Moisture-deficit-induced changes in leaf-water content,leaf carbon exchange rate and biomass production in groundnut cultivars differing in specific leaf area

Field experiments were conducted during two rainy seasons to study the effect of soil moisture deficit on total biomass, pod yield, harvest index (HI) and drought tolerance index (DTI) in groundnut (Arachis hypogaea L.) cultivars possessing a wide range of specific leaf area (SLA, 144–241 cm² g⁻¹). There were three soil moisture regimes: adequate irrigation (W₁), drought simulated under rain-out-shelter (W₂) and rain-fed (W₃). This experiment had two parts, in one, five cultivars were exposed to W₁, W₂ and W₃, and in a second, seven cultivars were exposed to W₁ and W₃. Using the same set of seven cultivars, pot-culture experiments were conducted to study relative water content (RWC), stomatal conductance (g_s) and single leaf carbon exchange rate (CER) during increasing moisture-deficit in two contrasting (rainy and summer) seasons. Variation in DTI was significant, and low SLA types had greater DTI under both W₂ and W₃. The ranking of SLA among cultivars was consistent between experiments conducted during the two seasons. The rate of reduction in leaf RWC during the progressive moisture-deficit was related directly to SLA (r=0.78, P<0.01). The coefficient of determination of the slopes calculated between RWC and soil moisture during the experimental period was more in the summer (r²=0.82) than the rainy (r²=0.54) season.Under increasing moisture-deficit, the low SLA types were able to maintain higher RWC, CER and g_s in both seasons. The relationships between RWC and CER (r=0.91, P<0.01), and RWC and g_s (r=0.65, P<0.01) were significant.It is suggested that under water-limited conditions there is a significant inverse relationship between SLA and RWC. The low SLA types (water use efficient) were found to be drought tolerant in terms of total dry matter production in the field studies, and maintenance of higher RWC under drought like situations in pot-culture experiments. Thus the ability of the low SLA types (higher water use efficiency, WUE) to maintain higher RWC may form the basis for the differences in drought tolerance vis a vis WUE in groundnut cultivars differing in SLA. Suggestions are made to select parents for drought tolerance or WUE, and to initiate breeding to combine traits like high HI, and WUE in terms of lower SLA. Ultimately, selection for both WUE (measured in terms of SLA) and yield traits (HI) should result in cultivars with improved performance in rain-fed agriculture.     

减少灌水次数对河北冬性强筋小麦产量和品质的影响

为明确不同生态环境下减少灌水次数对冬性强筋小麦产量和品质的影响,以冬性强筋小麦品种农优3号和中麦998为材料,分别在冀中北生态区的徐水区和冀东生态区的昌黎县进行大田试验,设3个灌水次数处理(CK:越冬水+拔节水+开花水;W_2:越冬水+拔节水;W_1:越冬水),研究了不同灌水次数对冬性强筋小麦叶面积系数、干物质积累、籽粒产量和品质的影响。结果表明,随灌水次数减少,两个供试小麦品种孕穗期叶面积系数呈下降趋势,W_1处理显著低于其他处理;减少灌水次数导致2个冬性强筋小麦地上部的干物质积累量显著降低,而对收获指数的影响因品种而异,其中农优3号收获指数呈上升趋势,而中麦998以W_2处理最大。减少灌水次数使冬性强筋小麦有效穗数、穗粒数和千粒重显著降低,导致产量显著降低。灌水次数减少造成冬性强筋小麦籽粒容重和蛋白质含量提高,稳定时间延长,但湿面筋含量和沉降值下降。本研究条件下,徐水点农优3号的产量较高,而昌黎点中麦998的产量较高;相同灌水处理下,同一品种在昌黎点的品质指标优于徐水试验点。综上,在河北冬性强筋小麦种植区可以选用灌越冬水和拔节水协调其籽粒产量和品质。     

Detection of powdery mildew in two winter wheat cultivars using canopy hyperspectral reflectance

