Posts Tagged ‘Field Crops Research’

Prediction of grain yield using reflectance spectra of canopy and leaves in maize plants grown under different water regimes

Posted by Carelia Juarez on , in Journal Articles

Published in  Field Crops Research  128(1): 82-90, 2012

Prediction of grain yield using reflectance spectra of canopy and leaves in maize plants grown under different water regimes

V.S. Weber, J.L. Araus, J.E. Cairns, C. Sanchez, A.E. Melchinger and E. Orsini

The ability to accurately estimate grain yield using spectral reflectance measurements prior harvest could be used to reduce phenotyping time and costs. In this study, grain yield of 300 maize testcrosses grown under different water and temperature regimes in the dry season 2010 was predicted using spectral reflectance (495–1853 nm) of both leaves and canopy measured between tassel emergence until milk-grain stage. Partial least square regression (PLSR) was used for data analysis. Coefficients of determination (R2) between predicted and actual grain yield were highest for measurements conducted at anthesis and milk-grain stage, explaining at maximum 23% and 40% of the genotypic variation in grain yield after validation, respectively. PLSR models explained a higher proportion of the genetic variation in grain yield under drought stress compared to well-watered conditions. The association between predicted and actual grain yield was stronger in spectral reflectance measurements taken at the leaf level compared to canopy level. By combining the most predictive PLSR models across trials, at maximum of 40% of the variation in grain yield could be explained in each trial with a relative efficiency of selection of 0.88 and 0.68 using leaf and canopy reflectance, respectively. The most relevant wavelengths for predicting grain yield were associated with photosynthetic capacity (495–680 nm), red inflection point (680–780 nm) and plant water status (900, 970, and 1450 nm, 1150–1260 nm, and 1520–1540 nm). Additional wavelengths based on leaf (800, 1000, and 1260–1830 nm) and canopy (988–999 nm and 1430–1640 nm) reflectance of unknown physiological relevance were also identified for prediction of grain yield. Caution must be exercised before integrating our spectral reflectance approach into a breeding program because this is a pilot study based on a single location and season.


The usefulness of iron bioavailability as a target trait for breeding maize (Zea mays L.) with enhanced nutritional value

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 123(2): 153-160, 2011

The usefulness of iron bioavailability as a target trait for breeding maize (Zea mays L.) with enhanced nutritional value

Kevin V. Pixley, Natalia Palacios-Rojas and Raymond P. Glahn

Iron (Fe) deficiency is the most widespread nutritional problem, affecting as many as half of the world’s population. Only a small fraction (2–15%) of Fe from plant sources is typically bioavailable, that is, available for absorption and nutritionally useful for humans. This study evaluated Fe concentration and bioavailability for three diverse sets of 12, 14 and 16 maize hybrids grown in two- or three-location trials to assess the feasibility of selecting for Fe bioavailability in breeding programs. Bioavailability of Fe, assessed using the in vitro digestion/Caco-2 cell model, varied significantly among hybrids in two of the three trials. Location effects were larger than location by genotype interaction effects, additive but not non-additive gene action was significant, and heritability estimates were mostly between 0.55 and 0.65 for Fe bioavailability estimators. Bioavailability of Fe was not associated with Fe concentration in grain or with grain yield. Negative correlation of Fe bioavailability with zinc concentration in grain for one of the three hybrid trials, and positive correlation with provitamin A concentrations in one trial were indicative of inhibitor and enhancer effects on Fe bioavailability, respectively. Although use of the Caco-2 cell model is promising, particularly because it integrates the whole meal, or food matrix effect on Fe bioavailability, the complex nature of the assay and moderate heritability of bioavailability estimators make it most suitable as an intermediate selection tool, following high throughput selection for molecular markers of Fe bioavailability, currently in development by other researchers, and preceding validation and efficacy trials with animal and human models.

