Single-row Plots Research Articles

The Impacts of Climatic Variability on the Grain Yield Performance of Open Pollinated Varieties (OPV) of Maize in a Rainforest Location of Nigeria

Aims: The objectives of the study were to examine the effects of climatic factors on maize yield and identify best planting date for maize in Rainforest Agroecology of Nigeria.
 Study Design: Grain yield of seventeen open pollinated varieties of maize evaluated in 21 randomly selected environments in the Rainforest Agroecology of Nigeria were used for the study. Each field experiment was laid out in a randomized complete block design with four replications and 5 m long single-row plots spaced at 0.75 m apart and three seeds were planted 0.5 m apart within the row.
 Place and Duration of Study: Grain yield of 17 maize varieties evaluated at the Obafemi Awolowo University Teaching and Research Farm (7°28'N, 4°33'E, altitude 224 m above sea level) during the late cropping seasons of 2001, 2005 and early cropping seasons of 2002, 2006 were used for this study.
 Methodology: The grain yield and climatic data within the period of evaluation was subjected to Analysis of variance and correlation analysis.
 Results: Rainfall alone significantly accounted for over 42 % of the total variation on grain yield across the environments while the combination of two climatic factors revealed significant variation across the combination ranging from over 41 % to 45 % with minimum relative humidity and maximum temperature together having the highest significant variation on grain yield of Maize. There was also highly significant positive correlation between grain yield and total rainfall (r = 0.65**) and minimum relative humidity (r = 0.64**).
 Conclusion: Ranking of the twenty-one environments for average grain yield, the most favourable planting date ranged from early April to early May in Rainforest Agro-ecology of Nigeria.

Multivariate analysis of seed yield and morphological characters of Okra (Abelmoschus esculentus L. Moench) accessions

Abstract. Enhancement of okra fruit production requires identification of genotypes with promising seed yield attributes, thus multivariate techniques were employed to reveal genetic and morphological attributes of sixteen diverse okra lines during wet and dry seasons in 2019 at Teaching and Research Farm, College of Agriculture, Osun State University, Ejigbo Campus. Seeds were sown in single-row plots of 5 m long, spaced 0.70 m apart and 0.50 m within on sandy loam soil in a randomized complete block design. The dry season crop was supported by the application of 12 mm water weekly. Data collected on growth and seed traits were subjected to the General Linear Model (GLM), principal component analysis (PCA), and cluster analysis using the Statistical Analysis System (SAS, 2018). The petiole color was scored according to IPGRI (1991) square root transformed prior to the analysis. Results showed highly significant lines, season, and their interactions for almost all traits. Four PCAs accounted for 85.77% and the first two PCA captured 51% of the total variations. Both PCA and cluster analysis grouped the lines into four and revealed the potentials of SAHARI F1, NGB01197, and LD-88 for high seed yield. It is concluded that these lines can be incorporated into okra yield improvement program.

Genetic Resistance of Switchgrass to Rust Evaluated in a Composite Upland × Lowland Population in Lab and Field Settings

