Environment Interaction Biplot Research Articles

Genotype × environment interaction and stability of grain yield and selected quality traits in winter wheat in Central Asia

Abstract: High grain yield and improved quality determine the commercial success of winter wheat (Triticum aestivum L.) varieties in Central Asia. This study was conducted to determine the effect of environment on grain yield, 1000-kernel weight (TKW), test weight (TWT), protein, and gluten content, and to identify superior wheat genotypes for yield and quality. Thirty winter wheat genotypes were evaluated in 3 years (2010-2012) over multiple locations. A genotype and genotype A— environment interaction biplot analysis was used to determine the superior genotypes. There were significant effects of environment and genotype A— environment interaction on yield and quality traits. The 30 wheat genotypes showed variations for grain yield (3.7-5.6 t ha-1), TKW (33.6-42.4 g), TWT (753-797 g/L), protein (13.3%-14.8%), and gluten (27.2%-29.5%) content. There was a significant positive correlation between grain yield and TKW in three out of seven environments. There was no correlation of grain yield with TWT, protein, and gluten content with one exception. There were different sets of five most superior genotypes for individual traits. However, certain genotypes were superior based on grain yield and quality traits. Gozgon, Elomon, ID800994.W/Vee//Lagos-12, Jaikhun, and Kroshka were the five most superior genotypes for four quality traits. Elomon, Gozgon, Jaikhun, ID800994.W/Vee//Lagos-12, and Kiriya were the five most superior genotypes based on grain yield, TKW, TWT, protein, and gluten content. This study demonstrates success in wheat breeding for combined high yield and improved quality in winter wheat. This study provides information on the combined stability of high yield and improved quality of the internationally important winter wheat genotypes. Therefore, the results of this study could be valuable for national and international winter wheat breeding programs to develop new varieties with high stable grain yield and quality.

Leaf and Fruit Yield Performance of <i>Telfairia occidentalis</i> Hook F. (Fluted Pumpkin) as Influenced by Fruit Size

An experiment to ascertain the influence of fruit size on the yield of fluted pumpkin (Telfairia occidentalis Hook F.) was conducted in 2011 and 2012 at Nsukka. The mature fruits of T. occidentalis were graded into three length groups: large (more than 50 cm), medium (34-50 cm) and small (less than 34 cm). The experiment was laid out in randomized complete block design with six replications. The following data were collected: length of the longest vine, number of leaves/plant, vine diameter, marketable leaf and fruit yield. Data collected were subjected to analysis of variance while Genotype by Genotype x Environment interaction biplot was used to show which-won-where among the groups. Significant means were separated using Fisher’s least significant differences. Medium sized fruits gave the highest marketable leaf yield that was significantly higher than the small sized fruits in both years. Small sized fruits were significantly (p<0.05) lower in total leaf yield, fruit weight/hectare, fruit circumference (33.9 cm) and length (22 cm). The biplot explained 100% of the variation in the fruit sizes. Large sized fruits were the best performer in fruit length, while medium sized fruits performed better in total marketable leaf yield, average fruit weight, number of fruits/hectare and total fruit weight/hectare. The highest Benefit Cost Ratio of 1.2 and 2.6 in 2011 and 2012, respectively were obtained from medium sized fruits Medium sized fruit are recommended in favour of small sized fruit for leaf and fruit production, having higher economic returns.

Identifying Mega‐Environments and Essential Test Locations for Pearl Millet Cultivar Selection in India

ABSTRACTPearl millet [Pennisetum glaucum (L.) R. Br.] is grown under a wide range of environmental conditions in India. The All India Coordinated Pearl Millet Improvement Project (AICPMIP) has the responsibility of testing and releasing pearl millet cultivars adapted to such conditions. As a part of this process, AICPMIP has divided the entire pearl millet growing regions into three different zones (A1, A, and B) based on the rainfall pattern and local adaptation of the crop. This study was conducted to define the presently used test locations into possible mega‐environments and to identify essential test locations for cost‐effective evaluation of pearl millet cultivars. Grain yield data of different sets of 34 to 45 medium‐maturity pearl millet hybrids tested at 29 to 34 locations during 2006 to 2008 were analyzed using genotype main effects and genotype × environment interaction biplot method. Two distinct pearl millet mega‐environments with consistent grouping of locations across the years and corresponding to AICPMIP's designated A and B zones were identified. No such consistent grouping of locations corresponding to AICPMIP's designated A1 zone was, however, observed. Based on the discriminating ability, uniqueness, and research resources, 13 locations were identified as essential test locations for evaluation across the two mega‐environments. Testing at these locations appeared to provide good coverage of the whole pearl millet growing areas of India. Based on these findings, it is suggested to conduct initial yield trials at identified 13 locations across all the pearl millet growing zones represented by two mega‐environments followed by testing of selected hybrids with specific adaptation in their respective adaptation zones.

