日光温室有机基质栽培番茄盛果期的光合特性

研究了日光温室有机基质栽培番茄盛果期的光合特性.试验结果表明,有机生态型栽培与土壤栽培番茄功能叶净光合速率在10:00～16:00差异显著;叶片光合速率日变化均呈单峰曲线,没有午休现象,峰值均出现在12:00左右,净光合速率最高值分别为12.00 μmol·m-2·s-1和9.04 μmol·m-2·s-1.     

不同光照下丁香属的光合生理特性研究

以不同品种丁香属植物为试材,采用便携式光合测定系统,研究了不同光照对丁香光合生理的影响,并测定了6种丁香的光响应曲线。结果表明:全光照下,布氏丁香和红丁香的净光合速率呈现双峰变化曲线,平均净光合速率比在庇荫条件下高出20倍以上。全光照下,光能利用效率和水分利用效率的高峰值出现在6:00和16:00,庇荫条件下,则是10:00—14:00光能利用效率最高,10:00左右水分利用效率出现高峰值。蒸腾速率的日变化与净光合速率存在明显的相关性,全光照下气孔开度显著高于遮荫条件下。光补偿点为52~90μmol·m-2·s-1;光饱和点在800~1 400μmol·m-2·s-1,也说明丁香属为阳性植物。不同丁香种类的光合能力,以什锦丁香最高,最大净光合速率达20μmol·m-2·s-1;小叶丁香最低约8μmol·m-2·s-1;朝阳丁香、北京丁香、垂丝丁香和四川丁香在13μmol·m-2·s-1左右。     

白及不同月份光合作用比较研究

以白及为试材,采用Li-6400便携式光合仪,研究比较了白及在6月份、8月份及10月份的光合日变化。结果表明:白及光合速率日变化曲线都有午休现象,其中6月份的光合速率最高,9:00出现峰值,为8.1μmol·m-2·s-1;8月份的光合速率也在9:00最高,为5.81μmol·m-2·s-1,10月份的光合速率整体都很低,平均为3.31μmol·m-2·s-1。相关性分析结果显示,6月份及10月份光合速率与光合有效辐射、气孔导度呈正相关,影响光合速率的因素气孔因子占主导地位。     

高温强光对花叶蔓长春花生理指标的影响

于2009年4月和8月对花叶蔓长春花的色素、光合和荧光参数的变化进行测定。结果表明:花叶蔓长春花的总叶绿素含量相对较高,不同叶位间成熟叶片的叶绿素含量相差不大。花叶蔓长春花为强阳性植物,光补偿点为16μmol.m-2.s-1,光饱和点为652μmol.m-2.s-1,最大的光合速率为6.470μmol.m-2.s-1,呼吸速率为0.923μmol.m-2.s-1;其CO2补偿点为57.6μmol.m-2.s-1,CO2饱和点为691.2μmol.m-2.s-1。花叶蔓长春花的净光合速率的日变化在4月份呈现出单峰曲线,最大值为6.1μmol.m-2.s-1,出现在12:00;8月份净光合速率的日变化呈现出双峰曲线,最大值分别出现在12:00点和14:00点,其最大值分别是6.2和6.1μmol.m-2.s-1。高温强光虽然对花叶蔓长春花有一定的影响,荧光产量增加,表现为Fo、Fm、Fo’和Fm’值增加;电子传递速率ETR值下降;PSⅡ实际的光化学量子效率ΦPSⅡ下降;但是整体变化幅度较小。花叶蔓长春花能适应8月23日平均气温为32℃,最高光强达2 130μmol.m-2.s-1的高温强光,也与净光合速率的日变化、光饱和点的测定数据相一致。     

设施杏梅光合特性研究

试验采用TPS便携式光合测定仪,对塑料大棚中龙亭杏梅的光合特性进行了研究.结果表明:龙亭杏梅的净光合速率日变化呈典型的双峰曲线.第一次高峰出现在9:00时左右,Pn为5.42CO2μmol·m-2·s-1;第二次高峰出现在14:00时左右,Pn为3.27CO2μmol·m-2·s-1;最低点出现在12:00时左右,Pn为2.14 CO2μmol·m-2·s-1,"光合午休"现象明显.光照和CO2浓度是影响大棚内杏梅Pn的重要环境因子.Gs日变化与Pn日变化呈明显正相关关系,而Ci和Pn日变化在15:00时以后呈相反趋势,为非气孔因素所致.PAR和环境中CO2浓度通过改变气孔导度影响Pn的日变化.     