To determine the most sensitive spectral parameters for powdery mildew detection, hyperspectral canopy reflectance spectra of two winter wheat cultivars with different susceptibilities to powdery mildew were measured at Feekes growth stage (GS) 10, 10.5, 10.5.3, 10.5.4 and 11.1 in 2007–2008 and 2008–2009 seasons. As disease indexes increased, reflectance decreased significantly in near infrared (NIR) regions and it was significantly correlated with disease index at GS 10.5.3, 10.5.4 and 11.1 for both cultivars in both seasons. For the two cultivars, red edge slope (dr_red), the area of the red edge peak (Σdr_{680−760 nm}), difference vegetation index (DVI) and soil adjusted vegetation index (SAVI) were significantly negatively correlated with disease index at GS 10.5.3, 10.5.4 and 11.1 in both seasons. Compared with other parameters, Σdr_{680−760 nm} was the most sensitive parameter for powdery mildew detection. The regression models based on Σdr_{680−760 nm} were constructed at GS 10.5.3, 10.5.4 and 11.1 in both seasons. These results indicated that canopy hyperspectral reflectance can be used in wheat powdery mildew detection in the absence of other stresses resulting in unhealthy symptoms. Therefore, disease management strategies can be applied when it is necessary based on canopy hyperspectral reflectance data.     

Observations on the occurrence and inheritance in wheat of resistance to the grain aphid Sitobion avenae

Glasshouse screening tests with the aphid, Sitobion avenae, demonstrated resistance or extreme susceptibility in a minority of winter wheat cultivars. Assessments of some, but not all, resistant cultivars were apparently affected by the conditions of the test, and field observations confirmed some, but not all, of the glasshouse results. Rapier and Galahad were the most resistant of the cultivars currently available to British wheat growers. F₄ lines of spring wheat from crosses of wheat stocks resistant to S. avenae were screened by two methods and on average were resistant. Crosses differed in the amount of variability available for further selection, and wide-ranging segregation among the lines indicated that resistance genes differed among the parent stocks.     

Purification of wheat flour high-molecular-weight glutenin subunits by fast protein liquid chromatography

Fast protein liquid chromatography has been developed for purification of high-molecular-weight glutenin subunits HMW-GSs from wheat flour. Flour samples from four wheat cultivars with different HMW-GS alleles at Glu-A1, Glu-B1 and Glu-D1 loci were used to establish the method. The column material used was Resource™ Phe, and the optimal elution was with a gradient formed with buffer A [0.05 M Tris–HCl containing 4 M urea and 0.25 M (NH₄)₂SO₄, pH 8.0] and buffer B [0.05 M Tris–HCl containing 4 M urea (pH 8.0)] at a flow rate of 0.5 ml/min. A pure single 1Dx-, 1Bx- HMW-GS, and all the y-type HMW-GSs present in one genotype can be reliably separated in a single step.     

Validation of a critical nitrogen dilution curve for hybrid ryegrasses

One of the challenges of modern grassland systems is to minimize nitrogen (N) fertilization without negatively affecting the forage yield. Therefore, critical N dilution curves (Nc = a_c W^?b) have been developed in different species to improve N fertilization management. The aim of this study was to validate a critical N dilution curve for hybrid ryegrasses. Two field experiments were conducted in southern Chile. Treatments were the factorial combination of two hybrid ryegrasses (Shogun and Trojan cultivars) and seven N fertilization rates (0, 50, 100, 200, 350, 525 and 700 kg N/ha). Factors were arranged in a split‐plot design, where forage species were assigned to main plots and N rates to subplots that were randomized into four blocks. A wide range in forage yield and plant N concentration was observed (yield: 0.16 and 3.9 Mg DM/ha and N: 1.6% and 5.1%). The variations in these traits were principally explained by the N levels and harvest times. Relative yield responses of both cultivars were significantly (p < 0.001, R² = 0.81–0.87) related to the nitrogen nutrition index (NNI) calculated with different critical N dilution curves. However, the NNI calculated with N dilution curves from annual ryegrass best described the relative yield response of hybrid ryegrass. Therefore, this validated critical N dilution curve (%N_c = 4.1W^?0.38) will serve as a useful diagnosis tool for improving the N fertilization management of grazing systems for hybrid ryegrasses.     

Effect of β-glucans on viscoelastic properties of barley kernels and their relationship to structure and soluble dietary fibre

The stress relaxation behaviour of barley kernels with differences in β-glucan was studied using the generalized Maxwell model for explaining the differences in quality. The relaxation moduli show that cultivar significantly affected the relaxation times (τ₂ and τ₃) and compressional viscosity (η_E2 and η_E3) of the 3 Maxwell elements and the pure elastic component (E₀). These data were twice as high in cultivars with high β-glucans compared to low β-glucans. Protein and malt extract, as well as β-glucan, showed similar patterns to the corresponding cultivars from the same locations. Malt extract was correlated with both insoluble fibre (−0.71; P < 0.0007) and total fibre (−0.66; P < 0.006). High β-glucan cultivars presented relatively high soluble fibre, wort viscosity and presented higher relaxation times. Soluble fibre and the wort viscosity were correlated with relaxation times τ₁, τ₂, τ₃. Also, β-glucans were correlated with τ₃ and viscosity η_E3. The overall importance of the effect of β-glucans on viscoelasticity, malting and food quality as shown in this investigation is in agreement with earlier investigations.     

