DETERMINATION OF GRAIN YIELD AND YIELD COMPONENTS OF SOME MAIZE (Zea mays L.) CULTIVARS UNDER KAYSERI CONDITIONS

Yield components are the most important breeding objectives, directly determining maize high-yield breeding. It is well known that these traits are controlled by a large number of quantitative trait loci (QTL). Therefore, deeply understanding the genetic basis of yield components and identifying key regulatory candidate genes can lay the foundation for maize marker-assisted selection (MAS) breeding. In this study, our aim was to identify the key genomic regions that regulate maize yield component formation through bioinformatic methods. Herein, 554 original QTLs related to 11 yield components, including ear length (EL), hundred-kernel weight (HKW), ear weight (EW), cob weight (CW), ear diameter (ED), cob diameter (CD), kernel row number (KRN), kernel number per row (KNR), kernel length (KL), grain weight per plant (GW), and kernel width (KW) in maize, were collected from the MaizeGDB, national center for biotechnology information (NCBI), and China national knowledge infrastructure (CNKI) databases. The consensus map was then constructed with a total length of 7154.30 cM. Approximately 80.32% of original QTLs were successfully projected on the consensus map, and they were unevenly distributed on the 10 chromosomes (Chr.). Moreover, 44 meta-QTLs (MQTLs) were identified by the meta-analysis. Among them, 39 MQTLs controlled two or more yield components, except for the MQTL4 in Chr. 1, which was associated with HKW; MQTL11 in Chr. 2, which was responsible for EL; MQTL19 in Chr. 3, which was related to KRN; MQTL26 in Chr. 5, which was involved in HKW; and MQTL36 in Chr. 7, which regulated EL. These findings were consistent with the Pearson correlation results, indicating that these traits exhibited co-linked heredity phenomena. Meanwhile, 159 candidate genes were found in all of the above MQTLs intervals, of which, 29 genes encoded E3 ubiquitin protein ligase, which was related with kernel size and weight. Other genes were involved in multiple metabolic processes, including plant hormones signaling transduction, plant growth and development, sucrose-starch synthesis and metabolism, and reproductive growth. Overall, the results will provide reliable genetic resources for high-yield molecular breeding in maize.

This study was conducted to determine the effects of different plant densities on yield and yield components of maize under main crop conditions in the Amik Plain. The maize cultivar P1541 was used, and the experiment was established at Mustafa Kemal University Agricultural Research and Application Center in Hatay, following a randomized complete block design with three replications. Six different plant density levels (7,519; 8,071; 8,606; 9,276; 9,990; and 10,989 plants da-1) were applied. The evaluated traits included plant height, stalk diameter, ear insertion height, ear length, ear diameter, number of kernels per ear, ear weight, kernel weight, 1000-kernel weight, and grain yield. Most morphological characteristics did not show statistically significant differences. However, plant density had a significant effect (P < 0.01) on grain yield, with the highest yield obtained at 10,989 plants da-1. These findings indicate that optimal plant density can enhance maize productivity under Amik Plain conditions.

In the present study, "Correlation and path coefficient analysis for grain yield components in maize (Zea mays L.)," the aim was to estimate genetic variability, genetic advance, correlation, and direct and indirect effects of yield contributing traits on yield. According to the analysis of variance, all traits exist. Hence, the data on all the 16 traits which showed significant differences among the entries were subjected to further statistical analysis. GP-184 had the shortest grain yield per plant in comparison to other genotypes, whereas GP-87 had the highest grain yield. Grain yield per plant, ear height, plant height, and cob weight exhibited the highest genotypic coefficient of variation. Cob weight. Among the traits, grain yield per plant, ear height, plant height, cob weight, and cob length showed a higher phenotypic coefficient of variation. The traits ear height, grain yield per plant, plant height, number of cobs per plant, cob length, number of kernels per row, cob weight, number of kernels per row per cob, anthesis to silking interval, shank weight, and days to 50% silking exhibited the highest heritability. Plant height, grain yield per plant, ear height, and cob weight were traits that showed higher genetic advances. These traits included grain yield per plant, ear height, plant height, cob weight, cob length, number of cobs per plant, tassel length, number of kernels per row, number of kernel rows per cob, 100-kernel weight, anthesis to silking interval, cob girth, and shank weight that showed higher genetic advance as a percent mean. The correlation coefficient indicates there is a significant positive correlation between grain yield and cob weight, number of cobs per plant, number of kernels per row, number of kernel rows per cob, 100 kernel weight, cob length, cob girth, plant height, ear height, shank weight, and tassel length at the phenotypic level. Grain yield per plant significantly positive correlation with cob weight, number of cobs per plant, number of kernels per row, number of kernel row per cob, 100 kernel weight, cob length, cob girth, plant height, shank weight, ear height, tassel length at the genotypic level the phenotypic level, the traits cob weight, 100 kernel weight, and plant height had the greatest direct impact on grain yield per plant. The traits were cob weight, number of kernel row per cob, 100 kernel weight showed higher direct effect on grain yield per plant at genotypic level.

