in plants that received irrigation with water at a normal temperature following cold stress, and mitigated the effects of cold water stress on yield. The two varieties exhibited differential responses to BR; the weaker cold-resistant variety was more sensitive to BR and displayed stronger responses to exogenous BR.

Yield and quality changes in lucerne of different fall dormancy ratings under three defoliation regimes

Abstract This study determined how fall dormancy rating (FD2, FD5 or FD10) of lucerne genotypes affected crop yield and quality. One field experiment was measured for three growing seasons as a seedling crop and then three defoliation frequency regimes (DF) of 28 (DF28), 42 (DF42) or 84 (DF84) days were imposed (October 2014 to April 2017). Annual shoot dry matter (DM) yields ranged from 5.2 t DM/ha in DF28 crops to 17.5 t DM/ha in DF84 crops. Higher shoot DM was associated with greater shoot elongation which was modified by photoperiod (Pp). In an increasing Pp environment, the rate of DM accumulation in shoots was ∼ 91 kg/ha for each 1.0 cm increase in shoot height. In a decreasing Pp environment, the rate of DM accumulation in shoots was constant at ∼50 kg/ha/cm. In the DF84 crops, shoot yield declined due to leaf senescence by ∼31 kg/ha/cm when lucerne was ≥65 cm height. The leaf stem ratio (LSR) declined by 0.56 for each 1.0 cm increase in plant height. The crude protein (CP) and metabolisable energy (ME) accumulation in whole shoots or in leaf, soft stem and hard stem followed an allometric relationship. As DM increased, CP and ME increased in a similar pattern for all treatments. Thus the relationship between the yield and quality of lucerne was independent of genotype and phenological stage and was explained allometrically by the leaf and stem ratio, associated with changes in plant height, as affected by photoperiod. These results suggest universal defoliation management strategies can be developed based on ontogeny and independently of genotype, growth stage and growing conditions.

Effects of strip-till with staggered planting on yield formation and shoot-root characteristics of spring maize in irrigation area of Xiliaohe plain

<p indent="0mm">A field research was conducted in the Agricultural High-tech Demonstration Park in Horqin District of Tongliao, Inner Mongolia, using the maize variety Nonghua 101 with two cropping modes, including strip-till with staggered planting (seeding strip tillage, <sc>15 cm</sc> + <sc>45 cm</sc> narrow-double row staggered sowing, TGCW) and conventional tillage with equal row space (rotary tillage with row space of <sc>60 cm,</sc> CK), and three planting densities (67,500 plants hm^–2, 82,500 plants hm^–2, and 97,500 plants hm^–2) in 2017 and 2018 to study the effect of strip-till with staggered planting on regulating spring maize yield formation and coordination characteristics of shoot-root in irrigation areas of Xiliao river plain. The model of that strip-till with staggered planting enhanced maize yield by 13.1% and 13.8% in 2017 and 2018, under the planting density 82,500 plants hm^–2 compared with CK, respectively. The strip-till with staggered planting showed a distinct advantage on the amount and rate of dry matter accumulation after silking, which obviously delayed the senility of leaves in later growth stage, meanwhile, compared with CK, the light transmittance significantly increased in or above panicle layers. The leaf area index, net photosynthetic rate and population photosynthetic potential in the model of strip-till with staggered planting were higher than those in CK in late growth stage. At later growing stage, the strip-till with staggered planting had significantly higher root dry weight than CK in different soil layers, with the highest root ratio in <sc>20–60 cm,</sc> especially under higher planting density. The grain yield against per unit of root weight at silking and root-shoot ratio at maturity had a distinct advantage. In conclusion the strip-till with staggered planting combined with high planting density can increase light transmission rate in above-spike layer in late growing stage, alleviate leaf area decline, increase production capacity, facilitate root growth and increase root ratio in deeper soil layers. Shoot-root coordination under dense planting is one of the main reasons facilitating yield increase of spring maize in irrigation areas of Xiliao river plain.

