Redistribution of minerals in apple fruit during storage: Effects of storage temperature,varietal differences and orchard management

Transverse calcium redistribution from the cores to the outer zones of the fruit was interrupted for a short period when calcium was imported by the cores of both Cox and Spartan apples, especially at 3.5°C. Bitter pit lesions developed in mid and outer cortical tissues of Cox fruit stored at 3.5°C 2 to 4 weeks after calcium concentrations in these zones were reduced. Redistribution of magnesium from the outer zones to the cores of Spartan apples occurred during storage at 3.5°C but was inhibited at 0°C. Redistribution of magnesium in Cox's Orange Pippin apples was mainly from inner cortex to the core and outer zones at 3.5°C and from central to outer zones at 0°C, but immediately low temperature breakdown become evident at 0°C, magnesium was transferred from the peel and core to the affected zones. The redistribution of phosphorus to the cores, which occurred in Spartan apples (resistant to low temperature breakdown) stored at either 3.5°C or 0°C was barely evident in Cox fruit (susceptible to low temperature breakdown) stored at 3.5°C and did not occur at 0°C. Irrigated grass compared with overall herbicide soil management increased the proportion of calcium in the core zones of both Cox and Spartan apples and the proportion of magnesium in the core zone of Spartan apples at harvest. Irrigated grass management also increased the rate of calcium redistribution in Cox and Spartan fruit during storage and altered magnesium redistribution in Spartan apples stored at 0°C.     

Effects of soil management systems and nitrogen fertiliser on the firmness and mean fruit weight of Cox's Orange Pippin apples at harvest

The firmness and mean fruit weight, at harvest, of Cox's Orange Pippin apples from a soil management and N fertiliser trial planted in 1972 were measured from 1979 to 1985 (excluding 1984). Trees growing in overall herbicide, or in 0.3-m herbicide-treated strips with irrigated grassed alleyways, produced significantly softer and/or larger apples than those from trees growing in unirrigated grass with narrow (0.3 m) or wide (1.7 m) herbicide-treated strips in 1982 and 1983. Both these years had drier than average summers. N fertiliser applied annually produced slightly larger and softer apples at 189 kg N ha^?1 than at 63 kg N ha^?1.     

Effects of grazing and nitrogen fertiliser on the soil microbial biomass under permanent pasture

Carbon and nitrogen in the soil microbial biomass were measured on eight occasions during a grassland production season, under swards of perennial ryegrass receiving 210 or 420 kg N ha^?1 per year or of ryegrass/white clover receiving no fertiliser N. The swards were either cut or grazed at monthly intervals. Soil microbial biomass C increased under all treatments in late April before declining until late July and rising slowly towards the end of the season. Values for microbial C under cutting and grazing were not significantly different but were usually larger under grass/clover than under grass. In contrast, the smallest values for soil microbial biomass N were recorded in late April. Larger N values were again recorded under grass/clover, and although values were nearly always smaller under grazing than under the corresponding cut treatment the differences were not significant. Soil biomass N comprised a large reservoir of mobile N, and at any one time contained 11, 3 and 5 times more N than was present in the mineral N component of the soil, the standing crop or excretal returns, respectively. It did not appear to be responsive, within a season, to the considerable returns of C and N from grazing animals or to N fertiliser management.     

The contribution of fertiliser nitrogen to leachable nitrogen in the UK: A review

Evidence relating to nitrate leaching was taken from series of extensive field experiments conducted to support guidance on fertiliser use. Over the last 50 years, it is estimated that increased fertiliser N use on intensive wheat in the UK, has resulted in an increase of 36 kg N ha^?1 year^?1 leachable nitrate. Probably more than one-third of this change is due to larger yields resulting in a gradual build up in soil organic matter, the remainder to annual effects of fertiliser application. This justifies the association generally made between fertiliser used and nitrate leached and supports the value of some control of fertiliser use in order to restrict nitrate concentrations in drinking water.     