GGE Biplot Exploration of Resistance to Sheath Blight Disease in Doubled‐Haploid Lines of Rice

ABSTRACTDevelopment of cultivars resistant to sheath blight (SB) disease caused by Rhizoctonia solani Kuhn is an important breeding objective for the southern U.S. rice (Oryza sativa L.) industry. The aim of this research was to explore performance, genotype (G) and genotype × environment (GE) interactions, and stability for SB resistance of 322 doubled‐haploid (DH) lines of the SB2 mapping population produced by the RiceCAP project. Analysis was performed by heritability‐adjusted genotype plus genotype × environment interaction (HA‐GGE) biplot analysis, Hühn's nonparametric stability statistics, median polish, and additive main effects and multiplicative interaction (AMMI). Genetic material was evaluated in replicated plots for 2 yr (2006 and 2007) in Louisiana and Arkansas. A single mega‐environment was identified consisting of the four year–location combinations. Heritability‐adjusted genotype plus genotype × environment interaction biplot analyses identified 11 DH lines with high and stable levels of resistance at both locations. Five susceptible DH lines were also identified with greater stability than the susceptible parent used to develop the SB2 population. Results from Hühn's nonparametric approach and median polish complemented those of HA‐GGE biplot analysis. Material identified in this study represents a potential source of high and stable SB resistance for cultivar development that warrants additional field‐plot evaluation.

Identifying Essential Test Locations for Oat Breeding in Eastern Canada

The oat (Avena sativa L.) breeding program at the Eastern Cereal and Oilseed Research Centre of Agriculture & Agri‐Food Canada has the responsibility to breed new oat cultivars for producers in eastern Canada, which includes Ontario, Quebec, and the Atlantic provinces. A 3‐yr multilocation test was conducted to understand the genotype × location interaction patterns and the relationships among test locations in eastern Canada. A genotype + genotype × environment interaction biplot analysis of yield data revealed three distinct oat mega‐environments in eastern Canada: (i) northern Ontario, (ii) southern and eastern Ontario, and (iii) Quebec and Atlantic Canada. To breed for all mega‐environments, initial yield screening must be conducted at locations representing each of these mega‐environments. Based on the relationships among test locations, six essential test locations were identified: three in Ontario, two in Quebec, and one in Atlantic Canada. Testing at all six locations appeared to provide a good coverage of the whole oat‐growing area in eastern Canada. Based on these findings, a breeding and test strategy was developed. This includes conducting initial yield screening at three locations in Ontario, Quebec, and Atlantic Canada, followed by a formal yield test at all six essential test locations. Specifically adapted genotypes selected from this test will then be tested in the Registration Tests in their respectively adapted subregions.

Changes in Isoflavone Concentration with 58 Years of Genetic Improvement of Short‐Season Soybean Cultivars in Canada

Soybean [Glycine max (L.) Merr.] seeds contain a high concentration of the isoflavones daidzein and genistein, which are considered to be compounds beneficial to human health. Our objective was to determine the influence of breeding and selection for yield on the isoflavone concentration of short‐season cultivars. A collection of 14 historical cultivars released from 1934 to 1992 was grown at Ottawa for 12 yr under identical cultural conditions. Seed samples, taken at harvest, were examined using near‐infrared reflectance in conjunction with traditional chemical methods to measure the concentration of daidzein, genistein, and total isoflavones (TIF). A linear regression equation developed based on the changes across time of cultivar release was used to determine the improvement rates for various soybean parameters. Across the 58 yr of breeding history, yield and oil concentration increased by 0.43 and 0.24% per year, respectively, while protein concentration decreased by 0.15% per year. Across the same time period daidzein, genistein, and TIF increased by 1.04, 1.47, and 0.98% per year, respectively. Moderate broad sense heritabilities of 43, 45, and 44% were calculated for the aforementioned isoflavones. Genotype main effects + genotype × environment interaction biplots revealed that recent cultivars with high isoflavone concentration were more prone to environmental influence than older cultivars. In the short‐season region, plant breeders should be aware that selecting for higher yield may indirectly select for higher isoflavone concentration.