高温强光对双荚决明的影响及其园林应用

对双荚决明的色素、光合和荧光参数的高温强光下的变化进行了测定研究。结果表明:双荚决明的总叶绿素含量相对较高,不同叶位成熟叶片的叶绿素含量相差不大。双荚决明为强阳性植物,其光补偿点为12μmol.m-2.s-1,光饱和点为632μmol.m-2.s-1,最大的光合速率为5.840μmol.m-2.s-1,呼吸速率为0.819μmol.m-2.s-1;其CO2补偿点为70.4μmol.mol-1,CO2饱和点为883.2μmol.mol-1。双荚决明的净光合速率的日变化在4月份呈现出单峰曲线,最大值为4.6μmol.m-2.s-1,出现在12:00;8月份净光合速率的日变化呈现出双峰曲线,最大值分别出现在12:00时和14:00时,其最大值分别是4.2和4.6μmol.m-2.s-1。高温强光虽然对双荚决明的一定的影响但是整体变化幅度较小。双荚决明能适应8月23日平均气温为32℃,最高光强达2 130μmol.m-2.s-1的高温强光,也与净光合速率的日变化、光饱和点的测定数据相一致。根据测定的结果,建议双荚决明在园林中的主要应用形式为中篱、丛植、片植、高速公路或铁路边坡绿化和剪成球形观赏。     

蒲公英光合特性的研究

应用CIRAS-2型便携式光合作用测定系统研究了蒲公英叶片的净光合速率日变化及光合作用对光强和C02的响应.结果表明:蒲公英的净光合速率日变化呈双峰变化趋势,有"光合午休"现象,且光合最大值出现在上午11:00;气孔导度(Gs)和细胞间隙CO2浓度(Ci)是蒲公英光合作用日变化中最重要的影响因子.蒲公英的表观量子效率(AQy)为0.0267,光补偿点(LCP)和饱和光强(5L)分别为91.78 μmol·m-2·s-1和1438μmol·m-2·s-1,羧化效率(CE)为0.0522,CO2补偿点(CCP)和饱和CO2(SC)分别为38.23μmol·mol-1和1190/μmol·mol-1.     

“绿宝”苹果光合特性及主要影响因子研究

以6年生"绿宝"苹果为试材,用CI-340光合仪(美国)测定其光合指标,以了解"绿宝"苹果的光合特性。结果表明:净光合速率(Pn)季节变化呈双峰曲线,9月为最高峰,6月为次高峰;Pn日变化呈单峰曲线,10:00—11:00的Pn最高为24μmol·m-2·s-1;光补偿点和饱和点分别为44.363、1 978.074μmol·m-2·s-1,表观量子效率(AQY)为0.038 7;CO2补偿点和饱和点分别为184.58、1 528.58μmol/mol,羧化效率(CE)为0.093 6。影响"绿宝"苹果净光合速率的主成分有3个,分别为气孔导度(C)因子、有效光合辐射(PAR)因子和叶绿素(Chl)含量因子。试验表明,"绿宝"苹果具有较高的光合能力。     

盐胁迫下白蜡和小胡杨光合生理日变化的响应研究

以小胡杨、白蜡盆栽苗木为试材,分析其在不同盐分浓度下的光合速率、蒸腾速率、气孔导度等光合生理特征的日变化动态。结果表明:在轻度盐浓度下,白蜡的光合速率、蒸腾速率、气孔导度日变化均呈单峰型,而小胡杨则呈双峰型,白蜡和小胡杨的光合速率最大值均出现在8:00～10:00之间,白蜡的最大值为CO29.4364μmol.m-2.s-1,低于小胡杨的CO216.304μmol.m-2.s-1,但二者的水分效率相接近;在中度盐浓度下,白蜡光合速率日变化由单峰型变为双峰型,小胡杨则仍为双峰型,白蜡光合速率最大值仍出现在8:00～10:00之间,而小胡杨则出现在14:00～16:00之间,白蜡的最大光合速率为CO25.6575μmol.m-2.s-1,比轻度盐胁迫的下降了40%,小胡杨为CO24.352μmol.m-2.s-1,比轻度盐胁迫的下降了73.3%,二者水分利用效率也基本接近。     

