Effect of elevated CO(2) and nitrogen levels on lentil growth and nodulation

Global carbon dioxide levels are rising, and could reach levels of 815 $\mu$mol mol$^{-1}$ by the year 2100. Since photosynthetic rate in C$_{3}$ species under the current levels of ambient CO$_{2}$ is still below physiological saturation levels, it is anticipated that photosynthesis and consequently productivity for most crops should be stimulated by the higher levels of atmospheric CO$_{2}$. A stronger response is expected in legumes as nitrogen is not considered as a limiting factor for growth. This study investigates the effect of elevated CO$_{2}$ and different nitrogen fertilizer levels on the growth and nodulation of lentils. Syrian lentil was grown under ambient CO$_{2}$ concentration of 400 $\mu$mol mol$^{-1}$, and under elevated CO$_{2}$ concentration of 700 $\mu$mol mol$^{-1}$, at five nitrogen levels equivalent to 5, 25, 50, 75 and 100 kg N ha$^{-1}$. Five harvests were conducted over the growth period and measurements of leaf area index (LAI), biomass dry weight, nodule number, and seed yield at the final harvest were recorded. The results showed that, compared to the ambient control, elevated CO$_{2}$ led to a significant increase in LAI after flowering (+20–30%), biomass dry weight (+35%) and seed yield (+60%) from 1292.74 kg ha$^{-1}$ to 2639.55 kg ha$^{-1}$ at the lowest and highest N levels respectively. Moreover these values increased with increasing levels of nitrogen. Nodule number also increased under elevated CO$_{2}$ and the highest nodule number was observed at the nitrogen level equivalent to 50 kg N ha$^{-1}$ under ambient and 75 kg N ha$^{-1}$ under elevated CO$_{2}$. The average increase of nodule number for all treatments under elevated CO$_{2}$ was +52%. Examination of total nitrogen and phosphorus concentrations in the dry matter showed that the total uptake was higher under elevated CO$_{2}$ but due to the increases in biomass concentration levels were slightly lower. For all parameters, no significant interaction between CO$_{2}$ and nitrogen treatment was recorded

Effect of nitrogen on safflower physiology and productivity

Safflower (Carthamus tinctorius L.) is an oil-crop suitable for semi-arid agriculture, but its physiological response to agronomic inputs has yet to be fully evaluated. The effect of fertiliser on the physiology and production of safflower grown in pots filled with standard grade perlite inside a semi-controlled glass house was studied. Plants were initially irrigated with 20-100 ml standard hydroponic solution and then one month after germination plants were irrigated using 50-200 ml complete Hoagland’s solution, supplemented with one of eight levels of nitrogen (0, 25, 50, 75, 100, 125, 150, 175 kg N ha-1) in the form of ammonium nitrate. Elevating nitrogen to 100 kg N ha-1 significantly increased the assimilation rate by about 42 %, transpiration rate by 32%, stomatal conductance by 52% and LAI by 42% compared with the control. The above ground dry weight, seed yield and Water Use Efficiency (WUE) increased incrementally with increases in nitrogen rate. Above ground dry weight increased by an average of 42%, seed yield by 76% and WUE by 41% at harvest compared with the control. This study clearly demonstrates how nitrogen fertilisation can affect physiology of safflower leading to improvement in seed yield

Effect of elevated CO(2) and nitrogen levels on lentil growth and nodulation

Global carbon dioxide levels are rising, and could reach levels of 815 $\mu$mol mol$^{-1}$ by the year 2100. Since photosynthetic rate in C$_{3}$ species under the current levels of ambient CO$_{2}$ is still below physiological saturation levels, it is anticipated that photosynthesis and consequently productivity for most crops should be stimulated by the higher levels of atmospheric CO$_{2}$. A stronger response is expected in legumes as nitrogen is not considered as a limiting factor for growth. This study investigates the effect of elevated CO$_{2}$ and different nitrogen fertilizer levels on the growth and nodulation of lentils. Syrian lentil was grown under ambient CO$_{2}$ concentration of 400 $\mu$mol mol$^{-1}$, and under elevated CO$_{2}$ concentration of 700 $\mu$mol mol$^{-1}$, at five nitrogen levels equivalent to 5, 25, 50, 75 and 100 kg N ha$^{-1}$. Five harvests were conducted over the growth period and measurements of leaf area index (LAI), biomass dry weight, nodule number, and seed yield at the final harvest were recorded. The results showed that, compared to the ambient control, elevated CO$_{2}$ led to a significant increase in LAI after flowering (+20–30%), biomass dry weight (+35%) and seed yield (+60%) from 1292.74 kg ha$^{-1}$ to 2639.55 kg ha$^{-1}$ at the lowest and highest N levels respectively. Moreover these values increased with increasing levels of nitrogen. Nodule number also increased under elevated CO$_{2}$ and the highest nodule number was observed at the nitrogen level equivalent to 50 kg N ha$^{-1}$ under ambient and 75 kg N ha$^{-1}$ under elevated CO$_{2}$. The average increase of nodule number for all treatments under elevated CO$_{2}$ was +52%. Examination of total nitrogen and phosphorus concentrations in the dry matter showed that the total uptake was higher under elevated CO$_{2}$ but due to the increases in biomass concentration levels were slightly lower. For all parameters, no significant interaction between CO$_{2}$ and nitrogen treatment was recorded

Genotypic resistance to brown heart incidence in swede parent lines and F1 hybrids and the influence of applied boron

Breeding trials for swede (Brassica napus var. napobrassica) in 2000–2010 showed that 0·85 of the incidence of brown heart (BH) in the trials was associated with genotypes that are progeny of Ag31, Or13 and Me77c. In order to investigate this and the effect of treatment with boron (B), established varieties and improved parent lines carrying male sterility (ms), and their F1 hybrids (test hybrids), were grown in a field trial in the UK in 2011 and subjected to four B treatments (0·00, 1·35, 1·80 and 2·70 kg B/ha). The results confirmed that BH incidence andseverity was affected by genotype but could be ameliorated by B application. Genotype Ag31 was very susceptible while Or13 and Me77c were of intermediate susceptibility and the hybrids between susceptible parents were also sensitive. Genotypes Gr19 and Ly01 were highly resistant even in the absence of B application. Hybrids between resistant and susceptible lines were highly resistant. The use of ms had no influence on BH. Resistance to BH was a dominant trait: homozygous dominant (BHBH) or heterozygous (BHbh) genotypes confer this trait, while susceptibility is recessive (bhbh). Some quantitative variation existed, suggesting that resistance was not a single gene effect. There was a significant negative correlation (r=−0·632) between root B content and the severity of BH in susceptible genotypes. Severe BH was associated with 12–21·5 μg B/g of root dry weight at zero B applied. Moderate discolouration was associated with 19·5–24·8 μg B/g recorded at moderate B applied and only Ag31 showed BH at 2·70 kg B/ha. Resistant varieties had root contents of 23 μg B/g or more while susceptible varieties required a minimum of 31 μg B/g to offset BH