Posts Tagged ‘yield’

Does low yield heterosis limit commercial hybrids in wheat?

Posted by Carelia Juarez on , in Journal Articles

Published in African Journal of Agricultural Research 8 (50) : 6663-6669, 2013

Sharma, R.K.

Heterosis has contributed to productivity gains in several crops like maize, rice, sorghum, cotton etc. Wheat breeders have largely been unsuccessful to take advantage from this technology at commercial level. Lack of commercial level yield heterosis is regarded as a major reason for this failure as compared to other technical barriers like difficult pollination control and seed production. The allopolyploidy nature of wheat endows even wheat purelines with a fixed intergenomic heterosis which perhaps is the foremost reason for lack of classical yield heterosis in wheat. The coming together of three diverse but functionally similar genomes causes differential gene expression among several other outcomes and leads to a diploid behaving self-sustaining intergenomic hybrid. A long history of highly successful pureline breeding and shortage of nicking parents are other two reasons responsible for failure to realize commercial level heterosis in wheat. Molecular biology tools now make it possible to dissect the phenomenon of heterosis into detectable Mendelian factors to tailor nicking parents to develop commercially sustainable wheat hybrids. This review probes the reasons for the absence of commercial-scale heterosis in wheat.

Postharvest insect pest and foliar disease resistance and agronomic performance of new maize hybrids in East Africa

Posted by Carelia Juarez on , in Journal Articles

Published in International Journal of Plant Breeding and Genetics 7 (2) : 92-104, 2013

Tadele Tefera, Stephen Mugo, Yoseph Beyene, Haron Karaya, John Gakunga and Girma Demissie

A study was carried out with the objectives to evaluate maize hybrids for grain yield, agronomic performance and reaction to foliar diseases. Twenty seven experimental maize hybrids with varying level of resistance to two postharvest insect pests: the Larger Grain Borer (LGB) and Maize Weevil (MW), tested in nine environments in Kenya and Ethiopia. The performances of the hybrids were not consistent across environments for all traits tested as evident from the significant genotypexenvironment interactions. The contribution of the environment main effect was 46.1% for grain yield, 84.9% for days to anthesis, 26.9% for ears per plant, 63.3% for anthesis-silking interval, 76.5% for plant height and 74.7% for ear height. The mean yield performance of the hybrids across locations was 4.8 t ha-1. The hybrids yielded high at Kiboko (6.13 t ha-1) followed by Mpeketoni (5.66 t ha-1) and Bako (5.47 t ha-1). The hybrids had similar days to anthesis (65-68 days), relatively taller plant (183 to 227 cm) and ear height (88-116 cm) compared to the commercial check (plant height 204 cm and ear height 98 cm). The hybrids were all resistant to rust and gray leaf spot diseases and moderately resistant to Turcicum leaf blight. However, they were susceptible to maize streak virus Two hybrids, CKPH08009 (4.9 t ha-1) and CKPH08025 (5.0 t ha-1) had high yield performance and resistance to both the LGB and MW compared to the commercial check, WH505 (5.1 t ha-1) which is susceptible. These results indicate that selection for insect resistant did not result in yield penalty. Therefore, the two resistant hybrids can be recommended for release and commercialization in eastern Africa where MW and LGB are the major storage pests.

Integrated nutrient management in Quality Protein Maize (Zea mays) planted in rotation with wheat (Triticum aestivum): Effect on productivity and nutrient use efficiency under different agro-ecological conditions

Posted by Carelia Juarez on , in Journal Articles

Published in Indian Journal of Agricultural Sciences 83 (4) : 391-396, 2013

 S.L. Jat,  C.M. Parihar, A.K. Singh, M.L. Jat, A.K. Sinha, B.N. Mishra, H. Meena, V.K. Paradkar, C.S. Singh, Dilip Singh and R.N. Singh

