Days To Physiological Maturity Research Articles

Optimizing Soybean Cultivation in Uttarakhand's Tarai Region Using the DSSAT CROPGRO Modeling Approach

Soybean (Glycine max) is a vital oilseed crop globally, but in India, its average grain yields remain relatively low despite the presence of high-yielding varieties. This study aimed to optimize soybean cultivation in the Tarai region of Uttarakhand, India, by exploring the impact of different sowing dates on crop growth and yield using the Decision Support System for Agrotechnology Transfer (DSSAT) CROPGRO model. The experiment was conducted in 2022 and 2023 at Pantnagar, Uttarakhand, using a split-plot design with three replications. The model was calibrated and validated for different sowing dates, and key parameters such as emergence days, physiological maturity days, grain yield, harvest index, and leaf area index were compared between simulated and observed values. During validation RMSE and R2 was 48.44 and 0.90 for grain yield, 1.10 and 0.99 for physiological maturity, 0.042 and 0.99 for harvest index and 1.14 and 0.97 for LAI respectively. The results showed that adjusting sowing dates can significantly affect soybean growth and yield, with optimal sowing times resulting in higher yields and better crop performance. Specifically, sowing on July 22nd resulted in the highest grain yield, while sowing on August 21st led to the lowest. The DSSAT CROPGRO model proved to be a valuable tool for simulating soybean growth and predicting crop outcomes under varying environmental conditions.

Genome-wide association mapping for component traits of drought tolerance in dry beans (Phaseolus vulgaris L.).

Understanding the genetic basis of traits of economic importance under drought stressed and well-watered conditions is important in enhancing genetic gains in dry beans (Phaseolus vulgaris L.). This research aims to: (i) identify markers associated with agronomic and physiological traits for drought tolerance and (ii) identify drought-related putative candidate genes within the mapped genomic regions. An andean and middle-american diversity panel (AMDP) comprising of 185 genotypes was screened in the field under drought stressed and well-watered conditions for two successive seasons. Agronomic and physiological traits, viz., days to 50% flowering (DFW), plant height (PH), days to physiological maturity (DPM), grain yield (GYD), 100-seed weight (SW), leaf temperature (LT), leaf chlorophyll content (LCC) and stomatal conductance (SC) were phenotyped. Principal component and association analysis were conducted using the filtered 9370 Diversity Arrays Technology sequencing (DArTseq) markers. The mean PH, GYD, SW, DPM, LCC and SC of the panel was reduced by 12.1, 29.6, 10.3, 12.6, 28.5 and 62.0%, respectively under drought stressed conditions. Population structure analysis revealed two sub-populations, which corresponded to the andean and middle-american gene pools. Markers explained 0.08-0.10, 0.22-0.23, 0.29-0.32, 0.43-0.44, 0.65-0.66 and 0.69-0.70 of the total phenotypic variability (R2) for SC, LT, PH, GYD, SW and DFW, respectively under drought stressed conditions. For well-watered conditions, R2 varied from 0.08 (LT) to 0.70 (DPM). Overall, 68 significant (p < 10-03) marker-trait associations (MTAs) and 22 putative candidate genes were identified across drought stressed and well-watered conditions. Most of the identified genes had known biological functions related to regulating the response to drought stress. The findings provide new insights into the genetic architecture of drought stress tolerance in common bean. The findings also provide potential candidate SNPs and putative genes that can be utilized in gene discovery and marker-assisted breeding for drought tolerance after validation.