Maintaining low levels of rust incidence (caused by Puccinia novopanici) in switchgrass (Panicum virgatum L.) breeding populations is a priority for the USDA-ARS program engaged in improving cultivars for high biomass yield and quality. Essential to this goal is the unbiased and accurate estimation of genetic parameters to predict the merits of parents and progeny. Spores of the fungus were inoculated in greenhouse-grown seedling progeny of 31 half-sib families in generation 2 (Gen 2) of a composite Summer × Kanlow population for evaluation of rust incidence on the leaves with a 0–9 rating scale. Two parents were later chosen to cross and develop a linkage mapping population as Gen 3. The Gen 2, 3, and Kanlow seedlings were transplanted into the field located near Mead, NE, in early June 2020 and laid out as a replicated row–column design with six blocks of single-row plots of five plants each. The field trial was rated in September 2021 and 2022 with a 0–4 scale. Lab and field data were subjected to univariate linear mixed models via the restricted maximum likelihood to extract the variance components needed to predict the breeding values. The additive genetic variation was substantial (p < 0.01), enough to result in high heritability estimates ranging from 0.42 ± 14 to 0.73 ± 0.09 at the individual and family mean levels. This result implies that rust resistance is under strong genetic control to use mass selection for obtaining satisfactory gains. A possible rust incidence x year interaction was detected with a Spearman correlation of breeding values of −0.38, caused by significant rank changes of the Gen 3 genotypes in 2022 (a high heat and drought year). Genetic gains were predicted to reduce rust incidence scores by at least two points on the rating scale when selecting backwards, and by one point when selecting individual candidates as parents of the next generation. Faster gains (31 and 59%) were realized relative to the second generation by respectively selecting the top 10% of the families in Gen 3 or the top 10% of genotypes within this group. Based on these results, strategies for controlling the incidence of rust will be developed to optimize gains in the other traits of economic importance.

Method of increasing yield indicators of rice varieties in process of seed production

The paper describes a method for creating new and increasing the yield of existing varieties based on analysis variability elements of rice varieties yield structure under influence of environmental conditions. Seeding rates are used as a source of variability. Following trait are analyzed: seeds field germination, survival plants before harvesting, total tillering of plants, realization of total tillering, graininess of panicle, fertility of spikelets, weight of 1000 grains. Based on analysis, through onnections conjugated elements, the optimal values of elements structure of yield are determined, at which it takes the maximum value. Based on a set of optimal values, theoretical model of studied rice variety is being developed. Then, according to panicles selected in variety, single-row plots are sown for further propagation, rows with parameters of the yield structure elements set same with model of variety are selected, which makes it possible to increase the yield of Mavr rice variety by 39.18 centners / ha or 45.61%.

НАСЛЕДОВАНИЕ ПРИЗНАКА « МАССА 1000 ЗЕРЕН» ЯРОВОЙ МЯГКОЙ ПШЕНИЦЫ В ДИАЛЛЕЛЬНЫХ СКРЕЩИВАНИЯХ

Weight of 1000 grains - one of the component characteristics of yield is included in the group of main characteristics that are used for wheat breeding. In addition, the weight of the grain along with its performance is a sign of grain quality, largely determining its milling properties. The aim of the research is to determine the inheritance of a trait in the system of diallel crosses. The research was performed on the experimental field of the Samara research Institute in 2016-2018. The following varieties from the Ekada program were studied: Arhat, Estivum 1079, Estivum 1311, Omskaya 36, Ekada 148, Ekada 113, and Ekada 204. The varieties selected for the study were characterized by stable yield and significant differences in the studied feature-the mass of 1000 grains. Sowing was carried out manually on single-row plots 1 meter long with rows of 20 centimeters of 20 grains, rendomized blocks in three-fold repetition. Phenological observations were noted for the phases of development: tillering, earing and maturation. The results were analyzed using the B. I. Hayman method. As a result, the following genetic and statistical effects were revealed: 1) the functioning of epistatic interactions based on the genetic systems of Arhat and Ekada148 varieties; 2) directed dominance, dominant genes increase feature values ; 3) dominant and recessive alleles are distributed asymmetrically across varieties, with the predominance of dominant alleles in the population as a whole; 4)interaction in locuses between alleles occurs with the demontration of superdominant effects; 5) the additive component was significant in all environments, which implies good heritability of the trait; 6) varieties Estivum 1079 and Ekada 204 carry the maximum number of dominant alleles in all environments and are donors of dominant alleles that increase the trait.

