Greater Kernel Number Research Articles

Utjecaj gustoće sklopa na lisnu površinu, interval od prašenja do svilanja, prinos i komponente prinosa inbred linija kukuruza i križanaca srodnih linija

Yield of maize inbreds is often a limiting factor in hybrid seed production. Thus, the main aim was to evaluate the effect of plant density on leaf area index (LAI), anthesis to silking interval (ASI), grain yield and yield components of inbreds and their sister-lines at two locations over two growing seasons. Inbreds Bc 279 and Bc 64, and their corresponding sister-lines Bc 279026-22 and Bc 822-1064, respectively, were grown at 60,000 and 86,000 plants*ha-1. When compared to inbreds, grain yields improved for sister-lines by an average of 1188 kg*ha-1 (21%) for Bc 279026-22 and 4816 kg*ha-1 (141%) for Bc 822-1064 primarily due to more kernel rows per ear and kernels per ear row. This greater kernel number per ear and per plant was associated with larger LAI for Bc 279026-22, while Bc 822-1064 out-yielded inbred Bc 64 despite of similar LAI and ASI. Inbred Bc 64 and its sister-line Bc 822-1064 increased LAI similarly at higher plant density, but the former showed limited yield increment because of a large increase in barren plants. In contrast, inbred Bc 279 and its sister-line Bc 279026-22 responded similarly for grain yields and LAI across plant densities. A growing season × location × plant density interaction indicated various grain yield responses to plant densities under different environmental conditions. Higher plant density significantly improved grain yields for sister-lines and inbred Bc 279, but had limited advantage for inbred Bc 64; these genotype-specific responses could not be always explained by changes in LAI and ASI.

Seedling characteristics and grain yield of maize grown under straw retention affected by sowing irrigation and splitting nitrogen use

The practice of straw retention often causes seedling issues, including slow seedling establishment and weak seedling. Irrigation shortly after sowing (namely ‘sowing irrigation’, abbreviated as SI) may help to accelerate the seedling establishment under straw retention, and appropriate split nitrogen (SN) management may further boost crop growth and grain yield. Here, we conducted a 2-year field trial to assess the impacts of SI and SN on crop growth, grain yield and water and nitrogen use efficiencies of a maize hybrid i.e. Zhengdan 958 grown under straw retention. The treatments consisted of two irrigation conditions and three splitting nitrogen regimes, with three replications. SI treatment was composed of 0 mm irrigation (denoted as W0) and 60 mm irrigation (denoted as W1) shortly after sowing. SN management contained a similar total nitrogen rate (300 kg ha−1) but was split in three proportions between sowing and big flare stage, i.e. 10:0 (denoted as N1), 5:5 (denoted as N2) and 3:7 (denoted as N3). Our results indicated that sowing irrigation accelerated seedling emergence by 2–7 days, and increased grain yield by 4.73% (2014) and 5.90% (2015), and water use efficiency by 1.69% (2014) and 3.80% (2015) compared to the treatment without sowing irrigation. N2 and N3 treatments increased grain yield by 9.00–10.12% via greater kernel number, and increased nitrogen partial factor productivity by 9.35–10.20% in both years. The improved grain yield by sowing irrigation or splitting nitrogen was due to greater canopy photosynthetic capacity with higher leaf area index, leaf chlorophyll content and net photosynthesis rate. It was found that the optimal ratio of basal: topdressing nitrogen depended on whether sowing irrigation was used. Without sowing irrigation, W0N2 produced the highest grain yield; while with irrigation, both W1N2 and W1N3 produced a greater production than W1N1. In conclusion, the combination of sowing irrigation and splitting nitrogen to the big flare stage could increase not only maize grain yield, but also resource-use efficiency under straw retention in lime concretion black soil of Huaibei Plain, Anhui Province, China.

