Mannitol and oligosaccharides as new criteria for determining cold tolerance in sugarcane varieties

Sugarcane can be very susceptible to damage by freezes. Freeze-deteriorated cane can cause problems in processing and sometimes leads to a factory shut-down. This study was undertaken during the 2000/2001 harvest season to assess the cold tolerance performance of six commercial sugarcane varieties and to establish new and more sensitive criteria to measure cold tolerance. Two varieties CP 70-321 and CP 79-318, with known cold tolerance, were planted in the study as controls. The other varieties included LHo 83-153, LCP 85-384, HoCP 85-845 and HoCP 91-555. Freezing temperatures occurred on 20 December 2000 when the min. field temperature was −4.4 °C, and again on 21 December, 30 December through 5 January 2001, 9–10 January and 20–21 January. The lowest field temperature recorded was −5.6 °C on 4 January. Freezing conditions prevailed for 8–15 h during each freeze incident. Stalks of all varieties were frozen to the ground following the initial freeze, with freeze cracks evident only after the 4 January freeze. For this study, samples were taken on the date of the first freeze, 20 December, and subsequently again at 7, 14, 22 and 30 days after the first freeze. Criteria used to measure overall stalk cold-tolerance included changes in pH, Brix, dextran (ASI-II method), sucrose, glucose, and fructose concentrations. Mannitol, ethanol and the oligosaccharides, palatinose, leucrose, iso-maltotriose and 1-kestose, were simultaneuously measured using IC-IPAD. Marked differences were observed in most criteria for all varieties, particularly 22 and 30 days after the first freeze. Mannitol was strongly correlated (r²=0.84) with dextran, confirming its use as an indicator for cane dextran deterioration. In comparison, ethanol was only weakly correlated (r²=0.55) with dextran and did not always predict cane dextran deterioration. Iso maltotriose was the most sensitive oligosaccharide indicator of freeze deterioration, although both leucrose and palatinose could be used to confirm whether severe dextran formation (>1500 ppm/Brix) has occurred in cane. Isomaltotriose was strongly correlated (r²=0.89) with dextran and pH (r²=−0.83); pH was also a strong indicator of both dextran (r²=−0.85) and mannitol (r²=−0.92) formation. Four of the varieties, CP 79-318, LCP 85-384, HoCP 85-845 and HoCP 91-555, were shown to be susceptible to other sources of microbial and enzymic deterioration as well as dextran deterioration from Leuconostoc bacteria, especially 30 days after the first freeze. This was indicated by increased glucose/fructose ratios, ethanol formation, changes in 1-kestose concentration, and further sucrose losses.     

Lime-induced iron chlorosis in sugarcane

Lime-induced chlorosis is a potential problem on most calcareous soils particularly in arid and semi-arid climates affecting most of the plants grown on them. Bicarbonates, phosphates, calcium, iron inactivation in plant tissue and organic anions have been held responsible as the mechanism leading to the disorder which is still not fully understood, and there is a lack of agreement as to the primary factor responsible for lime-induced chlorosis. To date, no hypothesis has adequately explained why chlorosis occurs on some high lime soils and not on others. Likewise, the nutrient ratios, K/Ca, P/Fe and Fe/Mn considered as diagnostic criteria for lime-induced chlorosis, have shown inconsistency. The presence of calcium carbonate, bicarbonate, calcium and imbalance of nutrient cations in the growth medium, injudicious addition of phosphates, quality of irrigation water, and other soil and plant factors have been held responsible for the disorder. Amelioration of lime-induced chlorosis by (i) acidification of calcareous soils, (ii) use of iron salts, (iii) use of synthetic iron chelates, and (iv) by management practices including the selection and development of varieties resistant to lime-induced iron chlorosis, is discussed. Suggestions for future research work are made.     

Sex pheromone of the mullein bug,Campylomma verbasci (Meyer) (Heteroptera: Miridae)

The first known sex pheromone for the family Miridae is reported for the mullein bug,Campylomma verbasci (Meyer) (Heteroptera: Miridae). Extracts of and Porapak Q-trapped volatiles from females were attractive to males in field bioassays. Butyl butyrate and hexyl butyrate were the predominant compounds in the females' volatiles, but these compounds previously had been found to be inactive when released alone or in combination. Butyl butyrate in combination with an isolated trace chemical, (E)-crotyl butyrate (which was inactive alone), rivaled the attraction elicited by five live females. When synthetic butyl butyrate and (E)-crotyl butyrate in a 16: 1 ratio were released at 91 or 183 g/day, they comprised an effective attractant for male bugs.     