جهت بررسی اثر زمان محلول‌پاشی هورمون‌های سیتوکینین (عدم مصرف، مصرف در مرحله V5-V6 و V8-V10) و اکسین (عدم مصرف، زمان ظهور ابریشم و دو هفته پس از آن) و الگوی کاشت (یک ردیفه، دو ردیفه و کف فارو) بر عملکرد و اجزاء عملکرد ذرت دانه‌‌ای (Zea mays L.) در شرایط شور آزمایشی در سال 1392 در مرکز تحقیقات کشاورزی و منابع طبیعی بوشهر به‌صورت اسپلیت فاکتوریل در قالب طرح بلوک‌‌های کامل تصادفی با سه تکرار اجرا گردید .الگوی کاشت به‌عنوان فاکتور اصلی و مصرف یا عدم مصرف هورمون‌‌‌‌‌‌‌‌‌‌های اکسین و سیتوکینین به‌صورت فاکتوریل در کرت‌های فرعی بررسی گردید. اثر الگوی کاشت بر ارتفاع بوته، طول و قطر بلال، تعداد ردیف دانه، تعداد دانه در ردیف، وزن هزار دانه، عملکرد بیولوژیک، عملکرد دانه و شاخص برداشت معنی‌دار بود. بیشترین عملکرد دانه با کشت کف فارو با 55/7 و کمترین آن با کشت معمول با 09/4 تن در هکتار بود. از نظر ارتفاع بوته و تعداد ردیف دانه برتری با زمان مصرف 8 تا 10 برگی بود ولی وزن هزار دانه و شاخص برداشت در زمان مصرف 5 تا 6 برگی حداکثر بود. بیشترین تعداد دانه در ردیف بدون مصرف سیتوکینین به‌دست آمد. اثر اکسین روی وزن هزار دانه، عملکرد بیولوژیک، عملکرد دانه و شاخص برداشت در سطح 1% معنی‌دار گردید و بیشترین عملکرد دانه با زمان مصرف ظهور ابریشم به‌دست آمد. به‌طور کلی با کاشت کف فارو و مصرف سیتوکینین در مرحله 8 تا 10 برگی و مصرف اکسین در زمان ظهور ابریشم به‌ترتیب با غلظت 50 و 10 گرم در لیتر اثرات شوری بر گیاه کاهش یافته و عملکرد دانه افزایش یافت.

The present study was undertaken to study the gene action, narrow sense heritability, interrelationships among traits and path coefficient analysis for grain yield and its components, silking date, plant and ear height, leaf area index (LAI), specific leaf weight (SLW) and specific leaf area (SLA). Fifteen hybrids produced using a half diallel fashion in 2008 season were evaluated for grain yield and its components and morpho- physiological traits during 2009 season. The obtained results indicate that all estimates of VA and VD were significant for all traits except VA for specific leaf weight and ear length. In addition, VD for grain yield per plot, leaf area index, specific leaf weight, plant height, ear length, ear diameter, number of rows per ear and number of kernel per row. However, the magnitude of VA was consistently larger than that of VD for all traits. High narrow sense heritability estimates were detected for leaf area index (93%), leaf angel (90%), plant height (90%), ear height (89%), ear length (89%), number of rows per ear (89%) and number of kernel per row (83%). However, moderate narrow sense heritability estimates were obtained for grain yield per plot (77%), one hundred kernel weight (77%), silking date (74%), ear diameter (74%), specific leaf area (64%) and specific leaf weight (55%). While it was very low for stay green (5%). These results indicate the importance of choosing the suitable segregating generations for exhibiting the best expression of gene of different studied traits. Correlation coefficients among traits indicated that grain yield was positively and significantly associated with ear diameter (0.788**), one hundred kernel weight (0.747**), ear length (0.600**), specific leaf weight (0.518**), leaf area index (0.466**), number of rows per ear (0.458**), plant height (0.408**), number of kernels per row (0.361*) and silking date (0.351*). The path coefficient analysis was calculated to detect the relative importance of characters contributing to grain yield per plot. Data show that each of ear diameter, one hundred kernel weight and ear length had high positive direct effects on grain yield per plot.