Commercial bumble bee (Bombus impatiens) hives under exclusion netting systems for apple pollination in orchards

AbstractExclusion netting systems are effective in various contexts and are increasingly used to control crop pests. However, factors affecting pollination management under nets are poorly known. The pollination effectiveness of commercial bumble bee hives ofBombus impatiensCresson (Hymenoptera: Apidae) was studied for apple production under exclusion netting systems in a research orchard located in Quebec, Canada during 2016–2017. Sixteen single-row plots of apple trees (plot length: 18.5 m, cultivar GingerGold) were subjected to one of the following four treatments during bloom: (1) introduction of a bumble bee hive placed at the end of the row, under nets; (2) introduction of a bumble bee hive placed in the middle of the row, under nets; (3) negative control with no pollinators, under nets and (4) agronomic control with nearby bee hives (<50 m), without nets. Resulting post-harvest fruit quality (e.g., fruit weight, size, number and distribution of seeds) was evaluated, as well as correlations between bumble bee visitation rates and fruit quality parameters were evaluated. Results suggest that bumble bees provided adequate pollination under exclusion netting systems and that resulting fruit quality was equivalent to that of apple fruit conventionally pollinated by honey bees and wild bees community (bumble bees and other bees) in the orchard environment. Positioning bumble bee hives in the middle of the row provided better fruit load homogeneity in pollinated trees. Additional discussion on bumble bees as apple pollinators and on pollen distribution methods is also included.

Advancing High-Throughput Phenotyping of Wheat in Early Selection Cycles

Enhancing plant breeding to ensure global food security requires new technologies. For wheat phenotyping, only limited seeds and resources are available in early selection cycles. This forces breeders to use small plots with single or multiple row plots in order to include the maximum number of genotypes/lines for their assessment. High-throughput phenotyping through remote sensing may meet the requirements for the phenotyping of thousands of genotypes grown in small plots in early selection cycles. Therefore, the aim of this study was to compare the performance of an unmanned aerial vehicle (UAV) for assessing the grain yield of wheat genotypes in different row numbers per plot in the early selection cycles with ground-based spectral sensing. A field experiment consisting of 32 wheat genotypes with four plot designs (1, 2, 3, and 12 rows per plot) was conducted. Near infrared (NIR)-based spectral indices showed significant correlations (p < 0.01) with the grain yield at flowering to grain filling, regardless of row numbers, indicating the potential of spectral indices as indirect selection traits for the wheat grain yield. Compared with terrestrial sensing, aerial-based sensing from UAV showed consistently higher levels of association with the grain yield, indicating that an increased precision may be obtained and is expected to increase the efficiency of high-throughput phenotyping in large-scale plant breeding programs. Our results suggest that high-throughput sensing from UAV may become a convenient and efficient tool for breeders to promote a more efficient selection of improved genotypes in early selection cycles. Such new information may support the calibration of genomic information by providing additional information on other complex traits, which can be ascertained by spectral sensing.

Repeated Multiview Imaging for Estimating Seedling Tiller Counts of Wheat Genotypes Using Drones.

Early generation breeding nurseries with thousands of genotypes in single-row plots are well suited to capitalize on high throughput phenotyping. Nevertheless, methods to monitor the intrinsically hard-to-phenotype early development of wheat are yet rare. We aimed to develop proxy measures for the rate of plant emergence, the number of tillers, and the beginning of stem elongation using drone-based imagery. We used RGB images (ground sampling distance of 3 mm pixel−1) acquired by repeated flights (≥ 2 flights per week) to quantify temporal changes of visible leaf area. To exploit the information contained in the multitude of viewing angles within the RGB images, we processed them to multiview ground cover images showing plant pixel fractions. Based on these images, we trained a support vector machine for the beginning of stem elongation (GS30). Using the GS30 as key point, we subsequently extracted plant and tiller counts using a watershed algorithm and growth modeling, respectively. Our results show that determination coefficients of predictions are moderate for plant count (R2 = 0.52), but strong for tiller count (R2 = 0.86) and GS30 (R2 = 0.77). Heritabilities are superior to manual measurements for plant count and tiller count, but inferior for GS30 measurements. Increasing the selection intensity due to throughput may overcome this limitation. Multiview image traits can replace hand measurements with high efficiency (85–223%). We therefore conclude that multiview images have a high potential to become a standard tool in plant phenomics.

