DDT effects on certain ATP related systems in the peripheral nervous system of the lobster Homarus americanus

Effects of DDT (1,1,1-trichloro-2,2-bis-(p-chlorophenyl) ethane) on various ATP utilizing enzymes in the lobster peripheral nerve were studied. On the basis of inhibition by ouabain and DDT, four classes of ATPase enzymes were recognized. They are: (1) ATPase activity that is sensitive to both ouabain and DDT inhibition, or Type A, (2) ATPase activity that is sensitive to DDT inhibition only, or Type B, (3) ATPase activity that is sensitive to ouabain only, and (4) ATPase activity that is not sensitive to either ouabain or DDT. The Type A ATPase is considered to be a part of the total (Na⁺K⁺) ATPase enzyme associated with the electrogenic pump. The Type B ATPase consisted of an uncharacterized Na⁺, K⁺, and Mg²⁺ stimulated ATPase and includes also a small portion of Mg²⁺ stimulated ATPase. Ca²⁺ stimulated ATPase activity was also detected but was not significantly affected by DDT. Proteins with actomyosin-like properties were also recognized to be present, though this superprecipitation process was only slightly affected by DDT.Other systems studied include the transfer of (γ-³²P) ATP to endogenous proteins and added histone in the presence and absence of c-AMP. DDT generally stimulated the process of ³²P incorporation, while it inhibited a portion of the specific c-AMP dependent protein kinase activity.It was concluded from these studies that DDT has a potential to inhibit or otherwise interfere with a variety of enzymatic reactions that utilize ATP as a substrate. Of these systems, the Type B ATPase bore overall resemblance to the possible target for DDT.     

DDT inhibition of Ca-ATPase of the peripheral nerves of the American lobster

A Ca-ATPase highly sensitive to DDT has been found in peripheral nerves of lobster, Homarus americanus. The observed I₅₀ for this Ca-ATPase toward DDT is on the order of 10^?9M and has a low temperature quotien. The ATPase seems to work over a wide range of ATP concentrations. It is stimulated by Ca²⁺ (optimum 0.1 mM) and shows sensitivity to Na⁺ (optimum 20 mM) and K⁺ (optimum 20 mM) ions. The fact that it is highly sensitive to ruthenium red (I₅₀ = 10 μM) suggests that the enzyme is a Ca-ATPase and not a Mg-ATPase. Furthermore the enzyme is not a CaMg-ATPase, since the presence of Mg²⁺ along with Ca²⁺ ion is not required for its activity. DDT is found to inhibit the process of Ca²⁺ binding in the axonic membrane only in the presence of ATP. The evidence suggests the important role of the Ca-ATPase in regulating Ca²⁺ concentrations in the membrane. The possible significance of DDT inhibition of the ATPase is discussed.     

A comparison of DDT and its biodegradable analogues tested on ATPase enzymes in cockroach

Analogues of DDT (ethoxymethyl and methoxymethio derivatives) compared with DDT for their inhibitory action on the ATPase system from tissues of the cockroach, Periplaneta americana show similar, but less inhibitory effects. The mitochondrial (oligomycin-sensitive) Mg²⁺ ATPase activity from coxal muscle preparations was more sensitive to DDT than the two analogues; whereas, the muscle and nerve cord homogenates showed about equal sensitivity to the biodegradable analogues. The mitochondrial Mg²⁺ ATPase from nerve cord preparation was more sensitive to the three compounds than the Na⁺K⁺ ATPase activity. The significance of these results in relation to recent reports on the effect of DDT on Na⁺K⁺ ATPase is discussed.     

Promotion of norepinephrine release and inhibition of calcium uptake by pyrethroids in rat brain synaptosomes