Development of a High Yielded Chlorsulfuron-Resistant Soybean (Glycine max L.) Variety through Mutation Breeding

This study was conducted to develop a novel herbicide resistance soybean using ethyl methanesulfonate (EMS) mutagen. In this study, 0.1% of EMS mutagen was applied to the soybean [Glycine max (L.) cv Arısoy] seeds. A single resistant mutant was selected in the M2 population evaluated under field and greenhouse conditions. The AHAS gene regions of the herbicide-resistant mutant progeny were mapped, and the nucleotide changes were defined conferring herbicide resistance. The sequence analysis of the AHAS gene indicated that three nucleotide substitutions were detected such as 407 (C/T), 532 (C/T), and 1790 (C/T). According to the AHAS gene protein sequence of Arabidopsis thaliana, Ala155Val, Pro197Ser, and Thr616Met amino acid alterations were found in the progeny of the resistant mutant. Pro197Ser alteration was common in all the progeny, while the others were diverse. The wild-type and the mutant plants were compared for seed yield, number of pods per plant, stem height to the first pod, 1000-seed weight, and physiological maturity days for two subsequent years. No statistical difference was found between the mutant and wild types with respect to seed yield and its components. The agronomic data indicated that EMS provided target-site resistance to sulfonylureas (SU) with no tradeoff between yield components and resistance.

Genotype-by-Environment Interaction in Tepary Bean (Phaseolus acutifolius A. Gray) for Seed Yield

Genotype-by-environment (GEI) analysis guides the recommendation of best-performing crop genotypes and production environments. The objective of this study was to determine the extent of GEI on seed yield in tepary bean for genotype recommendation and cultivation in drought-prone environments. Forty-five genetically diverse tepary bean genotypes were evaluated under non-stressed and drought-stressed conditions for two seasons using a 9 × 5 alpha lattice design with three replications in four testing environments. Data were collected on seed yield (SY) and days to physiological maturity (DTM) and computed using a combined analysis of variance, the additive main effect and multiplicative interaction (AMMI), the best linear unbiased predictors (BLUPs), the yield stability index (YSI), the weighted average of absolute scores (WAASB) index, the multi-trait stability index (MTSI), and a superiority measure. AMMI analysis revealed a significant (p &lt; 0.001) GEI, accounting for 13.82% of the total variation. Genotype performance was variable across the test environments, allowing the selection of best-suited candidates for the target production environment. The environment accounted for a substantial yield variation of 52.62%. The first and second interaction principal component axes accounted for 94.8 and 4.7% of the total variation in the AMMI-2 model, respectively, of surmountable variation due to GEI. The AMMI 2 model family was sufficient to guide the selection of high-yielding and stable genotypes. Based on best linear unbiased predictors (BLUPs), yield stability index (YSI), superiority measure (Pi), and broad adaptation, the following tepary bean genotypes were identified as high-yielding and suited for drought-prone environments: G40138, G40148, G40140, G40135, and G40158. The selected tepary bean genotypes are recommended for cultivation and breeding in Malawi or other related agroecologies.

Evaluation of Fonio (Digitaria exilis) Varieties for Improved Agronomic Traits in the Guinea and Sudan Savannah Agroecological Zones of Ghana

Background and Objective. Fonio is categorized as one of the neglected, under-utilized, or orphan crops of West Africa due to its poor yields and inadequate research information for its improvement and use. The need to improve the agronomic traits of this crop and also explore the possibility of growing it in different agroecologies has been felt over the years. A study was therefore conducted during the 2019 cropping season to determine variations among Fonio accessions and also assess the influence of genotype/accession, location, and genotype x location on growth and total grain yield of Fonio. Materials and Methods. Five accessions of the crop were planted in two locations in northern Ghana (Guinea and Sudan savannah) and replicated three times using factorial experiment in randomized complete block design. Results. The study indicated significant ( P &lt; 0.05 ) variations among accessions for most of the attributes measured. Accession OUSAI with 75 days to physiological maturity (DPHM) recorded highest grain yield of 1015.10 kg/ha, and NFAS4 with 98 DPHM recorded the least grain yield of 713.23 kg/ha. The most lodged accession was OUAS1 which recorded 65% lodging of its total plant population, and the least lodged accessions (NFAS4 and EYAS5) recorded about 10% lodging each. Conclusion. The results demonstrated a significant ( P &lt; 0.05 ) diversity among the accessions used in the study and influence of genotype/accession x location on growth and total grain yield of Fonio.

