Grain Yield Determination and Resource Use Efficiency in Maize Hybrids Released in Different Decades (original) (raw)

Field Crops Research, 1998

. Ž . Maize kernel weight KW results from kernel growth during two stages of grain filling, the lag phase formative period and the effective grain-filling phase. Environmental conditions may affect kernel biomass accumulation in each phase. This Ž . Ž . Ž . work analyzed: 1 changes in duration and rate of kernel growth on a thermal time 8C day basis; and 2 KW response to y1 Ž . postsilking biomass production kernel source:sink ratio . Sowing date, plant population, and nitrogen fertilization experiments were conducted in France and Argentina to induce changes in assimilate availability per kernel. Hybrids of different KW were tested. Hybrids differed in the duration of the lag phase, which determined kernel growth rate during the Ž . effective grain-filling period for hybrids with similar grain-filling duration ca. 7458C day . Environments with low air Ž . temperature -198C and less incident solar radiation led to a smaller final KW due to reductions in photoassimilate production and its partition to the grains. A value of 240 to 270 mg kernel y1 during grain filling was determined as a Ž . Ž threshold to have mobilization or storage of reserves. Small-kernel hybrids KW -300 mg , with large kernel number 3500 y2 . Ž . to 5500 kernels m , depended more on reserve mobilization than large-kernel hybrids KW ) 300 mg with reduced Ž y2 . kernel number 2800 to 4000 kernels m . For the former, grain yield increments should not be based on increased kernel number but on increased biomass production. q 1998 Elsevier Science B.V.

Grain yield of maize hybrids at different plant densities

Acta agriculturae Serbica, 2017

Field trials with 12 maize hybrids belonging to FAO maturity groups 500, 600 and 700 were established under the agro environmental conditions of Smederevo in 2010 and 2011 to analyse grain yield and moisture content at different plant densities. The hybrids were sown in two independent trials in the two years at 51,000 and 62,000 plants ha-1 , respectively, in a randomised block design with three replications. More favourable maize growing conditions i.e. more moderate air temperatures during the growing season, a more even distribution of precipitation and more rainy days were recorded in 2010 than in 2011, which had much lower precipitation amounts, particularly during July and August i.e. critical development stages (flowering and fertilization) of these hybrids. Grain yield of all maize hybrids was higher in 2010, mostly as the result of greater amounts of precipitation and their more even distribution during the growing season. In both years, significantly higher grain yields were obtained by FAO 600 maize hybrids. Grain yield in 2010 was significantly higher at the higher plant density in FAO 500 hybrids, as opposed to FAO 600 hybrids, which showed no significant difference in grain yield across plant densities. Grain moisture content at harvest did not significantly differ between plant densities in either year. Somewhat higher values for grain moisture at harvest in 2010 were recorded for FAO 600 hybrids. In 2011, there were no significant differences in grain moisture content among hybrids, nor between plant densities, mostly due to the very low amount of precipitation in the second part of the growing season.

Variation of physiological growth indices, biomass and dry matter yield in some maize hybrids2014-2 biotech025 paper

In order to determine variation of physiological growth indices, biomass and dry matter yield, for six maize hybrids (MH), it was set up a field trial on randomized complete block design (RCDB), with three replications, with 6 MH: BC38W, BC408, ZP434, NSSC444, ESP500 and LUCE, during the years 2010 and 2011 (Y), at Experimental Farm (EF), Faculty of Agriculture and Veterinary in Prishtina, located in geographical position: N 42º 38'97" and E 21º 08'45" and 570 MASL. Growth rate, biomass and dry matter of maize performance are depending from specific characteristics: maize hybrids (MH), environmental condition (EC) and cropping system (CS). Information on silage maize yield can help silage growers and users, to choose hybrids that best fit their needs. The physiological growth indices, biomass and dry matter yield, were conducted according to the formula: (MH-6 x Y-2 x P4 x R3) =144 combinations. Hybrid selection for a specific location, suitable for the agro-ecological condition is one of the essential principles for improving yield for silage or grain, without increasing of cost of maize production. Means results for evaluated maize hybrids and parameters were: Absolute growth rate (AGRµ=5.43), crop growth rate (CGRµ=30.98), total plant biomass (TPBµ=585.39 g plant -1 ) and total dry matter (TDMµ=22.52 ton ha -1 ).The aim of this study was to determine physiological growth indices, biomass and dry matter yield, in suitable agro-ecological conditions of Kosovo. The obtained results were with wide range variability and high significant differences between hybrids and years on the level P< 0.01.

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

Field Crops Research, 2006

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. #

Variation of physiological growth indices, biomass and dry matter yield in some maize hybrids

Determinants of grain weight in native cultivars and hybrids of maize

2012

The objective of this work was to study the physiological parameters that explain variations in individual grain weight among native cultivars and hybrids and analyze the genetic advance in grain yield of highland maize. There were evaluated two native cultivars (Ixtlahuaca and Jiquipilco), two ancient hybrid (H-30 and H-32) and two modern (Z- 60 and H-40), in four contrasting environments, varying planting date (OD: optimal 2/4/09 and LD: late 30/04/09) and production systems (AS: ancient 5 plants m -2 , 80N-40P-00K and MS: modern 8 plants m -2 , 180N-90P-60K), in 2009 in Toluca, Mexico. There were significant differences between genotypes and environments for maximum grain weight (MGW), grain yield (GY) and its major components, without GxA interaction effects. Variations in the MGW were mainly explained by changes in the grain filling rate (GFR). In the OD, native cultivars showed higher MGW and maximum water content in the grain (MWCG) due to increased RGF. The potential capacit...