A series of 25 pyrethroids were assessed for their effects on Na⁺-dependent norepinephrine release and on Ca²⁺ uptake in vitro using a crude rat brain synaptosomal preparation. The most effective pyrethroids required a concentration of 3–10 μM to promote norepinephrine release. Plotting release data versus lipophilicity (as log P) for each compound resulted in a parabolic curve with log P_opt being 5.4 for maximal release. The release promoted by most of the compounds assessed at 30 μM could not be or was only partially reversed by either tetrodotoxin or substituting choline for Na⁺ conditions which readily reversed the release promoting effects of veratridine. Thus, many pyrethroids, particularly those without the α-cyano group, did not display their expected effects on the Na⁺ channel in rat brain. When assessed at 5 μM, pyrethroids inhibited, had no effect, or caused increases in the amount of Ca²⁺ incorporated in the presence of ATP. The effectiveness of the various pyrethroids to inhibit Ca²⁺ uptake again displayed a parabolic relationship with log P_opt being 6.4. It was concluded that the variations in pyrethroid effects on norepinephrine release and Ca²⁺ uptake are not solely related to their particular chemical structures, but to lipophilicity. The effects of many pyrethroids on Ca²⁺ metabolism, particularly displacement of bound Ca²⁺, better explain the transmitter release promoting properties in vitro rather than a direct effect on the Na⁺ channel. No direct relationship between known toxicity to mammals and Ca²⁺ inhibition by pyrethroids was established.     

Interaction of insecticides with the Ca2+-pump activity of sarcoplasmic reticulum

The organophosphorus insecticides, parathion and azinphos (10^?5-10^?4M), significantly stimulate the Ca²⁺-pump activity of sarcoplasmic reticulum, while malathion has a limited effect. The rates of Ca²⁺ translocation and ATP hydrolysis are both stimulated and, apparently, the $\text{Ca}{}^{\mathrm{2+}}\text{ATP}$ ratio is improved. Parathion and azinphos maximally increase this ratio by 26 and 14%, respectively. The organochlorine compounds, DDT and aldrin, also stimulate the Ca²⁺ pump, and lindane has a reduced effect. These effects are smaller than those observed for parathion and azinphos. The order of effectiveness is similar to the toxicity of the compounds to mammals and can be described as follows: parathion > azinphos > DDT ≈ aldrin > malathion ≈ lindane.     

The sensitivity of mitochondrial Mg2+ ATPase to DDT and analogs at different temperatures

Oligomycin-sensitive (O-S) Mg²⁺ ATPase from American cockroach muscle was more sensitive to DDT, TDE, methoxychlor, and DDE at cool temperatures than at warm temperature, thus showing a negative temperature effect. In contrast, inhibition by acaricides dicofol, chlorfenethol, and Plictran shows a positive temperature effect. Oxidative phosphorylation in a mitochondrial preparation from cockroach coxal muscle was reduced by DDT, but the reduction was greater at a higher temperature (32°C) than at a cooler temperature (22°C). In addition, Na⁺K⁺ ATPase from cockroach nerve cord showed a positive temperature effect with DDT. The inhibition by DDT was much less on Na⁺K⁺ ATPase than on O-S Mg²⁺ ATPase. The negative temperature effect by DDT and analogs on O-S Mg²⁺ ATPase parallels toxicity effects on insects and fish as reported by numerous researchers. The results provide further evidence for this energy-regulating enzyme being a critical component in the biological action of DDT.     

Inhibition of calmodulin-dependent enzymes in rat brain by hexachlorocyclohexane

Ca²⁺ homeostasis is one of the major regulatory mechanisms operating in the nervous system, with calmodulin translating the Ca²⁺ message into cellular response. To check if hexachlorocyclohexane (HCH) acts as a calmodulin antagonist in the nervous system of rats, the in-vitro effect of HCH on calmodulin-dependent Ca²⁺-ATPase and cAMP-phosphodiesterase (PDE) in rat brain has been studied. In the membrane fraction from rat brain, a basal activity of Ca²⁺-ATPase was obtained in the absence of Ca²⁺. Inclusion of Ca²⁺ (1 mM) increased the enzyme activity by 70%. Further, addition of fluphenazine, a potent calmodulin antagonist, inhibited the Ca²⁺-dependent enzyme activity (IC₅₀ = 85 μM), demonstrating the calmodulin dependence of the enzyme activity. The Ca²⁺- and calmodulin-dependent Ca²⁺-ATPase was inhibited by HCH in a dose-dependent manner (IC₅₀ = 80–90 μM). Ca²⁺- and calmodulin-dependent cAMP-PDE from the cytosolic fraction of rat brain was inhibited by HCH (340 μM) by 79%. Addition of excess calmodulin reversed the inhibitory effects of HCH or fluphenazine on Ca²⁺-ATPase and cAMP-PDE, suggesting their direct interaction with calmodulin. By fluorescence interaction studies it has been shown that HCH interacts directly with calmodulin. These studies show that HCH may modulate the intracellular concentration of Ca²⁺ and cAMP, by decreasing the effectiveness of calmodulin towards its effector enzymes, resulting in an altered signal transduction in the nervous system.     