Water Shortage Affects Vegetative and Reproductive Stages of Common Bean (Phaseolus vulgaris) Chilean Landraces, Differentially Impacting Grain Yield Components.

Water availability for agricultural use is currently a global problem that worsens with climate change in several regions of the world. Among grain legumes, common bean (Phaseolus vulgaris) is the most cultivated in the worldwide. The Chilean germplasm of common bean is characterized by tolerance to water stress. Here, we analyzed a selection of nine ancient Chilean landraces in regard to their drought tolerance, simulating optimal (OW) and restricted watering (RW) in a Mediterranean environment. Phenological, growth, and yield traits were recorded, and correlation analysis was performed. Accordingly, leaf temperature and osmotic potential were higher under RW, while the leaf chlorophyll content decreased in all landraces. Physiological maturity days and seed-filling days were lower in RW than in OW. This similarly occurred with the grain yield. The % yield reduction was negatively correlated with the % pod reduction and the relative rate of leaf expansion (RLAE) reduction. However, the 100-seed weight value was not significantly modified by water treatment (p > 0.05). For instance, landraces that preferred to fill the grain with a lower rate of leaf expansion showed a lower loss in grain yield under drought conditions. These results suggest that the resource partitioning between growing leaves, flowers, and developing pods in Chilean landraces is variable, affecting the common bean drought tolerance.

Effect of varying levels of silicon and restricted irrigation on productivity of wheat (Triticum aestivum L.) under Bhal condition of Gujarat

A field experiment was conducted during rabi season 2019-20 at Agricultural Research Station, Anand Agricultural University, Dhandhuka, Gujarat, to evaluate the effect of different irrigation and silicon levels on wheat productivity. Results from the experiment indicate that significantly superior data were recorded with two irrigation (I3) in case of plant height (75.85), effective tillers per plant (6.18), ear length (cm) (8.71), grains per ear (35.42), test weight (g) (46.29) and grain yield (3360 kg ha-1) over control (I1) and being at par with three irrigation (I4). While 75% anthesis (73.33) and physiological maturity days (108.33) found significantly superior with three irrigation (I4) over control (I1) and being at par with two irrigation (I3) 72.83 and 107, respectively. Amongst different levels of silicon, 150 kg ha-1 (S3) significantly increased yield and yield attributes i.e., plant height (72.24), effective tillers per plant (6.12), ear length (cm) (7.67), grains per ear (32.81), test weight (g) (46.17) and grain yield (3182 kg ha-1) as compare to control (S1) and being at par with three irrigation (S4). The percent increase in case grain yield with silicon 150 kg ha-1(S3) is 40.29 over control (S1). Alike, results further pointed out that 75% anthesis (71.25) and physiological maturity days (104.42) found significantly superior with silicon 200 kg ha-1(S4) over control (S1) and at par with silicon 150 kg ha-1(S3).

Evaluation of DSSAT model (CERES rice) on rice production: A review

Rice is the staple food for over half of the world population. Crop models potentially offer a means to readily explore management options to increase yield, and to determine trade-off between yield, resource-use efficiency and environmental outcomes. This paper reviews the performance of CERES-Rice model in different regions of the world in relation to their potential application towards increasing resource use efficiency and yield of rice. In this article, the CERES-Rice model evaluation by using the simulated and observed values on crop phenology (anthesis, physiological maturity) and final grain yield mainly over Asian countries by different authors has been compiled and described. Mainly the model was evaluated based on different statistical measures such as RMSE and D-index. Several datasets for the prediction of grain yield and phenological period across different parts of Asia were examined. This particular model predicted those with high-accuracy (nRMSE1-5% for anthesis and 1-4% for physiological maturity days). For various data sets for grain yield, the nRMSE varied between 0.05–5.00 percent with error percentage of 2-5%. The model sometimes over-estimated or under-estimated the values of grain yield, especially under water stress conditions.