Effects of nutrient management on growth attributes and yield of high yielding rice (&lt;em&gt;Oryza sativa &lt;/em&gt;L.) varieties of Chhattisgarh

The present investigation entitled “Effects of different nutrient management on growth attributes and yield of high yielding rice (Oryza sativa L.) varieties of Chhattisgarh” was conducted in northern hilly zone of Chhattisgarh at Rajmohini Devi College of Agriculture and Research Station, Ambikapur C.G. during kharif 2016-17. The study was comprised four treatments of nutrient management practices viz. M1-RDF (100: 60: 40 kg NPK ha-1), M2-150% RDF, M3-RDF (N– LCC) (Basal application of 30% N and full P+K and top dressing of Nitrogen as per LCC) and M4-Soil test based recommended dose for 7.0 t ha-1 grain yield (214: 42: 111 kg NPK ha-1) as main plots and five rice varieties viz. Rajeshwari, Durgeshwari, Maheshwari, Karma masuri and Indira Aerobic-1 as sub plots. The present study revealed that the maximum value of plant population (m-2), plant height (cm), number of leaves hill-1, number of tillers hill-1, dry matter accumulation (g hill-1) and crop growth rate (g day-1 hill-1) were recorded under treatment M4-Soil test based recommended dose for 7.0 t ha-1 grain yield (214: 42: 111 kg NPK ha-1) which was superior over other rest of the nutrient management practices. The application of treatment M4-Soil test based recommended dose for 7.0 t ha-1 grain yield (214: 42: 111 kg NPK ha-1) with variety Maheshwari produced maximum growth attributes and grain yield (60.83 q ha-1).

Growth and physiological quality in clonal seedlings of Robusta coffee

The intrinsic characteristics of the vegetative propagule may influence the rooting speed and shoot growth, as well as the final physiological quality of clonal seedlings of Coffea canephora. The aim of this study was to evaluate the growth and physiological quality of ‘Robusta’ coffee seedlings produced from propagules (stem cuttings) with different cutting ages. The study was conducted in a greenhouse, in the district of Ouro Preto do Oeste, in Rondonia, Brazil (10˚45’43” S and 62˚15’10” W). The ages of the cuttings were 30, 60, 90, 120 and 150 days, corresponding to five positions on the secondary orthotropic stem (sprout), from the apex to the base. Dry matter accumulation, and relative and absolute growth rates were evaluated for 188 days after cutting, as well as the vegetative characteristics of the seedlings at 125 days after cutting. It appears that growth can be divided into three phases: 1) Initial: slow growth, lasting approximately 83 days; 2) Intermediate: fast growth, lasting approximately 40 days; and 3) Final: slow growth, starting approximately 125 days after cutting. With physiological quality, although all the cuttings showed similar growth curves, those of 60, 90 and 120 days produced, 125 days after cutting, the best vegetative performance in the seedlings.

Role of Phytohormones in Soybean (Glycine max) Seed Development

Phytohormones play a key important role in the sink development of the seed. Endogenous content of IAA, PAA, GA, ABA, and kinetin were estimated in two distinct varieties of soybean (Glycinemax (L.) Merr.) during the entire period of seed development. Antibodies against IAA, PAA, GA, ABA, and kinetin were raised in rabbits. By competitive ELISA, hormones were estimated from the two different varieties: Large seeded variety (L seed) and Small seeded variety (S seed). Growth analysis showed that L seed had more dry weight, the rate of dry matter accumulation and water content than S seed. Plant hormones are signal molecules that regulate many developmental processes, including sink size and dry matter accumulation in viable mature seed. In both the varieties, the free IAA increased gradually with the seed age; value was near to double in L seed. PAA was also observed higher in L seed than S seed during cell elongation period. While GA content was higher in S seed in compare to IAA and PAA. ABA content was observed 2–4 times lower as compared S seed. A significant difference was observed in kinetin levels which showed nearly 1.5 times higher in L seed compared to S seed. GA and ABA levels were more in S seed suggest that GA/ABA ratio and total hormonal balance determine the sink size. The probable role of hormones in seed development is discussed.

