Heat Stress Prevented the Biomass and Yield Stimulation Caused by Elevated CO2 in Two Well-Watered Wheat Cultivars

To investigate the interactive effects of elevated CO2 and heat stress (HS), we grew two contrasting wheat cultivars, early-maturing Scout and high-tillering Yitpi, under non-limiting water and nutrients at ambient (aCO2, 450 ppm) or elevated (eCO2, 650 ppm) CO2 and 22°C in the glasshouse. Plants were exposed to two 3-day HS cycles at the vegetative (38.1°C) and/or flowering (33.5°C) stage. At aCO2, both wheat cultivars showed similar responses of photosynthesis and mesophyll conductance to temperature and produced similar grain yield. Relative to aCO2, eCO2 enhanced photosynthesis rate and reduced stomatal conductance and maximal carboxylation rate (Vcmax). During HS, high temperature stimulated photosynthesis at eCO2 in both cultivars, while eCO2 stimulated photosynthesis in Scout. Electron transport rate (Jmax) was unaffected by any treatment. eCO2 equally enhanced biomass and grain yield of both cultivars in control, but not HS, plants. HS reduced biomass and yield of Scout at eCO2. Yitpi, the cultivar with higher grain nitrogen, underwent a trade-off between grain yield and nitrogen. In conclusion, eCO2 improved photosynthesis of control and HS wheat, and improved biomass and grain yield of control plants only. Under well-watered conditions, HS was not detrimental to photosynthesis or growth but precluded a yield response to eCO2.

Heat stress prevented the biomass and yield stimulation caused by elevated CO2 in two well-watered wheat cultivars

To investigate the interactive effects of elevated CO2 and heat stress (HS), we grew two contrasting wheat cultivars, early-maturing Scout and high-tillering Yitpi, under non-limiting water and nutrients at ambient (aCO2, 450 ppm) or elevated (eCO2, 650 ppm) CO2 and 22°C in the glasshouse. Plants were exposed to two 3-day HS cycles at the vegetative (38.1°C) and/or flowering (33.5°C) stage. At aCO2, both wheat cultivars showed similar responses of photosynthesis and mesophyll conductance to temperature and produced similar grain yield. Relative to aCO2, eCO2 enhanced photosynthesis rate and reduced stomatal conductance and maximal carboxylation rate (Vcmax). During HS, high temperature stimulated photosynthesis at eCO2 in both cultivars, while eCO2 stimulated photosynthesis in Scout. Electron transport rate (Jmax) was unaffected by any treatment. eCO2 equally enhanced biomass and grain yield of both cultivars in control, but not HS, plants. HS reduced biomass and yield of Scout at eCO2. Yitpi, the cultivar with higher grain nitrogen, underwent a trade-off between grain yield and nitrogen. In conclusion, eCO2 improved photosynthesis of control and HS wheat, and improved biomass and grain yield of control plants only. Under well-watered conditions, HS was not detrimental to photosynthesis or growth but precluded a yield response to eCO2.

Biofertilizer Activity of Azospirillum sp. B510 on the Rice Productivity in Ghana

Rice production in Ghana has become unsustainable due to the extremely nutrient-poor soils. It is caused by inadequate soil fertility management, including the inefficient application of fertilizers. A practical solution could be the biofertilizers, Azospirillum sp. B510. We performed field trials in Ghana and Japan to compare the effects of B510 colonization on selected Ghanaian rice varieties grown. The B510 inoculation significantly enhanced the rice cultivars’ growth and yield. The phenotypic characteristics observed in rice varieties Exbaika, Ex-Boako, AgraRice, and Amankwatia were mainly short length and high tillering capacity. These features are attributed to the host plant (cv. Nipponbare), from which the strain B510 was isolated. Furthermore, Azospirillum species has been identified as the dominant colonizing bacterium of rice rhizosphere across a diverse range of agroecologies in all major rice-growing regions in Ghana. Our results suggest that the utilization of B510 as a bio-fertilizer presents a promising way to improve rice growth, enhance soil fertility, and sustain rice productivity in Ghana.