Progeny selection from natural hybrids of ‘BRS Alegria’Amaranthus cruentus

Amaranth species have gained interest in modern agriculture as food, colouring and ornamentals, grown as field crops and garden plants. Their adaptation into production systems relies on exploiting genetic variability. Progenies originated from natural crosses, within 'BRS Alegria' Amaranthus cruentus, were evaluated in Brasilia, Brazil. Interpolated control design was used where progenies were alternated by plots of 'Dourada' (control). Progenies of typical 'BRS Alegria' plants were used, forming two blocks each, made by single row plots 4.0 m long and spaced by 0.5 m. The harvest area was 1.0 m long within a row. After height measurement, plants were cut near the ground line and dried until reaching constant weight. Total biomass, grain yield and seed weight were collected, while harvest index was calculated. The progenies were compared by multivariate analysis and the best performers, B2 and B7, with genetic diversity for further breeding were selected. The study demonstrated that natural hybrids in amaranth generate new recombinants associating agronomic characters and multiple colour plants, for cultivar acquisition.

Real-time, non-destructive and in-field foliage yield and growth rate measurement in perennial ryegrass (Lolium perenne L.)

BackgroundIn-field measurement of yield and growth rate in pasture species is imprecise and costly, limiting scientific and commercial application. Our study proposed a LiDAR-based mobile platform for non-invasive vegetative biomass and growth rate estimation in perennial ryegrass (Lolium perenne L.). This included design and build of the platform, development of an algorithm for volumetric estimation, and field validation of the system. The LiDAR-based volumetric estimates were compared against fresh weight and dry weight data across different ages of plants, seasons, stages of regrowth, sites, and row configurations.ResultsThe project had three phases, the last one comprising four experiments. Phase 1: a LiDAR-based, field-ready prototype mobile platform for perennial ryegrassrecognition in single row plots was developed. Phase 2: real-time volumetric data capture, modelling and analysis software were developed and integrated and the resultant algorithm was validated in the field. Phase 3. LiDAR Volume data were collected via the LiDAR platform and field-validated in four experiments. Expt.1: single-row plots of cultivars and experimental diploid breeding populations were scanned in the southern hemisphere spring for biomass estimation. Significant (P < 0.001) correlations were observed between LiDAR Volume and both fresh and dry weight data from 360 individual plots (R2 = 0.89 and 0.86 respectively). Expt 2: recurrent scanning of single row plots over long time intervals of a few weeks was conducted, and growth was estimated over an 83 day period. Expt 3: recurrent scanning of single-row plots over nine short time intervals of 2 to 5 days was conducted, and growth rate was observed over a 26 day period. Expt 4: recurrent scanning of paired-row plots over an annual cycle of repeated growth and defoliation was conducted, showing an overall mean correlation of LiDAR Volume and fresh weight of R2 = 0.79 for 1008 observations made across seven different harvests between March and December 2018.ConclusionsHere we report development and validation of LiDAR-based volumetric estimation as an efficient and effective tool for measuring fresh weight, dry weight and growth rate in single and paired-row plots of perennial ryegrass for the first time, with a consistently high level of accuracy. This development offers precise, non-destructive and cost-effective estimation of these economic traits in the field for ryegrass and potentially other pasture grasses in the future, based on the platform and algorithm developed for ryegrass.

Accuracy, Precision, and Harvesting Efficiency of a Cotton Plot Picker Installed with an Automatic Weighing System in a Cotton Breeding Program

