Grain Yield Of Cereal Crops Research Articles

Genetic analysis of biomass and photosynthetic parameters in wheat grown in different light intensities

Growth light intensities largely determine photosynthesis, biomass, and grain yield of cereal crops. To explore the genetic basis of light responses of biomass and photosynthetic parameters in wheat (Triticum aestivum L.), a quantitative trait locus (QTL) analysis was carried out in a doubled haploid (DH) population grown in low light (LL), medium light (ML), and high light (HL), respectively. The results showed that the wheat seedlings grown in HL produced more biomass with lower total chlorophyll content (Chl), carotenoid content, and maximum photochemical efficiency of photosystem II (Fv/Fm) while the wheat seedlings grown in LL produced less biomass with higher Chl compared with those grown in ML. In total, 48 QTLs were identified to be associated with the investigated parameters in relation to growth light intensities. These QTLs were mapped to 15 chromosomes which individually explained 6.3%-36.0% of the phenotypic variance, of which chromosomes 3A, 1D, and 6B were specifically involved in LL response, 5D and 7A specifically involved in ML response, and 4B specifically involved in HL response. Several light-responsive QTLs were co-located with QTLs for photosynthetic parameters, biomass, and grain weight under various conditions which may provide new hints to uncover the genetic control of photosynthesis, biomass, and grain weight.

Conservation tillage in a semiarid Mediterranean environment: results of 20 years of research

Conservation tillage techniques are becoming increasingly popular worldwide as they have the potential to generate environmental, agronomic, and economic benefits. In Mediterranean areas, studies performed on the effects of conservation tillage [in comparison with the conventional tillage technique (CT)] on grain yield of cereal crops have reported contradictory results as well as considerable year-to-year variation, demonstrating how the impact of different soil tillage techniques on crop productivity is strongly site-specific. The present paper summarises the main results from a set of experiments carried out in Sicily during the last 20 years in which we compared no tillage (NT) to CT in terms of their respective effects on the productivity and quality of durum wheat, while at the same time varying some other crop management practices ( e.g. crop sequence, N fertilisation, wheat genotype, sowing time). On average, no differences were observed between the two tillage techniques; yields were 3.84 and 3.87 Mg ha –1 for CT and NT, respectively. However, NT guaranteed superior yield when water stress during the crop cycle was high, whereas CT led to higher yields when water availability was adequate. Moreover, the results suggest that the use of NT needs to be accompanied by a rational crop sequence. In fact, a cumulative detrimental effect of NT over time was found for continuous wheat. Finally, grain quality in terms of protein content was slightly higher for CT (15.1%) than NT (14.4%). Thus, when using NT, the rate of nitrogen fertiliser application should be increased to offset this difference.

Expression of the Arabidopsis vacuolar H+‐pyrophosphatase gene (AVP1) improves the shoot biomass of transgenic barley and increases grain yield in a saline field

Cereal varieties with improved salinity tolerance are needed to achieve profitable grain yields in saline soils. The expression of AVP1, an Arabidopsis gene encoding a vacuolar proton pumping pyrophosphatase (H⁺-PPase), has been shown to improve the salinity tolerance of transgenic plants in greenhouse conditions. However, the potential for this gene to improve the grain yield of cereal crops in a saline field has yet to be evaluated. Recent advances in high-throughput nondestructive phenotyping technologies also offer an opportunity to quantitatively evaluate the growth of transgenic plants under abiotic stress through time. In this study, the growth of transgenic barley expressing AVP1 was evaluated under saline conditions in a pot experiment using nondestructive plant imaging and in a saline field trial. Greenhouse-grown transgenic barley expressing AVP1 produced a larger shoot biomass compared to null segregants, as determined by an increase in projected shoot area, when grown in soil with 150 mM NaCl. This increase in shoot biomass of transgenic AVP1 barley occurred from an early growth stage and also in nonsaline conditions. In a saline field, the transgenic barley expressing AVP1 also showed an increase in shoot biomass and, importantly, produced a greater grain yield per plant compared to wild-type plants. Interestingly, the expression of AVP1 did not alter barley leaf sodium concentrations in either greenhouse- or field-grown plants. This study validates our greenhouse-based experiments and indicates that transgenic barley expressing AVP1 is a promising option for increasing cereal crop productivity in saline fields.

Over‐expression of the rice LRK1 gene improves quantitative yield components

In rice (Oryza sativa L.), the number of panicles, spikelets per panicle and grain weight are important components of grain yield. These characteristics are controlled by quantitative trait loci (QTLs) and are derived from variation inherent in crops. As a result of the complex genetic basis of these traits, only a few genes involved in their control have been cloned and characterized. We have previously map-cloned a gene cluster including eight leucine-rich repeat receptor-like kinase (LRK) genes in Dongxiang wild rice (Oryza rufipogon Griff.), which increased the grain yield by 16%. In the present study, we characterized the LRK1 gene, which was contained in the donor parent (Dongxiang wild rice) genome and absent from the recurrent parent genome (Guichao2, Oryza sativa L. ssp. indica). Our data showed that rice LRK1 is a plasma membrane protein expressed constitutively in leaves, young panicles, roots and culms. The over-expression of rice LRK1 results in increased panicles, spikelets per panicle, weight per grain and enhanced cellular proliferation, leading to a 27.09% increase in total grain yield per plant. The increased number of panicles and spikelets per panicle are associated with increased branch number. Our data suggest that rice LRK1 regulates rice branch number by enhancing cellular proliferation. The functional characterization of rice LRK1 facilitates an understanding of the mechanisms involved in cereal crop yield, and may have utility in improving grain yield in cereal crops.