Identification of novel plant architecture mutants in barley

In grasses, biomass and grain production are affected by plant architecture traits such as tiller number, leaf size and orientation. Thus, knowledge regarding their genetic basis is a prerequisite for developing new improved varieties. Mutant screens represent a powerful approach to identify genetic factors underpinning these traits: the HorTILLUS population, obtained by mutagenesis of spring two-row cultivar Sebastian, is a valuable resource for this purpose in barley. In this study, 20 mutant families from the HorTILLUS population were selected and evaluated for tiller number, leaf angle and a range of other plant architecture and agronomic traits using an unreplicated field design with Sebastian as a check cultivar. Principal Component Analysis revealed strong relationships among number of tillers, upper canopy leaf angle, biomass and yield-related traits. Comparison to the Sebastian background revealed that most mutants significantly differed from the wild-type for multiple traits, including two mutants with more erect leaves and four mutants with increased tiller number in at least one phenological stage. Heatmap clustering identified two main groups: the first containing the two erect mutants and the second containing Sebastian and the high-tillering mutants. Among the high-tillering mutants, two showed significantly higher biomass and grain yield per plant compared to Sebastian. The selected mutants represent promising materials for the identification of genetic factors controlling tillering and leaf angle in barley.

THE INFLUENCE OF DATE OF PLANTING AND FERTILIZER APPLICATION ON GROWTH COMPONENTS OF COLUMBUS GRASS (SORGHUM ALMUM)

Trials were conducted at Gangora in the northern Guinea Savanna ecological zone of Nigeria during the 1990 and 1991 rainy seasons. The effects of date of planting (4th,14th, 24th June and 4th July) and levels of nitrogen fertilizer (0, 50,100, 150 and 200kg/ha) on growth components of Sorghum almum were investigated. Planting in mid-June (14th June) in 1990 and early-July (4th July) in 1991 resulted in superior stand established and dry matter yields (p<0.05) than other dates. In mid-June and early-July planting 14 day post-planting, plant densities were 7.0 and 9.0 culms/m2 while plant heights were 20.4 and 11.3cm for the respective years. It had high tillering capacity and irrespective of date of planting (except for early-June planting) plant densities by 56 days post-planting (DPP) were greater than 100 culms/m2. Plant height at this stage were greater than 100 culms/m2 and were generally above 200cm. ninety DPP the pasture was at full bloom/hard dough stage. Dm yields then ranged from 8.0 to 11.4 tDM/ha in 1990 and 9.6 to 14.7 tDM/ha in 1991. Similarly seed yield for the respective years were 894.7 and 836.3 kg/ha. Fertilizer application (p<0.05) plant vigour, tillering and dry matter yield up to the highest N applied. In the first years trial, plant density at 35 days post-planting ranged from 12.0 to 29.0 culms/m2 while in the second year the ranged was 13.0 to 26.0 culms/m2. The corresponding values at 56 DPP (i.e 42 days following N application) were 32.0 to 81.0 and 45.0 to 101.0 culms/m2. Dry matter yields rose steadily from 6.5 to 12.5 tDM/ha in 1990 and from 8.9 to 13.6 tDM/ha in 1991 as fertilizer was increased 0 to 200 kgN/ha. Seed yield during the same period for the respective years varied from 416.0 to 753.0kg/ha. This study has shown that planting between mid-June and early-July with fertilize application of 100 to 200 khN/ha favour S. almum establishment and production in the northern Guinea Savanna of Nigeria

HIGH-TILLERING AND DWARF 12 regulates photosynthesis and plant architecture by affecting carotenoid biosynthesis in rice

