Dang H.,Chinese Academy of Forestry |
Li W.,Chinese Academy of Forestry |
Zhang Y.,Chinese Academy of Forestry |
Mo B.,Gansu Academy of Forestry
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012
Water amount stored in sapwood and its participation in sap flow cycle are considered to be one of the important mechanisms for trees' drought resistance. Based on monitoring the sap flux of Populus bolleana at crown base and stem base with thermal dissipation probe technique (TDP), combined with synchronous meteorological observation, this paper analyzed the relationship between sap flow fluxes and atmospheric evaporation potential (ET0) at two positions. Results showed that sap flow flux at crown base (Qu) was a reliable indicator for estimating sap flux of P. bolleana individuals. The average daily Qu in typical sunny days from June to September was (7. 61 ± 0. 65) L/d, which was higher than those in cloudy and overcast days by 0. 41 and 2. 71 L/d respectively. The sap flow flux in stem base (Qd), varied greatly in different seasons, was lower than Qu during the sunny days from June to August but reversed rapidly in late August following continuous rainfall, by which P. bolleana maintained water-balance and solved water deficit partly. After continued rainfall in late August, soil moisture improved effectively, so the percentage of nocturnal sap flux to total daily Qd reduced from 31. 98-35. 36% to 6. 72% -7. 99%, by which water deficit could be compensated effectively. P. bolleana have experienced water supplement (in June), loss (in July and August) and re-supplement (in September) processes during the whole growing season. ET0 was a reliable integrated variable for evaluating sap flow environment-driving effects which could be modeled well with Qu by Logistic equation, the modeled results showed that the maximum of Qu was 7. 82 L/d. When ET0 is more than 5 mm/d, Qu and Qd no longer increased, which is a kind of positive drought resisting strategy of Populus bolleana. The continuous rainfall in late August caused the ratio of transpiration to ET0 (T/ ET0) increased from 0. 32 to 0. 47, obviously, the improvement of soil moisture affected sap flux of P. bolleana significantly.
Dang H.-Z.,Chinese Academy of Forestry |
Li W.,Chinese Academy of Forestry |
Li Y.-H.,Chinese Academy of Forestry |
Mo B.-R.,Gansu Academy of Forestry
Forest Research | Year: 2012
The change of sap flow rate along axial direction of trunk is considered to be the important evidence that water storage is involved in internal sap flow circulation. Based on monitoring sap flow rate at both crown base and stem base of half-mature Populus bolleana Lauche during the main growth season with thermal dissipation probe technique (TDP), the relationship between sap flow rate (Js) at two typical position and atmospheric evaporation potential (ET0) obtained with synchronous meteorological elements was analyzed. It was found that the diurnal variation pattern of sap flow rate at both crown (Js,u) and stem bases (Js,d) were consistent with ET0 in typical sunny days, but the former had more close correlation with ET0, which fitted well with the Hill function formula, while that between the latter and ET0 presented linear relation with different slopes. At noon, Js,u could be three times of Js,d, and started about 1 hour earlier than the latter in the early morning. The "net" sap flux between Js,u and Js,d changed with season, and was in a slight water-lose status in July and August but a slight water-surplus in June and September instead. Daily total amount of absorbed water was not completely consistent with water loss of crown. The average daily sap flux computed by Js,u from June to September was in the sequence of sunny > cloudy > overcast, which was consistent with solar radiation and ET0, while sap flux computed by Js,d sometimes was cloudy > sunny, showing the traits of leveling water stress by accelerated water-absorption in cloudy days for mid-serious atmospheric stress.
Chai C.-S.,Gansu Academy of Forestry |
Lu J.,Gansu Academy of Forestry |
Cai G.-J.,Gansu Academy of Forestry |
Wang S.-Y.,Gansu Academy of Forestry |
And 3 more authors.
Forest Research | Year: 2013
19 phenotypic characters of fruit were investigated for 44 Xanthoceras sorbifolia Bunge. The phenotypic variation was studied by using variance analysis, correlation analysis and variation coefficient. The results of variance analysis and variation coefficient analysis showed that the phenotypic characters of fruit were significantly different among individuals of X. sorbifolia, and had great variation in test area. Among 19 phenotypic characters, the variations in fruit number and seed yield were the biggest among different X. sorbifolia individuals and all theirs variation coefficients were over 76%, followed by fruit weight, seed weight and kernel weight with the variation coefficient about 30%, the seed number per fruit and stalk length with variation coefficient over 20%, whereas the characters of seed length, seed width, seed shape index and number of ventricle had smaller variation and their variation coefficients were less than 10%, the least variation was the oil yield of seed kernel and its variation coefficient was only 6.13%, which showed there was evident differences in fruit-bearing capacity for individuals of X. sorbifolia, and had determinate hereditary stability. The correlation analysis results indicated that the correlation of various phenotypic characters of fruit had significant differences. Among them, the correlations of characters for fruit length, fruit width, fruit weight, seed weight, kernel weight, seed length, seed ratio, 1 000-seed weight and stalk diameter of fruit were strong, and significantly related to many phenotypic characters, whereas the characters of fruit shape index, kernel ratio of seed, fruit number and seed yield were only significantly related to a few phenotypic characters, but the correlation of characters for number of ventricle and stalk length was weak and hardly related to any phenotypic characters of fruit. The genetic diversity of fruit phenotypic characters and their significant differences among X. sorbifolia individuals would play an important role in its elite tree selection and breeding.