新疆小麦品种 Glu A3和 Glu B3位点等位变异的分布

为给新疆小麦品质育种提供理论依据,利用 GluA3、 GluB3位点上的17个STS标记检测了185份新疆冬、春小麦品种 GluA3和 GluB3位点的等位变异。结果表明,新疆小麦品种以 GluA3c、 GluB3a和 GluB3j亚基为主,其分布频率分别为64.86%、22.70%和17.84%。新疆冬、春小麦品种在 GluA3位点上均以 GluA3c亚基为主,分布频率分别为63.30%和67.11%;在 GluB3位点上,新疆冬、春小麦品种分别以 GluB3j和 GluB3a为主,分布频率分别为22.02%和26.32%。新疆冬、春小麦农家品种亚基类型较少,冬小麦农家品种仅有5种类型（以 GluA3c和 GluB3i为主）,春小麦农家品种有10种类型（以 GluA3c和 GluB3d为主）。引进品种和自育品种亚基类型丰富,冬小麦引进品种以 GluA3c和 GluB3i为主,分布频率为12.84%和6.42%;春小麦引进品种以 GluA3c和 GluB3j为主,分布频率为17.11%和6.58%。冬小麦自育品种以 GluA3c和 GluB3j亚基类型为主,分布频率为45.87%和18.35%;春小麦自育品种以 GluA3c和 GluB3a亚基类型为主,分布频率为36.84%和18.42%。     

播种方式和灌水量对春小麦干物质和产量的影响

为筛选与新疆春小麦匀播技术配套的适宜灌水量,以春小麦品种新春34号为材料,进行二因素盆栽试验,设置匀播(U)和条播(D)2种播种方式,以及W75(拔节水)、W150(拔节水+扬花水)、W225(拔节水+扬花水+灌浆水)和W300(起身水+拔节水+扬花水+灌浆水)4个不同灌溉水平(每次灌水量75mm),研究了播种方式和灌水量对春小麦干物质和产量的影响。结果表明,与常规条播相比,匀播促进了小麦出苗20d后的分蘖,增加了有效分蘖,其中W75、W150、W225和W300条件下,匀播小麦的穗数分别提高25.62%、41.79%、43.39%、46.10%,分蘖成穗率分别提高20.15%、30.15%、30.68%、33.63%;匀播提高了小麦旗叶、倒二叶的SPAD值,延缓了叶片衰老,增强了群体生育后期的光合作用,且匀播方式下增大灌水量更有利于延长小麦叶片的功能期;匀播促进了小麦营养器官干物质的积累及其在花后向籽粒中的转运,有利于产量形成;在W75、W150、W225、W300条件下,匀播小麦产量较条播分别提高2.76%、4.41%、3.77%和3.42%,两种播种方式下W225处理产量均最大。因此,匀播方式下W225灌水模式最有利于春小麦生长发育和高产。     

Yield of Brassica napus L. hybrids developed using resynthesized rapeseed material sown at different locations

The utilisation of resynthesized Brassica napus (RS) genotypes in commercial breeding programmes is restricted to the development of intraspecific hybrids, so-called semi-synthetic rapeseed, and backcross progenies. In order to determine the general combining ability (GCA) of different rapeseed material, nine high-erucic acid RS lines and three old spring rapeseed cultivars were used as pollinators of male sterile double-low spring rapeseed lines (MSL-system). Yield performance of the single-cross hybrids was tested in a multi-location field trial that revealed a high yield potential of semi-synthetic rapeseed hybrids based on RS lines. The use of such resynthesized rapeseed forms in developing rapeseed hybrids and their possible use in future oilseed breeding is discussed.     

