Effects of Carbofuran on Availability of Macronutrients and Growth of Tomato Plants in Natural Soils and Soils Amended with Inorganic Fertilizers and Vermicompost

The effects of lower field rate (LFR), field rate (FR), and higher field rate (HFR) applications of carbofuran on ammonium (NH₄)-nitrogen (N), nitrate (NO₃)-N, available phosphorus (P), and available potassium (K) contents in natural soils and those amended with inorganic fertilizers and vermicompost on the growth of tomato plants were studied. The NH₄-N, NO₃-N, available P, and available K contents increased up to FR but the most significant increase in was observed at LFR of carbofuran application. At HFR there was a significant reduction in nutrient availability. With passage of time all these parameters increase up to 30 days; thereafter, a decrease was observed up to the end of the experiment in both unamended and amended soils. The greater plant growth was observed at LFR of carbofuran application and at HFR the plants exhibited phytotoxicity in the form of marginal leaf scorching in both systems. The morphological growth parameters of tomato plants were positively correlated with nutrients availability.     

1株低温地丝霉菌的鉴定及其分解角蛋白与纤维素特性

为筛选分解角蛋白与纤维素的低温菌株,从西藏当雄牧草地分离1株低温菌株,对其进行鉴定及部分生物学功能研究.形态学鉴定参照Oorschot的分类标准和系统进行,分子鉴定基于ITS1-5.8 SrDNA-ITS2序列进行分析.结果表明:确定该菌株为毡状地丝霉毡状变种(Geomyces pannorum var.pannorum(Link) Sigler & J.W.Carmich).其最低、最适、最高生长温度分别为5℃、15℃和30℃,在35℃时不能生长,可分解角蛋白和纤维素,有潜在应用价值.     

Reflectance-based assessment of spider mite “bio-response” to maize leaves and plant potassium content in different irrigation regimes

It is widely accepted that pest infestations elicit a change in plant physiology, which cause detectable changes in crop leaf reflectance. In this study, we test the hypothesis that crop leaf reflectance may also be used to forecast the risk of pest infestation before they actually occur. We collected reflectance data in 160 spectral bands from 405 to 907 nm from excised leaf pieces from field grown maize plants under 3 irrigation regimes. Leaf material was collected at weekly intervals in two growing seasons. The same leaf pieces were used in choice bioassays with carmine spider mites to assess attractiveness to mites (spider mite “bio-response”) across irrigation regimes. In one growing season, we also obtained nutritional element data (lipid, protein, soluble sugar, starch, lignin, Ca, P, Mg, K, S, and Cl) from whole maize plants. Principal component analysis showed that potassium content (K) was highly negatively correlated with spider mite bio-response. Relative reflectance at 740 nm showed a highly significant and positive trend across spider mite bio-response classes, and that potassium content showed a highly significant and negative trend across the same classes. Thus, we argue that relative reflectance at 740 nm may be used to predict both potassium content and risk of spider mite infestation. Based on extensive reviews, potassium leaf content is known to reduce susceptibility of crops to pests. The results presented provide encouraging support for remotely sensed risk assessment of pest infestations through reflectance-based monitoring of maize leaf attractiveness and highlight that reflectance based monitoring of crop susceptibility may be possible through careful management of macro element crop properties, such as potassium content.     

施钾对青引1号燕麦草产量及根系的影响

在缺钾地区，开展了不同施钾对青引1号燕麦（Avena sativa cv. Qingyin No.1）干物质产量和根系的影响，找出最佳施钾量，为青海省燕麦种子生产提供依据。结果表明，在施N 54.75 kg/hm2和施P2O5 51.75 kg/hm2的基础上，施K2O 40 kg/hm2，青引1号燕麦开花期收获时可获得最高的干物质产量和蛋白产量，分别为29575.0和2099.8 kg/hm2，二者均符合Y=a+bK+cK2函数变化。施K2O 40 kg/hm2，青引1号燕麦株高、总分蘖数、根长和根数最大，分别为184.5 cm、3.22个/株、15.90 cm和26.17 条/株； 施K2O 20 kg/hm2时，植株茎粗和根量达最大，分别为0.585 cm和0.540 g/株。各产量性状、地下生物量以及饲草和蛋白产量间均存在显著或极显著正相关关系。     

Short and long‐term distribution with depth of soil organic carbon and nutrients under traditional and conservation tillage in a Mediterranean environment (southwest Spain)

The impacts of tillage and cropping sequences on soil organic matter and nutrients have been frequently reported to affect the uppermost soil layers, but there is little published information concerning effects at greater depth. This article reports results on the distribution of soil organic carbon (SOC), active carbon (AC), N, Olsen‐P and extractable K within 100 cm in short (4 yr) and long (16 yr) term experiments under different tillage systems. Short (TT₄) and long (TT₁₆) traditional tillage are compared with conservation tillage, reduced (RT₁₆) and non‐tillage (NT₄). The results show more accumulation of SOC in the near‐surface under RT₁₆ and NT₄ in both experiments compared with traditional tillage. Moreover, greater C content occurs to 40 cm depth in the long‐term experiment. The results demonstrate the importance of time on C accumulation, not only in near‐surface layers but also at greater depths. Active C is an indicator of the increase in soil quality in the long‐term experiment. This trend is only apparent for the first 10 cm in the short‐term experiment. Patterns in N, Olsen‐P and extractable K are similar to that of SOC. However, only extractable K is significantly greater in soil under conservation tillage (RT₁₆ and NT₄) after short and long periods. Potassium availability is a good indicator of the changes caused by tillage. Our results indicate that studies of soils at depth could be very useful in long‐term experiments to demonstrate the effect of conservation tillage on C and nutrient distribution.     