Intra-specific competition in maize: Contribution of extreme plant hierarchies to grain yield, grain yield components and kernel composition

Field Crops Research, 2006

Maize (Zea mays L.) cropping conditions that promote high intra-specific competition pressure generate an increased plant-to-plant variability within the stand, and the appearance of individuals with different ability to capture scarce resources (i.e. dominant and dominated plants). The objectives of this paper were to analyze (i) stand density effects on plant biomass at physiological maturity (R 6 ), grain yield per plant (GYP), GYP components (KNP: kernel number per plant; KW: kernel weight), and kernel composition (starch, oil and protein contents per kernel) of the mean plant of the stand (i.e. considering all individuals) and of the dominant (D) and dominated (d) individuals; and (ii) the contribution of these extreme plant hierarchies to GYP, GYP components and kernel composition of the mean plant of a stand. Four maize hybrids of contrasting KW (small and large KW) were cropped at a wide range of stand densities (3-15 pl m À2 ) during 1999/2000 and 2001/ 2002 in Argentina. The mean value of measured variables declined as plant density increased from 3 to 15 pl m À2 , and plant-to-plant variability (CV: coefficient of variation) of the same variables increased with enhanced crowding. The magnitude of the reduction in mean plant values differed among variables: plant biomass at R 6 , GYP and KNP underwent a larger reduction (ca. 66%) than KW (ca. 14-19%) or kernel contents (ca. 22% for oil and protein contents, and 13% for starch content). Similarly, the increase in CVs was larger for plant biomass at R 6 (from ca. 13 to 40%) and GYP (from ca. 30 to 58 and 15 to 38% for small and large KW hybrids, respectively) than for KW (ca. from 7 to 20%). Only a slight increase in CVs of oil (6-17%) and protein (9-12%) concentrations of large KW hybrids was recorded. The CV of KNP followed a trend similar to that for GYP. Differences between plant categories increased when mean GYP and KNP of all individuals of the stand were smaller than 157 g pl À1 and 649 kernel pl À1 , respectively. Below these thresholds, the d/D ratio dropped from 0.76 to 0.30 (small KW hybrids) or to 0.40 (large KW hybrids) for GYP (r 2 = 0.76, P < 0.001), and from 0.75 to 0.38 (small KW hybrids) or to 0.46 (large KW hybrids) for KNP (r 2 = 0.59, P < 0.001). In contrast, the d/D ratio for KW varied always from 1 to 0.80 in response to decreased mean KW (r 2 = 0.39, P < 0.01). The concentration of kernel contents did not differ between plant types. Results indicate that grain yield of maize crops grown at high stand densities is composed by plants bearing very different kernel numbers, with slight differences in kernel size, and similar starch, oil and protein concentration. #

Response of maize kernel number to plant density in Argentinean hybrids released between 1965 and 1993

Field Crops Research, 2000

We investigated the response of maize kernel number to plant density in four hybrids released in Argentina between 1965 and. Assuming kernel number is the main yield component, and using as a framework the relationship between kernel number per plant (KNP) and plant growth rate bracketing silking (PGR s ), we tested the alternative hypotheses that modern hybrids produce more kernels because they have (a) greater PGR s or (b) more kernels per unit PGR s than their older counterparts. Three experiments were carried out including a range of plant densities from 3±5 to 15±18 plants m À2 . PGR s was calculated from shoot dry matter measured 10 days before and 20 days after silking. Shoot dry matter, grain yield and its components were measured at physiological maturity. Grain yield of the oldest hybrid averaged 7.7 t ha À1 , and increased with year of release at a rate of 173 kg ha À1 per year. The response of grain yield to plant density was curvilinear. Kernel number per square meter accounted for most of the variation in yield with both year of release and plant density. For both sources of variation, there was a trade-off between kernel number and mass. Both PGR s and KNP decreased with increasing plant density in all four hybrids. Whereas variation in PGR s among hybrids was small, the oldest hybrid set 93 (low density) and 113 (high density) kernels per unit PGR s in comparison to the newest that set 167 and 193. We conclude that more kernels per unit PGR s , rather than greater PGR s , accounted for the genetic improvement of yield potential in the hybrids investigated. #

Grain yield and quality of maize hybrids in different FAO maturity groups

Acta Agraria Debreceniensis, 2010

An improvement in the quality of maize grain by increasing the level of components responsible for its biological value is possibleby using genetic means. However, a change in the genotype, together with improving the nutrient properties of the grain, also has someadverse consequences connected with a fall in yield and in resistance to diseases.Field experiments were conducted during three years (2003, 2004and 2005) to evaluate environmental effects on grain yield andquality responses of maize hybrids. Twenty one hybrids of various maturity groups (FAO 150-400) were planted to achieve an optimum(60-70 000 plants per hectare) plant populations and grown under the medium-N (80 kg N ha-1) fertilization. Environmental conditionssignificantly affected maize hybrid responses for grain yield, starch, oil and protein contents, and consequently, starch, oil and proteinyields per hectare. Hybrids of flint type, which have a short vegetation period, had high protein and oil content but the yie...

Grain Yield Determination and Resource Use Efficiency in Maize Hybrids Released in Different Decades (original) (raw)

Related papers