Many cotton breeding programs in the U.S. have installed an automatic weighing system in a cotton plot picker to increase operating efficiency in recent years. However, no experimental data are available to document the reliability of such a system. The objective of this study was to evaluate the accuracy, precision, and harvesting efficiency of a two-row cotton plot picker installed with an automatic weighing system with two scales based on results from replicated field tests from 2013 to 2016. Three tests each year, each containing 32 genotypes were arranged in a randomized complete block design in two-row plots by 10 m in length. The 2013 to 2015 results showed a highly significant positive correlation in seedcotton weights between the two rows of the same plot for each genotype harvested and weighed by the two scales in the picker, indicating that the two scales are consistent and reliable. In three tests in 2016, one row of each two-row plot was harvested by the picker, and seedcotton weight was compared with another row harvested by hand. A highly significant positive correlation was detected between the two harvesting methods that had similar coefficients of variation (16.14% for hand harvest vs. 16.90% for mechanical harvest). The two-row plot picker harvested a total of 368 single-row plots (10-m long) in six hours daily, whereas hand harvest by one person averaged two plots in four hours. An average of 417 kg ha-1 was lost due to the mechanical harvest.

Developing new tools for pasture plant breeding

The rate of genetic gain represented in the Forage Value Index of perennial ryegrass (Lolium perenne) is a major factor underpinning sustained profitability in pastoral farming. Effective new technologies for trait data acquisition and parent plant selection are used in many animal and crop improvement programmes to lift the rate of gain, but have yet to be developed and integrated in forage breeding. For forage improvement, hypotheses tested were: a) genomic selection (GS) offers a viable breeding strategy, and b) key enabling technologies for non-destructive, high-throughput phenotyping (HTP) in the field will improve trait data acquisition. To evaluate GS, extensive molecular marker and phenotypic datasets in structured populations of perennial ryegrass were developed. Phenotypic data for seasonal dry matter yield (DMY), the core trait in the Dairy NZ Forage Value Index, were obtained replicated field trials. Data on heading date (HD) as a useful trait to assess the efficacy of GS for simply inherited traits, were also collected. Genomic prediction models were developed for seasonal DMY and HD. Application of GS for HD was effective in selecting for both early and late heading, with movement of up to 7 days in a single generation of selection. The HTP research used iterative development of computational methods supporting a repeatable, non-invasive means of accurately and rapidly measuring DMY of perennial ryegrass in single row plots. These findings demonstrate effective genetic prediction and phenotyping approaches which may enable breeders to lift the rate of genetic gain in perennial ryegrass.

Field-based high-throughput phenotyping of plant height in sorghum using different sensing technologies

BackgroundPlant height is an important morphological and developmental phenotype that directly indicates overall plant growth and is widely predictive of final grain yield and biomass. Currently, manually measuring plant height is laborious and has become a bottleneck for genetics and breeding programs. The goal of this research was to evaluate the performance of five different sensing technologies for field-based high throughput plant phenotyping (HTPP) of sorghum [Sorghum bicolor (L.) Moench] height. With this purpose, (1) an ultrasonic sensor, (2) a LIDAR-Lite v2 sensor, (3) a Kinect v2 camera, (4) an imaging array of four high-resolution cameras were evaluated on a ground vehicle platform, and (5) a digital camera was evaluated on an unmanned aerial vehicle platform to obtain the performance baselines to measure the plant height in the field. Plot-level height was extracted by averaging different percentiles of elevation observations within each plot. Measurements were taken on 80 single-row plots of a US × Chinese sorghum recombinant inbred line population. The performance of each sensing technology was also qualitatively evaluated through comparison of device cost, measurement resolution, and ease and efficiency of data analysis.ResultsWe found the heights measured by the ultrasonic sensor, the LIDAR-Lite v2 sensor, the Kinect v2 camera, and the imaging array had high correlation with the manual measurements (r ≥ 0.90), while the heights measured by remote imaging had good, but relatively lower correlation to the manual measurements (r = 0.73).ConclusionThese results confirmed the ability of the proposed methodologies for accurate and efficient HTPP of plant height and can be extended to a range of crops. The evaluation approach discussed here can guide the field-based HTPP research in general.

Evaluation of Alternatives to an Organophosphate Insecticide with Selected Cultural Practices: Effects on Thrips, Frankliniella fusca, and Incidence of Spotted Wilt in Peanut Farmscapes.