氮钾配施对水稻空育131品质的影响

为了探究空育131的高产优质栽培的合理氮钾配施技术,试验采用随机区组设计,研究不同氮肥与钾肥互作对空育131品质的影响。结果表明:不同肥料处理对水稻碾磨品质、外观品质、营养品质及食味品质的影响显著(P0.05),不同肥料处理对水稻食味评分的影响均达到显著水平,且存在极显著的互作效应,氮钾互作下的食味评分以处理N_3K_4最高,即氮肥180kg·hm~(-2),钾肥135kg·hm~(-2)时为最佳配置,食味达到85.2分,较不施肥提高10.5%,差异达显著水平。     

Long-Term Effect of Fertilizer and Rice Straw on Mineral Composition and Potassium Adsorption in a Reddish Paddy Soil

Increasing K⁺ adsorption can be an effective alternative in building an available K pool in soils to optimize crop recovery and minimize losses into the environment. We hypothesized that long-term fertilization might change K⁺ adsorption because of changes in the chemical and mineralogical properties of a rice (Oryza sativa L.). The aims of this study were (i) to determine clay minerals in paddy soil clay size fractions using X-ray diffraction methods and a numerical diagram-decomposition method; (ii) to measure K⁺ adsorption isotherms before and after H₂O₂ oxidation of organic matter, and (iii) to investigate whether K⁺ adsorption is correlated with changes in soil chemical and mineral properties. The 30-yr long-term fertilization treatments caused little change in soil organic C (SOC) but a large variation in soil mineral composition. The whole-clay fraction (<5 μm) corresponded more to the fertilization treatment than the fine-clay fraction (<1 μm) in terms of percentage of illite peak area. The total percentage of vermiculite-chlorite peak area was significantly negatively correlated with the total percentage of illite peak area in the <5 μm soil particles (R=-0.946, P<0.0006). Different fertilization treatments gave significantly different results in K⁺ adsorption. The SOC oxidation test showed positive effects of SOC on K⁺ adsorption at lower K⁺ concentration (?120 mg L^?1) and negative effects at higher K⁺ concentration (240 mg L^?1). The K⁺ adsorption by soil clay minerals after SOC oxidization accounted for 60–158% of that by unoxidized soils, suggesting a more important role of soil minerals than SOC on K⁺ adsorption. The K⁺ adsorption potential was significantly correlated to the amount of poorly crystallized illite present (R=0.879, P=0.012). The availability of adsorbed K⁺ for plant growth needs further study.     

Pulverizing Soils for Laboratory Analysis

Soil-testing laboratories utilize a range of grinder types to pulverize soils for laboratory analysis. This study was conducted to evaluate the effects of soil particle diameter and laboratory subsample size on analysis variability on nitrate, Bray 1 extractable phosphorus (P), extractable potassium (K), and soil organic matter (SOM). Four soils collected for the Agricultural Laboratory Proficiency Program were pulverized using four types of commercial grinders and analyzed for particle-size distribution, P, and K. In a second study, soils were pulverized to pass sieves of 2.0, 1.0, and 0.50 mm and subsampled for P, K, and SOM. Results of the commercial grinders indicate a range in mean particle diameters from 0.15 to 0.60 mm, with the lowest for the grinder utilizing a hammer mill design. Sieve-size analysis results indicate that the coarsest 2.0-mm fraction had the largest variability for all soil analyses evaluated. Analyte variability decreased with decreasing sieve size. Mean Bray P, K, and SOM-LOI (Loss-on-Ignition) mean concentrations were not statistically significantly different across the sieve sizes evaluated. Laboratory analysis variability for extractable Bray P increased as subsample size was reduced.     

Impact of Variable Potassium on Metabolism,Oil, and Seed Quality of Groundnut

To study the impact of variable potassium (K) on biomass, economic yield, and role of K in groundnut (Arachis hypogeae L.) metabolism, plants were grown in refined sand at different levels of K, ranging from 0.5 to 16 mM. The concentration of K increased with increase in supply in all parts of groundnut. Both low (<4 mM) and excess (>4 mM) K increased the activity of peroxidase, ATPase, and acid phosphatase and decreased the concentration of chlorophyll in leaves significantly. Low (<4 mM) and excess (>4 mM) concentrations of K inhibited pod and kernel (seed) formation in groundnut. Potassium stress (both low and excess) deteriorated the quality of groundnut seed by decreasing the concentrations of starch, protein, and oil and increasing that of sugars in seeds. The activities of certain enzymes also altered in K stress in leaves and seeds of groundnut.