Surface disposition and stability of pest-interactive,trichome-exuded diterpenes and sucrose esters of tobacco

The precise physical location of trichome-exudate biochemicals on the plant surface is undoubtedly important in plant-pest interactions, perhaps particularly those involving fungal and bacterial pathogens that invade the plant through the epidermal layer. The chemical stability of exuded compounds is also important in this regard. Here we have studied these two aspects of trichome biology using the highly exuded tobacco line,Nicotiana tabacum, T.I. 1068. Particularly under high relative humidity growth conditions, sucrose esters (SE) were found to migrate from the exudate droplet around the gland down the trichome stalk to the epidermal cells below. Six days after labeling leaf midveins on plants grown in a high humidity environment, 29 and 71% of label found in SE were recovered with trichome glands and below gland regions, respectively. Corresponding disposition in the moderate humidity environment was 40 and 60%, respectively. Migration of less polar duvatrienediols (DVT) was less marked. Staining of SE with rhodamine B showed the occurrence of more extensive and physically different migration in the high humidity versus moderate humidity case. Both SE and DVT were stable between six and 18 days postlabeling, the period encompassing the time of maximum exudate formation through the beginning of tissue senescence. Our results suggest that even under conditions that avoid mechanical disturbance of tissue, SE and DVT are chemically stable, at least until senescence, and appear to migrate from the gland region to the epidermal surface, apparently according to their relative polarity.     

Oxidation and intergranular disintegration of the aluminides NiAl and NbAl3 and phases in the system Nb-Ni-Al

The oxidation behavior is very different for an aluminide with a wide homogeneity range such as -NiAl than for a line compound such as NbAl ₃.Oxidation of -NiAl at temperatures 1273 K leads to a slow-growing -alumina layer. The metal phase beneath the scale remains as -NiAl; however, cavity formation is observed. The cavity formation may be favored by sulphur surface segregation. Oxidation of NbAl ₃ at temperatures 1273 K initially leads to -Al ₂O₃,but the Al depletion causes the formation of Nb ₂ Al beneath the oxide layer. Cracking of the Al ₂O₃ layer opens Nb ₂ Al to the atmosphere, which oxidizes rapidly to Nb ₂O₅ and NbAlO₄.After consumption of the Nb ₂ Al, a layer of Al ₂O₃ formed again on the NbAl ₃ phase, but failure of the alumina and the fast growth of the other oxides occur as a repeated process. Thus, NbAl ₃ exhibited rapid linear oxidation kinetics. Multiphase alloys in the system Nb-Ni-Al generally behave better than NbAl ₃,and the low oxidation rates of -NiAl can be approached. In the temperature range below 1273 K, with a maximum at 1000 K, both NiAl and NbAl ₃ show the pest phenomenon, an intergranular disintegration. Preceding the disintegration, oxygen diffuses into the grain boundaries of the material and Al ₂O₃ is formed at the grain boundaries, beginning from the surface region. NiAl is susceptible only in a very limited range of oxygen pressures and temperatures, whereas NbAl ₃ is much more susceptible.     

嵌入式技术在虫害测报系统中的应用研究

通过对嵌入式系统定义及嵌入式技术特点的阐述,说明了ARM嵌入式技术的优势。结合嵌入式技术在虫害测报系统中的具体应用实例,说明了运用ARM嵌入式系统的必要性、有效性以及必然趋势。     

广西糖料蔗小管出流灌溉方式不同灌溉定额研究成果分析

通过小管出流灌溉方式,采用不同灌溉定额:150 m3/亩、250 m3/亩、350 m3/亩,研究不同灌溉定额条件下糖料蔗的出苗率、分蘖率、株高、茎粗、叶面积、蔗汁锤度、水分生存率、水分利用效益等糖料蔗生长指标。试验证明:糖料蔗对养分的吸收强度不仅与养分在土壤中的存在状态有关,还与甘蔗不同生长阶段的土壤水分、湿度有关。糖料蔗在不同的生长阶段对灌水量也有不同的要求,在不同时期对糖料蔗进行有效、合理的灌水,对糖料蔗的生长发育起着极其重要的作用。而在250 m3/亩灌溉定额条件下,更能促进糖料蔗的生长发育,从而提高糖料蔗的品质形状和产量。     

基于物联网的苹果树病虫防治专家系统的设计与应用

提出一种基于物联网技术的专家系统结构,并以苹果树病虫防治专家系统为例,介绍专家系统的设计方法,以及物联网技术在专家系统中的应用和管理.     

几种诱捕器对储粮害虫诱捕效果的评价

利用不同形状的诱捕器对几种主要储粮害虫的诱捕效果进行了评价.以碎麦作为食物引诱剂,在粮堆的纵向中线及墙边缘布置4种诱捕器;并在粮堆的中线上布置不同数量的诱捕器,使得诱捕器的摆放密度不同.研究结果表明:4种诱捕器放在墙边缘诱到的蛾类、书虱和锈赤扁谷盗较放在粮堆中线要多,并且差异显著(P<0.05);4种诱捕器对于不同习性的害虫诱捕的效果差异显著:诱捕蛾类时,圆顶诱捕器的诱捕效果最好,其次是三角诱捕器.探管诱捕器对于书虱、锈赤扁谷盗、米象的诱捕效果最好.同时结果显示,圆盘诱捕器对多种储粮害虫都表现出良好的诱捕效果;诱捕器的摆放密度对于诱捕器的诱捕效果影响显著.     

330kV龙乌线不明闪络原因研究分析

330kV龙乌线自1999年11月25日投运以来，至今已连续发生多次不明原因闪络跳闸事故。攻关小组进行了大量的现场调查、污秽取样分析以及大量模拟试验研究工作。根据试验研究结果，对龙乌线闪络事故成因做了进一步的分析，较为准确地确定了龙乌线闪络事故的基本原因。并提出了具体的切实有效的防范措施，取得了良好的效果。