DDT and pyrethroids: Receptor binding and mode of action in the house fly

The mode of action of DDT and pyrethroids was investigated in the house fly, Musca domestica L, using drug:receptor binding techniques. Both in vivo and in vitro binding studies demonstrated the existence of membrane receptors which bind specifically to [¹⁴C]DDT and [¹⁴C]cis-permethrin. The receptors show properties to be expected of a critical target site of these insecticides. These include negative temperature correlation with binding, relatively nonsensitivity to DDE, and sensitivity to Ca²⁺. The receptor sites are readily saturated at 45–90 nM [¹⁴C]DDT and have an apparent disassociation constant (K_d) of 12.2 nM. The maximum number of binding sites was estimated to be 17 pmol DDT/mg membrane protein (0.34 pmol/house fly head). Competition studies showed DDT, cis-permethrin, and cypermethrin bind to the same receptor but not at precisely the same site. The addition of Ca²⁺ to the incubation buffer significantly inhibited the binding of both [¹⁴C]DDT and [¹⁴C]cis-permethrin, suggesting the receptor binding is Ca²⁺ sensitive and may have a role in ion conductance.     

The in vivo sensitivity of ATPases to DDT,DDE, and physical immobilization in American cockroaches

American cockroaches injected with sublethal doses of DDT (0.75 μg/roach) at 5-day intervals showed a 40% reduction in oligomycin-sensitive Mg²⁺ATPase from muscle homogenates, and a 23% reduction of Na⁺-K⁺ATPase from nerve cords. Thus, the maximum effect measured occurred with the same enzyme and tissue as determined from in vitro studies. The metabolite, DDE, used at 15 μg per roach, gave no significant change in activity of the ATPase system following injection. In contrast, high single doses of DDT (7.5 μg/roach) and 100 μg DDE and dicofol per roach caused over 30% increase in oligomycin-sensitive Mg²⁺ATPase of muscle and a 10–15% increase in Na⁺-K⁺ATPase of nerve cords measured 24 and 48 hr later. While a similar response was observed for Mg²⁺ATPase activities in cockroaches that were immobilized, the increase in enzyme activities were much greater than that caused by the pesticides.     

Action of deltamethrin on the calcium/calmodulin-dependent protein kinase from the rat brain

The action of deltamethrin on the calcium/calmodulin-dependent protein kinase (CaM-Kinase II) and phosphatase system in the rat brain synapse was studied under various experimental conditions to optimize these enzyme activities and to facilitate the studies of the mechanism of interaction of this pesticide with several components of this enzyme system. To obtain a clear-cut inhibition of this enzyme by deltamethrin the following conditions must be met: (a) the enzyme system should be purified by precipitation with ammonium sulfate (450 g litre^?1) prior to the addition of deltamethrin, (b) both Ca²⁺ and calmodulin (CaM) should be added to the incubated media before the addition of [y-³²P]ATP, (c) deltamethrin should be incubated at least 10 min (but less than 30 min) with the enzyme system before [y-³²P]ATP addition, (d) the incubation temperature should be above 20°C (optimum 30°C), (e) [y-³²P]ATP concentration should be in the order of 10^? M (concentration adjusted using cold ATP), and (f) the incubation time with [y^?P]ATP for incorporation of ³²P into the protein should be in the neighborhood of 60 s. Under these conditions, the inhibitory potency of various active and inactive isomers or analogs of pyrethroids and DDT was tested. The order of the inhibitory power of these active forms of pesticides was 1 R-deltamethrin > (S)(RS) fenvalerate ≥ p,p′-DDT. Other compounds were not active at the concentration tested, indicating the differential sensitivity of this enzyme and the existence of a correlation of inhibitory power to insecticidal activity.     