芍药‘粉玉奴’与野生种主要光合特性的比较

以芍药栽培品种‘粉玉奴’和野生种为试材,对二者主要光合特性进行了比较研究。结果表明:‘粉玉奴’和野生种的净光合速率(Pn)日变化均为"单峰型"曲线,峰值均出现在10:00左右,且在全天变化中,野生种的光合速率始终高于‘粉玉奴’;野生种的光饱和点(LSP)和光补偿点(LCP)分别为889.23μmol.m-2.s-1和53.28μmol.m-2.s-1,‘粉玉奴’LSP和LCP分别为519.86μmol.m-2.s-1和60.34μmol.m-2.s-1,野生种对强光的耐受能力和对弱光耐受能力较‘粉玉奴’强;‘粉玉奴’叶片叶绿素a(Chla)、叶绿素b(Chlb)及叶绿素总量(Chla+b)均高于野生种,叶绿素含量差异不是造成二者光合能力差异的主要因素。     

Ergebnisse der Leistungsprüfungen der Süßkirschensorte ‚Stella‘ auf Gisela- und Weiroot-Unterlagen in Bulgarien

Zusammenfassung Die Leistungsprüfungen wurden im Zeitraum 1997 bis 2003 mit den Unterlagen Gisela 4 und 5, den Klonnummern 195/20 und 497/8 aus der Gisela-Serie sowie Weiroot 10, 13, 53, 72 und 158 durchgeführt. Dabei dienten Sämlinge von P1 (bulgarische Selektion aus Prunus mahaleb) als Kontrolle. Alle Unterlagen waren mit der Sorte Stella veredelt und im Dezember 1996 in der Versuchsanlage der Agraruniversität in Plovdiv, Bulgarien, im Abstand von 6 m×4,5 m gepflanzt worden. Dabei erfolgte ein Pflanzschnitt. Nach Abschluss der natürlichen Kronenentwicklung wurde jedes Jahr ein Winterschnitt vorgenommen. Der Boden wurde durch mechanische Bearbeitung offen gehalten und nach dem 4. Standjahr wurden die Baumstreifen mit Herbiziden behandelt. Die Wasserversorgung erfolgte durch eine dem natürlichen Gefälle folgende Überflutung, allerdings nicht immer zum optimalen Zeitpunkt, da keine eigene Wasserquelle zur Verfügung stand.Basierend auf den Ergebnissen bis zum Anfang des 7. Standjahres können die untersuchten Unterlagen in zwei Gruppen differenziert werden: starkwüchsig—Weiroot 10, P1 und Weiroot 13; mittelstarkwachsend bis schwachwüchsig—Gi 497/8, Gisela 4, Weiroot 53, Weiroot 158, Gi 195/20, Weiroot 72 und Gisela 5. Letztere zeichnete sich durch besondere Schwachwüchsigkeit aus. Die meisten Wurzelschosser bildeten Gisela 4, Weiroot 10 und Weiroot 13. Weiroot 53, Weiroot 72 und Weiroot 158 entwickelten deutlich weniger und P1, Gisela 5, Gi 195/20 sowie Gi 497/8 keine Wurzelschosser. Den frühesten Blühbeginn induzierte Gisela 4. Die anderen Unterlagen führten, in Abhängigkeit von den Temperaturbedingungen des jeweiligen Jahres, zu einer Verspätung der Blüte: P1 und Weiroot 10 um 1–2 Tage; Gi 497/8, Weiroot 13 und Weiroot 158 um 2–4 Tage; Weiroot 72 um 2–7 Tage; Gi 195/20 um 3–6 Tage; Weiroot 53 um 3–8 Tage und Gisela 5 um 3–10 Tage. Die Reifezeit der Früchte war bei den Bäumen auf Gisela 5 im Vergleich zu den anderen Varianten um 2–3 Tage verspätet. Gisela 5, Weiroot 72 und Gisela 4 induzierten bei der aufveredelten Sorte die höchsten Ertragsleistungen, P1 die geringsten. Bei den Bäumen auf Gisela 5 war die Fruchtgröße geringer als bei den anderen Unterlagen. Bäume auf Gisela 5 brauchen intensive Pflege. Nur wenn alle Produktionsfaktoren und kulturtechnischen Maßnahmen optimiert werden, kann das hohe Ertragspotenzial dieser Unterlage ausgeschöpft werden.     