 

 

Wheat yield and tillage–straw management system × year interaction explained by climatic co-variables for an irrigated bed planting system in northwestern Mexico

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Published in Field Crops Research 124(3): 347-356, 2011

Wheat yield and tillage–straw management system × year interaction explained by climatic co-variables for an irrigated bed planting system in northwestern Mexico

Nele Verhulst, Ken D. Sayre, Mateo Vargas, Jose Crossa, Jozef Deckers, Dirk Raes, Bram Govaerts

Wheat is an important food and income source and estimated demand for wheat in the developing world is projected to increase substantially. The objectives of this study were to gain insight into (i) the effect of tillage–straw system on yield and yield components (number of grains per m2 and thousand kernel weight), (ii) the relation between climatic conditions and yield and yield components, (iii) the explanation of tillage–straw system × year interaction for yield and yield components by climatic co-variables. Wheat grain yield and yield components were measured in a long-term trial established in 1992 under irrigated, arid conditions in northwestern Mexico. Five tillage–straw management systems (conventionally tilled raised beds [CTB] with straw incorporated and permanent raised beds [PB] with straw burned, removed, partly retained or fully retained) were compared for a wheat–maize rotation. Daily climatic data were averaged over six periods corresponding approximately to advancing wheat growth stages. The PB-straw retained and PB-straw removed had the highest yields (average yield of 7.31 and 7.24 t ha−1, respectively) and grains per m2. The PB-straw burned had the lowest yield (average yield of 6.65 t ha−1) and grains per m2, but the highest thousand kernel weight. Maximum temperature was positively correlated to final grain yield during tillering and head differentiation, but was negatively correlated to thousand kernel weight during grain-filling. For the tillage–straw system year interaction, three groups of management systems were distinguished for yield and grains per m2: PB-straw burned, CTB-straw incorporated and PB where straw is not burned. The CTB-straw incorporated had a positive interaction with year in favorable years with high radiation and evapotranspiration. The PB-straw burned was relatively more affected by excess water conditions and showed positive interactions in years with high relative humidity. The PB-straw retained was the most stable in different climatic conditions, indicating that this management system could contribute to maintaining wheat yield in a changing climate scenario.

 

Large-scale screening for maize drought resistance using multiple selection criteria evaluated under water-stressed and well-watered environments

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Published in Field Crops Research 124(1); 37-45, 2011 

Large-scale screening for maize drought resistance using multiple selection criteria evaluated under water-stressed and well-watered environments

Yanli Lu, Zhuanfang Hao, Chuanxiao Xie, Jose Crossa, Jose-Luis Araus, Shibin Gao, Bindiganavile S. Vivek, Cosmos Magorokosho, Stephen Mugo, Dan Makumbi, Suketoshi Taba, Guangtang Pan, Xinhai Li, Tingzhao Rong, Shihuang Zhang, Yunbi Xu

A total of 550 maize inbred lines collected from global breeding programs were evaluated for drought resistance under both well-watered and water-stressed environments. The evaluation was based on multiple measurements of biomass taken before and after the drought stress was applied using the normalized difference vegetation index (NDVI), along with other selection criteria including anthesis-silking interval, leaf senescence, chlorophyll content, root capacitance, final grain yield, and grain yield components. Kernel weight was the most stable trait under drought stress. Correlations between the primary trait (grain yield) and the secondary traits, except the root capacitance and ASI under water-stressed condition, were all significant. Root capacitance had relatively low heritability and low genetic correlation with other drought resistance criteria, and is not recommended as a drought resistance criterion. Significant reduction of NDVI values measured in the afternoon when the leaves became rolling, compared to those measured in the morning when the leaves were open, provides a reliable index for leaf rolling, which however was not significantly correlated with grain yield. NDVIs measured across different developmental stages were highly correlated with each other and with most of the secondary traits as well as, grain yield, indicating that NDVI can be used as a secondary trait for large-scale drought resistance screening. Regression models built based on non-yield drought criteria and yield components explained about 40% and 95% of the variation for the grain yield, respectively. Some maize lines developed in China for temperate regions showed strong drought resistance comparable to tropical maize lines when tested under tropical condition, indicating that temperate lines with a wide adaptability can be used in drought resistance breeding for both temperate and tropical environments.