不同灌水处理对滨海盐碱地土壤阳离子组成及玉米干物质累积的影响

采用田间试验对不同灌水处理灌水后玉米地（天津滨海盐碱地）0~60 cm土层土壤K⁺/Na⁺、Ca²⁺/Na⁺及玉米干物质累积量进行研究,共设计4个处理,分别为LI₁₀（常规滴灌,灌水10 mm）、LI₂₀（常规滴灌,灌水20 mm）、FI₁₀（膜下滴灌,灌水10 mm）和FI₂₀（膜下滴灌,灌水20 mm）。结果表明：灌水后不同灌水方式下灌水量较大的处理0~60 cm各土层K⁺/Na⁺均大于灌水量较小的处理,且均表现出0~20 cm土层K⁺/Na⁺较大,40~60 cm土层K⁺/Na⁺较小;相同灌水量下膜下滴灌处理0~60 cm各土层Ca²⁺/Na⁺均较大,灌水后不同灌水处理0~60 cm各土层Ca²⁺/Na⁺差异较小,变化范围为0.10~0.22;FI₂₀处理0~20 cm土层K⁺/Na⁺和Ca²⁺/Na⁺大于其他处理,分别达到0.78和0.22;随着灌水次数的增多,LI₂₀和FI₁₀处理0~20 cm土层K⁺/Na⁺和Ca²⁺/Na⁺均逐渐增大,LI₁₀处理则均逐渐减小;灌水后各处理之间0~60 cm各土层K⁺/Na⁺和Ca²⁺/Na⁺差异均达显著水平;全生育期干物质累积量与其对应的0~20 cm土层（K⁺/Na⁺）/Ca²⁺二次拟合相关系数均达0.90以上,相同（K⁺/Na⁺）/Ca²⁺下,FI₂₀处理干物质累积量始终最大,LI₁₀处理始终最小;（K⁺/Na⁺）/Ca²⁺>1.72时,各处理干物质累积量均随（K⁺/Na⁺）/Ca²⁺的增大而增大。     

塔里木河流域水化学组成分布特征

于2010年6月对塔里木河干流及主要支流地表水进行水化学采样,共设25个点采集50个样品。分析表明：塔里木河干流水体中阳离子Na⁺+K⁺＞Ca²⁺＞Mg²⁺,与南北侧支流Na⁺+K⁺＞Mg²⁺＞Ca²⁺存在显著差异,但均以Na⁺+K⁺为主,阳离子浓度分别占干流、南北侧支流的68.6%、62.6%和62.5%。与1965年对应采样点同月份水化学成分相比,塔里木河流域主要可溶性离子浓度增幅较大,整体平均增加8.0倍,尤其是Cl^-达21.7倍,这可能是近年来塔里木河流域气温上升降水增加等自然因素,间接促进降水过程中水化学侵蚀地表可溶性物质所致。同时,流域内工农业快速发展,生活污水、工农业废水大量排放到塔里木河,这可能是影响塔里木河水质变化的重要因素之一。     

Effect of temperature on toxicity of pyrethroids and endosulfan, activity of mitochondrial Na-K-ATPase and Ca-Mg-ATPase in Chilo suppressalis (Walker) (Lepidoptera: Pyralidae)

The toxicity of deltamethrin, bifenthrin, and endosulfan to the fourth-instar larvae of rice stem borer, Chilo suppressalis (Walker), was measured at 17, 27, and 37 °C. The three insecticides all displayed a positive temperature coefficient between 17 and 37 °C. The temperature coefficients of deltamethrin, bifenthrin, and endosulfan were 5.59, 1.68, and 2.85, respectively. However, temperature coefficients of deltamethrin and bifenthrin between 17 and 27 °C and between 27 and 37 °C varied. The inhibition of the above three insecticides to mitochondrial Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase from the fourth-instar larvae of rice stem borer was determined at 17, 27, and 37 °C. The inhibition of deltamethrin to the specific activities of Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase showed a negative temperature coefficient, but endosulfan exhibited a positive temperature coefficient. Inhibition of bifenthrin exhibited the contrary temperature coefficients between Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase and a negative temperature coefficient for the former and a positive temperature coefficient for the later.     