Yield and yield components of wheat and maize in wheat–maize intercropping in the Netherlands

Abstract Intercropping is widely used by smallholder farmers in developing countries, and attracting attention in the context of ecological intensification of agriculture in developed countries. There is little experience with intercropping of food crops in Western Europe. Yields in intercrops depend on planting patterns of the mixed species in interaction with local growing conditions. Here we present data of two years field experimentation on yield and yield components of a wheat–maize intercrop system in different planting configurations in the Netherlands. Treatments included sole crops of wheat (SW) and maize (SM), a replacement intercrop consisting of strips of six wheat rows alternating with two maize rows (6:2WM), as well as subtractive or additive designs, based on skip-row (6:0WM, 0:2WM) and add-row (8:2WM, 6:3WM) configurations. The land equivalent ratio (LER) of intercrops varied from 1.18 to 1.30 in 2013 and from 0.97 to 1.08 in 2014. Wheat grown in the border rows of wheat strips had higher ear number per meter row, greater kernel number per ear, and greater yield per meter row than wheat in inner rows and sole wheat, indicating reduced competition. Wheat in the border rows in the intercrops had, however, reduced thousand kernel weight and harvest index, indicating that competition in border rows intensified over time. Intercropping negatively affected maize biomass and thousand kernel weight, especially in add-row treatments. This study indicates that there is a potential yield benefit for the wheat–maize intercropping system under Western European growing conditions. However, the LER was affected by yearly variation in weather conditions and significantly greater than one in only one of the two years of the study.

High productivity of wheat intercropped with maize is associated with plant architectural responses

Mixed cultivation of crops often results in increased production per unit land area, but the underlying mechanisms are poorly understood. Plants in intercrops grow differently from plants in single crops; however, no study has shown the association between plant plastic responses and the yield advantage. Here, we assessed the productivity of wheat-maize intercropping as compared to sole wheat and sole maize, and the associated differences in wheat shoot and leaf traits. In two field experiments, intercrop wheat and maize were both grown in alternating strips consisting of six rows of wheat and two rows of maize. The traits of wheat plants in border rows of the strips were compared to the traits of plants in the inner rows as well as those in sole wheat. Leaf development, chlorophyll concentration and azimuth, as well as the final leaf and ear sizes, tiller dynamics of wheat and yield components of both crops were determined. The relative densities of wheat and maize in the intercrop were 0.33 and 0.67, respectively, but the corresponding relative yields compared to the respective monocultures were 0.46 for wheat and 0.77 for maize. Compared to wheat plants in the inner rows of the intercrop strips as well as in the monoculture, border-row wheat plants in the intercrop strips had (a) more tillers owing to increased tiller production and survival, and thus more ears, (b) larger top leaves on the main stem and tillers, (c) higher chlorophyll concentration in leaves, (d) greater number of kernels per ear and (e) smaller thousand-grain weight. Grain yield per metre row length of border-row wheat was 141% higher than the sole wheat, and was 176% higher than the inner-row wheat. The results demonstrate the importance of plasticity in architectural traits for yield advantage in multispecies cropping systems.

Agronomic traits and deoxynivalenol contamination of two tetraploid wheat species (Triticum turgidum spp. durum, Triticum turgidum spp. turanicum) grown strictly under low input conditions

An evaluation of the agronomic performance of two tetraploid wheat varieties ( Triticum turgidum spp. durum , Claudio ; Triticum turgidum spp. turanicum , Kamut ® ) grown strictly under low input conditions was carried out over three consecutive cropping years. The study reported grain yield values ranging from 1.8 to 2.6 t ha -1 . Productivity showed to be primarily affected by environmental conditions, while no differences were observed between the two genotypes. The study of the yield components highlighted that the durum wheat variety had a higher plant density than Kamut ® , but this discrepancy was offset by a greater number of kernels per spike and the kernel weight of khorasan wheat. The investigated wheat genotypes were also analysed to assess the mycotoxin (DON) levels of wholegrain semolina and the efficiency of cleaning treatments to reduce contamination. Results showed that both wheat varieties had a good hygienic and sanitary quality with a DON content ranging from 0.35 to 1.31 mg kg -1 , which was lower than the maximum acceptable level set by the European regulation at 1.75 mg kg -1 . In addition, our research work investigated the effects of premilling cleaning procedures, such as water washing and brushing, on mycotoxin levels, which yielded interesting results in terms of decontamination efficiency. These methods were particularly efficient with Kamut ® semolina (46-93% DON reduction), suggesting that mycotoxins accumulate in this variety at more superficial levels than in the durum wheat variety. On the whole, our study provided additional knowledge on the traits to be further improved to respond to low input requirements and to enhance the potential adaptability of wheat genotypes to organic agriculture. Our results emphasized the need to develop wheat varieties that can provide adequate performance without high levels of nitrogen inputs by selecting specific traits, such as kernel weight, spike length and kernel/spike. This may help achieve productivity gains in organic systems.

