RESUMO
To meet future food needs, grain production must increase despite reduced water availability, so waterproductivity must rise. One way to do this is to raise the ratio of biomass produced to water transpired, which is controlled by the ratio of CO2 assimilation (A) to transpiration (E) (i.e. the transpiration ratio, A : E divided by vapour pressure deficit) or anything affecting stomatal movement.. We describe the genetic variation and basis of A, E and A : E among 70 recombinant inbred lines (RILs) of sorghum (Sorghum bicolor (L.) Moench), using greenhouse experiments. Experiment 1 used 40% and 80% of field capacity (FC) as water regimes; Experiment 2 used 80% FC. Genotype had a significant effect on A, E and A : E. In Experiment 1, mean values for A : E were 1.2-4.4 mmol CO2 mol-1 H2O kPa-1 and 1.6-3.1 mmol CO2 mol-1 H2O kPa-1 under 40% and 80% FC, respectively. In Experiment 2, values were 5.6-9.8 mmol CO2 mol-1 H2O kPa-1. Pooled data for A : E and A : E VPD-1 from Experiment 1 indicate that A : E fell quickly at temperatures >32.3°C. A : E distributions were skewed. Mean heritabilities for A : E were 0.9 (40% FC) and 0.8 (80% FC). Three significant quantitative trait loci (QTLs) associated with A:E, two on SBI-09 and one on SBI-10, accounted for 17-21% of the phenotypic variation. Subsequent experiments identified 38 QTLs controlling variation in height, flowering, biomass, leaf area, greenness and stomatal density. Colocalisation of A : E QTLs with agronomic traits indicated that these QTLs can be used for improving sorghum performance through marker assisted selection (MAS) under preflowering drought stress.
RESUMO
Device closure of atrial septal defect (ASD) is commonly performed in older children and adults. Infants and toddlers (age <4 years) are seldom referred for ASD closure due to size constraints. However, in many cases device ASD closure can be performed in this population. Between 2002 and 2012, 61 infants and toddlers were taken to the catheterization laboratory at our institution for ASD closure. Precatheterization transthoracic echocardiograms, intracatheterization transesophageal echocardiograms, and catheterization reports were reviewed. Fifty-three infants and toddlers presented for percutaneous ASD occlusion. Forty-eight (79 %) underwent successful closure, and 13 were referred for surgery without device attempt (n = 8) or after unsuccessful device occlusion (n = 4). Median age and weight at time of ASD closure were 2.99 years (range 0.3-3.8) and 11.7 kg (range 3.7-16.5). The device-to-septal length ratio was 0.81 (range 0.44-1.03). The 12 unsuccessful cases occurred in patients with larger defects (ASD diameter 17.5 ± 6.1 vs. 12.1 ± 4.2, p < 0.01). Deficient rims (absent or ≤ 4 mm) were seen in 9 of 12 (75 %) unsuccessful cases and in 19 of 41 (46 %) successful cases (p = 0.12). Multivariate analysis showed that patient size and ASD size were not independently associated with procedural success but that ASD size-to-patient weight ratio <1.2 (hazard ratio 9.5 [range1.7-17]) was associated with successful ASD closure. ASD device occlusion can be safely achieved in small children. An ASD size-to-patient weight ratio >1.2, not absolute patient weight or age, is associated with failure of the percutaneous approach. The midterm outcomes in these young patients are excellent.