The effect of tillage, crop rotation and residue management on maize and wheat growth and development evaluated with an optical sensor

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Published in  Field Crops Research 120(1), 2011

The effect of tillage, crop rotation and residue management on maize and wheat growth and development evaluated with an optical sensor

Nele Verhulst, Bram Govaerts, Victoria Nelissen, Ken D. Sayre, Jose Crossa, Dirk Raes, Jozef Deckers

Crop growth and development as well as yield are the result of the efficiency of the chosen agricultural management system within the boundaries of the agro-ecological environment. End-of-season yield results do not permit the evaluation of within-season management interactions with the production environment and do not allow for full understanding of the management practice applied. Crop growth and development were measured during the 2004, 2006 and 2008 crop cycles with an optical handheld NDVI sensor for all plots of the different management treatments of a long-term (since 1991) sustainability trial in the highlands of Mexico. Cropping systems varying in (1) tillage (conventional vs. zero tillage); (2) residue management (retention vs. removal); (3) rotation (monocropping vs. a maize [Zea mays L.]/wheat [Triticum aestivum L.] rotation) were compared. The NDVI-handheld sensor was evaluated as a tool to monitor crop growth and development and was found to be an excellent tool for this purpose. There was a strong relation between NDVI and biomass accumulation of maize and wheat. The measurement with the handheld sensor was non-destructive and fast so that a representative plot area could be measured easily and time-efficiently. Zero tillage induced different crop growth dynamics over time compared to conventional tillage. Zero tillage with residue retention is characterized by a slower initial crop growth, compensated for by an increased growth in the later stages, positively influencing final grain yield. Also crop rotation influenced early crop growth, with lower NDVI values for crops sown after wheat than crops after maize. Zero tillage with residue removal had low NDVI values throughout the growing season. Zero tillage with retention of crop residues results in time efficient use of resources, as opposed to conventional tillage, regardless of residue management, and zero tillage with residue removal. The results indicated that different tillage, rotation and residue management practices influence crop growth and development. It is important to monitor and understand crop growth under different management systems to select the right varieties and adjust timing and practice of input supply (fertilizer, irrigation etc.) in a holistic way in each cropping system.

Specification effects in zero tillage survey data in South Asia’s rice-wheat systems

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Published in Field Crops Research 111(1-2): 166-172

Specification effects in zero tillage survey data in South Asia’s rice–wheat systems

Olaf Erenstein

Specification effects in terms of how technology options are contrasted can introduce bias in impact assessment. In a companion paper we evaluated the on-farm impacts of zero tillage (ZT) wheat as a resource-conserving technology in the rice–wheat systems of India’s Haryana State and Pakistan’s Punjab province [Erenstein, O., Farooq, U., Malik, R.K., Sharif, M., 2008. On-farm impacts of zero tillage wheat in South Asia’s rice–wheat systems. Field Crop Res. 105, 240–252]. The underlying field work surveyed plots of full adopters (only ZT plots), partial adopters (ZT and conventional tillage [CT] plots on same farm) and non-adopters (only CT plots). The companion paper assumes that the comparison between the ZT plots of full plus partial adopters and CT plots of partial adopters is the least-biased assessment of ZT’s on-farm impact. Here we revisit this underlying assumption and draw on complementary farm survey findings to illustrate the extent of specification effects in the assessment of on-farm impacts of ZT wheat in the same study areas. The study thereby distinguishes between three contrasts between ZT and CT within the same dataset: (1) plain contrast (all plots of adopters and non-adopters); (2) adopter-only contrast (full and partial adopters only, as used in Erenstein et al. [Erenstein, O., Farooq, U., Malik, R.K., Sharif, M., 2008. On-farm impacts of zero tillage wheat in South Asia’s rice–wheat systems. Field Crop Res. 105, 240–252]); (3) pair-wise contrast (partial adopters only). Proceeding from type 1 to type 3 comparisons the number of observations decrease but this is compensated by an increasing ability to control for variation. The ability of type 3 comparisons to pick up relatively small but significant differences is an important consideration in farm survey impact assessment. However, there is also an increase in partial adoption bias and further follow-up studies are needed to understand the implications of this. The comparisons show that the ZT effects on savings for diesel, tractor time and cost for wheat cultivation are particularly robust. In Haryana ZT’s positive implications for yield and the other financial indicators were also statistically robust, but in Punjab these were sensitive to specification effects. Particularly sensitive to specification effects were the ZT effects on the productivity of applied water in both sites.

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.