Evaluation of reduced-tillering (tin) wheat lines in managed, terminal water deficit environments.

Small or shrivelled wheat kernels (screenings) that reduce crop value are commonly produced in terminal drought environments. The aim of this study was to establish whether the incorporation of the tiller inhibition (tin) gene would contribute to maintenance of kernel weight and reductions in screenings under terminal water deficit. Five Silverstar near-isogenic lines contrasting in high and low tiller potential and their recurrent Silverstar parent were established at two plant densities under managed terminal water deficit (mild and severe) and irrigated conditions. With irrigation (grain yield of 5.6 t ha–1), kernels of all lines weighed ~31mg, with restricted-tillering (R-tin) lines producing an average 15% lower grain yield. Under both mild and severe terminal water deficit (4.1 t ha–1 and 2.8 t ha–1), free-tillering lines had relatively high screenings ranging from 11.9% to 16.2%. Compared with free-tillering lines, R-tin lines maintained large kernel weight (~29mg kernel–1) and had 29% and 51% fewer screenings under the two stresses, and a significantly greater (+11%) grain yield under mild stress. Higher kernel weights in tin lines were realized even with the greater kernel number per spike. The higher kernel weight of the R-tin lines under stress conditions was associated with greater anthesis biomass and increased stem water-soluble carbohydrates, ensuring more assimilate for later translocation to filling grain. The incorporation of the tin gene into genetic material adapted to the target environments provides scope for improvement in both grain yield and kernel weight, and a reduction in screenings in terminal water deficit environments.

Location, Seeding Date, and Variety Interactions on Winter Wheat Yield in Southeastern United States

In the Southeast, winter wheat (Triticum aestivum L.) is typically planted from late October to early December. However, grain yield is reduced by an interaction of weather, soil, and plant factors. From 2009 to 2012 a study was conducted at three locations in Alabama to evaluate the seeding date effect on yield and yield components of three cultivars. The AGS 2060, AGS 2035, and Baldwin cultivars were evaluated within four seeding dates at approximately 15‐d intervals. Results showed that grain yield, spikes per m2, and kernel weight declined linearly with seeding delay; however, the impact changed among years and locations within a year. The variability of kernels per spike was location specific, in the north delayed planting resulted in a greater number of kernels per spike while the opposite occurred at the central and southern locations. At most location–year combinations, seeding 2 to 4 wk later than the Extension’s best seeding date resulted in yield losses; especially if warm and dry conditions were prevalent during winter and spring months at locations with sandy loam soils. Under warm and dry growing conditions, the impact of delayed planting on yield and kernel weight was the greatest for Baldwin and AGS 2035 and least for the AGS 2060. In contrast, when cold and wet growing conditions were prevalent, there were not significant planting date differences on yield and yield components. Cultivar and seeding date should be selected on a location basis due to the plant interactions with soil and weather factors.

Kernel weight and its response to source manipulations during grain filling in Argentinean maize hybrids released in different decades