Genotype-by-trait association of sorghum (Sorghum bicolor (L.) Moench) advanced lines grown under arid and semi-arid regions of Zimbabwe

Inadequate information is available on trait relations and profiles of sorghum genotypes, yet this information is vital for precise decisions to be undertaken in breeding programs. Here, 17 sorghum experimental lines were evaluated together with three checks at five locations, representing the major sorghum production environments in Zimbabwe. Across site analysis of variance (ANOVA) showed significant genotypic effects on grain yield (GYD) as well as the other traits, including panicle length (PL) and stem diameter (SD). Distance-based clustering indicated the possibility of indirectly selecting for GYD using; SD, exertion (EXSTN), panicle length (PL), panicle width (PW) and number of leaves (NL). In addition, the vector view of the genotype-by-trait (GT) biplot also revealed strong correlations between GYD and, PW, SD and FYD, as well as the other physiological traits including, days to male flowering (DMA) and days to physiological maturity (DPM). Genotypes superior for a combination of traits were, G6, G7, G11, G18 and G20, which were strong for GYD, PL and PW, as well as, G5 which was strong for sugar content (SC), number of leaves (NL) and SD. Genotypes 15, 16 and 17, were specifically strong for GYD whereas, genotypes 4 and 9 were strong for FYD. Overall, results revealed the key traits which can be considered singularly or in combination, when selecting suitable sorghum genotypes, either for feed or food purposes, under arid and semi-arid conditions. This information is vital for decision making in sorghum breeding programs.

Bazı İleri Soya (Glycine max. L.) Hatlarının Şanlıurfa İkinci Ürün Koşullarında Verim ve Kalite Özellikleri Yönünden Değerlendirilmesi

Bu çalışma, bazı ileri soya hatlarının Şanlıurfa ikinci ürün koşullarında performanslarının belirlenmesi amacıyla 2018-2019 yıllarında yürütülmüştür. Çalışmada, melezleme yöntemiyle geliştirilmiş olan 12 ileri hat (Antjc-17,Antwa-20, Antwa-4, Antjc-14, Batem-210, Antjc-15, Antwa-2, Batem-204, Batem-316, Antsoy-2, Antjc-20, Antjc-23) ve 3 standart çeşit (Kocatürk, Göksoy, Adasoy) materyal olarak kullanılmıştır. Araştırma, GAP Tarımsal Araştırma Enstitüsü Gündaş Araştırma istasyonunda 2018-2019 yıllarında iki yıl üst üste yürütülmüştür. Araştırmada, çiçeklenme gün sayısı, fizyolojik olgunluk gün sayısı, bitki boyu, ilk bakla yüksekliği, verim ve bin tane ağırlığı gibi morfolojik özelliklerin yanında ham protein ve ham yağ gibi kalite özellikleri de incelenmiştir. Araştırma sonuçlarına göre; bitkide ilk bakla yüksekliği (p&lt;0.05) dışında incelenen tüm özellikler bakımından soya hatları arasında istatistik olarak oldukça önemli (p&lt;0.01) farklar tespit edilmiştir. İncelenen soya genotiplerin arasında tane verimi 171,4-560,1 kg da-1 bitki boyu 67.6-126,6 cm, ham protein oranı %28.9 ile 39.9, ham yağ oranı %18.1 ile 23.6 ve bin tane ağırlığı 125,8-179,4 gr arasında değişmiştir.

