Effect of neutralization and addition of urea,sucrose, and various glycols on phosphorus absorption and leaf damage from foliar-applied phosphate

Summary Inclusion of sucrose in the solution applied to soybean (Glycine max L. merr.) leaves much reduced the severity of the damage to the leaves from application of urea and, to a lesser extent, from application of phosphorus (P) as orthophosphoric acid. Sucrose had no evident effect on P absorption. Damage to the leaves from joint application of orthophosphoric acid and urea exceeded the sum of the damage caused by the substances individually. Urea did not seem to influence P absorption, but the effect, if any, was not readily determined because nearly all values for P absorption exceeded 90%.Neutralization of orthophosphoric acid with nitrogen-containing organic bases, including choline, guanidine, and guanyl urea, did not prove useful as a technique for increasing the quantity of orthophosphate that could be applied without damage to the leaves.Absorption and translocation of orthophosphate by corn (Zea mays L.) and soybean leaves were not influenced by the pH of the solution within the range from 2 to 10. Absorption of tripolyphosphate by corn leaves decreased with an increase in pH of the solution applied, but translocation of the absorbed P was not influenced by pH. With soybeans, absorption of tripolyphosphate decreased with an increase in pH of the solution. Translocation of P applied to soybean leaves as tripolyphosphate was less than 5% of the amount absorbed within the first 24 hr and decreased with an increase in pH after 10 days.     

Body fat,rank, and nutritional status in a captive group of Rhesus Macaques

Using weight and skinfold thickness to calculate relative body fat, the fat content of 21 captive female rhesus macaques was estimated. Although age and. pregnancy had no effect on fat, rank was significant, especially during winter, with high-rank females having the highest fat scores. Rank therefore has a significant effect on the health of captive animals and may also affect the health of individuals in feral groups.     

Mass propagation techniques currently being used in the spawning and rearing of marine fish species

Propagation techniques for marine fish species, applicable to public aquariums, are reviewed based on work with ornamental tropicals and foodfish species. Adult conditioning, spawning procedures, incubation of eggs, larval rearing, larval food culture, and facilities are discussed with specific references to techniques used at Instant Ocean Hatcheries, Inc, for Anemonefish (Amphiprion spp) culture in synthetic seawater.     

A comparison between the amino acid composition of an egg parasitoid wasp and some of its hosts

Amino acid compositions of the eggs of five lepidopteran hosts for Trichogramma minutum were compared with each other and with a non-host species, Rhodnius prolixus, in which T. minutum oviposits but does not develop. Host eggs are quite homogeneous, particularly when compared according to groupings of potentially interconvertible amino acids. Combined mole percent values for glycine, serine and alanine were higher in hosts (27.5–29.2 mole%) than in R. prolixus eggs (21.5 mole%), in bovine serum albumin (14.9%), which has been used as a protein source in artificial diets for T. minutum, or in many of the mixtures used in published diets for this species. Since these three amino acids make up 26.3 mole% of the adult amino acid content of T. minutum, their deficiency in diets could require metabolic compensation detrimental to development.Adult T. minutum arising from eggs of Manduca sexta, Choristoneura fumiferana, and Sitotroga cerealella are similar in amino acid composition to each other and, in general, to their hosts. Variability appears greater in hosts than in adult wasp composition, suggesting some interconversion of host amino acids to accommodate inflexible nutritional requirements of T. minutum.In the three host species tested, free amino acids constituted 15.8–19.3% by weight of the amino acid in egg contents. In M. sexta eggs, glycine, serine and alanine together make up 28.4% by weight of the total free amino acid, a much higher proportion than in many published diets. The four free amino acids (isoleucine, leucine, phenylalanine and histidine) reported to be oviposition stimulants in experiments on encapsulated diets are present in sufficient concentrations to induce oviposition in the host species tested and in R. prolixus. S. cerealella egg contents having approximately 1.8 g amino acid, yield one or rarely two adult T. minutum (1g amino acid/insect). In contrast, M. sexta eggs with 94 g amino acid each yield an average of 10–12 adults (8.2g amino acid/insect). This suggests that small hosts are allocated few eggs which can only develop into small adults because of nutrient supply (parasitoid size in metabolically restricted), whereas much larger hosts are allocated proportionately fewer eggs than the former resulting in larger, and presumably more viable and fecund, adults (parasitoid size is established behaviourally).     