Peanut growers use a combination of tactics to manage spotted wilt disease caused by thrips-transmitted Tomato spotted wilt virus (TSWV). They include planting TSWV-resistant cultivars, application of insecticides, and various cultural practices. Two commonly used insecticides against thrips are aldicarb and phorate. Both insecticides exhibit broad-spectrum toxicity. Recent research has led to the identification of potential alternatives to aldicarb and phorate. In this study, along with reduced-risk, alternative insecticides, we evaluated the effect of conventional versus strip tillage; single versus twin row seeding pattern; and 13 seed/m versus 20 seed/m on thips density, feeding injury, and spotted wilt incidence. Three field trials were conducted in Georgia in 2012 and 2013. Thrips counts, thrips feeding injuriy, and incidence of spotted wilt were less under strip tillage than under conventional tillage. Reduced feeding injury from thrips was observed on twin-row plots compared with single-row plots. Thrips counts, thrips feeding injury, and incidence of spotted wilt did not vary by seeding rate. Yield from twin-row plots was greater than yield from single-row plots only in 2012. Yield was not affected by other cultural practices. Alternative insecticides, including imidacloprid and spinetoram, were as effective as phorate in suppressing thrips and reducing incidence of spotted wilt in conjunction with cultural practices. Results suggest that cultural practices and reduced-risk insecticides (alternatives to aldicarb and phorate) can effectively suppress thrips and incidence of spotted wilt in peanut.

Интенсивность влагоотдачи зерна в период созревания у самоопыленных линий кукурузы в условиях Приморского края

Создание гибридов с низкой уборочной влажностью зерна является одним из важных направлений в селекции кукурузы. Однако для получения таких гибридов нужен новый исходный материал, обладающий высокой интенсивностью влагоотдачи зерна при созревании. В 2012 – 2014 гг. на опытных полях Приморского края впервые изучены и проанализированы динамика влажности и интенсивность высыхания зерна при созревании у самоопыленных линий кукурузы. Объектом исследования служили 22 самоопыленные линии кукурузы селекции Приморского НИИСХ. Самоопыленные линии высевали в селекционном питомнике на однорядковых делянках площадью 5 м2. Густота стояния в селекционном питомнике составляла 3 – 4 растения на 1 пог. м или 30 – 40 тыс. раст./га. Выделены линии с высокой интенсивностью высыхания зерна, которые использованы в селекционной работе по созданию гибридов кукурузы с низкой уборочной влажностью зерна. Наиболее высокая начальная влажность зерна отмечена у линий Прим 14, Прим 7 и Прим 27 (59,7; 61,3 и 61,5 % соответственно), наименьшая — у линий Прим 2 (50,3 %) и Прим 31 (49,6 %). Низкой конечной (уборочной) влажностью зерна характеризовались самоопыленные линии: Прим 22 — 22,0 %, Прим 2 — 22,7 %, Прим 27 — 24,5 %, Прим 29 — 24,7 %, Прим 30 — 24,9 %. Наибольшей интенсивностью влагоотдачи характеризовались линии Прим 7, Прим 14, Прим 22, Прим 27, Прим 34 — 1,06 – 1,31 % за сутки (в среднем за весь период изучения). При этом конечная влажность у них составляла 22,0 – 31,3 %.

Character Association in Okra Hybrids Established at Different Planting Dates

ABSTRACTThe most effective means of combating reduced productivity in Okra [Abelmoschus esculentus (L.) Moench] is development of genotypes with potential for high yield. Selection for crop yield improvement can only be effective when information is available on yield association with component characters. A study was conducted to identify indirect selection criteria for yield in okra. Sixteen hybrid genotypes obtained through North Carolina Design II mating between four genotypes as males and four as females were established in single-row plots in Oct. and May of 2013 and 2014, respectively. Beginning at flowering, data were recorded on number of days to 50% flowering, stem diameter, plant height, number of leaves per plant, number of branches per plant, number of pods per plant, pod width, number of ridges per pod, number of seed per ridge, number of seed per pod, 100-seed weight, and seed yield·per hectare. Analysis of variance was performed on separate and combined data and analysis of covariance was performed on data from individual planting dates. Genotypic and phenotypic correlation coefficients were estimated from variance and covariance analyses. Genotypic correlation coefficients of characters were partitioned into direct and indirect effects for early planting. Correlation and path coefficient analyses identified characters having useful association with seed yield/plant. Sufficient strength of the relationship existed for indirect selection of characters with seed yield. Number of pods/plant appears to be the most reliable indicator of yield in okra.

