Citrus replant problem in Iraq II. Possible role of allelopathy

The role of allelopathy in citrus replant problems was investigated in Iraq. The failure of citrus seedlings to grow normally in old citrus orchards was not caused by differences between old and non-citrus soils in electrical conductivity, pH, organic matter, soil texture and those minerals tested. Extracts of soil collected from old citrus orchards significantly reduced the growth of sour orange seedlings. Extracts and decaying sour orange roots reduced the growth of sour orange seedlings as did extracts of non-senescent sour orange leaves and decaying senescent leaves. Thus it appears that allelopathy is at least partly involved in the citrus replant problem.     

Mechanism of Acetic Acid Gustatory Repulsion in Drosophila

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‘赛蜜酥1号’枣及其芽变品系果实的性状差异北大核心CSCD

该试验以‘赛蜜酥1号’枣及其芽变品系‘赛蜜酥2号’果实为试验材料,运用流式细胞术对它们的倍性进行鉴定,采用石蜡切片法进行果实细胞组学的观察,并对两者果实生长发育过程中的内外观品质及决定果实口感的蔗糖代谢相关酶活性进行比较分析,为深入研究芽变对枣果实口感、品质造成的影响提供理论支持。结果表明:(1)‘赛蜜酥2号’芽变品系的细胞倍性未发生改变,仍为二倍体。(2)两个枣品种(系)果实在外部形态上有明显区别,‘赛蜜酥1号’为卵圆型,‘赛蜜酥2号’为扁圆型,且后者的果形指数成熟时大于1,单果质量高于前者,核小、可食率更高,皮薄果实更加酥脆;‘赛蜜酥1号’果皮的蜡质层厚度一直大于其芽变枣,两者角质层厚度和表皮层厚度的变化趋势基本一致,但厚度之间具有显著差异。(3)影响果实细胞生长、分裂,果实脱落的各类激素水平在品种间均存在显著差异,‘赛蜜酥2号’IAA和GA_(3)含量显著高于‘赛蜜酥1号’,使之果形更大。(4)两个枣品种(系)果实可溶性糖、可滴定酸、维生素C、植物淀粉、可溶性蛋白含量等随发育时期的变化趋势一致,但含量水平之间存在差异,‘赛蜜酥2号’果实的糖含量、维生素C含量更高,可滴定酸含量更低,口感更甘甜。(5)两品种枣果实的蔗糖代谢相关酶活性在果实迅速生长的膨大期都存在着显著差异,也导致‘赛蜜酥2号’果实甜度明显高于‘赛蜜酥1号’。研究发现,两个枣品种均为二倍体,它们在果实外部形态上存在明显区别,易于分辨;芽变品系‘赛蜜酥2号’果实更大,核小、可食率更高,皮薄更加酥脆,口感更甘甜。     

Modulation of rat chorda tympani NaCl responses and intracellular Na+ activity in polarized taste receptor cells by pH

Mixture interactions between sour and salt taste modalities were investigated in rats by direct measurement of intracellular pH (pH(i)) and Na(+) activity ([Na(+)](i)) in polarized fungiform taste receptor cells (TRCs) and by chorda tympani (CT) nerve recordings. Stimulating the lingual surface with NaCl solutions adjusted to pHs ranging between 2.0 and 10.3 increased the magnitude of NaCl CT responses linearly with increasing external pH (pH(o)). At pH 7.0, the epithelial sodium channel (ENaC) blocker, benzamil, decreased NaCl CT responses and inhibited further changes in CT responses induced by varying pH(o) to 2.0 or 10.3. At constant pH(o), buffering NaCl solutions with potassium acetate/acetic acid (KA/AA) or HCO(3)(-)/CO(2) inhibited NaCl CT responses relative to CT responses obtained with NaCl solutions buffered with HEPES. The carbonic anhydrase blockers, MK-507 and MK-417, attenuated the inhibition of NaCl CT responses in HCO(3)(-)/CO(2) buffer, suggesting a regulatory role for pH(i). In polarized TRCs step changes in apical pH(o) from 10.3 to 2.0 induced a linear decrease in pH(i) that remained within the physiological range (slope = 0.035; r(2) = 0.98). At constant pH(o), perfusing the apical membrane with Ringer's solutions buffered with KA/AA or HCO(3)(-)/CO(2) decreased resting TRC pH(i), and MK-507 or MK-417 attenuated the decrease in pH(i) in TRCs perfused with HCO(3)(-)/CO(2) buffer. In parallel experiments, TRC [Na(+)](i) decreased with (a) a decrease in apical pH, (b) exposing the apical membrane to amiloride or benzamil, (c) removal of apical Na(+), and (d) acid loading the cells with NH(4)Cl or sodium acetate at constant pH(o). Diethylpyrocarbonate and Zn(2+), modification reagents for histidine residues in proteins, attenuated the CO(2)-induced inhibition of NaCl CT responses and the pH(i)-induced inhibition of apical Na(+) influx in TRCs. We conclude that TRC pH(i) regulates Na(+)-influx through amiloride-sensitive apical ENaCs and hence modulates NaCl CT responses in acid/salt mixtures.     