Relationship between renal hypertension and cardiac α1-adrenoceptor autoantibodies in rats

AIM: To examine the autoantibody against α₁-adrenoceptor and its biologic activities during the development of renal hypertension. METHODS: Renal hypertension of rat was achieved by clipped renal artery, the titre of autoantibody to α₁-adrenoceptor was detected using ELISA immunoassay. Furthermore, the biological offects of these autoantibodies on cultured cardiomyocytes were also examined. RESULTS: After two weeks of clipping renal arteries, both the frequency of occurrence and the titre of autoantibodies to cardiac α₁-adrenergic receptor were significantly increased as compared with the control of pre-treatment. The increased autoantibodies lasted for several weeks and then automatically decreased gradually to the pre-clipping level at 12 weeks. The biological effects of these autoantibodies displayed an "agonistic-like" activities on the beating frequency of cultured neonatal cardiomyocytes. CONCLUSION: Autoantibodies against α₁-adrenoceptor may play a role in the elevation of peripheral vascular resistance and in the development of cardiac hypertrophy in rats with renal hypertension.     

Effects of radiation from 188Re on smooth muscle cell proliferation

AIM: Although endovascular radiotherapy inhibits neointimal hyperplasia, the exact alterations induced by β-particles irradiation remain to be elucidated. The objective of this study was to investigate the ability and the cellular mechanism of local β^-particles emission from ¹⁸⁸Re to inhibit vascular smooth muscle cells (SMCs). METHODS: The SMCs in vitro were irradiated by ¹⁸⁸Re with single doses of 2.6 Gy-25.8 Gy. The effects of β-particles on SMCs, such as effective irradiate doses, the period of inhibition for SMCs proliferation, the changes of cell proliferation rate and DNA synthesis rate, cell cycle progression and related gene expression, were investigated by cell count, [³H]-TdR incorporation, cell cycle progression analysis, cell viability and immunocytochemistry, respectivecy. RESULTS: β-particles irradiation with dose of 5.2 Gy could inhibit significantly SMCs proliferation. At dose of 20.6 Gy DNA synthesis inhibitory rate was 92%, SMCs proliferation rate was only 3%. Renoval of ¹⁸⁸Re did not abolish the inhibitory effects of β-particles on SMCs proliferation. The expression of P53 was up regulation and PCNA was down regulation after irradiation. CONCLUSION: β-particles from ¹⁸⁸ Re was significantly effective and permanent in inhibiting SMCs proliferation, and inhibitory effect was in dose-dependet manner ED50was 5 Gy, the best dose to inhibit SMCs proliferation was 20 Gy. β-particles irradiation induced SMCs to occur G₀/G₁ arrest, damaged the ability of SMCs reproliferation and led to cell clonogenic death. P53 and PCNA had regulatiory effects on SMCs proliferation after β-particles irradiation.     

Influence of Mineral Nutrients on Strawberry Fruit Quality and Their Accumulation in Plant Organs

Abstract

This review is based partly on complete articles and partly on abstracts. Three of the 60 articles deal with the total uptake of elements in strawberry plant organs in two different strawberry production systems, both considered as optimal concerning amount and balance of elements. The effect on fruit quality may be dramatic if the level of a particular element is outside this range, but there may also be effects initiated by differences within the optimal range of elements. Most articles refer to product oriented quality, but some focus on consumer oriented quality, as discussed by Shewfelt (1999). The discussion here is on a general basis, so one should keep in mind that there are cultivar differences and that specification of nutrition ideally should mirror the needs of a single cultivar, or a group of cultivars with similar requirements. Also, to get a complete understanding of the subject future reviews should embrace a broader access of information including the effect on plant development of individual elements, such as the role of calcium in fruit firmness and its importance in cell wall structure. However, the intention here is to narrow the information to results that suggest a direct connection between nutrient uptake and fruit quality.     