Enhanced tolerance to boron toxicity in two-rowed barley by marker-assisted introgression of favourable alleles derived from Sahara 3771

Boron (B) is an essential micronutrient for higher plant, but toxic levels can seriously diminish grain yield in cereal crops by affecting root growth, and thus restricting water extraction from the subsoil. Amelioration of high concentrations in soils is expensive and not always feasible, so breeding for B tolerance is the most viable alternative. This article reports the marker-assisted (MAS) transfer of favourable alleles from an unadapted six-rowed barley (Hordeum vulgare L.) variety, Sahara 3771, into two-rowed lines adapted to southern Australia. During the backcrossing process, the SSR marker, EBmac679, located on chromosome 4H was used to control the target region in foreground selection, but no background selection was applied. Gene introgression was confirmed with 40 BC6F1-derived doubled haploid lines segregating for the SSR marker EBmac679. We used a combination of molecular and conventional assays to unequivocally classify the 40 BC6F1-derived DH lines as B tolerant or sensitive, and then compared their means for grain yield measured over 2 years and four locations. Results showed modest improvements in grain yield of lines carrying B tolerance genes at some B toxic environments, and negative impact at others. Our results also showed that malting quality profile was not adversely affected through the introgression of the B tolerance allele from Sahara 3771, allowing the newly developed material to be used by breeding programs without risk of a penalty on malt quality.

Theoretical Expected Genetic Gains for Among‐and‐Within‐Family Selection Methods in Perennial Forage Crops

Genetic gains in forage yield lag far behind the gains made in grain yield of cereal crops, partly because of the use of inefficient selection methods that make little use of additive genetic variance within half‐sib or full‐sib families. The objectives of this study were (i) to compute expected genetic gains for among‐and‐within‐family (AWF) selection methods, (ii) to compare these selection methods to standard family and progeny‐test selection methods, and (iii) to define the conditions under which AWF selection methods may be superior to progeny‐test selection. Among‐and‐within‐family selection is equal to or better than family selection under all circumstances provided the within‐family selection criterion (X or Y) is heritable and has a positive genetic correlation with the desired trait (Y). Among‐and‐within‐family selection is favored over progeny‐test selection by (i) high heritability on an individual‐plant basis (relative to heritability on a family‐mean basis), (ii) within‐family selection intensity ≥ among‐family selection intensity, and (iii) possibly a shorter cycle time (for some species and some breeding programs). These conditions are more frequently achieved for half‐sib mating systems due to the greater partitioning of additive genetic variance within families, but AWF selection can also be heavily favored in a full‐sib mating system under conditions that are a bit more restrictive.

Grain filling duration, a crucial determinant of genotypic variation of grain yield in field-grown tropical irrigated rice

Grain filling, a crucial determinant of grain yield in cereal crops, is characterized by duration and rate of grain filling. This study aimed to (1) seek genotypic variations in grain filling duration and rate on area basis, (2) compare the contribution of grain filling duration and rate to grain yield and (3) examine the influence of temperature and solar radiation on grain filling duration and rate for effective grain filling period in the field-grown tropical irrigated rice. Six tropical genotypes were used in the 2004 dry season and wet season at the International Rice Research Institute (IRRI), Laguna, Philippines. Grain filling rate and duration exhibited highly significant genotypic variations in each crop season. Grain weight on area basis was positively associated with grain filling duration, irrespective of crop seasons, but negatively or not significantly associated with grain filling rate. Grain filling rate and duration were negatively correlated with each other. Final grain weight linearly increased with the rise in cumulative mean temperature and cumulative solar radiation. Longer grain filling duration resulted in higher cumulative mean temperature and cumulative solar radiation for effective grain filling. Higher daily mean temperature and radiation did not accelerate daily grain filling rates of different rice genotypes. It was concluded that longer grain filling duration, which provided rice plants with more cumulative mean temperature and cumulative solar radiation for effective grain filling period, was the main factor that determined grain yield on unit area basis in the field-grown tropical irrigated rice genotypes.