3种盐胁迫对玉米幼苗生长及叶片抗氧化酶和离子累积的影响

选取2个玉米品种(金玉819和金单999),探讨了3种盐胁迫(NaCl、Na_2SO_4和NaNO_3)对玉米幼苗生长、抗氧化酶活性以及叶片中K~+、Na~+、Ca~(2+)累积的影响。结果表明:3种不同类型的盐胁迫均会导致玉米幼苗鲜重下降,地上部鲜重金玉819下降超过28.6%,金单999下降超过18%;盐胁迫下金玉819叶片SOD酶活上升2.1倍以上, POD酶活性最高上升4.5倍,APX最高上升2.1倍,CAT最高上升2.2倍;金单999叶片SOD酶活最高上升2.1倍,APX最高上升1.6倍,CAT最高上升1.9倍。2个基因型玉米胁迫下叶片内Na~+含量上升4.5～6.3倍;NaCl和NaNO_3处理下,K~+/Na~+比对照降低90%～93%,而Na_2SO_4处理下K~+/Na~+下降78%～82%,金玉819和金单999的Ca~(2+)/Na~+比对照分别降低了85%～90%和92%～94%。综合分析表明NO~-_3引起的次生盐害对玉米生产危害较大。与金单999相比,金玉819对盐胁迫更加敏感,相同Na~+浓度处理下,金玉819的鲜重和SOD酶活性下降显著且拥有较低的K~+/Na~+和Ca~(2+)/Na~+值。     

Calcium and calmodulin may not regulate the disease resistance and pisatin formation responses of Pisum sativum to chitosan or Fusarium solani

No correlation was found between the chitosan or Fusarium solani-induced disease resistance responses in pea pod tissue and fluctuations in [Ca²⁺], inhibition of calmodulin, blockage of Ca²⁺ channels or host membrane leakage. Addition of exogenous Ca²⁺ 3 h before or after chitosan or F. solani treatments of pea pod tissue failed to alter the host response within 6 h, the time when the host actively resists both the compatible (F. solani f. sp. pisi) and incompatible (F. solani f. sp. phaseoli) macroconidia. Additionally, Ca²⁺ applied exogenously 3 h before or after chitosan significantly altered the level of UV-absorbing material released from the host tissue; however, it failed to affect the chitosan's ability to elicit phytoalexin formation by 24 h. Addition of exogenous Ca²⁺ 3 h before or after inoculation with either the compatible (f. sp. pisi) or incompatible (f. sp. phaseoli) fungi did not significantly change the host response by 24 h. The addition of EGTA or Ca²⁺ channel antagonists with the chitosan treatments also failed to significantly alter the chitosan-induced host response, thereby suggesting that chitosan probably does not function in the pea system by causing a Ca²⁺ influx into the host tissue which might then activate the host's resistance response. Inhibition of calmodulin related activities by calmidazolium failed to inhibit the chitosan or fungal induced host response. These results suggest that the response(s) induced in pea pod tissue by chitosan treatment or fungal inoculation may not be mediated by Ca²⁺, calmodulin or membrane leakage.     

DDT and sodium transport in the eel electroplaque

DDT inhibits the ATPase activity of the intact eel electroplaque. At a concentration of 10^?5M, DDT inhibited 46% of the total ATPase activity, and 10^?4M DDT inhibited 62% of the total ATPase activity and 62% of the ouabain-sensitive ATPase activity. The latter concentration of DDT reduced the rate of Na efflux from intact electroplaques and slowed the rate of recovery of the membrane potential following a large depolarization produced by carbamylcholine application. Repetitive direct stimulation of the innervated membrane at 10 Hz during the application of 10^?4M DDT produced a significant irreversible depolarization. Ouabain, 10^?4M, produced similar effects. The possible role of the inhibition of active NaK transport in producing the symptoms of DDT poisoning is discussed.     

Ion flux kinetics in blue light‐grown field dodder (Cuscuta campestris) seedlings

Previous studies have revealed that blue light stimulates coiling and prehaustoria development in young de‐etiolated dodder seedlings prior to host attachment. In this study, the Ca²⁺ and H⁺ flux kinetics that are associated with blue light‐mediated coiling and prehaustoria development in de‐etiolated dodder seedlings were measured uninvasively using the ion‐selective, vibrating microelectrode ion flux system. The findings showed that blue light induces rapid transient changes in the net Ca²⁺ and H⁺ fluxes. A clearly pronounced lag of about several minutes was observed between the blue light‐induced changes in the Ca²⁺ and H⁺ fluxes, with H⁺ being a leading ion. The addition of 1 mol L^?1 vanadate, a known blocker of the plasma‐membrane H⁺‐ATPase, to the bathing solution completely prevented both the H⁺ and the Ca²⁺ flux responses and inhibited coiling and prehaustoria development, suggesting a causal relationship between the blue light‐induced changes in the net Ca²⁺ and H⁺ fluxes and seedling movements. It is concluded that the plasma‐membrane H⁺‐ATPase plays a key role in a dodder's parasitic mode of growth and its adaptive response to the environment.     