Straw Mulching under a Drip Irrigation System Improves Maize Grain Yield and Water Use Efficiency

ABSTRACTReasonable use of water is required for the sustainable development of maize production in the North China Plain (NCP). In this study, straw mulching (SM) was evaluated in a 2‐yr field experiment to determine whether its effect on maize (Zea mays L.) yield and water use efficiency (WUE) differed under different irrigation systems. Compared with no mulching (NM) treatment, SM increased maize yield by 10.6 and 12.5% under a drip irrigation system in 2016 and 2017, respectively, which was mainly attributed to an 11.7 and 13.5% increase in total dry matter (DM). The increased soil water content in the 0‐ to 40‐cm layer at the six‐leaf (V6), silking (R1), and maturity (R6) stages for SM improved the soil mineral N content (Nmin) in that layer and then increased the N accumulation from V6 to R1 and post‐silking by 7.6 and 21.1% averaged over 2 yr compared with NM, respectively. The enhanced N accumulation for SM increased the leaf area index and DM accumulation rate, which increased the DM accumulation from V12 to R1 and post‐silking by 16.2 and 16.4% averaged over 2 yr compared with NM, respectively, and then the grain number and grain weight. Straw mulching also improved the WUE under the drip irrigation system due to the greater grain yield and 6.1% lower water consumption. This demonstrated that SM combined with the drip irrigation system effectively improved the yield and WUE of maize due to improved DM and N accumulation promoted by the increased water content and Nmin in the upper soil layers.

ПРОДУКЦИОННЫЙ ПРОЦЕСС СОРТОВ FRAGÁRIA X ANANÁSSA В УСЛОВИЯХ ОРЛОВСКОЙ ОБЛАСТИ*

The purpose of the study was to study the characteristics of the main components of the production process of Fragaria x ananassa varieties of different ecological and geographical origin in the conditions of the Oryol region. It has been shown that the varieties “Alba”, “Sonata”, “Solovushka” and “Tzaritsa”, in comparison with Korona, Sara, Marmolada and Kokinskaya rannyaya, demonstrated more efficient photosynthetic activity, high rates of dry matter accumulation, effective outflow, and accumulation of assimilates into ripening fruits, which ultimately affected their high yields.

DRY MATTER AND NUTRIENT ACCUMULATION CURVE IN CABBAGE CROP

Abstract Cabbage cultivars currently cultivated present high yield potential and may present differences regarding absorption and use of nutrients. Thus, studies quantifying plant growth and nutrient accumulation are the basis to improve fertilization efficiency and optimize yield. This study aimed to determine the dry matter and nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn, and Zn) accumulation curve of cabbage cultivars during two growing seasons. Cultivars Astrus Plus and Green Valley were cultivated during summer-autumn crop season, while Astrus Plus and Fênix during the autumn-winter crop season. Plants were sampled after transplanting at 10-day intervals until harvest. Dry matter and nutrient accumulations are variable with growing season and cultivar. The highest dry matter and nutrient accumulation rates occur in the last ten days of the cycle. Fertilizations with N, P, K, Fe, and Zn should receive more attention due to higher harvest indices.

Reduced 15N Losses by Winter and Spring Night-Warming Are Related to Root Distribution of Winter Wheat

To develop efficient N management strategies for high wheat NUE and minimizing the environmental impact of N losses under asymmetric warming, 15N micro-plot experiments were conducted to investigate the effects of night-warming during winter (warming by 1.47–1.56°C from tillering to jointing), spring (warming by 1.68–1.82°C from jointing to booting), and winter + spring (warming by 1.53–1.64°C from tillering to booting) on root growth and distribution of winter wheat, the fates of 15N-labeled fertilizer, and their relationships in 2015–2017. The results showed that night-warming increased the recovery of basal 15N and top-dressed 15N, while reduced the residual and loss of basal 15N and top-dressed 15N. The losses decreases of top-dressed 15N were higher than those of basal 15N, indicating that night-warming reduced losses of fertilizer 15N mainly by reducing losses of top–dressed 15N. Moreover, pre-anthesis root dry matter accumulation rate in 0–60 cm soil layer were promoted, resulted in improved root biomass and root/shoot ratio, which favored increasing recovery of fertilizer 15N and reducing losses of fertilizer 15N. Furthermore, residual fertilizer 15N content in 0–100 cm soil layer was reduced, which was associated with improved root weight density in 0–60 cm soil layer, resulted in reduced leaching losses of fertilizer 15N. The path analysis showed that root dry matter distribution in 0–20 cm soil layer was the most important in contributing to reducing losses of total fertilizer 15N compared with other soil layers. Two years data showed that winter and spring night-warming gave better root growth and distribution in 0–20 cm soil layer, resulted in reduced the losses of fertilizer 15N and improved the recovery of fertilizer 15N, while maximizing grain yield of winter wheat, and winter + spring night-warming resulted in higher advantages than winter night-warming and spring night-warming.