Effect of puerarin on pulmonary arterioles wall collagen metabolism of chronic hypoxia hypercapnia rats

AIM:To investigate the effect of puerarin on pulmonary vessel collagen metabolism in pulmonary hypertension rats induced by chronic hypoxia and hypercapnia.METHODS:Collagen Ⅰ, Ⅲ and their mRNA were observed in pulmonary arterioles by the technique of immunohistochemistry and in situ hybridization.RESULTS:① Light microscopy showed media thickness of pulmonary arterioles was much higher in HH(hypoxic-hypercapnia) group than that of NC(normal control) group, and, vessel cavity turned more straiter in HH group than that of NC group.However, the damage of pulmonary arterioles in HP(hypoxic-pueratin) group was much slighter than that of HH group. ② The levels of plasma ET-1 and lung homogenates Hyr were much higher in HH group than those of NC group(P＜0.01), and lower in HP group than HH groups(P＜0.01).Plasma NO content in group HH was lower than that of group NC(P＜0.01), it was higher in group HP than that of group HH(P＜0.01).③Expression of collagen Ⅰ and collagen Ⅰ mRNA in pulmonary arterioles were significantly higher in HH groups than those of NC group (P＜0.01), and they were lower in HP group than those of HH group (P＜0.01).Expression of collagen Ⅲ and collagen Ⅲ mRNA showed no difference among three groups(P＞0.05).CONCLUSION:Puerarin inhibited the deposition of collagen and improved pulmonary vessel remodeling.     

Mixed-severity fire regime in a high-elevation forest of Grand Canyon,Arizona, USA

Fire regime characteristics of high-elevation forests on the North Rim of the Grand Canyon, Arizona, were reconstructed from fire scar analysis, remote sensing, tree age, and forest structure measurements, a first attempt at detailed reconstruction of the transition from surface to stand-replacing fire patterns in the Southwest. Tree densities and fire-/non-fire-initiated groups were highly mixed over the landscape, so distinct fire-created stands could not be delineated from satellite imagery or the oldest available aerial photos. Surface fires were common from 1700 to 1879 in the 4,400 ha site, especially on S and W aspects. Fire dates frequently coincided with fire dates measured at study sites at lower elevation, suggesting that pre-1880 fire sizes may have been very large. Large fires, those scarring 25% or more of the sample trees, were relatively infrequent, averaging 31 years between burns. Four of the five major regional fire years occurred in the 1700s, followed by a 94-year gap until 1879. Fires typically occurred in significantly dry years (Palmer Drought Stress Index), with severe drought in major regional fire years. Currently the forest is predominantly spruce-fir, mixed conifer, and aspen. In contrast, dendroecological reconstruction of past forest structure showed that the forest in 1880 was very open, corresponding closely with historical (1910) accounts of severe fires leaving partially denuded landscapes. Age structure and species composition were used to classify sampling points into fire-initiated and non-fire-initiated groups. Tree groups on nearly 60% of the plots were fire-initiated; the oldest such groups appeared to have originated after severe fires in 1782 or 1785. In 1880, all fire-initiated groups were less than 100 years old and nearly 25% of the groups were less than 20 years old. Non-fire-initiated groups were significantly older (oldest 262 years in 1880), dominated by ponderosa pine, Douglas-fir, or white fir, and occurred preferentially on S and W slopes. The mixed-severity fire regime, transitioning from lower-elevation surface fires to mixed surface and stand-replacing fire at higher elevations, appeared not to have been stable over the temporal and spatial scales of this study. Information about historical fire regime and forest structure is valuable for managers but the information is probably less specific and stable for high-elevation forests than for low-elevation ponderosa pine forests.This revised version was published online in May 2005 with corrections to the Cover Date.     

瓜叶绿素降解关键酶基因PPH和PAO cDNA片段的克隆与表达初步分析

 以西双版纳黄瓜和‘华黄5号’黄瓜叶片为试验材料,研究了衰老过程中两种黄瓜叶片叶绿素含量变化及脱镁叶绿素脱镁叶绿酸水解酶基因PPH和脱镁叶绿酸a加氧酶基因PAO的表达。结果表明：随着叶片衰老,叶绿素a和叶绿素b含量显著降低,叶绿素a与叶绿素b的比值在0.5左右,推测叶绿素b的含量可能对黄瓜叶片保绿起到重要作用。荧光定量RT-PCR分析结果显示：PPH和PAO在西双版纳黄瓜叶片生长35 d时表达量最高,分别为5.50和1.86;PPH在‘华黄5号’叶片35 d时表达量最高,为7.14,而PAO在35和45 d表达量都很高,分别为3.90和3.91;PPH和PAO在西双版纳黄瓜叶片中的表达量低于在‘华黄5号’中。     

