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81.
Water relations of the tomato during fruit growth   总被引:10,自引:5,他引:5  
Fruit and stem water potentials of tomato plants were measured continuously for several days using automated psychrometers. A linear voltage displacement transducer was used to simultaneously measure diameter changes on an adjacent fruit. A strong correlation was observed between the water potential gradient of the fruit and stem, and changes in fruit diameter. Fruit diameter increased when the apoplasmic water potential gradient favoured solution flow into the fruit and fruit shrinkage occurred only when the water potential gradient was inverted. Based on our data and other published data (Ehret & Ho 1986; Lee 1989a) on phloem transport in tomato, we have concluded that low stem water potentials have an immediate and direct effect on phloem turgor; reducing the driving force for sap flow into the fruit. Since fruit water potential remained relatively constant, the diurnal variation in stem water potential was sufficient to account for the correlation with changes in fruit diameter. There are consequences with respect to predicting the accumulation of dry matter in tomato fruit.  相似文献   
82.
After 10 days of infestation by the aphid Myzus persicae growth of radish seedlings was reduced by 38 %, and the volume of sap bleeding from the stumps of cut stems of infested seedlings was 4% of that exuding from the stumps of uninfested seedlings of the same age. Diminished bleeding could not be accounted for by the 52 % reduction in the weight of the roots of infested seedlings. After 14 days of infestation, necrotic patches developed along the veins of the cotyledons which yellowed noticeably. If freed of aphids the seedlings subsequently resumed growth and their was an increase in the volume of bleeding sap produced by their cut stems. Symptoms associated with aphid infestation cannot be attributed either to virus disease or initially to exhaustion of the seedling's carbohydrate and nitrogen reserves. Possible causes of the symptoms described are discussed.  相似文献   
83.
From 10°C to 25°C Sitobion avenae reared on wheat developed faster, had a higher mean relative growth rate and a higher intrinsic rate of increase on ears than on the flag leaves. At temperatures above 25°C there is a marked decline in the performance of the aphid. The intrinsic rate of increase is strongly correlated with the mean relative growth rate during development for both aphids reared on ears and flag leaves from 10°C to 25°C.  相似文献   
84.
Evidence has been sought for an interaction between native auxinand manganese in vivo by observing the effect of an excess ofmanganese on the growth and photosensitivity of etiolated oatseedlings. Intact plants were supplied with manganese via theirroots in conjunction with other growth-modifying treatments,glycine, ethanol, carbon dioxide, and nitrates. The data showthat neither growth nor photosensitivity was changed by theadditional manganese; consequently no evidence for the occurrenceof such an interaction was obtained.  相似文献   
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