Diallel Analysis and Evaluation of Parents and F&lt;sub&gt;1&lt;/sub&gt; Progenies of Maize (&lt;i&gt;Zea mays&lt;/i&gt; L.) for Tolerance to Drought and &lt;i&gt;Striga hermonthica&lt;/i&gt; (Del.) Benth in the Guinea Savanna Agro-Ecological Zone of Ghana

Field studies were conducted to evaluate 6 parents and 30 F1 hybrids of maize for tolerance to drought and Striga hermonthica in Nyankpala, Ghana during the 2014 and 2015 cropping seasons. These genotypes were evaluated for two years on single-row plots of three replicates, in a randomized complete block design. The control plants were planted in July each year which is the normal and usual time of planting of maize in the study area, whilst the water-stressed plants were planted six weeks later to ensure that their growth period coincides with the drought period. The Striga hermonthica infested plants were also planted at the normal time of planting maize in the study area. Results showed that highly negative significant GCA effect for the parent populations was observed in TAIS03, KOBN03-OB, DT-STR-W-C2 and IWD-C3-SYN-F2 for majority of the traits. The four parents were good general combiners for majority of the traits observed. For the F1 hybrids, KOBN03 × DT, DT × TAIS03, TAIS03 × KOBN03, IWD × GUMA03, GUMA03 × DT, GUMA03 × SISF03 and SISF03 × TAIS03 gave the highest negative significant SCA effect for most of the traits studied and are good specific combiners for the traits observed. The highly significant negative GCA and SCA effects of parents and F1 hybrids for majority of observed traits showed that those genotypes were highly tolerant to drought and/or Striga hermonthica. Drought rating, leaf-rolling rating, striga rating, striga count and Anthesis-Silking Interval (ASI) had been reduced significantly when plants were watered throughout the experimental period (control) as compared to the water-stressed and striga-infested plants. However, grain yield, hundred-grain weight, number of ears harvested, plant height, ear height, days to 50% anthesis, days to 50% pollen shed and days to 50% silking were significantly higher (p<0.05) for the normal (control) plants as compared to the water-stress and striga-infested plants. In drought-prevalent or striga-infested geographical areas like Northern Ghana, parent and F1 hybrid populations such as (TAIS03, KOBN03-OB, DT-STR-W-C2 and IWD-C3-SYN-F2) and (KOBN03 × DT, DT × TAIS03, TAIS03 × KOBN03, IWD × GUMA03, GUMA03 × DT, GUMA03 × SISF03 and SISF03 × TAIS03) respectively, can be used for increased grain yield.

La importancia del intervalo de la floración en el mejoramiento para la resistencia a sequía en maíz tropical

The length of the Interval between anthesis and silking (ASI) is increased by drought which coincides with flowering. Four elite CIMMYT lowland tropical populations are undergoing recurrent selection (S1 or full-sib) for improved grain yield and several other traits under drought and well watered conditions. Data collected from more than 200 families per population grown In single row plots under three water stress levels (pre and post-flowering stress; post-flowering stress; normal irrigation, all in the absence of rain) showed weak or no correlation between grain yield and traits related to plant water status, such as leaf rolling and senescence, photooxidation, leaf chlorophyll concentration, shoot elongation rate, canopy temperature and predawn water potential. Yield under all levels of stress was significantly negatively correlated with AST, and as AST increased due to drought, kernels and ears per plant were significantly reduced. In all populations yield decreased by approximately 10 % per day increase in AST up to 8 days. In several stress situations broad-sense heritability of AST was greater than that of grain yield and the genetic correlation between grain yield and AST approached -1.00. Synthetics formed from one population following bidirectional selection and tested under drought showed adaptive advantage of cool canopy temperature, delayed leaf senescence, reduced AST and erect leaves, especially when all were combined with grain yield in a single index during selection. Selection for reduced AST and high grain yield under drought can be an effective means of improving drought tolerance in tropical maize.