Physiological Growth Indices of Durum Wheat (&amp;lt;i&amp;gt;Triticum turgidum&amp;lt;/i&amp;gt; L. Var. durum) as Affected by Rates of Blended and Nitrogen Fertilizers

In order to investigation the effects of blended NPSB and N fertilizer rates on physiological and growth indices in durum wheat, a randomized complete block design in a factorial arrangement and replicated 3 times per treatment was conducted in research field of Debre Zeit Agricultural Research Center in 2017 and 2018 under rain-fed condition. The treatments consisted of 4 levels of blended (0, 50, 100, and 150 kg NPSB ha^-1) and N (0, 46, 69 and 92 kg N ha^-1) fertilizers. The results revealed that leaf area index (LAI) at 64 days after sowing (DAS), crop growth rate (CGR) at 34-64 and 64-94 DAS, relative growth rate (RGR) at 34-64 DAS were significantly (P<0.05) affected by the interaction effects of blended NPSB and N fertilizers. Chlorophyll content (CHL), plant height (PH), days to heading (DH), and days to physiological maturity (DPM) were significantly influenced only by N levels. The highest LAI (4.50), CGR (4.37 g m^-2°Cdays^-1) at 34-64 DAS and (14.81g m^-2°Cdays^-1) at 64-94 DAS and RGR (0.0077 g g^-1°Cdays^-1) at 34-64 DAS were observed at combined application of 150 kg blended NPSB with 92 kg N ha^-1. The highest PH (89.4 cm), CHL (40.09), DH (60.92 days) and DPM (116.75 days) were noted in 92 kg N ha. On overall performance application of 150 kg NPSB with 92 kg N/ha levels showed better results on the growth and physiological traits of durum wheat as compared to other blended and N levels.

English

Crop models are highly useful for simulating crop and soil processes in response to variations in climate and crop management. However, well estimated crop genetic coefficients are required. So the purpose of this study is to calibrate and evaluate the performance of CERES-wheat model and to simulate the climate change impacts on phonological stages and grain yield of bread wheat (Tay and Senkegna varieties) in the study area. Observed climate data from National Meteorological Agency of Ethiopia from 1983 to 2015 and future climate from Climate Research Programme’s Fifth Coupled Model Intercomparison Project (CMIP5) database across 20 Global Circulation Models for Representative Concentration Pathway (RCP4.5 and 8.5) emission scenarios in the time horizon of early-term (2010-2039), mid-century (2040-2069) and end-century (2070-2100) were used. Crop and soil data were obtained from Adet Agricultural Research Center. Decision Support System for Agro-technology Transfer (DSSAT) crop model was employed. There was strong agreement between the simulated and observed values with R2 being 96, 79 and 79% for days to anthesis, grain yield and days to maturity, respectively for Tay wheat variety while 75% for days to anthesis, 92% for grain yield, and 75% for days to maturity of Senkegna bread wheat variety. On the other hand, during model validation, the goodness of fits (R2) was 86% for anthesis day, 70% for grain yield and 96% for physiological maturity days of Tay wheat variety. Similarly for Senkegna bread wheat variety, R2 was 89, 82 and 75% for anthesis day, grain yield, and physiological maturity days, respectively. The yield of both bread wheat varieties showed increase except in 2080s under RCP4.5 relative to the baseline. However, days to flowering and to maturity showed decreased in each time slice under both RCPs. Key words: Calibration, validation, crop model, wheat, Ethiopia, East Africa.

Contributo para o estudo do desempenho agronómico de híbridos na principal região produtora de girassol no Brasil (Chapadão do Parecis)

The objective of this study was to evaluate the agronomic performance of sunflower hybrids in the main producing sunflower region in Brazil, Campo Novo do Parecis - MT (Brazil) in the second season. The study was conducted in the experimental field of the Instituto Federal de Educacao, Ciencia e Tecnologia de Mato Grosso, from February to June 2015. 13 sunflower hybrids were analyzed in a randomized complete block design with four replications. The following characteristics were evaluated: days for early flowering (DEF), days to physiological maturity (DPM), plant height (PH), stem curvature (SC), capitulum size (CS), mass capitulum (MCA), grain mass per capitulum (GMC), harvest index (HI), thousand grain weight (TGW), yield grains (YG), oil content (OC) and oil yield (OY). Data were submitted to analysis of variance and the Scott-Knott test at 5% of significance. In 2015, the hybrid BRS G44 was the one that best adapted to Parecis region, State of Mato Grosso, Brazil, with good performances in grain and oil yields, also with higher precocity and lower size compared to other hybrids.