Effects of simvastatin on PDGF-BB and serum-induced proliferation of vascular smooth muscle cells and on the expression of tumor suppressor gene PTEN

AIM:To observe the effect of simvastatin on the proliferation of vascular smooth muscle cells(VSMCs) induced by serum and growth factor PDGF-BB and the effect of simvastatin on the expression of PTEN,a important regulator of G₁/S cell cycle transition. METHODS:The DNA synthesis was determined by [³H]-TdR incorporation, cell cycle was examined with flow cytometry, the protein level of PTEN was measured by Western blot method. RESULTS: (1)Simvastatin inhibited [³H]-TdR incorporation in a dose dependent manner. (2) Flow cytometric DNA analysis revealed that simvastatin induced significantly enhancement of G₀/G₁ phase and decrease in S phase VSMCs.(3)Simvastatin increased protein level of PTEN and mevalonate, a metabolite of HMG-COA, reversed the effect of simvastatin on PTEN protein expression. CONCLUSION:Simvastatin may inhibit proliferation of VSMCs and retarded cell cycle in G₀/G₁ phase by increasing PTEN expression through inhibiting synthesis of mevalonate.     

Multi-scale landscape and seascape patterns associated with marbled murrelet nesting areas on the U.S. west coast

Habitat for wide-ranging species should be addressed at multiple scales to fully understand factors that limit populations. The marbled murrelet (Brachyramphus marmoratus), a threatened seabird, forages on the ocean and nests inland in large trees. We developed statistical relationships between murrelet use (occupancy and abundance) and habitat variables quantified across many spatial scales (statewide to local) and two time periods in California and southern Oregon, USA. We also addressed (1) if old-growth forest fragmentation was negatively associated with murrelet use, and (2) if some nesting areas are more important than others due to their proximity to high quality marine habitat. Most landscapes used for nesting were restricted to low elevation areas with frequent fog. Birds were most abundant in unfragmented old-growth forests located within a matrix of mature second-growth forest. Murrelets were less likely to occupy old-growth habitat if it was isolated (> 5 km) from other nesting murrelets. We found a time lag in response to fragmentation, where at least a few years were required before birds abandoned fragmented forests. Compared to landscapes with little tono murrelet use, landscapes with many murrelets were closer to the ocean's bays, river mouths, sandy shores, submarine canyons, and marine waters with consistently high primary productivity. Within local landscapes (≤ 800ha), inland factors limited bird abundance, but at the broadest landscape scale studied (3200 ha), proximity to marine habitat was most limiting. Management should focus on protecting or creating large, contiguous old-growth forest stands, especially in low-elevation areas near productive marine habitat. This revised version was published online in July 2006 with corrections to the Cover Date.     

Relationships of landscape,prey and agronomic variables to the abundance of generalist predators in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis>) fields

A two-year field study investigated the possible effects of grain sorghum (Sorghum bicolor [L.] Moench) and uncultivated areas on the abundance of generalist predators in commercially-managed cotton (Gossypium hirsutum L.) fields in Texas, USA. From 63 to 70 fields were sampled for pests and predators over nine consecutive weeks during early stages of cotton development. Additional data on agronomic practices and landscape composition at three spatial scales were also collected for each field. Stepwise regression analyses were used to determine the relationships of landscape, agronomic and prey variables to the abundance of generalist predators. Because the variables most closely linked to predator levels could vary over time, separate regressions were conducted for three time periods corresponding to stages of grain sorghum growth (half-bloom, hard-dough, maturity) in each year. Significant relationships between predator abundance and agricultural landscape composition appear in both years and in all three time periods, but the specific relationships of landscape variables to cotton predator levels differed between and within years. At maturity in 2001, predator levels rose as the amount of uncultivated land from 1.6 to 3.2 km distant and the perimeter shared with grain sorghum increased. During 2002, the area of grain sorghum (half-bloom) and uncultivated land (hard-dough) within 1.6 km of cotton fields were both positively related to predator numbers. Cotton planting dates and the abundance of cotton fleahoppers (Pseudatomoscelis seriatus [Reuter]) were also strongly linked to predator numbers during both years. Results suggest that the total amount of grain sorghum or uncultivated land in an area is more important than the presence of these habitats adjacent to cotton fields, and that landscape composition may sometimes be the most important factor in determining predator abundance.