Field experiments were conducted during two consecutive years 2007 and 2008 at seven locations, viz. Ambikapur, Bahraich, Banswara, Chhindwara, Ranchi, Udaipur and Varanasi of different agro-ecologies to evaluate the effect of integrated nutrient management on productivity of quality protein maize (Zea mays L.) sown in sequence of wheat (Triticum aestivum L.). Integrated application of total nutrient doses from both organic and inorganic sources (225 N+ 105 P2O5 + 90 K2O kg/ha) to maize resulted in maximum grain yield of quality protein maize hybrid (HQPM 1) during both the years at all the locations studied. The pooled analysis also showed that the application of FYM@ 6 tonnes/ha at N4 level resulted into significantly higher grain yield during both the years across the locations. However the response of FYM application was higher at Ambikapur, Chhindwara, Ranchi and Varanasi as compared to other three locations. The pooled analysis of the nutrient productivity across the locations showed that it was highest with the application of O0N1 treatment. The productivity gained with the application of O0N4 can be obtained with the application of O1N2 although there is less than 50% of the nutrients applied through the FYM are utilized by the first crop. Hence the application of the organic manure up to the N2 fertility levels leads to enhance the overall productivity of the land in the system as compared to sole application of N4 levels. The SREG biplot analysis by SAS software for the yield and nutrient productivity also showed the similar trend in the results.


Breeding progress for yield in winter wheat genotypes targeted to irrigated environments of the CWANA region

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2013

W. Tadesse, A. I. Morgounov, H. J. Braun, B. Akin, M. Keser, Yuksel Kaya, R. C. Sharma, S. Rajaram, M. Singh, M. Baum and M. van Ginkel

The international winter wheat improvement program (IWWIP), an alliance between Turkey–CIMMYT–ICARDA, has distributed improved germplasm to different National Agricultural Research Systems (NARS) partners through international nurseries and yield trials for the last 25 years. This study was carried out in order to determine the rate of breeding progress for yield and yield related traits at IWWIP using data of the international winter wheat yield trials (IWWYT), IWWYT 1–13, collected from 1997 to 2010 in irrigated environments across different countries. The relative grain yield of the best line expressed as percent of the best check (Kinaci-97), widely grown cultivar (Bezostaya) and trial mean (TM) increased at a rate of 0.6, 1.6 and 0.2 %/year, each non-significant (P > 0.05), respectively. Regression analysis indicated that TM has increased at a rate of 91.9 kg/ha/year (P = 0.007). The net realized breeding progress was estimated by accounting the variability due to management and weather conditions using surrogate variables such as integrated biological indices taken as means of common checks. The net realized gain for the BL was 66.2 ± 19.7 kg/ha/year (P = 0.01). Success rate of the BL, per cent of sites where the BL exceeds the local check in grain yield, ranged from 50 to 87 % across trials. To date, more than 55 varieties of IWWIP origin have been released in 10 countries of Central and West Asia including Afghanistan, Turkey, Iran, Uzbekistan and Tajikistan. Some varieties, such as Solh and Kinaci-97, have been released under different names in different countries indicating their broad adaptation. Cluster analysis of IWWYT sites indicated that IWWIP sites in Turkey and Syria are associated with most of the testing sites in Central and West Asia and North Africa (CWANA) region. The recently identified high yielding genotypes are recommended for direct release and/or parental purposes by the respective NARS.


Infrared thermal imaging as a rapid tool for identifying water-stress tolerant maize genotypes of different phenology

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Agronomy and Crop Science, 2013

S. Zia, G. Romano, W. Spreer, C. Sanchez, J. Cairns, J.L. Araus and J. Muller

The main task of this research was to evaluate canopy temperature and Crop Water Stress Index (CWSI) by assessing genotype variability of maize performance for different water regimes. To that end, three hundred tropical and subtropical maize hybrids with different phenology in terms of date of anthesis were evaluated. The influence of phenology on the change in canopy temperatures and CWSI was not equal during the three dates of measurement. At the end of vegetative growth (82 days after sowing, DAS) and at the blister stage (DAS 97), a high significant difference in temperatures and CWSI (P < 0.001) were obtained between the early- and late-maturity genotypes. During anthesis (DAS 89), phenology had a significant effect (P < 0.01) only for the well-watered genotypes, while under water-stress conditions, no differences were found between early and late genotypes in terms of canopy temperature and CWSI. High significant differences (P < 0.001) in stomatal conductance (gs) between early and late genotypes for different treatments were observed. A relationship (R2 = 0.62) between gs and canopy temperature was obtained. Under a water-stress canopy, temperature was measured at anthesis, which was negatively correlated with grain yield of the early (r = −0.55)- and late (r = −0.46)-maturity genotypes in the water-stressed condition.