Nitrogen fertigation schedule and irrigation effects on productivity and economics of spring sugarcane

The field experiment was conducted to find the appropriate irrigation method, fertilization schedule and its influence on growth, yield and quality of sugarcane. The soil of the experimental site was sandy clay loam, neutral in reaction (pH 7.7), low in organic carbon (0.41%) and available nitrogen (167.0 kg ha-1), medium in available phosphorus (19.1 kg ha-1) and potassium (208.0 kg ha-1). Experiment was laid out in split plot design with four replications. The treatments consisted of three irrigation methods in main plot viz., flood, furrow and drip; five nitrogen scheduling in sub plot viz., farmers practice, 4 splits, 6 splits, 8 splits and 10 splits. In flood method of irrigation all growth and quality parameter were recorded lowest. Thus, it may be concluded that to achieve highest millable cane and quality parameters, drip irrigation is a better option. The number of tillers (177.2 thousand ha-1), number of millable canes (123.3 thousand ha-1), cane length (367.98 cm), cane yield (168.51 t ha-1), commercial cane (CCS) yield (25.05 t ha-1) and economic return were found significantly higher under drip irrigation during first year. Similar trends were recorded during second year of experimentation. The highest dry matter accumulation and crop growth rate were also recorded under drip irrigation during both the years. Similarly, water use efficiency and water productivity were found maximum under treatment of drip irrigation. Significantly highest number of tillers (165.6 thousand ha-1), millable canes (116.3 thousand ha-1), cane yield (154.72 t ha-1), dry matter accumulation, crop growth rate, CCS yield (23.39 t ha-1) and economic return were recorded with 6 splits of nitrogen application. The overall effect of nitrogen scheduling was in the order of 6 splits &gt; 8 splits &gt; 10 splits &gt; 4 splits &gt; farmer’s practice.

СОЗРЕВАНИЕ ЗЕРНА ЯРОВОЙ ТВЁРДОЙ ПШЕНИЦЫ В СВЯЗИ С ПОГОДНЫМИ ФАКТОРАМИ И ПРИЁМАМИ АГРОТЕХНИКИ В ОРЕНБУРГСКОМ ПРИУРАЛЬЕ

The aim of the study is to increase the yield of spring durum wheat in the Orenburg Urals. Spring hard wheat makes more demands on the temperature region during the formation and filling of grain. Due to the growing aridity conditions of the second half of the growing season, when the grain falls asleep, have become more unfavorable. As you know, the nature of the filling, favorable weather conditions in this period are determined by the yield and quality of grain. The studies were carried out in 2016-2018 in the Central zone of the Orenburg region on chernozems ordinary in two stages of the main tillage. Weather conditions contrasted sharply. The research method is a field experiment. Experience and research were conducted according to conventional methods. Analysis of the grain samples was performed using a laboratory balance Adam NSV 602N and furnace SESH-3M. Mathematical analysis was performed in the program Statistica 6.0. It is established that the duration of grain loading in the study area depends on the weather conditions of the year, ranging from 20-21 days to 31 days. The growth rate of dry matter accumulation in durum wheat grain is observed in the air temperature range 18.7-26.2°C, followed by an increase in temperature reduces the increase. Amid the subsurface processing plowed fields, reducing grain moisture is less intense: 10 grade Orenburg-plowing is of 0.99 – 2.46% on a day, subsurface tillage-0.80 – 2.50% daily; cultivar bezenchukskaya 210 – plowing 1.64-of 2.34%, subsurface tillage-1.03-2.32%.