Efficiency of use of imported nitrogen, phosphorus, and potassium and potential for reducing phosphorus imports on Idaho dairy farms

Eight commercial dairies from south central Idaho were surveyed to estimate the whole-farm surpluses of N, P, and K and to investigate the possibility of reducing P excretions through dietary manipulation. Nitrogen, P, and K imports and exports were monitored in a 12-mo period, and samples from the diets, feeds, feces, urine, and manure were collected at regular farm visits. Soils from manure-amended fields were sampled in the spring and fall. In all cases, the largest import of N, P, and K to the dairy was with purchased feeds. Major nutrient export items were milk and manure and forages, in the case of a dairy with a large land base (dairy F). Whole-farm N surplus varied from 90 to 599 t/yr (91 to 222 kg/yr per cow). The efficiency of use of imported N varied from 25 to 64%, with dairy F having the greatest efficiency of imported N use. Phosphorus and K surpluses were also significant (average of 29 and 182 t/yr and 12 and 76 kg per cow per year, respectively). During the study period, dairy F was a net exporter of K. The average efficiency of use of imported P and K was 66 and 58%, respectively. Soil P levels in the 30-cm layer were above state threshold standards, most likely from overapplication of manure. Soil nitrate-N concentrations were also high, but K concentrations were within the accepted range. Average P content of the lactating cow diets at the start of the study was 0.49% and was reduced to 0.38%. The estimated reduction in imported P due to the reduced dietary P levels was from 5.7 to 61.4 t/yr per farm, or on average 12 kg per cow per year. This study demonstrated that in addition to exports with milk and manure, export of nutrients with forages produced on the farm (dairy F) is a major factor in reducing whole-farm N, P, and K surpluses.     

N、P互作对烤烟碳氮代谢关键酶活性的影响

通过大田试验研究了氮磷互作对烤烟碳氮代谢关键酶活性和叶绿素含量的影响。结果表明:钾肥施用量一定的情况下,随着氮素水平的提高,烟叶硝酸还原酶活性在团棵期、旺长期呈上升趋势,转化酶活性下降时间前移,淀粉酶活性在中后期也增加,Chl含量在叶片生长前期升高速度加快。施磷量45~105 kg/ hm2范围内增加团棵期NR活性;施磷量105 kg/ hm2和135 kg/ hm2对转化酶活性影响无显著差异;增加施磷量可以明显增加叶片中后期淀粉酶的活性;施氮量为60 kg/ hm2水平下,施磷量45~105 kg/ hm2范围内提高Chl含量。总体来看,中氮水平能使碳氮代谢适时转化,满足优质烟叶的生长要求,氮用量为60 kg/ hm2水平下,m(N):m(P205):m(K2O)=1:1.75:3.375的肥料配比相对有利于烤烟的生长发育。      

氮营养水平对植烟土壤养分含量及土壤酶活性的影响

田间试验研究了植烟土壤不同土层养分含量及土壤酶活性的变化规律。结果表明:在同一氮水平条件下,随着土层深度的增加,土壤有机质、全氮、速效氮、速效磷、速效钾以及土壤脲酶,蛋白酶,转化酶活性均呈降低趋势,通过方差分析可知,各处理间差异达到5%显著水平;0~40 cm土层范围内,随着施氮量的增加,土壤有机质、全氮、速效氮含量也增加,土壤脲酶活性增加,而蛋白酶活性呈降低趋势,转化酶活性呈先增加后降低的趋势,且在该土层范围内,酶与土壤养分之间存在显著或极显著的相关关系;60~80 cm土层范围内,氮对土壤养分及土壤酶的影响能力相对降低。以上说明在植烟土壤-土壤养分-土壤酶相互作用的系统中,土壤养分含量和土壤酶活性明显受氮营养水平和土层深度的共同影响。     

Genetic and phenotypic relationships among milk urea nitrogen, fertility, and milk yield in holstein cows