Diverse no-till irrigated crop rotations instead of burning and plowing continuous wheat

Field burning of residue is a traditional management tool for irrigated wheat (Triticum aestivum L.) production in the Inland Pacific Northwest of the United States (PNW) that can result in reduced air quality. A 6-year no-till field experiment to evaluate two complete cycles of a 3-year irrigated crop rotation of winter wheat–spring barley (Hordeum vulgare L.)–winter canola (Brassica napus L.) was sown (i) directly into standing residue of the previous crop, (ii) after mechanical removal of residue and, (iii) after burning of residue. The traditional practice of continuous annual winter wheat sown after burning residue and inverting the topsoil with a moldboard plow was included as a check treatment. Over-winter precipitation storage efficiency (PSE) was markedly improved when residue was not burned or burned and plowed after grain harvest. Grain yield of winter wheat trended higher in all no-till residue management treatments compared to the check treatment. Average grain yields of spring barley and canola were not significantly different among the no-till residue management treatments. Winter canola failed in 5 of 6 years due to a combination of a newly identified Rhizoctonia damping-off disease caused by Rhizoctonia solani AG-2-1 and cold temperatures that necessitated replanting to spring canola. Six-year average net returns over total costs were statistically equal over all four systems. All systems lost from $358 to $396 ha^?1. Soil organic carbon (SOC) increased linearly each year with no-till at the 0–5 cm depth and accumulated at a slower rate at the 5–10 cm depth. Take-all of wheat caused by Gaeumannomyces graminis var. tritici was most severe in continuous annual winter wheat. The incidence and severity of Rhizoctonia on roots of wheat and inoculum of R. solani AG-8, was highest in the no-till treatments, but there was no grain yield loss due to this disease in any treatment. Residue management method had no consistent effect on Rhizoctonia root rot on barley. The annual winter grass downy brome (Bromus tectorum L.) was problematic for winter wheat in the standing and mechanically removed residue treatments, but was controlled in the no-till residue burned and the burn and plow check. Another winter annual grass weed, rattail fescue (Vulpia myuros L.), infested all no-till treatments. This was the first comprehensive and multidisciplinary no-till irrigated crop rotation study conducted in the Pacific Northwest.     

Effect of β-glucans on viscoelastic properties of barley kernels and their relationship to structure and soluble dietary fibre

The stress relaxation behaviour of barley kernels with differences in β-glucan was studied using the generalized Maxwell model for explaining the differences in quality. The relaxation moduli show that cultivar significantly affected the relaxation times (τ₂ and τ₃) and compressional viscosity (η_E2 and η_E3) of the 3 Maxwell elements and the pure elastic component (E₀). These data were twice as high in cultivars with high β-glucans compared to low β-glucans. Protein and malt extract, as well as β-glucan, showed similar patterns to the corresponding cultivars from the same locations. Malt extract was correlated with both insoluble fibre (−0.71; P < 0.0007) and total fibre (−0.66; P < 0.006). High β-glucan cultivars presented relatively high soluble fibre, wort viscosity and presented higher relaxation times. Soluble fibre and the wort viscosity were correlated with relaxation times τ₁, τ₂, τ₃. Also, β-glucans were correlated with τ₃ and viscosity η_E3. The overall importance of the effect of β-glucans on viscoelasticity, malting and food quality as shown in this investigation is in agreement with earlier investigations.     

Use of petal test in early-flowering varieties of oilseed rape (Brassica napus L.) for predicting the infection pressure of Sclerotinia sclerotiorum (Lib.) de Bary

Sclerotinia sclerotiorum is one of the most important pathogens of winter oilseed rape plants. It causes the white mould disease of rape, thus significantly reducing the yield. The aim of our research was to use a spring oilseed rape variety sown in autumn or an early-flowering variety of winter oilseed rape to predict the infection pressure of S. sclerotiorum in a given year. Field experiments were conducted in 2008–2012 at the experimental station of the Czech University of Life Sciences Prague at Červený Újezd, 20 km west of Prague. In the experiment, we used one variety of spring oilseed rape (Lužnice, LU) and one early-flowering variety of winter oilseed rape (Californium, CA). The methodology of the petal test involved isolating pathogenic fungi from fallen petals on a nutrient medium (potato dextrose agar) in Petri dishes. The first term of collection was the beginning of petal fall (BBCH 61) and the last term was the end of flowering (BBCH 69). The dishes with petals were visually analysed after 1 week. The results were compared with the actual occurrence of white mould of rape in the stand. The occurrence of white mould of rape was strongly influenced by the progress of weather conditions over the given year. Infected petals and stems with symptoms of white mould of rape were found to be moderately correlated (r = 0.80). Spread of white mould spores was mostly observed in two terms (BBCH 62 and BBCH 65). Statistically significant differences were not observed in the infection of petals of spring (LU) and winter (CA) oilseed rape. Spring oilseed rape (LU) and early-flowering varieties of winter oilseed rape (CA) can be used to determine the strength of infection pressure of S. sclerotiorum in the stand in a given year, thereby improving protection against white mould of rape.     