Photosynthetic efficiency and relationship to mesocarp dry matter content of ‘Carmen’ avocado (Persea americana Mill.) fruit in a cool subtropical climate

Physiological changes associated with leaf chlorophyll fluorescence and gas exchange are the key components towards understanding performance of fruit trees. In this study, the photosynthetic efficiency of leaves from inside and outside canopy positions of avocado trees was assessed during the fruit growing season. The aim was to determine to what extent photosynthesis and gas exchange of the leaves correlates with the position of the leaf inside canopy and outside canopy of an avocado tree, and how does that affect fruit maturity. The study was conducted in a commercial orchard at Everdon Estates in the KwaZulu-Natal, South Africa during 2017/18 season. A total of fifteen 8-year old avocado trees (cv. ‘Carmen’) were selected in a completely randomised design with three replicates and each replicate consisting of five trees. Data was collected bi-weekly from full bloom to fruit physiological maturity (25% dry matter content). Measured variables included gs, Ci, T, A, F0, Fm, Fv/Fm, ΦPS II, qP, qN, ETR, 1-qP and DM content, were estimated within and outside canopy. Results showed that leaves from the outside position had higher A (22.28 mol CO2 m−2 s−1), gs (0.22 mol CO2 m−2 s−1), ΦPS II (0.35), and qP (0.57) compared to those on the inside position of the canopy with lower values of 14.19 mol CO2 m−2 s−1, 0.14 mol CO2 m−2 s−1, 0.047 and 0.071, for A, gs, ΦPS II and qP respectively. Conversely, Fo’, Fm’, Fv’, Fv’/Fm’, and 1-qP were about two times higher on the inside canopy than on the outside. The high photosynthetic efficiency of outside fruit was linked fruit maturity with fruit from the outside maturing earlier with an average mesocarp dry matter content of 27.6% compared to 26.5% on fruit from the inside canopy. The findings suggest that the high sunlight interception by leaves from the outside position improved photosynthetic efficiency, increased rate of dry matter accumulation and maturation of avocado fruit. There is a strong sink demand within the outside canopy demanding more carbohydrates, and thus commanding leaves from the outside canopy to photosynthesize more efficiently leading to fast maturity.

Effects of combined application of pig manure with urea on grain yield and nitrogen utilization efficiency in rice-wheat rotation system

To examine the effects of pig manure application on dry matter production, nitrogen accumulation and distribution, grain yield and nitrogen use efficiency of rice and wheat, the field trial was conducted with wheat 863 and rice 498. Fertilization treatments consisted of seven rates of organic manure supply: control (CK, no chemical nitrogen fertilizer, no pig manure), conventional fertilizing (T1, no pig manure), 2500 kg·hm-2 pig manure with 75% conventional fertilizing (T2), 5000 kg·hm-2 pig manure with 50% conventional fertilizing (T3), 10000 kg·hm-2 pig manure (T4), 15000 kg·hm-2 pig manure (T5) and 20000 kg·hm-2 pig manure (T6). Combined application of pig manure with chemical fertilizer promoted dry matter accumulation of rice and wheat throughout the growing season. At the maturity stage of rice and wheat, the highest aboveground dry matter accumulation presented under highest pig manure input (T6). The dry matter accumulation and nitrogen distribution were enriched in stem or leaf. The dry matter accumulation and nitrogen distribution rate in grain at T6 was significantly lower than T2 treatment. The high-est nitrogen fertilizer partial productivity, fertilizer agronomic efficiency and grain yield of rice pre-sented at T3 treatment, which increased by 11.4%, 55.4%, 11.4% than that of conventional chemical fertilizer treatment, respectively. These vaules for wheat were at T2, which was 14.0%, 29.1%, 14.0% higher than that of conventional fertilizer treatment, respectively. The combined application of pig manure with appropriate rates of chemical fertilizer (T2 and T3) could promote dry matter accumulation, the migration of nitrogen to grains, the increase of yield and the nitrogen use efficiency. Too much pig manure input (15000-20000 kg·hm-2) could lead to excessive supply of nitrogen for crops. In this case, the transportation of dry matter to economic organs would be blocked and the nitrogen enriched to stem. The late-maturing phenomenon occurred, resulting in significant decrease of grain yield.

Post-Anthesis Photosynthetic Properties Provide Insights into Yield Potential of Tartary Buckwheat Cultivars