Two CaMK genes with different biochemical characteristics exist in Magnaporthe oryzae

Two types of Ca²⁺/calmodulin-dependent protein kinase (CaMK) were found in Magnaporthe oryzae. MgCaMK1 and MgCaMK2 were both cloned and sequenced. High similarities in amino acid sequence to other reported CaMKs in fungi suggested that CaMKs were relatively conserved. Both MgCaMK1 and MgCaMK2 have a serine/threonine protein kinase active site and a calmodulin (CaM)-binding domain. Southern blot analysis showed that MgCaMK1 or MgCaMK2 existed as a single copy in the M. oryzae genome. Subsequently, MgCaMK1 or MgCaMK2 was expressed in Escherichia coli BL21 via a pET-32a (+) plasmid. The purified proteins exhibited protein kinase activity. The autophosphorylation and substrate phosphorylation of MgCaMK1 exhibited a Ca²⁺/calmodulin-dependent manner, and suggested that it belonged to the group of Ca²⁺/calmodulin-dependent protein kinases. However, the autophosphorylation and substrate phosphorylation of MgCaMK2 exhibited a Ca²⁺-dependent manner and suggested that it belonged to the group of Ca²⁺-dependent protein kinases.     

Effect of salinity on tissue nutrient contents of the four dryland tree species of Indus flood plains

Salinity is a common issue of semi-arid and arid lands rendering them unfit for agriculture. Saline wastelands can be converted into productive ecosystems by rehabilitating them with salt tolerant native tree species. The objective of this work was to study the effect of NaCl salinity on tissue nutrient contents of the four dryland tree species. Saplings were grown in pots under nonsaline and high salinity conditions. After eighteen weeks the plants were harvested and their tissue nutrient contents were analyzed. Results revealed that all species accumulated high amounts of Na⁺ under saline conditions, while concentrations of N, P and Mg²⁺ decreased in their tissues. Concentrations of K⁺ and Ca²⁺ showed more variable trend in various tissues in response to increase in soil salinity. Na⁺: K⁺ ratios of roots (1.57), stems (1.27), and leaves (1.66) of salinized Salvadora oleoides plants were lowest among all the four species. Root Na⁺: K⁺ ratio of salinized plants was significantly higher for Prosopis cineraria (7.10), while these ratios for stem (1.85) and leaf (3.42) were highest for Tamarix aphylla. Plants of P. cineraria showed lowest Stem-Na⁺/root-Na⁺ ratio (0.30) when subjected to salinity. Results showed that salinity induces nutrient deficiency in all species. Salinity tolerance of these species can be attributed to their ability to (i) restrict translocation of Na⁺ from roots to stem; (ii) keeping low tissue Na⁺: K⁺ ratios; and (iii) selectivity of K⁺ and Ca²⁺ over Na⁺, and can be used for the screening of salt-tolerant ecotypes for the rehabilitation of saline wastelands.     

微咸水离子组成对膜下滴灌土壤孔隙结构的影响

为探讨不同阳离子组成微咸水灌溉对膜下土壤孔隙结构的影响,开展2a田间定位试验,设置当地地下水灌溉（CK）、NaCl微咸水灌溉（T1）、KCl微咸水灌溉（T2）、CaCl₂微咸水灌溉（T3）、MgCl₂微咸水灌溉（T4）5个处理,利用CT扫描技术研究不同阳离子组成微咸水对土壤孔隙结构的影响。结果表明：与CK处理相比,随灌水次数增多,添加Na⁺处理的土壤大孔隙度显著降低,添加K⁺、Ca²⁺、Mg²⁺处理的土壤大孔隙度显著增加,2022年添加Na⁺处理的大孔隙度平均降低了44.49%,添加K⁺、Ca²⁺、Mg²⁺处理的土壤大孔隙度平均分别增加了5.73%、80.73%、25.75%;在2021—2022年期间,与CK相比,4种不同阳离子处理土壤孔隙成圆率均呈增加趋势,其中添加Ca²⁺、Mg²⁺处理增加显著,土壤孔隙成圆率平均增加区间分别为25.52%~30.94%、17.46%~23.19%;连续灌溉2a之后,添加Na⁺和K⁺处理的土壤开裂程度加重,土壤稳定性变差,而添加Ca²⁺和Mg²⁺对改善土壤结构、提高土壤入渗性能作用明显。