Protein extraction from defatted wheat germ by reverse micelles: Optimization of the forward extraction

In this work, the forward extraction of defatted wheat germ protein (DWGP) by reverse micelles was studied. The reverse micellar systems were formed by sulphosuccinic acid bis (2-ethylhexyl) ester sodium salt (AOT), isooctane and KCl solution. The effects of AOT concentration, pH, KCl concentration, extraction time, the amounts of defatted wheat germ flour (DWGF), W₀ (the molar ratio of water to surfactant, i.e. W₀ = [H₂O]/[AOT]) and temperature on the forward extraction efficiency of DWGP were tested. On the basis of single-factor experiments, the optimum extraction was achieved by response surface methodology (RSM). The experimental results lead to the conclusion that the highest forward extraction efficiency of DWGP was reached at the AOT concentration 0.06 g/mL, pH 8, KCl concentration 0.1 mol/L, time 30 min, the amounts of DWGF 0.500 g, W₀ 25 and temperature 36 °C. Under these conditions, the forward extraction efficiency of DWGP achieved 37%.     

Consistent differences among wheat cultivars in osmotic adjustment and their relationship to plant production

Osmotic adjustment (OA) is generally considered an important component of drought resistance. Several reports by J.M. Morgan [Morgan, J.M., 1983. Osmoregulation as a selection criterion for drought tolerance in wheat. Aust. J. Agric. Res. 34, 607–614; 1992. Osmotic components and properties associated with genotypic differences in osmoregulation in wheat. Aust. J. Plant Physiol. 19, 67–76; 1995. Growth and yield of wheat lines with differing osmoregulative capacity at high soil water deficit in seasons of varying evaporative demand. Field Crops Res. 40, 143–152; Morgan, J.M., Condon, A.G., 1986. Water-use, grain yield and osmoregulation in wheat. Aust. J. Plant Physiol. 13, 523–532] from Australia concluded that consistent genetic differences in OA existed among wheat cultivars and that high OA cultivars tended to yield better than low OA cultivars under drought stress. Our study was performed to assess his results with his and other genetic materials.Two of Morgan’s spring wheat lines with high OA (‘H.Osm-134’) and low OA (‘L.Osm-136’) capacity in addition to eight other diverse spring wheat cultivars were tested for OA and plant production when grown in small plots under a rain exclusion shelter at Bet Dagan, Israel in 1996. OA of five of these cultivars (including Morgan’s lines) was also measured in two independent greenhouse tests in 1997 (Israel) and 1998 (Texas).The five cultivars differed significantly and ranked consistently for OA in all tests. No significant cultivar by test interaction for OA was revealed. OA was well correlated across cultivars between tests. The significantly higher OA capacity of H.Osm-134 as compared with L.Osm-136 was repeated in all tests. OA of all ten cultivars was positively correlated with biomass (r = 0.73; p = 0.02) and yield (r = 0.55; p = 0.09) under pre-flowering drought stress in the rain exclusion shelter. H.Osm-134 line performed significantly (p ≤ 0.05) better than L.Osm-136 line for both biomass and yield under drought stress. We therefore support Morgan’s results and conclude that consistent differences in OA exist among wheat cultivars and that these differences can be associated with plant production under pre-flowering drought stress.     

Weed control efficacy and winter wheat safety of a novel herbicide HW02

HW02, a pyruvate dehydrogenase inhibitor, is a newly developed herbicide for broadleaf weed control in wheat, maize and turf in China. Greenhouse and field experiments were conducted to evaluate its efficacy against weeds and safety to winter wheat. In the greenhouse experiment, this herbicide had higher activities than 2,4-D against Descurainia sophia (L.) Schur., Amaranthus retroflexus L., Capsella bursa-pastoris (L.) Medic., and Malachium aquaticum (L.) Fries.. When it was applied at late tillering stage of winter wheat in spring, the herbicide provided weed biomass reduction of 98%–100% at the rates 225–525 g a.i. ha⁻¹ and was safe to the crop at the rate of up to 900 g a.i. ha⁻¹. These results showed HW02 could be an alternative herbicide for resistant weed management because its mode of action is different from herbicides presently used.     