Photosynthesis is the basis for plant productivity, and improvement of photosynthetic efficiency is an important way to improve crop yield. However, the relationship between photosynthetic parameters and the yield of Tartary buckwheat (Fagopyrum tataricum) under rainfed conditions is unclear. A two-year field trial was conducted during 2016 and 2017 to assess the photosynthetic capacity of different leaves, dry matter accumulation, and yield of four Tartary buckwheat cultivars from flowering to maturity. The leaves of all cultivars aged gradually after flowering, and the leaf chlorophyll (Chl) and soluble protein (SP) contents, net photosynthetic rates (Pn), transpiration rates (Tr), and stomatal conductance (Gs) tended to decline. The Chl, SP, Pn, Tr, and Gs of cultivars (cvs.) XiQiao2 and QianKu3 were significantly higher than those of LiuKu3 and JiuJiang at each sampling time from 18 days after anthesis to maturity, but the intercellular CO2 content (Ci) showed the opposite trend. Cultivars XiQiao2 and QianKu3 produced more total dry matter (mean 17.1% higher), had higher harvest index (HI, mean 16.4% higher), and yield (mean 29.0% higher) than cvs. LiuKu3 and JiuJiang at maturity, and the difference was remarkably consistent. The yield of all the cultivars was positively correlated with leaf Chl, SP, Pn, Tr, and Gs, but negatively correlated with Ci. At late growth stages, the high-yielding cultivars maintained higher Chl, SP contents, Pn, Tr, and Gs, and showed higher dry matter accumulation and lower Ci than the low-yielding cultivars, consistent with their higher leaf photosynthetic capacity. The important factors determining the yield of Tartary buckwheat were maintaining higher leaf Chl and SP content and photosynthetic capacity and delaying aging during the grain formation stage. Enhanced rates of photosynthesis and dry matter accumulation led to higher post-anthesis accumulation of biomass with a positive impact on grain number and higher yield.

Simulated Assessment of Summer Maize Drought Loss Sensitivity in Huaibei Plain, China

In an agricultural drought risk system, crop drought loss sensitivity evaluation is a fundamental link for quantitative agricultural drought loss risk assessment. Summer maize growth processes under various drought patterns were simulated using the Cropping System Model (CSM)-CERES-maize, which was calibrated and validated based on pit experiments conducted in the Huaibei Plain during 2016 and 2017 seasons. Then S-shaped maize drought loss sensitivity curve was built for fitting the relationship between drought hazard index intensity at a given stage and the corresponding dry matter accumulation and grain yield loss rate, respectively. Drought stress reduced summer maize evapotranspiration, dry matter, and yield accumulation, and the reductions increased with the drought intensity at each stage. Moreover, the losses caused by drought at different stages were significantly different. When maize plants were exposed to a severe water deficit at the jointing stage, the dry matter and grain yield formation were greatly affected. Therefore, maize growth was more sensitive to drought stress at the jointing stage when the stress was serious. Furthermore, when plants encountered a relatively slight drought during the seedling or jointing stage, which represented as a lower soil water deficit intensity, the grain yield loss rates approached the maximum for the sensitivity curves of these two stages. Therefore, summer maize tolerance to water deficit at the seedling and jointing stages were weak, and yield formation was more sensitive to water deficit during these two stages when the deficit was relatively slight.

Integrated agronomic practice increases maize grain yield and nitrogen use efficiency under various soil fertility conditions

Crop yield potential can be increased through the use of appropriate agronomic practices. Integrated agronomic practice (IAP) is an effective way to increase maize (Zea mays L.) grain yield and nitrogen use efficiency (NUE); however, the physiological processes associated with gains in yield potential obtained from IAP, particularly the different under various soil fertility conditions, remain poorly understood. An IAP strategy including optimal planting density, split fertilizer application, and subsoiling tillage was evaluated over two growing seasons to determine whether the effects of IAP on maize yield and NUE differ under different levels of soil fertility. Compared to farmers' practices (FP), IAP increased maize grain yield in 2013 and 2014 by 25% and 28%, respectively, in low soil fertility (LSF) fields and by 36% and 37%, respectively, in high soil fertility (HSF) fields. The large yield gap was attributed mainly to greater dry matter (DM) and N accumulation with IAP than with FP owing to increased leaf area index (LAI) and DM accumulation rate, which were promoted by greater soil mineral N content (Nmin) and root length. Post-silking DM and N accumulation were also greater with IAP than with FP under HSF conditions, accounting for 60% and 43%, respectively, of total biomass and N accumulation; however, no significant differences were found for post-silking DM and N accumulation between IAP and FP under LSF conditions. Thus, the increase in grain yield with IAP was greater under HSF than under LSF. Because of greater grain yield and N uptake, IAP significantly increased N partial factor productivity, agronomic N efficiency, N recovery efficiency, and physiological efficiency of applied N compared to FP, particularly in the HSF fields. These results indicate that considerable further increases in yield and NUE can be obtained by increasing effective soil N content and maize root length to promote post-silking N and DM accumulation in maize planted at high plant density, especially in fields with low soil fertility.