ABSTRACTThis study aimed to (i) estimate additive (a), dominance (d), aa, ad, and dd genetic variances and effects; (ii) investigate the differences for five genetic variances or effects among crosses between a maize (Zea mays L.) line from the Suwan‐1 heterotic group and five inbred lines from other groups; and (iii) develop a theory to explain the results from Hayman's model and low‐, mid‐, and high‐parent heterosis. Hayman's model was used to evaluate the genetic effects in five six‐generation sets between the Suwan‐1 cross with five lines from other groups. The magnitude of variance was consistent among all crosses for grain yield (GY) and ear length (EL) but different for ear diameter (ED), row number per ear (RE), kernel number per row (KR), and 100‐kernel weight (KW). The a, d, aa, ad, and dd effects were similar for EL among crosses between lines from different groups, indicating that the effects for EL could be used to differentiate Reid and non‐Reid heterotic groups. We postulated a ‘linked coexpressed genes’ (LCG) model to (i) explain why a, d, aa, ad, and dd variances and effects might be different when a common line is crossed with other lines and (ii) serve as an improved model explaining heterosis. The LCG model explains what dominance–overdominance theories can explain and explains what dominance–overdominance models do not. For example, it can explain why an inbred line cannot perform like a hybrid and why an F2 population for a quantitative trait has a normal distribution.

Drought stress poses a major challenge to global maize (Zea mays L.) production, significantly affecting food security. This study aimed to identify drought-tolerant maize genotypes by evaluating their morphological characteristics under controlled and field conditions. Morphological traits, such as shoot and root length in the seedling stage and plant height, canopy temperature, ear length, and kernel weight at vegetative and reproductive stages, were analyzed under drought stress conditions induced by PEG and reduced field capacity. Significant genetic variability was observed among the genotypes for most traits, with phenotypic coefficient of variation (PCV) consistently higher than genotypic coefficient of variation (GCV). Heritability estimates ranged from 37% to 99.82%, with traits such as plant height, kernel weight per ear, ear weight, hundred-seed weight, and yield per pot demonstrating both high heritability and genetic advance. Yield showed positive correlations with plant height, ear length, ear diameter, kernel number per row, and kernel weight per ear, while negatively correlating with days to ear moisture loss. Principal Component Analysis (PCA) revealed that the first five components explained 83.46% of the total variation, with yield-related traits contributing most to the variation. Cluster analysis revealed eight distinct groups at the seedling stage and six at the vegetative and reproductive stages, with genotypes in Clusters 5 and 6 exhibiting superior drought tolerance, particularly in traits like root number, kernel number per ear, and kernel weight per ear. This study identified BHM-7, BHM-14, and BHM-15 as genotypes with superior drought tolerance at the reproductive stage, while Black, Violet, and White Vutta showed resilience at the seedling stage, exhibiting greater plant vigor under drought stress. Recognizing these genotypes as a significant step toward breeding drought-resistant maize varieties, contributing to food security and sustainable agriculture.

This article was investigated to study the correlation and analysis of drought stress regression on maize cultivars' yield and components. The variance analysis results showed a significant difference between drought stress levels in terms of plant height, total dry weight and number of seeds per row, the total weight of cob, grain yield, harvest index, stem diameter, and cob weight with protective leave. Also, there was a significant difference in ear weight without protective leaves, ear diameter, ear length, plant weight, 100-seed weight, and seed per ear on hybrid treatments. There were statistically significant differences between cultivars in plant height, leaf area, ear diameter, ear length, number of seeds per row, number of seeds per ear, the total weight of cob wood, 100-seed weight, harvest index, plant dry weight. The results of the correlation of traits for the mean levels of drought stress showed a positive and significant correlation between plant yield and plant height, seed per row, ear length and weight of 5 pieces of wood and also with a total weight of cob wood, ear weight with bark showed the highest correlation. There is a significant correlation between leaf area and stem diameter, plant weight, total dry weight at the probability level of 0.05. Correlation coefficients between traits in non-stress conditions showed a positive and significant correlation between grain yield and height, ear length and grain in the row, which was a significant increase compared to stress conditions. The correlation of traits under full stress conditions also showed that the correlation coefficient between cob length trait and positive height was positive and significant. From the study of correlation coefficients between maize traits in non-stress conditions, it can be concluded that the most important components of grain yield are cob length and grain per row. While the correlation coefficients under moisture stress conditions show that the grain trait in the row has a positive and significant correlation with yield, under stress conditions in the cob stage did not show any traits with correlation yield.