The aims of the study were to evaluate the relationships among milk urea nitrogen and nonreturn rates at the phenotypic scale, and to estimate genetic parameters among milk urea nitrogen, milk yield, and fertility traits in the early period of lactation. Milk yield, protein percentage, the interval from calving to first service, and 56- and 90-d nonreturn rates were available from 73,344 Holstein cows from 2,178 different herds located in a region in northwestern Germany. Generalized linear models with a logit link function were applied to assess the phenotypic relationships. Bivariate threshold-threshold, linear-threshold, and linear-linear models, fitted in a Bayesian framework, were used to estimate genetic correlations among traits. Milk yield, protein percentage, and milk urea nitrogen were means from test-day 1 (on average 20.8 d in milk) and test-day 2 (on average 53.1 d in milk) after calving. An increase in milk urea nitrogen was associated with decreasing 56-d nonreturn rates on the phenotypic scale. At fixed levels of milk urea nitrogen, greater values of protein percentage, indicating a surplus of energy in the feed, were positively associated with nonreturn rates. Heritabilities were 0.03 for 56- and 90-d nonreturn rates, 0.07 for interval from calving to first service, 0.13 for milk urea nitrogen, and 0.19 for milk yield. Service sire explained a negligible part (below 0.15%) of the total variance for nonreturn rates. Genetic correlations between the interval from calving to first service and nonreturn rates were close to zero. The genetic correlation between nonreturn rates was 0.94, suggesting that a change from nonreturn after 90 d to nonreturn after 56 d in the national genetic evaluation would not result in any loss of information. The genetic correlation between milk yield and nonreturn after 56 d was −0.31, and between milk yield and calving to first service was 0.14, both indicating an antagonistic relationship between production and reproduction. The genetic correlation between milk yield and milk urea nitrogen was 0.44, reflecting an energy deficiency in early lactation. The genetic correlations between milk urea nitrogen and nonreturn rates were too weak (−0.19 for 56-d nonreturn rate, and −0.23 for 90-d nonreturn rate) to justify the use of milk urea nitrogen as an additional trait in genetic selection for fertility, as demonstrated by selection index calculations.     

覆膜滴灌对日光温室甜瓜土壤环境及产量的影响

为探明不同覆膜滴灌条件下,大棚甜瓜土壤水、热等环境因素变化对脲酶及甜瓜产量的影响,该文采用正交试验设计,研究了日光温室内不同覆膜方式(全覆膜、半覆膜、无膜)、灌水下限(田间持水量的60%、70%、80%)、滴灌毛管密度(1管1行、3管4行、1管2行)以及3种因素的交互作用下的土壤水、热、pH值等的变化,以及对甜瓜土壤脲酶活性及甜瓜产量的影响。结果发现,半膜覆盖、80%田间持水量的灌水下限、1管2行滴灌毛管密度等的甜瓜根区土壤水分分布均匀、土壤温度较高、pH值较低,可显著提高土壤脲酶活性;60%田间持水量下限处理脲酶活性在果实膨大期和成熟期高,70%田间持水量下限处理在苗期高,80%田间持水量下限处理在各个生育阶段都最高;半膜覆盖、1管2行和80% 田间持水量下限组合和半膜覆盖、3管4行和70%田间持水量下限组合的甜瓜产量分别为34.46、31.27 t/hm²,显著高于全膜覆盖、1管1行和80% 田间持水量下限组合的28.02 t/hm²;半膜覆盖、1管2行和80% 田间持水量下限组合甜瓜的可溶性糖和可溶性固形物含量高,有机酸含量低。在陕西关中地区的日光温室栽培甜瓜,建议采取半膜覆盖,1管2行的滴灌管密度,灌水量下限分别为苗期70%、开花坐果期80%、果实膨大期80%和成熟期60%田间持水量。     