Grain yield is greater in newer than in older Argentinean maize ( Zea mays L.) hybrids. Kernel number per plant was the main yield component accounting for grain yield increments. It is not clear, however, how breeding efforts affected kernel weight. The objectives of this work were (i) to characterize kernel weight, kernel weight components (i.e., kernel growth rate and effective grain filling duration) and ear demand (i.e., the product between kernel number per plant and effective kernel growth rate) in six maize hybrids released in different decades and (ii) to determine whether kernel weight of more recent hybrids is more susceptible than that of older ones to variations in source capacity during the grain filling period. Hybrids released between 1965 and 1993 were compared in field experiments in 1995–1996 (Exp. 1) and 2000–2001 (Exp. 2). Exp. 2 included three treatments to increase (crop thinning) or decrease (crop defoliation) the supply of assimilates during grain filling in comparison to untreated controls. Kernel weight was different among hybrids, but it did not present a clear trend with the year of release. Kernel weight was associated with kernel growth rate. Newer hybrids had larger ear demand than older ones by two distinct mechanisms: a greater kernel number per plant or a large potential kernel weight. Source reductions during the grain filling period resulted in larger kernel weight reduction in newer than in older hybrids. This indicates that individual grain weight stability of newer hybrids is lower than that of older hybrids in response to source reductions during the grain filling period.

Supplemental Irrigation at Reproductive Growth Stages to Improve Popcorn Grown at Different Populations

When irrigation sources are limited, supplemental irrigation at selected growth stages may help avoid crop stress. The objective of this study was to determine the effect of limited, supplemental irrigation at two reproductive growth stages of popcorn (Zea mays L.) grown at different populations. The experiment was conducted from 1995 through 1998 on a Parsons silt loam (fine, mixed, thermic Mollic Albaqualf). The experimental design was a randomized complete block with a split‐plot arrangement of treatments. Six irrigation schemes of no irrigation, application of 2.5 or 5 cm at R1 (silk stage) or R3 (milk stage), and 2.5 cm at both R1 and R3 were main plots, and populations of 37000, 49000, and 62000 plants ha−1 were subplots. Popcorn yield was affected by irrigation in only 2 of 4 yr. In the driest growing season (1996), yields were low, but either 2.5 or 5 cm of irrigation applied at R1 increased yields by 60% or more compared with irrigations at R3 or no irrigation. In 1997, 2.5 cm of irrigation at R1 or 2.5 cm at both R1 and R3 resulted in 23 to 27% greater yield than with no irrigation. These responses were partially explained by 12 to 13% greater number of kernels per ear. The optimum plant population was 49000 plants ha−1; this treatment maximized yield, kernel weight, and produced one ear per plant. Responses to irrigation were not affected by plant populations for any measured parameters. Popping expansion ratio was unaffected by treatments. Supplemental irrigation at critical reproductive growth stages influences yield but is inadequate to provide consistent yield and quality improvements for popcorn grown in the eastern Great Plains.

Leaf Posture, Grain Yield, Growth, Leaf Structure, and Carbon Isotope Discrimination in Wheat

The purpose of this study was to examine how differences in leaf angle may affect grain yield of wheat by changes in the relative contribution of yield components or changes in the pattern of crop growth. Leaf structural changes and their influence on plant water status and carbon isotope discrimination were also studied. A collection of pairs of bread wheat (Triticum aestivum L.) lines (PL) differing in leaf angle were grown under irrigation during two consecutive years at Sonora, Mexico. Erect leaf lines did not have higher yields than droopy leaf lines, but erect lines did have 5 to 16% greater number of kernels per unit of ground area. Droopy lines had a lower number of spikes per unit ground area, a greater number of kernels per spike, and a greater weigh of mature kernels than droopy lines. Therefore, the lack of differences in yield apparently was associated with yield component compensation. Differences between PL in discrimination against 13C (∆) in mature kernels, relative water content of flag leaves, canopy temperature, leaf area, and degree of leaf tip burning suggested higher transpiration rates (and thus lower water use efficiency) in the erect lines. For example, ∆ in kernels was consistently higher in the erect lines than in the droopy lines. In addition there was a significant (r = −0.85, P < 0.05) negative correlation between canopy temperature during grain filling and ∆. Grain yield was positively correlated (r = 0.50, P < 0.05) with ∆ of kernels. Although wheat genotypes with erect leaves did not show conclusive superiority, nevertheless selection for a more erect growth habit may result in increased yield. However, the possible existence of allometric relationships among leaf erectness and smaller leaves, spikes, and stems make progress in increasing yield a complex task.