枣园节肢动物群落的时间动态

将枣园节肢动物群落视为一个整体,根据群落内物种的组成和数量,采用不同群落参数和群落分析法对太谷地区枣园节肢动物群落的时间格局进行了比较。结果表明,影响枣园节肢动物群落时间格局的主导因子及时间格局分化较为明显。可将枣园节肢动物群落在时序上分为发展期、过渡期、鼎盛期和衰减期4个阶段,并结合气候、物候变化,讨论了各阶段群落的发生特点和主要害虫的治理对策。     

枣种质缩果病抗性多样性研究

为充分发掘抗缩果病枣种质资源,对保存于河北沧县（2006年~2009年,77个品种）及山西太原（2006年~2007年,53个品种）和山西太谷（2006年,231个品种）的共268个枣品种资源进行了田间缩果病抗性调查。结果表明,枣品种间缩果病抗性差异显著,其中病果率变幅为0%~66.18%、变异系数为2.01,病情指数变幅为0%~55.06%、变异系数为2.46;同一品种的发病程度因年份和地点不同而有明显差异。根据在发病严重的沧县枣资源圃连续4年（2006~2009）的观测结果,枣品种的缩果病抗性可分为高抗、抗病、中抗、感病和高感5类,相应的平均缩果率分别为5%以下、5%~10%、10%~15%、15%~25%和25%以上;在沧县的77个品种中,表现高抗、抗病、中抗、感病、高感的品种分别占调查总数的80.52%,2.60%,7.79%,6.49%和2.60%。在我国主栽枣树品种中,金丝小枣、圆铃枣、长红、冬枣等为高抗品种,婆枣、壶瓶枣为高感品种。本研究表明,我国有着非常丰富的抗缩果病枣树种质资源。     

3个枣品种的核型分析

采用酶解去壁低渗法对大荔龙枣、骏枣和冬枣3个枣品种进行了核型研究.结果表明:3个枣品种的染色体数目均为2n=24,核型公式分别为大荔龙枣(Zizphus jujuba Mill 'Dalilongzao')2n=2x=24=20m(4SAT)+4sm,骏枣(Z.jujuba Mi1l.'Junzao')2n=2x=24...     

Alterations in blood pressure due to chronic exposure to natural sour gas leakage containing sulfur compounds

In order to show the alteration of blood pressure in subjects chronically exposed to natural gas containing sulfur compounds, the present study was done. The blood pressure of 94 (43 males, 51 females) of healthy individuals living in the polluted area of Masjid-i-Sulaiman (Khozestan province, southwest of Iran) was measured. The non-parametric Sign test was applied in order to detect differences between the study subjects and the normal mean values according to the sex and age of subjects. Statistical analysis showed that the systolic blood pressure significantly decreased (Z=-2.74; P=0.0031) while the diastolic blood pressure (Z=+2.11; P=0.0174) and heart rate (Z=+3.62; P<0.001) significantly increased in individuals living in the contaminated areas compared with those of normal mean values. The systolic and diastolic blood pressure decreased and increased, respectively, in individuals chronically exposed to natural sour gas containing sulfur compounds.     

几个引进枣品种枣头及果实生长发育规律的研究

研究得知湘南地区引进沾化冬枣、梨枣和骏枣的枣头一次枝(下简称枣头)伸长生长节律与本地品种鸡蛋枣相似,幼树期枣头有两次明显的伸长生长过程,其间出现生长暂缓期。从枣头年生长量看,三个引进品种均比本地品种鸡蛋枣要小,但秋季生长量比重均比鸡蛋枣还要大。三个引进品种果实均较鸡蛋枣大,果实生长规律均与鸡蛋枣相似。但各个品种果实生育期均长于鸡蛋枣。冬枣果实生育期最长为100天~110天,梨枣与骏枣果实生育较短,梨枣70天~75天,骏枣约85天,而鸡蛋枣只有65天~70天。     

不同间作枣园害虫的群落结构与动态

对5种不同间作枣园的害虫群落结构特征进行了研究,结果表明,在不同的间作枣园中,害虫的科、种与个体数是各不相同的,其多样性、均匀度和Berger-Parker指数也有明显差异(p<0.05)。间作牧草或保留杂草的枣园,害虫的科与种以及多样性和均匀度明显(p<0.05)大于间作小麦、大豆和单作枣园,而个体数和Berger-Parker指数则显著(p<0.05)小于单作枣园。枣园害虫个体数的时序动态随季节交替而有明显(p<0.05)的变化,4~8月份害虫的个体数明显(p<0.05)大于3月份、9~10月份。在枣园间作作物、牧草或者适当保留一定数量的杂草,不仅能够充分有效地利用枣园的空间和自然资源,而且增加了生物的多样性,改善了枣园的生态环境,同时提高了有害生物相互制约的能力和枣园单位面积的纯收入。