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Luo Z.-Z.,Gansu Agricultural University | Luo Z.-Z.,Gansu Key Laboratory of Aridland Crop Science | Li L.-L.,Gansu Key Laboratory of Aridland Crop Science | Niu Y.-N.,Gansu Key Laboratory of Aridland Crop Science | And 4 more authors.
Acta Prataculturae Sinica | Year: 2016

This study used dry and wet sieving methods to investigate the distribution and stability of soil aggregates, their mean weight diameter (MWD) and the percentage of aggregate destruction (PAD) in land that had been planted with alfalfa (Medicago sativa) for a range of different growth years (3, 10, and 12 years), and compares these results with those for cropland from a long-term experiment. The relationships between soil aggregates and both stability and soil organic carbon fractions were also studied. The results showed that soil aggregates had a "V"-shaped distribution under the different treatments. With dry sieving, the aggregates primarily involved small (<0.25 mm) and large (>5 mm) particle sizes, while with wet sieving they were dominated by <0.25 mm particles. The MWD of the alfalfa soils was significantly higher than that of the cropland soils at 0-10 cm depth. The PAD of alfalfa soils was significantly lower than that of cropland and it decreased with the increasing number of alfalfa growth years. Soil organic carbon fractions diverged greatly in the different treatments. The order of TOC (total organic carbon), HFOC (heavy fraction organic carbon) and ROOC (readily oxidized organic carbon) in 0-10 cm topsoil was 12 yrs>10 yrs>cropland>3 yrs, indicating that improvement in the organic carbon of alfalfa field topsoils is associated with the number of growth years. Correlation analysis returned the highest coefficients between water-stable aggregates and LFOC (light fraction organic carbon) and ROOC, suggesting that LFOC and ROOC rather than TOC play a vital role in maintaining soil aggregate stability on the Loess Plateau. Copyright © ACTA PRATACULTURAE SINICA. All rights reserved.


Lu J.-W.,Gansu Key Laboratory of Aridland Crop Science | Lu J.-W.,Gansu Agricultural University | Qiu H.-Z.,Gansu Key Laboratory of Aridland Crop Science | Qiu H.-Z.,Gansu Agricultural University | And 15 more authors.
Chinese Journal of Applied Ecology | Year: 2013

In 2010, a field experiment with potato (Solanum tuberosum) cultivar 'Xindaping' was conducted at the Dingxi Extension Center of Gansu Province, Northwest China, aimed to understand the accumulation and distribution patterns of dry matter (DM) and potassium (K) in the organs of potato plant in semi-arid rainfed areas. During the whole growth period of the cultivar, the DM accumulation in root, stem, and leaf all showed a unimodal curve, with the DM accumulation rate being leaf > stem > root, whereas the DM accumulation in whole plant and tuber was an S-curve. The maximum DM accumulation rate of the whole plant was higher than that of the tuber, and appeared 17 days earlier. The distribution of DM in different organs showed two turning points, i. e. , during the tuber formation (TF) period and the tuber growth (TG) period. During TF period, the DM accumulation was the greatest in leaf, followed by in tuber. The TF period was also the DM balance period, which occurred 90 days after emergence. Before the DM balance period, the DM accumulation in tuber was lesser than that in root, stem, and leaf, and there was a positive correlation between the DM accumulation in tuber and in root, stem, and leaf. However, after the DM balance period, the DM accumulation in tuber was greater than that in root, stem, and leaf, and the correlation was negative. At seedling stage and in TF period, TG period, starch accumulation period, and maturity period, the DM accumulation in whole plant was 5%, 30%, 60%, 4%, and 1%, while that in tuber was 0, 18%, 62%, 18%, and 2%, respectively. In the whole growth period, more than 50% of the DM was formed in TG period. The K concentration was the highest in stem and the lowest in tuber, though the K was mostly concentrated in root before the DM balance period. The K accumulation before the DM balance period was mostly in root, stem, and leaf, with the sequence of stem > leaf > root, but after the DM balance period, the K was mainly allocated in tuber, with >60% of the K accumulated in tuber in maturity period.


Han G.-J.,Gansu Key Laboratory of Aridland Crop Science | Han G.-J.,Gansu Agricultural University | Chen N.-L.,Gansu Key Laboratory of Aridland Crop Science | Chen N.-L.,Gansu Agricultural University | And 4 more authors.
Chinese Journal of Applied Ecology | Year: 2013

By using polyethylene glycol (PEG-6000) solution to regulate the water potential of tomato (Lycopersicon esculentum) rhizosphere to simulate water stress, this paper studied the dynamic changes of net photosynthetic rate, dark respiratory rate and CO2 compensatory concentration of detached tomato leaves in the process of photosynthetic induction. Under 1000 μmol·m-2·s-1 of light induction, the time required to reach the maximum net photosynthetic rate of water-stressed tomato leaves was shortened by 1/3, while the stomatal conductance was increased by 1.5 times, as compared to the non-stress control. Also, the light saturation point (LSP) of water-stressed tomato leaves was lowered by 65% to 85%, and the light compensation point (LCP) was increased by 75% to 100%, suggesting that the effective range of light utilized by tomato leaves was reduced. Furthermore, water stress decreased the maximum photosynthetic capacity of tomato leaves by 40%, but increased the dark respiration rate by about 45%. It was suggested that rapid water stress made the stomata of tomato leaves quickly opened, without initial photosynthetic induction stage. In conclusion, water stress could induce the decrease of plant light-energy use efficiency and potential, being the main reason for the decrease of plant productivity, and stomatal regulation could be the main physiological mechanism of tomato plants to adapt to rapid water stress.


Luo Z.-Z.,Gansu Agricultural University | Luo Z.-Z.,Gansu Key Laboratory of Aridland Crop Science | Li L.-L.,Gansu Key Laboratory of Aridland Crop Science | Niu Y.-N.,Gansu Key Laboratory of Aridland Crop Science | And 4 more authors.
Chinese Journal of Applied Ecology | Year: 2015

This paper investigated soil moisture in alfalfa (Medicago sativa) cropland with different growth years (1, 3, 8, 12 and 14 years) and discussed the optimum growth years of alfalfa on the Loess Plateau of central Gansu. The results showed that the soil moisture along 0-300 cm soil profile of alfalfa croplands with different growth years was obviously lower than that of the local soil stable moisture. The soil water contents in croplands with alfalfa that had grown for 12 and 14 years were only 9.2% and 7.1% of local soil stable moisture, respectively, which were even lower than the lower limit of alfalfa growth. The average soil dryness indexes along 0-300 cm soil profile in 1, 3, 8, 12 and 14 years alfalfa croplands were 125.4%, 30.5%, 18.4%, -34.2% and -83.3% respectively. The results indicated that soil dryness occurred to varying degrees with different growth years except croplands with alfalfa grown for 1 year. With the increase of growth years of alfalfa, the soil dryness intensity increased and the soil dryness rate decreased. According to the soil moisture and alfalfa productivity results in this study, it could be concluded that the optimum growth years of alfalfa are 8-10 years in semi-arid areas of the Loess Plateau. ©, 2015, Editorial Board of Chinese Journal of Applied Ecology. All right reserved.

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