Rapid gains in yield and adoption of new maize varieties for complex hillside environments through farmer participation. II. Scaling-up the adoption through community-based seed production (CBSP)

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Published in Field Crops Research 111(1-2): 144-151
Rapid gains in yield and adoption of new maize varieties for complex hillside environments through farmer participation. II. Scaling-up the adoption through community-based seed production (CBSP)
 
T.P. Tiwari, G. Ortiz-Ferrara, C. Urrea, R.B. Katuwal, K.B. Koirala, R.C. Prasad, D.B. Gurung, D. Sharma, B. Hamal, B. Bhandari and M. Thapa.
 
Abstract:  Participatory varietal selection (PVS) led to the identification of Population-22 and its later release as Manakamana-3. Subsequently further mother–baby trials tested five unreleased open-pollinated varieties (OPVs), ZM-621, Shitala, Population-45, Hill Pool White, and Hill Pool Yellow to compare them with Manakamana-3. Farmers again preferred Manakamana-3 as well as ZM-621 for their stable, higher grain yield, and for other traits such as stay-green, non-lodging, large white grains, and tolerance to foliar diseases. However, Manakamana-3 and ZM-621 both had late maturity, open husks and dented grain. Both were tested with farmers on-farm co-ordinated farmers field trials (CFFTs) and had not been identified as this was more contractual type of participatory research. Individual traits were measured but overall farmers’ preferences were not elicited. In the more collaborative participation of the mother–baby trials the overall preference was determined and farmers traded-off the late maturity and dented grains of Manakamana-3 and ZM-621 against other favourable traits. Depending on location, these genotypes yielded 15–45% more grain than the local varieties in the mother–baby trials. These results led to the release of ZM-621 as Deuti in 2006. Farmers had adopted Manakamana-3 (released in 2002) and ZM-621 (Deuti) as a direct result of PVS trials and increased area under them year after year. Farmers awareness of the varieties has increased and seeds of these varieties are under community-based seed production (CBSP). Involving farmers through a collaborative mode of participation in varietal selection overcame bottlenecks to finding new varieties that had occurred with more contractual on-farm research.

 

Specification effects in zero tillage survey data in South Asia’s rice–wheat systems

Posted by on , in Journal Articles

Published in Field Crops Research 111(1-2): 166-172

Specification effects in zero tillage survey data in South Asia’s rice–wheat systems

Olaf Erenstein

Abstract:  Specification effects in terms of how technology options are contrasted can introduce bias in impact assessment. In a companion paper we evaluated the on-farm impacts of zero tillage (ZT) wheat as a resource-conserving technology in the rice–wheat systems of India’s Haryana State and Pakistan’s Punjab province [Erenstein, O., Farooq, U., Malik, R.K., Sharif, M., 2008. On-farm impacts of zero tillage wheat in South Asia’s rice–wheat systems. Field Crop Res. 105, 240–252]. The underlying field work surveyed plots of full adopters (only ZT plots), partial adopters (ZT and conventional tillage [CT] plots on same farm) and non-adopters (only CT plots). The companion paper assumes that the comparison between the ZT plots of full plus partial adopters and CT plots of partial adopters is the least-biased assessment of ZT’s on-farm impact. Here we revisit this underlying assumption and draw on complementary farm survey findings to illustrate the extent of specification effects in the assessment of on-farm impacts of ZT wheat in the same study areas. The study thereby distinguishes between three contrasts between ZT and CT within the same dataset: (1) plain contrast (all plots of adopters and non-adopters); (2) adopter-only contrast (full and partial adopters only, as used in Erenstein et al. [Erenstein, O., Farooq, U., Malik, R.K., Sharif, M., 2008. On-farm impacts of zero tillage wheat in South Asia’s rice–wheat systems. Field Crop Res. 105, 240–252]); (3) pair-wise contrast (partial adopters only). Proceeding from type 1 to type 3 comparisons the number of observations decrease but this is compensated by an increasing ability to control for variation. The ability of type 3 comparisons to pick up relatively small but significant differences is an important consideration in farm survey impact assessment. However, there is also an increase in partial adoption bias and further follow-up studies are needed to understand the implications of this. The comparisons show that the ZT effects on savings for diesel, tractor time and cost for wheat cultivation are particularly robust. In Haryana ZT’s positive implications for yield and the other financial indicators were also statistically robust, but in Punjab these were sensitive to specification effects. Particularly sensitive to specification effects were the ZT effects on the productivity of applied water in both sites.