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81.
82.
Rolf Stegmark 《Euphytica》1991,53(2):87-95
Summary A partially downy mildew resistant pea line was back-crossed to a susceptible cultivar with more pods per node and lower seed weight. Breeding lines with different degrees of infection in a greenhouse test were selected. These lines and the two parental lines were investigated in field trials and tested in the greenhouse for four generations. Significant genetic variation among lines was found for infection of seedlings in greenhouse tests, and infection of pods, pod set and seed weight in field-trials. Infection of seedlings in the greenhouse was correlated with infection of pods in the field. In greenhouse tests, the non-genetic variance component was large in comparison with the genetic component and a significant genotype trial interaction was found. Significant repeatability was obtained for downy mildew on seedlings and pods, number of pods per node and seed weight. An unfavourable correlation between susceptibility to downy mildew and number of pods per node was found. No single breeding line showed the ideal combination of good resistance, high number of pods per node and small seeds. However, one line showing better resistance than the susceptible parent, with smaller seeds and more pods per node than the resistant parent was found. The susceptible parent also carries some resistance factor that is not present in the resistant parent.  相似文献   
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Summary Grain filling rate in wheat (Triticum aestivum L. emend. Thell.) positively influences grain yield under a wide range of conditions. The effective utilization of this trait in breeding depends on an understanding of its genetic control. A study was, therefore, conducted to determine the genetic basis of grain filling rate in six crosses of wheat. Higher order genic interactions and/or linkage were important in the genetic regulation of grain filling rate (GFR) in the majority of crosses. Additive ([d]) and dominance ([h]) gene effects were important in the control of GFR in main ears (ME) and whole plant ears (WPE). Additive and additive × additive epistatic effects were the most important in the genetic control of GFR in last ears (LE). Location effects on genetic effects for GFR were significant (P < 0.05) in all ear types of some crosses except in ME. Genotype × environment interaction effects were important (P < 0.001) in LE and WPE.It was concluded that the inheritance of GFR is complex and is dependent on ear type. Breeding procedures that facilitate the exploitation of non-additive and additive gene effects were recommended for the genetic improvement of grain filling rate of wheat.  相似文献   
85.
The goal of this research was to study the introgression of the high regeneration capacity of Lycopersicon pimpinellifolium Mill line WV-700, in recalcitrant tomato cultivars (L. esculentum Mill cvs. Petomech, Santa Rita and VFN-8) using backcrossing. Hypocotyl explants of in vitro germinated seeds were cultivated in half strength MS medium supplemented with 5mg/l 6-BA to assess their shoot regeneration capacity. The apical shoot of the in vitro germinated seeds were cultured on a separate medium. Apical shoots from genotypes showing high regeneration rates were acclimated in a glasshouse and used as pollen donors for the next backcrossing. After four backcrossings, the material showed a similar mean fruit weight for the cultivated tomato and a high regeneration capacity similar to the wild species. It is shown that L. pimpinellifolium can be used with success as donor parent to introgress in vitro regeneration capacity to recalcitrant tomato cultivars. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
86.
Bioavailability of dietary folate might be impaired by the polyglutamate chain to which approximately 70% of dietary folates are bound. This chain must be removed enzymatically in the intestine before folate is absorbed as a monoglutamate. To increase formation of monoglutamate folate in vegetables, the vegetables were subjected to various processing treatments. Treatments included freezing (-18 degrees C, 16 h) and thawing (4 degrees C, 24 h) and hydrostatic high-pressure treatment (200 MPa, 5 min). Both freezing/thawing and high-pressure treatment increased the proportion of folate in the monoglutamate form in leeks, cauliflower, and green beans 2-3-fold. However, loss of total folate after these treatments was >55%. It is concluded that conversion of folate polyglutamate to the monoglutamate form in vegetables is possible by certain processing treatments. Potentially this could lead to vegetables with higher folate bioavailability. However, to prevent folate loss into processing water, processing in a closed system should be applied.  相似文献   
87.

The performance of lab-scale compostbiofilters for the purification of waste gasescontaining high (>70 mg m-3) ammoniaconcentrations was studied. When using fresh compostmaterial, no effect of inoculating the compostmaterial with a nitrifying culture was observed sincehigh elimination capacities (up to 350 gNH3 m-3 d-1) were obtained in both theinoculated and the non-inoculated biofilter. Due tothe physico-chemical interaction of NH3 with thecompost material at the start of the experiment, nomicrobiological start-up period was observed and highremoval efficiencies were obtained from the first dayon. Next to this, no NH3-toxicity was observedeven at concentrations up to 550 mg NH3 m-3.About 50% of the NH3-removal was found to benitrified, while the other 50% remained in thebiofilter as NH +4 . As a result of this, noacidification of the carrier material was observed andNH4NO3 accumulated in the biofilter. Due toosmotic effects, however, a complete inhibition innitrification and NH3-removal was obtained at ameasured NH4NO3-concentration in the compostmaterial of 6–7 g N kg-1, corresponding to acumulative NH3-removal in the biofilter of ±6000 g m-3. Finally, it was illustrated that theremoval of the odorant dimethyl sulfide (Me2S) ina Hyphomicrobium MS3-inoculated compostbiofilter is completely inhibited due toNH3-toxicity at a waste gas concentration of 100 mg NH3 m-3. Next to this, theNH +4 - and NO ?3 -concentrations inthe compost material that were shown to inhibit thenitrification, also strongly affected theMe2S-degrading activity of Hyphomicrobium MS3.

  相似文献   
88.
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It is well established that increasing soil bulk density (SBD) above some threshold value reduces plant root growth and thus may reduce water and nutrient acquisition. However, formation and elongation of maize seminal roots and first order lateral (FOL) roots in various soil layers under the influence of SBD has not been documented. Two studies were conducted on a loamy sand soil at SBD ranging from 1.25 g cm–3 to 1.66 g cm–3. Rhizotrons with a soil layer 7 mm thick were used and pre‐germinated plants were grown for 15 days. Over the range of SBD tested, the shoot growth was not influenced whereas total root length was reduced by 30 % with increasing SBD. Absolute growth rate of seminal roots was highest in the top soil layer and decreased with increasing distance from the surface. Increasing SBD amplified this effect by 20 % and 50 % for the top soil layer and lower soil layers, respectively. At the end of the experiment, total seminal roots attributed to approximately 15 % of the total plant root length. Increasing SBD reduced seminal root growth in the lowest soil layer only, whereas FOL root length decreased with SBD in all but the uppermost soil layer. For FOL, there was a positive interaction of SBD with distance from the soil surface. Both, increasing SBD and soil depth reduced root length by a reduction of number of FOL roots formed while the length of individual FOL roots was not influenced. Hence, increasing SBD may reduce spatial access to nutrients and water by (i) reducing seminal root development in deeper soil layers, aggravated by (ii) the reduction of the number of FOL roots that originate from these seminal roots.  相似文献   
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