The effect of planting date on maize grain yields and yield components

Abstract. Ritonga AW, Mukhlisin, Sutjahjo SH. 2025. Estimation of genetic parameters and path analysis in sweet-waxy corn (Zea mays var. ceratina). Biodiversitas 26: 879-889. Waxy corn is commonly consumed as a staple food in Eastern Indonesia. The development of hybrid sweet-waxy corn is crucial for enhancing its quality and productivity. The information about genetic parameters and yield-related traits is essential in plant breeding programs to obtain high-yielding hybrids. This study aimed to determine the genetic variability, heritability, and yield-related traits in sweet-waxy corn hybrids. This research was carried out at two locations, Bogor and Lampung, from September 2023 to February 2024. Fifteen sweet-waxy corn hybrids were sown in a randomized complete block design with three replicates. The recorded data were plant height, ear height, stem diameter, leaf width, leaf length, the number of leaves, the number of kernels per row, the number of rows per ear, ear diameter, ear length, and ear weight without husk. The findings revealed that the G1, G7, and G12 hybrids demonstrated superior yield traits at both locations. All observed traits demonstrated high heritability, with the exception of stem diameter and the number of kernels per row. The phenotypic and genotypic coefficients of variation were within the moderate to high, with percentages ranging from 4.15% to 16.69%. Correlation analysis suggested a positive association between ear weight without husks with the other traits. Ear diameter, ear length, and the number of kernels per row had highly positive direct effects on the ear weight without husks, while leaf width had a strong indirect effect through ear diameter (0.415). Thus, these traits may be utilized as selection criteria in corn breeding programs.

Drought is arguably the most important abiotic stress that affects bread wheat productivity in Mediterranean environments. In these environments exacerbated this problem by the incidence of extreme temperatures during grain filling periods.This study aims to determine the most important grain yield components characters which can be used as effective selection criteria for bread wheat grain yield improvement. One hundred seventy inbred lines (RILs) from a cross between Cham-6 and Cham-8 in addition to six checks were used. The experiment was conducted at Breda drought selection station of International Centre for Agricultural Research in the Dry Areas (ICARDA) in 2009-2010 and 2010-2011 growing seasons.The predicted mean yield ranged from 802 to 1916 kg/ha-1. Significant yield advantages were found between lines. Harvest index and kernel number per m2 were the highest positively correlated (P<0.001) with grain yield, correlation coefficient of them (r=0.83, 0.82) respectively, while thousand kernel weight was the lowest (r=0.28) positively correlated (P<0.001) with grain yield. Path coefficient analysis showed that maximum positive direct effect on grain yield was contributed by kernel number per spike (0.318), followed by harvest index (0.292), and the highest positive indirect effect was of harvest index and kernel number per spike (0.27, 0.255) respectively via kernel number per m2. Indirect effect of thousand kernel weight on grain yield via others traits was low. Our results suggest that kernel number per spike play significant roles in contributing to increased grain yield in bread wheat under drought stress. This trait may assist in improving harvest index and yield particularly in dry environments.

Maize is a crop with broad usage globally and is significant in various areas. From an agronomic perspective, it is known for its diversity in both quality traits and adaptation to different conditions. Particularly, there is notable variation in maize genotypes regarding color-related traits and anthocyanin compounds, which have been the focus of recent studies. Commercial maize varieties are widely grown, but efforts to develop new varieties with superior agronomic and nutritional traits are ongoing. Rich in genetic variation, colored maize genotypes are characterized by their high phenolic content and antioxidant activity, which are essential in terms of nutritional and health benefits. This study was conducted to determine the agronomic characteristics of 14 local maize genotypes with varying grain colors and 2 standard varieties under Çanakkale conditions during the main summer cropping seasons of 2021 and 2022, using a randomized block design with three replications. In the study, traits such as days to flowering, plant height, first ear height, ear length, ear diameter, ear weight, kernel weight per ear, and the number of kernels per ear were examined. Significant variation was observed among the local maize genotypes for the traits examined. The days to flowering ranged from 54.9 to 70.0 days, plant height from 114.61 to 230.8 cm, first ear height from 40.8 to 110.8 cm, ear length from 12.9 to 17.7 cm, ear diameter from 29.1 mm to 37.7 mm, ear weight from 59.8 to 109.4 g, kernel weight per ear from 46.3 to 93.7 g, and the number of kernels per ear ranged from 324.5 to 611.4. The local maize genotypes coded as POP3, POP4, POP14, POP5, POP7, and POP9 were found to be promising in terms of kernel weight per ear and plant height traits. These materials are considered potential genetic resources for future breeding programs, especially when evaluated for grain quality and color characteristics.