Grain Sorghum Yield and Yield Component Response to Timing and Number of Irrigations1

AbstractEfficient use of irrigation water becomes more essential as the availability of this resource declines. Research evaluating the effect of timing and number of irrigation water applications on yield and yield components of grain sorghum [Sorghum bicolor(L.) Moench] was initiated in 1976. The experiment was conducted on a Richfield silty clay loam (fine, montmorillonitic, mesic, Aridic Argiustoll). Irrigation water treatments were applied at preplant (PP), PP + growth differentiation (GD), PP + boot (B), PP + GD + B growth stages, and PP + initiation of irrigation at 50% available soil moisture. Maximum grain yields were consistently achieved when three or more irrigations were applied. Two irrigation water applications reduced grain yields, but the timing of the in‐season water application (GD or B) had no effect on yields. Yield components were evaluated in 1982 and 1983 to determine what effect timing of water application had on these parameters. Irrigation at GD resulted in a greater number of kernels per head and per unit area, whereas applications at B increased seed weight. Head weight showed no response to the timing of water applications, suggesting that the same amount of dry matter was accumulated in the head whether water was applied at GD or B. Therefore, producers of grain sorghum have a broader time period over which to apply limited quantities of irrigation water without reducing grain yield than is reported in most literature. However, if maximum yield potential is desired, it is necessary to have adequate water available to the plant at GD to set the maximum number of kernels.

A New, Rapid, Interactive Image Analysis Method for Determining Physical Dimensions of Milled Rice Kernels

ABSTRACTA method was developed using Image Analysis technology whereby rice kernels may be classified in less than a third of the time required by conventional methods. Image Analysis permits the use of much greater number of kernels, providing a more representative measure of dimension while giving a better estimation of the actual sample variation among kernels. The Image Analysis method was found to compare very favorably with the conventional method using a Gaertner microscope and found to be superior to that using a projecting microscope. The reproducibility of the Image Analysis method was found to be better than ± 10%.

Recovery Processes after Leaf Cuttng in Cereals and Forage Grasses : 1. Activation of growth hy defoliation at several growth stage in rice plant.

Leaf-blade cuttings at several growth stages were conducted on rice plants grown under paddy field conditions in 1957 and under pot cultures filled with river sand in 1958, and the subsequent growth processes were observed mainly morphologically and the starch content in the shoot was measured. Two cutting treatments were conducted; all the expanded blades in every culm except the newly appearing leaf were clipped (old-leaf cut), or, on the contrary, only newly expanding blades were clipped every day as they appeared above the top of the leaf-sheaths which enclosed them (new-leaf cut). Some results obtained are outlined as follows: 1. Tillering and rooting stopped for a while after the both treatments, and growth in terms of dry matter production was heavily checked. However, the leaf formation in already established tillers were rather accelerated and the area of newly formed blades became gradually larger, and the dry-weight percentage of green leaves in the whole plant was maintained higher compared with those of undefoliated plants. On the contrary, the starch amount in stem and leaf-sheath was very much decreased as a result of defoliation, since most of the reserved carbohydrates might be consumed to make up for compensatory growth of new leaf. 2. Shortly after the treatments, both tillering and rooting were activated even during ear developlment, while the undefoliated plants tended to stop tillering and to decrease root formation during the same period. At the later stages of growth, the relative growth rate in dry matter production was much accelerated in the treated plants probably due to intensified respiration, photosynthesis and other life processes by enlarged blades. Under these situations, the amount of starch in the shoot was always less than that of the untreated plants, indicating the greater consumption of carbohydrates for the stimulated growth with much nitrogen absorbed by newly formed vigorous roots. 3. Defoliation might have lead the rice plant to rejuvenescent state, resulting in higher growth rate, larger panicle and greater number of kernels per plant, if there was enough time to recover from the clipping damage untill the flower initiation began. In the two experiments, the cutting of newly expanding leaves did not promote heading, but delayed it much more than the cutting of old leaves. 4. The clipping of the leaf-blades some days before ear formation retarded the elongation of the lower internodes, hence the resistance to lodging of rice plant might sometimes become stronger by defoliation treatments.