褐土上不同氮、钾比例对烟叶化学成分的影响

采用田间随机区组设计,测定不同施氮量和氮、钾比例的褐土和烟叶样品中化学成分含量,经统计分析得出:①N:K₂O为1:2的施肥处理可以提高叶重,在施氮量较高的情况下,N:K₂O为1:2的处理可以略降低烟叶中的烟碱。N:K₂O为1:1的处理烟叶烟碱含量较高,其处理在生育后期总氮处于相对较高的水平。②不施钾的情况下,低氮处理烟叶钾含量略高于高氮处理;施钾情况下,相同氮、钾比例,高氮处理的烟叶钾含量和钾累积量分别高于相应的低氮处理。在褐土上,氮素可以促进烟株对钾的吸收。③施钾量提高,烟叶含钾量增加,烟叶含钙量和含镁量降低。④烟叶中的钾含量与钙、镁含量呈显著负相关,钙和镁对烟株吸收钾有强烈的拮抗作用。烟叶钾含量与土壤速效钾含量呈极显著正相关。      

覆膜滴灌对日光温室甜瓜土壤环境及产量的影响

为探明不同覆膜滴灌条件下,大棚甜瓜土壤水、热等环境因素变化对脲酶及甜瓜产量的影响,该文采用正交试验设计,研究了日光温室内不同覆膜方式(全覆膜、半覆膜、无膜)、灌水下限(田间持水量的60%、70%、80%)、滴灌毛管密度(1管1行、3管4行、1管2行)以及3种因素的交互作用下的土壤水、热、pH值等的变化,以及对甜瓜土壤脲酶活性及甜瓜产量的影响。结果发现,半膜覆盖、80%田间持水量的灌水下限、1管2行滴灌毛管密度等的甜瓜根区土壤水分分布均匀、土壤温度较高、pH值较低,可显著提高土壤脲酶活性;60%田间持水量下限处理脲酶活性在果实膨大期和成熟期高,70%田间持水量下限处理在苗期高,80%田间持水量下限处理在各个生育阶段都最高;半膜覆盖、1管2行和80% 田间持水量下限组合和半膜覆盖、3管4行和70%田间持水量下限组合的甜瓜产量分别为34.46、31.27 t/hm²,显著高于全膜覆盖、1管1行和80% 田间持水量下限组合的28.02 t/hm²;半膜覆盖、1管2行和80% 田间持水量下限组合甜瓜的可溶性糖和可溶性固形物含量高,有机酸含量低。在陕西关中地区的日光温室栽培甜瓜,建议采取半膜覆盖,1管2行的滴灌管密度,灌水量下限分别为苗期70%、开花坐果期80%、果实膨大期80%和成熟期60%田间持水量。     

Redistribution of minerals in apple fruit during storage: Effects of late summer pruning,calcium sprays and low temperature breakdown

Transverse distribution patterns of calcium, magnesium and phosphorus in Cox's Orange Pippin apples at harvest and subsequent redistribution patterns during storage in air at 0°C were measured. Distribution and redistribution patterns differed from those in Spartan apples measured in the previous year. Orchard calcium sprays increased the proportion of calcium in the outer parts and slightly increased the proportion of magnesium towards the centre of the fruit. Late summer pruning slightly increased the proportion of magnesium in the core at harvest and increased the rate of redistribution of calcium from the core to the outer fruit parts during storage. Redistribution patterns, especially those of magnesium, were drastically altered when low temperature breakdown developed and minerals moved into the affected zones.     