Twin-Row Production of Cotton Genotypes Varying in Leaf Shape

Twin-row planting for soybean and maize has proliferated in Mid-South production systems during the past decade. Knowledge of cotton production with twin-row planting is limited. The objective of this research was to determine how cotton leaf-type isolines (varying in size and the degree of lobing) performed in both twin-row and single-row planting patterns. Field studies were conducted in 2011 and 2012. Four genotypes (MD 65-11 normal, MD 65-11 okra, MD 65-11 super okra, and ST 4554B2RF) were grown in both twin-row and single-row planting patterns. Dry matter partitioning, leaf area index, light interception, nodes above white bloom, lint yield, and fiber quality data were collected. The response to twin-row planting when compared to single-row planting was consistent across all the cotton genotypes evaluated in this study. Twin-row canopies produced a greater early season leaf area index that intercepted more sunlight than the single-row pattern, but these differences diminished as the season progressed. Twin-row plots reached cutout approximately two days earlier than the single-row plots. Despite increased early season leaf area production and sunlight interception, no differences between planting patterns were detected for lint yield, the yield components, or fiber quality traits. Convenience of using a standard planting configuration across multiple crops may be the only justification for twin-row planting in cotton because neither lint yield nor fiber quality were impacted.

Effect of Plant Population and Breeding Lines on Fresh-market, Compact Growth Habit Tomatoes Growth, Flowering Pattern, Yield, and Postharvest Quality

Compact growth habit (CGH) tomatoes (Solanum lycopersicum) are determinate plants with shortened internodes and strong side branching due to the brachytic gene (br) that grow either prostrate or upright as a result of unidentified gene(s). Compact growth habit tomatoes do not require staking, tying, or pruning and can potentially be mechanically harvested, lowering Florida fresh-market tomato production costs. Therefore, the objective of this study was to evaluate the effects of two planting configurations (single and double row) and breeding lines (BLs) on CGH tomato plant growth, flowering pattern, yield, and postharvest fruit quality. Two experiments were conducted in Immokalee, FL, during Spring 2013 and 2014 in a split-plot design with four replications. Planting configurations affected CGH tomato growth at midseason in 2013 but not in 2014; however, in 2014, CGH tomato vines grew outside the beds into the row middles, which is uncommon for this tomato type and undesirable. Plants of CGH tomatoes had a similar flowering pattern to a conventional upright tomato cultivar, which was unexpected. Planting configurations did not affect marketable yields in 2013, but single-row plots produced higher extra-large and total marketable yields at first and total season harvests in 2014. Total season marketable harvests ranged from 26.1 to 53.6 and 29.3 to 45.6 Mg·ha−1 in 2013 and 2014, respectively. Fla 8916 was among the highest yielding BLs, maximizing extra-large and total season marketable yields. Unmarketable fruit ranged from 22% to 31% and 25% to 52% of the total season harvest in 2013 and 2014, respectively, and the most common defects were sunscald, off-shape, catface, and graywall. All CGH evaluated may be suitable for mature-green harvest regarding postharvest fruit quality, although fruit ripening uniformity was of concern in 2014. Average CGH total season marketable yields harvested twice were lower than expected yields of staked-upright tomato cultivars that may be harvested three times, but higher than Florida average yields. However, CGH tomato total production cost can potentially be lower than staked-upright cultivars making CGH tomatoes a viable alternative for the Florida mature-green fresh-market industry to remain sustainable.