Analysis of Pina and Pinb alleles in the micro-core collections of Chinese wheat germplasm by Ecotilling and identification of a novel Pinb allele

Kernel hardness is mainly conditioned by allelic variations of Pina-D1 and Pinb-D1 genes located on the short arm of chromosome 5D. In this work, the Ecotilling approach was optimized to investigate Pina and Pinb alleles in the micro-core collections of Chinese wheat germplasm, and three Pina and eight Pinb alleles were found. Generally, more Pinb alleles were detected in the accessions coming from the regions that grow winter or a mixture of spring and winter wheats. This was particularly evident for the Southwestern winter wheat, Xinjiang winter–spring wheat and Yellow and Huai River Valley winter wheat regions. A novel variant (designated as Pinb-D1x) was discovered in one of the accessions from the Xinjiang winter–spring wheat region. Compared to wild type (WT) allele Pinb-D1a, two nucleotide substitutions occurred in the coding region of Pinb-D1x, one (at nucleotide position 257) resulting in the replacement of a WT cysteine residue by tyrosine and the other (at nucleotide position 382) creating a premature stop codon. The implications of our data to understanding the diversity of Pina and Pinb alleles in wheat and to future molecular breeding of wheat kernel hardness are discussed.     

滴灌量对冬小麦耗水特性和干物质积累分配的影响

为给滴灌冬小麦高产栽培的水分管理提供理论依据,在播前足墒和越冬前灌水750 m33·hm-2的条件下分析了起身后不同滴灌量(2550、3150和3750 m3·hm-2,分别用W1、W2、W3表示)对冬小麦耗水及干物质积累、分配的影响.结果表明,随滴灌量的减少,冬小麦孕穗期至花后20 d的0～100 cm土层含水量明显降低,但土壤含水量沿毛管的横向差异增大,总耗水量减少,土壤贮水的消耗量明显增加;群体的叶面积指数和干物质积累量降低,尤其是远离毛管处下降更明显;开花前营养器官贮藏同化物向籽粒的转运量、运转率及对籽粒的贡献率增加,开花后干物质同化量和对籽粒的贡献率显著降低;籽粒产量降低,灌溉水利用效率呈增加趋势.3个处理中,W2的水分利用效率最高,产量与W3差异不显著.在本试验条件下,起身后滴灌冬小麦的适宜灌溉定额为3150～3750 m3·hm2.     

Discrimination of wheat grain varieties using image analysis and neural networks. Part I. Single kernel texture

The development of non-destructive methods for the evaluation of cereal grain varieties has important implications for the food processing industry. The described experiment investigated 11 varieties of spring and winter wheat of different quality class. The analysis was performed on images acquired from a flatbed scanner interfaced to a PC. Kernel images were digitalized at high resolution (2673 × 4031) with 24-bit depth and 400 dpi. The variables input into the statistical model were the textures of single kernel projections. Textures were computed separately for seven channels (R, G, B, Y, S, U, V). The results were examined with the application of discriminant analysis and neural networks. The accuracy of texture-based classification of 11 wheat varieties reached 100%. The experimental design which yielded the most satisfactory results comprised texture measurements from the combined area of 20 kernels and variables from seven channels input into the neural network. The final classification quality was not affected by the year of cultivation, moisture content or grain variety.     

Diallelic analysis of genetic effects determining days to flowering in kenaf

The genetic control determining the days to flowering, defined as the number of days from emergence to the beginning of flowering is considered an important characteristic for breeding purpose. We investigated this factor in kenaf (Hibiscus cannabinus L.), as part of an agroindustrial project in northwest Argentina. A diallelic cross approach was considered in this study. Six highly inbred photosensitive cultivars were used in the cross, namely, Endora, Pandora, Tainung 1, Line 42, Line 21, and Line 29. Significant differences among F₁ family means as well as among general combining ability (GCA) and specific combining ability (SCA) components were found based on the Griffing genetic-statistical method IV, Model 1. A predominant additive effect was detected for the days to flowering, giving high heritability estimates (H = DGD = 0.96; h² = 0.69), and suggests the possibility of effective selection for earliness in these cultivars. Early flowering in Line 29 was highly heritable, and therefore, is important for breeding purposes. Line 42, despite being the earliest, did not transmit this characteristic to its progenies, possibly because of epistatic genetic effects. The regression of the covariances of F₁ families on the non-recurrent parent (W_r) and the variance of the “n” families (V_r) revealed that some dominance effects also occurred in the form of a partial dominance for early flowering. These results support the evidences revealed by the analysis of means of combinations between early and late flowering lines.