F1 and F2 seeds of four crosses were formed during 2001 and 2002 growing sea-sons. The F2 population’s plants were evaluated during 2003 growing season under the two planting dates (14th May and 29th June) to estimate the phenotypic correla-tion coefficients among eight plants characters and their contributions in the varia-tion of grain yield/ plant at the Agric. Res. Stat. of Fac. of Agric., Ain Shams Univ., Shalakan, Kalubia Governorate, Egypt. Results showed that grain yield/ plant under normal planting date correlated positively and significantly - in most cases - with each of ear diameter, ear length, number of kernels/ row, 100-kernel weight, number of rows/ ear, ear height, plant height and days to silking, while under late planting date, it correlated with each of number of kernels/ row, ear diameter, 100-kernel weight, ear length, number of rows/ ear, ear height and days to silking. Path coeffi-cient analysis estimates indicated that ear diameter; ear length and number of ker-nels/ row can be considered as the most important sources of plant grain yield varia-tion under normal planting date while, under late planting date they were number of kernels/ row, ear diameter, 100-kernel weight and ear length. It was concluded that each of ear diameter, ear length and ear length through its indirect effects via ear di-ameter are considered as the most important sources of plant grain yield variation.

Aim: A study was carried out to evaluate the magnitude of correlation between grain yield and its various contributing characters. Methodology: 39 genotypes of maize, comprising 31 hybrids and 8 parents, were assessed using randomized block design with three replications. The data recorded on twelve quantitative characters including days to 50 percent tasseling, days to 50 percent silking, days to maturity, plant height (cm), ear height (cm), ear length (cm), ear diameter (cm), number of kernel rows per ear, number of kernels per row, 100 kernel weight, shelling percentage and grain yield per plant. Results: The results of this study showed higher genotypic correlation coefficient for all the characters studied compared to the corresponding phenotypic correlation coefficient. This suggests that, despite the strong inherent association between the traits under study, environments’ influence masked its expression. Ear diameter was found to have a strong and significant positive correlation with grain yield per plant at phenotypic (0.9016) and (0.9540) genotypic level followed by ear length (0.8976, 0.9360), number of kernels per row (0.8905, 0.9247), plant height (0.8399, 0.8697), 100 seed weight (0.8070, 0.8544), ear height (0.7170, 0.7550) and number of kernel rows per ear (0.3240, 0.3901). Days to 50% silking and days to 50% tasselling, however, exhibited significant negative association with grain yield, while days to maturity showed non-significant negative. In path coefficient analysis the maximum positive direct effect on grain yield per plant was found by the ear diameter (0.3505), followed by the 100 seed weight (0.2362), ear length (0.2273), number of kernels per row (0.1827), days to 50% silking (0.1269), and shelling percentage (0.1223). Conclusion: The strong correlation of ear diameter, 100 seed weight, ear length and number of kernels per row (0.2971) with grain yield per plant appears to be mostly due to their high direct effects. Therefore, improving yield could be achieved through direct selection for these attributes.

Analysis of yield components to address inconsistent maize (Zea mays L.) grain yields across plant populations is limited in Europe and the United States. The research objectives were to compare maize yield components at low and high plant populations in eastern Nebraska and central Croatia using path analysis to better understand maize grain yield determination with changing plant population and determine relative importance among maize primary and secondary yield components. Research was conducted by planting three maize hybrids at 65,000 plants ha−1 to 105,000 plants ha−1 in 2012 and 2013 at Zagreb, Croatia, and Mead, NE. Grain yield, ears per square meter, rows per ear, ear circumference, kernels per ear, kernels per row, ear length, and kernel weight were determined. Average grain yield was 10.7 Mg ha−1 and plant population influence on yield was inconsistent and &lt;2 Mg ha−1. Among yield components, the number of rows per ear (direct effect of 0.54 [P ≤ 0.01] with kernels per ear and 0.39 [P ≤ 0.01] with kernels per row) and the number of kernels per ear (direct effect of 0.54 [P ≤ 0.01] with grain yield) were of most importance for maize at high plant populations, while the number of kernels per row (direct effect of 0.93 [P ≤ 0.01] with kernels per ear and 0.61 [P ≤ 0.01] with kernel weight) and kernel weight (direct effect of 0.47 [P ≤ 0.01] with grain yield) were most important at low plant populations. Future maize management research for low plant population environments should focus on production of the number of kernels per ear and kernel weight, while for high plant populations, the focus should be on the number of rows per ear.