Genetic improvements in New Zealand forage cultivars

Substantial genetic gains have been achieved across a range of temperate forage grass and legume species in New Zealand during the past 60 years. The genetic gains reported here compare favourably with those achieved in cereals and with those achieved for similar species internationally. Substantial improvements in grain yield of cereal crops have been achieved through changes in harvest index; however, increases in yield of forage grasses and legumes reflect increases in total above ground biomass. Rates of genetic gain have been lower in lucerne (Medicago sativa L.) than in red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) and lower in perennial ryegrass (Lolium perenne L.) than in annual ryegrass (Lolium multiflorum Lam.) and tall fescue (Festuca arundinacea Schreb.). Gains in forage yield and quality have often exceeded 1% per year and have led to significant (0.3 to 1.3% per year) increases in animal performance. Keywords: animal performance, forages, genetic improvement, quality, symbiotic associations, yield

Influence of rate and timing of nitrogen fertilization on yield and quality of hard red winter wheat in Ontario

Several previous studies have reported that grain yield of cereal crops was greater from multiple than from single nitrogen (N) applications. The purpose of the study was to determine the influence of the time and rate of N application on the yield and quality of hard red winter wheat grown in Ontario. One experiment was conducted in each of 2 yr using a factorial arrangement of treatments. Factors were rate of N application (40, 80, 120, 160, 200 or 240 kg N ha−1), and timing of N application (100/0/0, 75/25/0, 50/50/0 or 25/50/25 percent of the N applied at Zadok’s growth stages 22/32/45). Early N application reduced grain yield in a year of below-average precipitation, increased grain yield in a year of average precipitation, and increased straw yield in both years. Late N application increased grain crude protein concentration and harvest index in both years. Given the lack of a consistent yield increase and the added cost of application, it is unlikely that multiple N applications will be economical for hard red winter wheat production in Ontario.Key words: Triticum aestivum, intensive cereal management, yield components, wheat

Effect of Erect Leaf Angle on Grain Yield in Barley1

Breeding for erect leaf angle has been suggested as a method for increasing grain yield in cereal crops. This study was designed to investigate the effect of erect leaf angle on grain yield in barley (Hordeum vulgare L.). Five cycles of crossing and selection were used to incorporate the erect leaf of C16146 into adapted Minnesota barleys. Subsequently, erect leaf lines from five populations were evaluated in yield trials. In addition, the yield response of erect leaf lines was compared to check cultivars at planting rates of 56, 94, and 132 kg ha−1. No significant difference was found for grain yield between erect leaf lines and check cultivars in three populations. Comparisons of erect and horizontal leaf progeny in two other populations showed no difference in one population; however, the horizontal leaf group was higher yielding in the second. The yield responses of erect and horizontal leaf‐types to the three planting rates were similar, although significant interaction was observed for kernel number and weight, suggesting that canopy type may influence these components. Erect leaf lines had less culm flex, more erect spikes, lower head number, later maturity, and greater lodging resistance than horizontal leaf lines. These associations with the erect leaf trait, which likely resulted from pleiotropy, were confounded with the effect of erect leaves and likely reduced the chances of finding a positive grain yield response. Although the potential of increased lodging resistance and the leaf‐type density interaction for kernel number and weight offer some encouragement for continuing research, results from our study provide little or no evidence that erect leaf angle enhances grain yield in barley.

Organic materials applied as seed treatments or foliar sprays fail to increase grain yield of wheat

Organic materials derived from fish, seaweed or bacterial cultures, and being sold as 'natural' aids to crop production, were tested for their effects on wheat yield in Western Australia. Six products based on seaweed (Seasol powder and liquid, Kelpak 66), fish (Eco, 10.8.8, Crop Booster) or bacterial culture (Cytozyme Seed Plus), and Complesal, an inorganic nutrient spray, were tested as seed treatments or foliar sprays. Thirty-two replicated field trials (plot size 100 m2) were conducted over 3 years using recommended rates of fertiliser and 'commercial' weed and pest control practices. No statistically significant increases in grain yield were detected from the use of any product in any trial. Average treatment grain yields in 18 trials in 1982 ranged from 99.4 to 10 1.2% of the control and in 12 trials in 1983 from 96.2 to 99.3% of the control. The results give no indication that, at the application rates used, organic materials applied as seed dressings or foliar sprays can increase the grain yield of cereal crops in commercial cultivation.

A Rapid Method of Evaluating Growth Rate in Pearl Millet and Its Weedy and Wild Relatives1

Vegetative growth rate is a physiological trait that has been hypothesized to be useful in the improvement of grain yield in cereal crops. Usefulness of this physiological trait in a breeding program depends upon a rapid method that allows the evaluation of large numbers of lines. In this study, the objective was to determine if the rates of growth calculated from periodic samplings could be estimated by using only one or two dates of harvest relating to specific stages in the plant's development. Periodic samples of vegetative growth were made on 12 pearl millet (Pennisetum americanum) genotypes, plus three weedy (ssp. stenostachyum) and one wild (ssp. monodii) accession in two seasons once every 2 weeks starting at 21 days after emergence and continuing to maturity. With use of the rates calculated on these periodic samples as the actual growth rate, it was found that samples taken at either one or two dates of harvest could be used to adequately estimate this rate. The two dates of harvest were taken at either 10 days after flowering or at maturity. The rate was calculated as (vegetative dry weight at flowering + 10 days or at maturity)/(number of days to flowering + 10).