Yield Performance and Stability Evaluation of Peanut Breeding Lines with the CSM‐CROPGRO‐Peanut Model

Multienvironment trials of crop breeding lines consume many resources. Crop models have a potential to assist in this process. The goal of this study was to evaluate the potential of the CSM‐CROPGRO‐Peanut model in assisting with yield performance and stability evaluation of peanut (Arachis hypogaea L.) breeding lines. Seventeen peanut lines were tested in 11 environments in Thailand during both the rainy and the dry seasons of 2002 to 2004. Yields of these lines were also simulated with the CSM‐CROPGRO‐Peanut model for the same 11 test sites. The cultivar coefficients of the peanut lines used for model simulation were derived from a separate experiment conducted in two seasons and were evaluated against an independent data set from another experiment. Yield performance and stability of the peanut lines were evaluated on the basis of observed and simulated data using the genotype and genotype × environment interaction biplot method. The results showed that the model predicted the relative performances and yield stability for pod yield of the test peanut lines for the 11 actual test sites reasonably well. Out of the nine highest yielding lines, that is, the upper 52%, identified by observed data, six were identified by model simulation. Similarly, out of the nine stable lines identified by observed data, six were common with those identified by simulated data. We conclude that the CSM‐CROPGRO‐Peanut model could be used in assisting yield performance and stability evaluation of peanut breeding lines.

Performance of Early Maize Cultivars Derived from Recurrent Selection for Grain Yield and Striga Resistance

Maize (Zea mays L.) production in west and central Africa (WCA) is constrained by the parasitic weed Striga hermonthica (Del.) Benth and recurrent drought. Two early maize populations, TZE‐W Pop DT STR C0 (white) and TZE‐Y Pop DT STR C0 (yellow), developed from diverse genetic backgrounds, were subjected to three cycles of S1 recurrent selection under artificial Striga infestation. Inbreds and synthetic cultivars were developed from the different cycles of selection. The populations (C0), derived cultivars, and check cultivars were evaluated in 2002 and 2003 under Striga‐infested and Striga‐free environments in WCA. The objective was to assess the performance of the derived cultivars from the different cycles of selection. Under Striga infestation, ACR 94 TZE Comp5‐Y and ACR 94 TZE Comp5‐W, which were not from the selection program, were the highest‐yielding group (2158 and 2124 kg ha−1, respectively). The second group comprised six products of the selection program, with grain yield ranging from 1806 to 1954 kg ha−1 The third group, with grain yield of 1498 to 1759 kg ha−1 contained mostly Striga‐susceptible cultivars and the C0 of the selection program. Under Striga‐free conditions, the performance of several cultivars from the selection program was equal to or better than ACR 94 TZE Comp5‐Y and ACR 94 TZE Comp5‐W. The genotype plus genotype × environment interaction biplot analysis demonstrated that EV DT‐Y 2000 STR C1 and TZE‐W Pop DT STR C3 from the selection program, along with ACR 94 TZE Comp5‐W, had stable grain yield under Striga‐infested and noninfested conditions.

Performance of Yield and Stability of Advanced Wheat Genotypes under Heat Stress Environments of the Indo‐Gangetic Plains

A set of 25 advanced breeding lines and released varieties of wheat (Triticum aestivum L.) developed by different breeding centers in India were assessed for their adaptation in 18 different environments across the Indo‐Gangetic plains. The study was aimed at identifying genotype(s) with high yield stability across the environments in general and heat stress environments in particular. Jaipur and Varanasi were hotter than any other locations considered in this study. Considerable intralocation variation in genotypic response pattern was observed over the years and dates of sowing, and this was more conspicuous at Varanasi. Longer crop duration and short grain growth duration at Varanasi were in contrast to shorter crop duration and relatively longer grain growth period that supported better grain growth at Jaipur. The genotype × environment interaction biplots for grain yield revealed that genotypes Raj 3765 and Raj 4027, developed at Jaipur, were more stable across all environments. This was due to their adaptability to high‐temperature environments, and hence they are being proposed as promising germplasm sources for late‐sown and/or warmer environments. Since the pattern of genotypic response observed at Jaipur was not similar to that observed at Varanasi, it is suggested that a common breeding strategy, if any, should emphasize grain yield stability for breeding for high‐temperature tolerance. This can also take care of intralocation variation in genotypic response over the years and dates of sowing at Varanasi.