Maximizing productivity and improving nutrition through intercropping quality protein maize and potato

Posted by Carelia Juarez on , in Journal Articles

Published in Acta Agronomica Hungarica 60 (3) : 221-230, 2012

T. R. Chapagain, B. B. Khatri, P. Bhattarai, B. P. Luitel, G. Ortiz-Ferrara and  R. C. Sharma

Intercropping potato with quality protein maize (QPM) could improve the livelihood and nutritional status of the resource-poor farmers who produce and consume them. A study was conducted from 2008 to 2010 to assess the performance of three improved potato varieties in an intercropping system with an improved QPM in the high hills of Nepal. The QPM was sown for four consecutive weeks following potato planting. The commercial potato varieties Janak Dev, Kufri Jyoti and Khumal Seto-1 were used, while the improved QPM was Poshilo Makai-1. Delayed intercropping caused a reduction in the maize yield, but an increase in the potato yield. The highest potato yield was obtained from maize intercropping after four weeks. The grain yield of maize was significantly reduced by late planting beyond the second week. The average weekly rate of increase due to maize intercropping was better for Janak Dev and Kufri Jyoti, while Khumal Seto-1 was less suitable for intercropping. The land equivalent ratio for potato-maize intercropping was 2.23. The results suggest that Poshilo Makai-1 could be incorporated in potato-maize intercropping, leading to higher returns and nutritional benefits. The findings underline the importance of variety and date of intercropping to maximize production. The findings have implications for harnessing higher productivity on resource-poor farms, and could contribute to food and nutritional security for resource-poor farmers.

Effect of intercropping maize and soybeans on Striga hermonthica parasitism and yield of maize

Posted by on , in Journal Articles

Published in Archives Of Phytopathology And Plant Protection 44(2): 158-167, 2011

Effect of intercropping maize and soybeans on Striga hermonthica parasitism and yield of maize

J. A. Odhiambo; B. Vanlauwe; I. M. Tabu; F. Kanampiu; Z. Khan

Striga hermonthica a major biotic constraint to cereal production can be controlled by trap crops. Soybean cultivars vary in ability to stimulate suicidal germination of the weed. An experiment was conducted to select soybean (Glycine max) varieties with the ability to stimulate germination of S. hermonthica seeds. Experiments were conducted with strigol Nijmegen 1® (GR 24), a synthetic stimulant, as a check. In the pot and field experiments, maize (variety WH507) was intercropped with soybeans. Variation occurred among soybean varieties in inducing germination of S. hermonthica. The relative germination induction by soybean varieties ranged from 8% to 66% compared to 70% for synthetic stimulant check. Varieties TGX1448-2E, Tgm 1576, TGX1876-4E and Tgm 1039 had the highest relative germination. Soybean varieties TGX 1831-32E, Tgm944, Tgm 1419 and Namsoy4m had high stimulation but low attachment. Intercropping maize with soybeans in the field led to a low S. hermonthica count and high maize yield.

Dual Alpha13C/Delta18O response to water and nitrogen availability and its relationship with yield in field-grown durum wheat.

Posted by on , in Journal Articles

Published in Plant Cell and Environment 34(3): 418-433, 2011

Dual Alpha13C/Delta18O response to water and nitrogen availability and its relationship with yield in field-grown durum wheat

Cabrera-Bosquet L.; Albrizio, R.; Nogues, S.; Araus, J.L.

The combined use of stable carbon and oxygen isotopes in plant matter is a tool of growing interest in cereal crop management and breeding, owing to its relevance for assessing the photosynthetic and transpirative performance under different growing conditions including water and N regimes. However, this method has not been applied to wheat grown under real field conditions. Here, plant growth, grain yield (GY) and the associated agronomic components, carbon isotope discrimination (Δ13C) plus oxygen isotope composition (δ18O) as well as leaf and canopy gas exchange were measured in field-grown wheat subjected to different water and N availabilities. Water limitation was the main factor affecting yield, leaf and canopy gas exchange and Δ13C and δ18O, whereas N had a smaller effect on such traits. The combination of Δ13C and δ18O gave a clear advantage compared with gas exchange measurements, as it provides information on the instantaneous and the long-term plant photosynthetic and transpirative performance and are less labour intensive than gas exchange measurements. In addition, the combination of plant Δ13C and δ18O predicted differences in GY and related agronomical parameters, providing agronomists and breeders with integrative traits for selecting crop management practices and/or genotypes with better performance under water-limiting and N-limiting conditions.