Physiological basis for controlling water consumption by two snap beans genotypes using different anti-transpirants

Enhancing water use efficiency (WUE), while maintaining productivity, represents a challenge, particularly, in arid and semi-arid environments. The use Antitranspirants (ATs) is an effective approach to mitigate water deficit- and drought-induced yield losses, via reducing transpiration. This study aimed to determine the effects of ATs compounds on WUE and root and shoot physiological responses of two snap bean genotypes with different ozone sensitivity [tolerant (R123) and sensitive (S156)]. Under glasshouse conditions, plants were sprayed (25 days after planting) with 4% (w/v) kaolin (KPF); 0.0015% (w/v) Fulvic acid (FA); 1% (v/v) Pinolene (PIN) or water (control). Treatments were subjected to three irrigation/drying cycles, and then exposed to survivability test by ceasing irrigation. Water consumption (WC), leaf water potential (Ψw), total dry matter (TDM), dry matter accumulation rate (DMAR), leaf temperature, plant survival and root development were determined. There was a minimal genotype effect on all parameters, except TDM, DMAR, and fine-root diameter and length. KPF treatment was cooler than the control (<3.83 °C), consequently, had higher Ψw and lower WC, without affecting TDM and DMAR. Therefore, biomass-WUE (total dry matter/transpired water) of KPF treatment increased (29.4% and 13.3% for R123 and S156, respectively). Pinolene and FA treatments exerted no effects on those parameters. KPF treatment alleviated most of the physiological effects of water deficit, hence plants survived longer. KPF and FA treatments had thicker very fine (0.0726 to 0.29 mm) and fine (0.308 to 0.562 mm) roots than the control, with KPF having the strongest effect on roots development. Pinolene treatment showed no effect on the roots of R123, but conditioned significant thickening of S156 roots; a notable reversal of the observed effect of KPF and FA. In conclusion, conserved water by KPF, could reduce irrigation frequency and, later, play as a crucial water resource for plant survival. Moreover, future research with ATs must take root responses into account.

Effects of supplemental irrigation on the accumulation, distribution and transportation of 13C-photosynthate, yield and water use efficiency of winter wheat

Water resources are increasingly scarce, and droughts are frequent in the Huang-Huai-Hai Plain of China. There is an urgent need for developing water-saving technologies for winter wheat production in this region. Field experiments were carried out in silty loam soil from 2012 to 2014. Based on the same water condition in seeding period and the normal emergence of winter wheat, five supplemental irrigation (SI) regimes differing in the timing of SI were established. Crop development was categorized using the Zadoks scale. T1: no irrigation after emergence; T2: SI at jointing (4th node detectable, Z34); T3: SI at pre-wintering (average daily temperature drops to about 2 ° and the wheat plant basically stops growing) and jointing; T4: SI at jointing and anthesis complete (Z69); T5: SI at pre-wintering, jointing and anthesis complete. The results showed that SI brought the soil water content in the 0–20 cm profile to 100% field capacity at the pre-wintering, jointing and anthesis complete stages of winter wheat, mainly improving the water supply condition in the 0–40 cm soil layer. Compared with no irrigation after emergence, SI at jointing and anthesis complete significantly increased grain yield by increasing the spike number, kernel number and grain weight. SI at the pre-wintering stage can improve grain number and yield under the condition of no SI at anthesis complete (comparing T3 with T2), but had no significant effect on grain yield when SI was supplied at jointing and anthesis complete (comparing T5 with T4), and even worse, the irrigation water use efficiency decreased. The decrease of water supply before anthesis complete significantly reduced the dry matter accumulation and photosynthetic rate at anthesis but promoted the translocation of photosynthates to the plant ear. SI at anthesis complete is advantageous for the assimilation of carbohydrates in the middle and late grain filling stage and for the distribution of those carbohydrates from vegetative organs to grain. These results indicated that SI at jointing and anthesis complete was conducive to coordinating the relationship between photosynthesis and photosynthates retranslocated after anthesis, and may improve the harvest index, grain yield and water use efficiency.