Photosynthesis and plant architecture are important factors influencing grain yield in rice (Oryza sativa L.). Here, we identified a high-tillering and dwarf 12 (htd12) mutant and analyzed the effects of the HTD12 mutation on these important factors. HTD12 encodes a 15-cis-ζ-carotene isomerase (Z-ISO) belonging to the nitrite and nitric oxide reductase U (NnrU) protein family, as revealed by positional mapping and transformation experiments. Sequence analysis showed that a single nucleotide transition from guanine (G) to adenine (A) in the 3’ acceptor site between the first intron and second exon of HTD12 alters its mRNA splicing in htd12 plants, resulting in a 49-amino acid deletion that affects carotenoid biosynthesis and photosynthesis. In addition, compared with the wild type, htd12 had significantly lower concentrations of ent-2’-epi-5-deoxystrigol (epi-5DS), a native strigolactone, in both roots and root exudates, resulting in an obvious increase in tiller number and decrease in plant height. These findings indicate that HTD12, the rice homolog of Z-ISO, regulates chloroplast development and photosynthesis by functioning in carotenoid biosynthesis, and modulates plant architecture by affecting strigolactone concentrations.

Financial Impact of Irrigation and Nitrogen: Topdressing in Rural Enterprises of Sugarcane in Uruaçu, Brazil

The success of a project depends on a good planning of activities focused on increasing yield and minimizing production costs. The objective of the present work was to assess the economic viability of irrigated sugarcane crops (plant crop and ratoon crop) under nitrogen topdressing, in northern state of Goiás (GO), Brazil. The data needed for the research were obtained in a sugarcane crop area in the Estrela do Lago Farm, which belongs to the Uruaçu industry, in the municipality of Uruaçu, GO. The CTC4 sugarcane variety was used, which has high tillering and yield, and great adaptability to mechanized planting and harvest. The sugarcane was planted in double rows spaced 1.80 m apart. The total nitrogen topdressing rate (100 Kg ha-1) was divided into three applications with 60-day intervals during the crop development. The costs were obtained based on the following items: mechanized operations; manual operations; consumed material, and other expenses. The production cost was calculated using the total production operational cost structure used by the Brazilian Institute of Agricultural Economy. The highest costs for sugarcane in plant crop, with and without nitrogen topdressing, are due to mechanized operations and consumed material, which reached approximately 60% of the costs.

Response of weedy rice (Oryzaspp.) germplasm from Arkansas to glyphosate, glufosinate, and flumioxazin

Weedy rice (Oryzaspp.) is one of the most competitive weeds in rice (Oryza sativaL.) production. Rapid growth, high tillering, enhanced ability to uptake fertilizers, asynchronous maturation, seed shattering, and high seedbank longevity makeOryzaspp. more competitive than cultivated rice and highly persistent.Oryzaspp. may be a source of useful traits for crop improvement such as herbicide tolerance. Greenhouse studies were conducted to evaluate the response of 54Oryzaspp. accessions collected between 2008 and 2009 from Arkansas to glyphosate, glufosinate, and flumioxazin applied at field rates. Rice cultivars ‘CL163’ and ‘REX’ were included for comparison. Accessions B20, B2, and S11 and B49, B51, and S59 showed reduced sensitivity to glyphosate and flumioxazin, respectively. These accessions had less than 40% injury 5 wk after treatment (WAT). Rice cultivars (CL163 and REX) were sensitive to both glyphosate and flumioxazin, with more than 95% plant mortality at 5 WAT. On average, blackhull accessions were more tolerant to glyphosate and flumioxazin than strawhull accessions. Dose–response analysis of B20, B2, and S11 confirmed 3- to 8-fold higher tolerance of these accessions to glyphosate. AllOryzaspp. and cultivated rice were not affected by glufosinate applied at 874 g ai ha−1(1X) and were controlled 100% by 1,311 g ai ha−1(1.5X).Oryzaspp. lines with reduced sensitivity to glyphosate and flumioxazin will be studied further for use in rice crop improvement.