覆膜滴灌对日光温室甜瓜土壤环境及产量的影响

为探明不同覆膜滴灌条件下,大棚甜瓜土壤水、热等环境因素变化对脲酶及甜瓜产量的影响,该文采用正交试验设计,研究了日光温室内不同覆膜方式(全覆膜、半覆膜、无膜)、灌水下限(田间持水量的60%、70%、80%)、滴灌毛管密度(1管1行、3管4行、1管2行)以及3种因素的交互作用下的土壤水、热、pH值等的变化,以及对甜瓜土壤脲酶活性及甜瓜产量的影响。结果发现,半膜覆盖、80%田间持水量的灌水下限、1管2行滴灌毛管密度等的甜瓜根区土壤水分分布均匀、土壤温度较高、pH值较低,可显著提高土壤脲酶活性;60%田间持水量下限处理脲酶活性在果实膨大期和成熟期高,70%田间持水量下限处理在苗期高,80%田间持水量下限处理在各个生育阶段都最高;半膜覆盖、1管2行和80% 田间持水量下限组合和半膜覆盖、3管4行和70%田间持水量下限组合的甜瓜产量分别为34.46、31.27 t/hm²,显著高于全膜覆盖、1管1行和80% 田间持水量下限组合的28.02 t/hm²;半膜覆盖、1管2行和80% 田间持水量下限组合甜瓜的可溶性糖和可溶性固形物含量高,有机酸含量低。在陕西关中地区的日光温室栽培甜瓜,建议采取半膜覆盖,1管2行的滴灌管密度,灌水量下限分别为苗期70%、开花坐果期80%、果实膨大期80%和成熟期60%田间持水量。     

覆膜滴灌对日光温室甜瓜土壤环境及产量的影响

为探明不同覆膜滴灌条件下,大棚甜瓜土壤水、热等环境因素变化对脲酶及甜瓜产量的影响,该文采用正交试验设计,研究了日光温室内不同覆膜方式(全覆膜、半覆膜、无膜)、灌水下限(田间持水量的60%、70%、80%)、滴灌毛管密度(1管1行、3管4行、1管2行)以及3种因素的交互作用下的土壤水、热、pH值等的变化,以及对甜瓜土壤脲酶活性及甜瓜产量的影响。结果发现,半膜覆盖、80%田间持水量的灌水下限、1管2行滴灌毛管密度等的甜瓜根区土壤水分分布均匀、土壤温度较高、pH值较低,可显著提高土壤脲酶活性;60%田间持水量下限处理脲酶活性在果实膨大期和成熟期高,70%田间持水量下限处理在苗期高,80%田间持水量下限处理在各个生育阶段都最高;半膜覆盖、1管2行和80% 田间持水量下限组合和半膜覆盖、3管4行和70%田间持水量下限组合的甜瓜产量分别为34.46、31.27 t/hm²,显著高于全膜覆盖、1管1行和80% 田间持水量下限组合的28.02 t/hm²;半膜覆盖、1管2行和80% 田间持水量下限组合甜瓜的可溶性糖和可溶性固形物含量高,有机酸含量低。在陕西关中地区的日光温室栽培甜瓜,建议采取半膜覆盖,1管2行的滴灌管密度,灌水量下限分别为苗期70%、开花坐果期80%、果实膨大期80%和成熟期60%田间持水量。     

Varietal differences in the mineral composition of bulked samples of fruit from Cox's Orange Pippin,Crispin (Mutsu) and Spartan apple trees

Concentrations of dry matter, nitrogen and major mineral constituents in samples of Cox's Orange Pippin and Crispin fruit from interplanted trees were measured for 4 years. Similar measurements were made over a 6 year period in Cox and Spartan fruit samples from trees interplanted in another orchard. Concentrations varied greatly in all varieties from year to year. In comparison with Cox, fruit calcium concentrations were higher for a given mean mass per apple in Crispin in all years and in Spartan for 4 of the 6 years at harvest. Concentrations of nitrogen, potassium, magnesium and phosphorus were lower in Crispin and Spartan than in Cox fruit at harvest in all years, but dry matter and sodium concentrations differed only in some years. Changes in concentrations during fruit growth were measured in 2 years for each comparison. Differences between nitrogen, phosphorus and potassium concentrations in either Crispin or Spartan and Cox apples were evident throughout fruitlet enlargement in both years. Calcium concentrations were higher in Crispin and Spartan fruitlets than in Cox fruitlets of equivalent mass. Variations in the concentrations of potassium, magnesium and calcium from tree to tree were greater for Cox than Crispin samples but relationships between potassium and magnesium concentrations were similar for both varieties.     