无机营养对春小麦抗旱适应性的影响

本文研究了无机营养对春小麦一些抗旱适应性的影响,主要包括:渗透调节的大小和变化过程、可溶性糖的积累、脯氨酸的积累、叶片导度的变化、离体叶片的失水速率、叶面积和耗水量的变化、根系生长和根/植冠值,并且分析了各个处理植株的水分利用效率(WUE)和产量的变异。认为,在干旱条件下,无机营养对于春小麦不同器官、不同生理功能,并不都具有一致的作用。有的利于提高植株的抗旱性,有的可以改变一些适应性产生的时间和发展过程,有的则不利于植株的抗旱性。通过综合分析,提出旱地施肥使作物增产的主要原因是,营养元素满足了作物生长所需,促进了根系发育,利于吸收水分、维持水分平衡和正常生理功能,但对作物自身的耐旱性并没有产生显著影响。     

Nutritive value of the nuña popping bean

Nuñas (Thaseolus vulgaris, Fabaceae), commonly called popping beans, are traditionally grown in the Andean highlands of South America, and are consumed as a snack food after a quick toasting process. Proximate analysis of their nutritive value revealed that nunas have a higher content of starch, amylose, and copper than four dry bean varieties and a lower mean content of protein, phosphorous, iron, and boron. The unique texture and taste of nuñas may be related to their high starch content. Antinutritional factors such as lectins were higher in raw and boiled nuña samples than in toasted nuñas, while tannin levels did not change from raw to toasted treatments. Overall in-vitro digestibility was slightly lower for toasted nunas than boiled dry bean.     

Root-microbial effects on plant iron uptake from siderophores and phytosiderophores

Collaborative experiments were conducted to determine whether microbial populations associated with plant roots may artifactually affect the rates of Fe uptake and translocation from microbial siderophores and phytosiderophores. Results showed nonaxenic maize to have 2 to 34-fold higher Fe-uptake rates than axenically grown plants when supplied with 1 μM Fe as either the microbial siderophore, ferrioxamine B (FOB), or the barley phytosiderophore, epi-hydroxymugineic acid (HMA). In experiments with nonsterile plants, inoculation of maize or oat seedlings with soil microorganisms and amendment of the hydroponic nutrient solutions with sucrose resulted in an 8-fold increase in FOB-mediated Fe-uptake rates by Fe-stressed maize and a 150-fold increase in FOB iron uptake rates by Fe-stressed oat, but had no effect on iron uptake by Fe-sufficient plants. Conversely, Fe-stressed maize and oat plants supplied with HMA showed decreased uptake and translocation in response to microbial inoculation and sucrose amendment. The ability of root-associated microorganisms to affect Fe-uptake rates from siderophores and phytosiderophores, even in short-term uptake experiments, indicates that microorganisms can be an unpredictable confounding factor in experiments examining mechanisms for utilization of microbial siderophores or phytosiderophores under nonsterile conditions.     

The involvement of mycorrhizas in assessment of genetically dependent efficiency of nutrient uptake and use

This article summarises the way in which mycorrhizal infection of roots affects the mineral nutrition of plants and how the symbiosis may interact with the evaluation of efficiency of nutrient uptake and use by plants. A brief account of the processes of infection and the way they are affected by host genotype and environmental conditions is given and the relationships between this and mineral nutrition (especially phosphate nutrition) are outlined.The interactions between mycorrhizal infection and P efficiency are considered at two levels. Mycorrhizas may act as general modifiers of efficiency regardless of the extent to which the plants are infected and in some mycorrhiza-dependent plants infection may change the ranking of genotypes. The extent of infection is also under genetic control and shows considerable variability between genotypes in some species. This variation could be used in programs to select varieties in which infection is rapid and nutrient uptake from nutrient deficient or low input systems is, in consequence, increased.     

Magnesium deficiency enhances resistance to paraquat toxicity in bean leaves

Effects of deficient (20mmol m^?3) and sufficient (1000 mmol m^?3) magnesium (Mg) supply and of varied light intensity (100 μmol m^?2 s^?1 to 580 μmol m^?2 s^?1) on paraquat-dependent chlorophyll destruction in bean (Phaseolus vulgaris) plants grown in nutrient solution were studied over a 12-d period using leaf discs or intact primary leaves. Treatment of leaf discs with 10mmol m ³ paraquat for 15h caused severe chlorophyll loss, especially with increasing light intensity. This chlorophyll destruction by paraquat was very much higher in Mg-sufficient than Mg-deficient leaves. The occurrence of paraquat resistance in Mg deficient leaves was already apparent after 6d growth in nutrient solution, i.e. before any decrease in chlorophyll or growth by Mg deficiency was evident. Also, following foliar application of paraquat (10–140 mmol m^?3) to intact plants, Mg-deficient plants were much more resistant to paraquat, even following longer exposure duration (72 h) and four to 14 times higher paraquat concentrations than those received by Mg sufficient plants. From experiments where exogenous scavengers of superoxide radical (O₂^.-), hydroxyl radical (OH^·) and singlet oxygen (¹O₂) were applied to leaf discs, it appears that O₂^.-, and partly, OH^· are the main O₂ species which contribute to chlorophyll destruction by paraquat. The results demonstrate that Mg-deficient bean plants become highly resistant to O₂^.--mediated and light-induced paraquat injury. The mode of this paraquat resistance is attributed to well-known stimulative effects of Mg deficiency on O₂^.- and H₂O₂ scavenging enzymes and antioxidants.