Character association and path co-efficient analysis in wheat (Triticum aestivum L.)

The experiment was carried out with 50 wheat lines to study their mean, range, cv (%), correlation co- efficient, and path co- efficient considering 14 different morphological characters at the experimental field of Regional Wheat Research Centre (RWRC), Bangladesh Agricultural Research Institute (BARI), Gazipur during December 2010 to April 2011. Significant variation was observed among the genotypes for all characters studied. In general, genotypic correlations were higher than the phenotypic correlations. It indicates that there was an inherent association among them which was adversely influenced by the environment. The correlation coefficients showed that, seed yield was negatively and significantly correlated with days to heading (DTH), plant height (PHT), days to anthesis (DTA), days to physiological maturity (DPM), and canopy temperature at anthesis stage (CTanth.) but only negatively correlated with canopy temperature at vegetative stage (CTveg.), canopy temperature at grain filling stage (CTgf.), spikelets per spike both genotypically and phenotypically and grain per spike showed genotypically negative correlation. Path analysis showed that plant height (PHT), days to physiological maturity (DPM), canopy temperature at grain filling stage (CTgf.), and thousand grain weight (TGW) influenced seed yield directly in positive direction but days to heading (DTH), days to anthesis (DTA), grain filling duration (GFD), grain filling rate (GFR), Chlorophyll content at anthesis stage (CHLA), canopy temperature at vegetative stage (CTveg.), canopy temperature at anthesis stage (CTanth.), spikelets per spike, and grains per spike had negative direct effect on seed yield. Considering analytical findings of correlation co-efficient, path co-efficient analysis and field performance, the genotypes G 3, G 10, G 11, G 12, G13, G 21, G 29, G 35, G 38, G 40, G 46 and G 48 were found suitable for future breeding programme.Bangladesh J. Agril. Res. 42(3): 571-588, September 2017

Variability of Grain‐Filling Traits in Early Maturing CIMMYT Tropical Maize Inbred Lines

ABSTRACTGrain‐filling rate (GFR), effective grain‐filling duration (EGFD), and total grain‐filling duration (TGFD) are important physiological traits of maize (Zea mays L.) grain yield (GY) formation. To devise effective breeding strategies, the genetic nature of these traits is a prerequisite for improvement in early maturing maize. A study was conducted at CIMMYT‐Zimbabwe using an α‐lattice design with two replications in two environments to investigate the genetic variability of grain‐filling traits in 18 early maturing tropical maize inbred lines derived from CIMMYT germplasm. Highly significant differences were observed for GY, thousand‐grain weight (TGW), GFR, EGFD, TGFD, kernels per row (KR), and rows per cob (RC). The broad‐sense coefficient of genetic determination (the fixed parent equivalent of broad‐sense heritability) was above 70% for all of the traits. The highest GY was obtained from the inbred line T032‐30 (79.2 g plant–1) and the lowest from inbred line CML506 (37.6 g plant–1), respectively. Therefore, selecting for higher GFR and longer TGFD, especially the EGFD, can increase GY of early maize without extending days to physiological maturity (DPM).

Analysis on genetic contribution of some traits to seed yield in rapeseed by additive-dominance genetic method of mixed model