Effects of soil compaction,seed depth,form of nitrogen fertiliser,fertiliser placement and manganese availability on barley

Investigations on light soils from 1977 to 1981 revealed important effects and interactions of husbandry methods and fertiliser placement on barley growth and yield which were largely due to their effects on Mn availability to the crop. Thus combine-drilling an acidifying fertiliser (but not a non-acidifying fertiliser) with the seed rather than broadcasting it, was very effective in controlling Mn deficiency and increasing yield substantially on Mn deficient sites. Soil compaction was beneficial where the fertiliser was broadcast, primarily because it forced shallow sowing of seed and thus kept the seminal roots near the acidifying fertiliser. Deep sowing of seed greatly reduced yield when fertiliser was broadcast but not when fertiliser was placed near the seed. These effects and interactions explain why poor crops were frequently associated with loose seedbeds, deep sowing and broadcast fertilisers.     

Effects of cultivar and soil fertility on grain protein yield,grain protein content,flour yield and breadmaking quality of wheat

Grain protein content affects the flour yield and breadmaking characteristics of wheat (Triticum aestivum L). In this study, grain protein yield, grain protein content, flour yield and loaf volume were quantified for four wheat cultivars (Inia, Carina, Kariega and SST 86) grown under six different soil fertility regimes in a long-term fertilisation and irrigation experiment at the University of Pretoria. The experimental design was a randomised complete block replicated four times, with fertility as the main plots and cultivars as the subplot treatments. Grain protein yield, flour yield, loaf volume and mixograph dough peak mixing time varied among cultivars and soil fertility situations. Grain protein content differed among cultivars, but mixograph water absorption and dough characteristics did not differ. The highest grain protein yield was 873 kg ha⁻¹ for Carina and the lowest 527 kg ha⁻¹ for SST 86. Grain protein content averaged 131 g kg⁻¹ for Carina and 122 g kg⁻¹ for Kariega. Breadmaking performance showed that in a well-balanced soil fertility situation, Kariega produced 1025 cm³ of loaf volume while Inia averaged 950 cm³. Grain protein yield increased with increasing soil fertility, but grain protein content, flour yield, loaf volume, water absorption and mixograph peak mixing time varied with soil fertility. The interaction between cultivar and soil fertility was significant for grain protein yield, grain protein content, flour yield, loaf volume and water absorption but not dough peak mixing time. The results indicate cultivar differences in breadmaking quality characteristics and that soil fertility status affects grain protein yield, grain protein content, flour yield, loaf volume potential and water absorption but not mixograph peak mixing time and dough characteristics. © 1999 Society of Chemical Industry     

Effects of available soil volume on growth, bud fertility and water relations of young Shiraz grapevines

Effects of available soil volume (ASV) on growth, water relations and bud fertility of drip-irrigated Shiraz grapevines ( Vitis vinifera ) were examined during their establishment in the 2000/01 growing season under field conditions in the Goulburn Valley, Australia. Vines were planted into different size subterranean containers to create a range of confined ASV treatments (viz. 0.15, 0.4, 0.8 and 1.2 m³/vine referred to as ASV₁₅, ASV₄₀, ASV₈₀ and ASV₁₂₀, respectively) and compared with a deep ripped treatment where the ASV was unconfined (ASV_UC). Pruning weight, trunk cross-sectional area, and daily average fractional photosynthetically active radiation interception ( f_daily ) increased with increasing ASV but were lowest in the ASV_UC treatment. f_daily attained a maximum by mid-February 2001 in ASV₁₅ but continued to increase in all other treatments. Water relations data showed high leaf water potential (φ_leaf) in ASV₁₅ compared to the other treatments. Our results suggest that reduced growth in smaller soil volumes was not a consequence of water stress. Leaf conductance ( g _L) tended to be low in the ASV₁₅ treatment in comparison with the ASV_UC treatment. Increasing ASV from 0.15 to 1.2 m³/vine increased the number of bunches per vine in the following season by 32%. This increase was not due to improvement in the number of bunches per shoot, but resulted from an increased number of shoots bursting per node. By contrast, ASV_UC significantly reduced bud fertility. The implications of these results for vine establishment in shallow soils are discussed.