Drought stress and tropical maize: QTL-by-environment interactions and stability of QTLs across environments for yield components and secondary traits

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Published in Theoretical and Applied Genetics 119(5): 913-930, 2009

Drought stress and tropical maize: QTL-by-environment interactions and stability of QTLs across environments for yield components and secondary traits

Rainer Messmer, Yvan Fracheboud, Marianne Bänziger, Mateo Vargas, Peter Stamp and Jean-Marcel Ribaut

A recombinant inbred line (RIL) population was evaluated in seven field experiments representing four environments: water stress at flowering (WS) and well-watered (WW) conditions in Mexico and Zimbabwe. The QTLs were identified for each trait in each individual experiment (single-experiment analysis) as well as per environment, per water regime across locations and across all experiments (joint analyses). For the six target traits (male flowering, anthesis-to-silking interval, grain yield, kernel number, 100-kernel fresh weight and plant height) 81, 57, 51 and 34 QTLs were identified in the four step-wise analyses, respectively. Despite high values of heritability, the phenotypic variance explained by QTLs was reduced, indicating epistatic interactions. About 80, 60 and 6% of the QTLs did not present significant QTL-by-environment interactions (QTL × E) in the joint analyses per environment, per water regime and across all experiments. The expression of QTLs was quite stable across years at a given location and across locations under the same water regime. However, the stability of QTLs decreased drastically when data were combined across water regimes, reflecting a different genetic basis of the target traits in the drought and well-watered trials. Several clusters of QTLs for different traits were identified by the joint analyses of the WW (chromosomes 1 and 8) and WS (chromosomes 1, 3 and 5) treatments and across water regimes (chromosome 1). Those regions are clear targets for future marker-assisted breeding, and our results confirm that the best approach to breeding for drought tolerance includes selection under water stress.

Phenotypic plasticity of yield and phenology in wheat, sunflower and grapevine

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Published in Field Crops Reseach 110(3): 242-250

Phenotypic plasticity of yield and phenology in wheat, sunflower and grapevine

V.O. Sadras, M.P. Reynolds, A.J. de la Vega, P.R. Petrie and R. Robinson

Abstract:  This paper focuses on the interaction between genotype and environment, a critical aspect of plant breeding, from a physiological perspective. We present a theoretical framework largely based on Bradshaw’s principles of phenotypic plasticity (Adv. Gen. 13: 115) updated to account for recent developments in physiology and genetics. Against this framework we discuss associations between plasticity of yield and plasticity of phenological development. Plasticity was quantified using linear models of phenotype vs environment for 169 wheat lines grown in 6 environments in Mexico, 32 sunflower hybrids grown in at least 15 environments in Argentina and 7 grapevine varieties grown in at least 14 environments in Australia.

In wheat, yield ranged from 0.6 to 7.8 t ha−1 and the range of plasticity was 0.74–1.27 for yield and 0.85–1.17 for time to anthesis. The duration of the post-anthesis period as a fraction of the season was the trait with the largest range of plasticity, i.e. 0.47–1.80. High yield plasticity was an undesirable trait as it was associated with low yield in low-yielding environments. Low yield plasticity and high yield in low-yielding environments were associated with three phenological traits: early anthesis, long duration and low plasticity of post-anthesis development.

In sunflower, yield ranged from 0.5 to 4.9 t ha−1 and the range of plasticity was 0.72–1.29 for yield and 0.72–1.22 for time to anthesis. High yield plasticity was a desirable trait as it was primarily associated with high yield in high-yielding environments. High yield plasticity and high yield in high-yielding environments were associated with two phenological traits: late anthesis and high plasticity of time to anthesis.

In grapevine, yield ranged from 1.2 to 18.7 t ha−1 and the range of plasticity was 0.79–1.29 for yield, 0.86–1.30 for time of budburst, 0.84–1.18 for flowering, and 0.78–1.16 for veraison. High plasticity of yield was a desirable trait as it was primarily associated with high yield in high-yielding environments. High yield plasticity was associated with two phenological traits: plasticity of budburst and plasticity of anthesis.

We report for the first time positive associations between plasticities of yield and phenology in crop species. It is concluded that in addition to phenology per se (i.e. mean time to a phenostage), plasticity of phenological development merits consideration as a distinct trait influencing crop adaptation and yield.