Analysis on genetic contribution of some traits to seed yield in rapeseed by additive-dominance genetic method of mixed modelA genetic model is developed with additive, dominance and genotype x environment interaction effects for the progeny from a diallel mating design. To uncover the genetic contributions of some traits of rapeseed to seed yield and find indicator traits for indirect selection, multivariable conditional analysis was conducted based on this method. Therefore, an experiment was conducted to estimate genetic parameters using a half diallel of nine international rapeseed cultivars. The 36 Fl hybrids, the parents and four additional cultivars were planted in the breeding nurseries in 2008 and 2009. Several traits including number of pods per plant (NPP), pod length (LP), height of the first pod (HFP), height of the first lateral branch (HFB), stem diameter (SD), days of flowering period (FP), days to physiological maturity (DPM) and seed yield were recorded. The genetic variance component (VDxY) was significant for all the studied traits but the genetic variance component (VA) was significant for NPP, HFB, HFP, DPM and SY traits and the genetic variance component (VD) was significant for HFB, HFP, LP and FP traits. There was significant positive phenotypic correlation (rA) between seed yield with NPP and HFP and there was significant positive dominance x year interaction correlation (rDxY) between seed yield with NPP and DPM while there was significant negative dominance x year interaction correlation (rDxY) between seed yield with HFB, LP and FP. There were significantly positive additive effects of SY for two parents Orient and Talaye. Finally according to additive-dominance genetic model and conditional genetic effects, the genotypes Talaye proved good general combiner for seed yield improvement and crosses 4 × 8 (Orient × Talaye), 7 × 8 (Opera × Talaye) were found the best specific combiner for all the studied traits.

Field performance of imazamox-resistant spring wheat

The imidazolinone herbicides possess high biological potency at low application rates, and are an attractive alternative for weed control in spring wheat (Triticum aestivum L.). Four mutation-derived spring wheat lines resistant to the imidazolinone class of herbicides were evaluated in field trials to investigate the levels of resistance to imazamox. Imazamox was applied post-emergence at 0 g (hand-weeded control; HWC) 20 g, 40 g, 80 g and 160 g active ingredient (a.i.) ha-1. A standard herbicide treatment (SHT; clodinafoppropargyl, bromoxynil and MC PA ester) representing a common herbicide application to spring wheat in western Canada was also included. The cultivar CDC Teal was included as a susceptible control. At 160 g ha-1, imazamox reduced yield in lines with a single resistance gene (TealIMI 10A, TealIMI 11A, and BW755) by up to 43% and delayed maturity up to 13 d. TealIMI 15A, the only line evaluated with two resistance genes, was the most resistant of all lines, with no significant increases in days to spike emergence (DSE), days to physiological maturity (DPM), and no reduction in yield at the highest rate of imazamox. The susceptible control was killed within 2 wk of imazamox application, regardless of application rate. These results indicate that two resistance genes are preferable for ensuring satisfactory levels of resistance to the formulation of imazamox used in these studies. Key words: Triticum aestivum L., imazamox, resistance, gene stacking

Inheritance of Early Maturity of Indeterminate Dry Bean

Knowledge of the heritability and genetic relationships among traits associated with harvest maturity should facilitate selection of bean (Phaseolus vulgaris L.) genotypes having earlier harvest maturity. The objectives of this study were to estimate the narrow sense heritabilities of days to first flower (DFF), days to physiological maturity (DPM), and length of the reproductive period (HP) and to measure the genetic correlations among these traits. Progeny derived from three different crosses between early and later maturity indeterminate genotypes were evaluated for two planting dates at Isabela, PR. Narrowsense heritability estimates for DFF were generally large (0.29 to 0.75), which suggests that early generation selection for DFF in these populations would be successful. Narrow‐sense heritability estimates for DPM were intermediate to large (0.31‐0.63); however, magnitude of estimates varied between planting dates. Narrow‐sense heritability estimates for RP of the three crosses were generally intermediate to low, indicating that selection for the RP trait would be most effectively conducted in replicated nurseries in advanced generations. F3 lines with RP = 10 d longer than the parental genotypes were identified in all three crosses. Genetic correlation coefficients between DFF and DPM were positive and significant, ranging from r = 0.43 to r = 0.85. Genetic correlation coefficients between DFF and RP were generally negative and significant, suggesting that selection for a greater RP would likely be related to a reduced DFF. Genetic correlation coefficients between DPM and RP varied among crosses and between years.