Concentrations of total nitrogen in squash,cucumber and melon in relation to growth,and to a piper‐steenbjerg effect

Abstract

Squash (Cucurbita pepo), cucumber (Cucranis sativus), and sweet melon (Cucumis dudain) were grown in sand cultures with N supply concentrations as the variable. For several reasons, total‐N values were found to be less satisfactory than NO ‐N for the purpose of determining the critical nitrogen concentration for maximum growth. Concentrations of total‐N in mature petioles were higher in plants severely deficient in N than in less deficient plants, characteristic of a Piper‐Steenbjerg effect.     

Further study on iodine toxicity in relation to “Reclamation Akagare” disease of lowland rice

On the basis of the study on iodine behaviour in soil-plant system and other related informations. Tensho and Yeh(1,2,5) have suggested and demonstrated that the iodine toxicity is responsible for the “Reclamation Akagare” disease of lowland rice. Some additional evidences for this view will be presented. which were obtained particularly in connection with field studies on local problem.     

Mehlich‐1‐ and DTPA‐extractable lead in soils in relation to soil properties

Abstract

Mehlich‐1 and DTPA extractants are frequently used to predict metal availability in soils. Metal extractability by the acid or chelate extractant reflects the metal characteristics and metal‐soil interactions. In this study, samples of eight topsoils from the southeastern United States were incubated with added lead (Pb) at the rate of 40 mg#lbkg^‐1. After five months in the greenhouse, Mehlich‐1 and DTPA extractants were employed to extract Pb in both metal‐amended and natural soils. For the natural soils, Pb concentration in the DTPA extractant was always higher than that in the Mehlich‐1 extractant. This indicates that the DTPA chelate extractant is able to dissolve some Pb in soils which is not solubilized by protons. The negative correlation found between Mehlich‐1‐extractable Pb and soil clay content might result from two mechanisms: i) strong association between Pb and soil surfaces, or ii) readsorption of Pb during extraction. None of the correlations between DTPA‐extractable Pb and soil properties was significant, suggesting that the DTPA‐extractable Pb is not heavily dependent on soil properties. The DTPA extractant showed a high ability to solubilize Pb in the natural soils possibly due to a high affinity of Pb for soil organic matter.     

Polyphenol oxidase activity and ortho‐diphenolic content in sunflower leaves in relation to boron nutrition.

Homogenates were prepared from the leaves of hydroponically cultivated sunflowers (Helianthus annuus, L.) under deficient, normal and toxic B conditions and the polyphenol oxidase activity together with the ortho‐diphenolic and micronutrient content was measured every week from one month to flowering.

B deficiency slightly depressed polyphenol oxidase activity and B toxicity decreased it significantly at all times, the response fitting a line versus the logarithm of the B concentration in solution. We found a positive correlation between polyphenol oxidase activity and the B content in leaves.

B action on enzymatic activity seemed not to be caused by direct interaction with substrates as the infiltration of B into deficient leaves did not restore the normal activity

According to our results we suggest that polyphenol oxidase activity may be a valid functional parameter to indicate the nutritional status of B in sunflower plants, if its specificity for B can be demonstrated.

The ortho‐diphenolic content did not change with the B levels used in our experiments. Neither did we find any correlation between enzymatic activity and the o‐diphenolic content of the leaves.     

Pea–oat intercrops to sustain lodging resistance and yield formation in northern European conditions

Abstract

Locally produced crop protein is urgently needed in Europe. Pea is a good protein source and is well adapted to northern conditions. Pea can fix nitrogen that the following crop in rotation can benefit from. In cereal-dominated cropping systems pea is a break crop disrupting the life cycle of cereal diseases, leading to less fungicide application and thereby minimizing off farm inputs and benefiting the environment. Grain legumes provide animals with protein and energy, and the seeds of pulse crops are complementary to those of cereals. Field peas can be cultivated in most parts of Scandinavia and interest in peas has increased for inclusion in organic farming. Growing pea as a sole crop is a challenge since its stem is prone to lodging thereby resulting in harvesting difficulties, reduced yield and decreased profits. Intercropping of pea with oat could minimize the above listed problems but to our knowledge proportion of seeds mixture of the two crops and selection of pea cultivars without compromising the pea yield, especially protein production, at high latitudes conditions is limited. Therefore, our objective was to evaluate performance of sole cropped pea (Karita, Perttu, Hulda) and oat (seed proportions 7.5% and 15%) and their intercrop combinations and establish an appropriate seed mixture for a pea–oat intercropping systems that prevents lodging without markedly reducing pea yield. Field experiments were conducted at three locations (Jokioinen, Mietoinen, Ylistaro) of the Agrifood Research Finland in 2002–2004. Intercropping peas with oats prevented peas from lodging and made their harvest easier. Optimal numbers of oats in pea intercrops were difficult to determine, varying according to pea cultivar and local growth conditions. Excess oats in the seed mixture or conditions favouring oat growth prevented peas from lodging but pea yield was decreased.     

Fruit growth and mineral element accumulation in pacific rose™ apple in relation to orchard management factors and calyx‐end splitting

Abstract

The effect of irrigation and crop load of apple (Malus domestica Borkh cv. Pacific Rose) on the fruit growth and mineral element accumulation was investigated. Fruit growth and changes in the concentration and contents of nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), and potassium (K) in the flesh of Pacific Rose? apple fruit were recorded over a growing season at the Massey University Fruit Crops Units orchard in the 1998–99 crop season. Fresh mass showed a linear growth while fruit diameter followed a curvilinear growth pattern during the growing season. Low crop load significantly increased fruit size, particularly during the final expansion phase, whereas irrigation had little effect on this attribute. Both low crop load and frequent irrigation treatments increased fruit growth rate, but the effect of the irrigation treatments fluctuated considerably during the season. The incidence of frait splitting was detected at about 20 WAFB when the fruit attained an asymmetrical growth in shape (L/D). The concentrations of N, P, Ca, Mg, and K declined throughout the sampling period. There was however, an increase in concentrations of P and K at the last harvest. The quantity of individual nutrient elements accumulated by the fruit showed an increasing trend during the season. Nitrogen accumulation however, reached maximum at 16 WAFB after which it declined until the last harvest. Fruit mineral element analysis of sound and split fruit revealed that split fruit had higher concentrations and contents of Mg and K and lower contents of Ca and P. As a result, the ratios of Ca: Mg and Ca: K were lower in split fruit as compared with sound fruit.     

Soil organic carbon pools and productivity in relation to nutrient management in a 20-year-old rice–berseem agroecosystem

Labile fractions of soil organic C (SOC) can respond rapidly to changes in C supply and are considered to be important indicators of soil quality. An attempt is made in this paper to investigate into the dynamics of total organic C (C _tot), oxidisable organic C (C _oc), very labile C (C _{frac 1}), labile C (C _{frac 2}), less labile C (C _{frac 3}), non-labile C (C _{frac 4}), microbial biomass C (C _mic), mineralizable C (C _min) and particulate organic C (C _p) in relation to the system productivity of a 20-year-old rice (Oryza sativa L)–berseem (Trifolium alexandrium L) cropping system with different management strategies [no fertilization, only NPK and NPK + FYM (farmyard manure) applied in different seasons] in the hot humid, subtropics of India. Cultivation over the years caused a net decrease, while balanced fertilization with NPK maintained the SOC. About 62% of the C applied as FYM was stabilized into SOC. The passive pool (C _{frac 3} + C _{frac 4}) constituted about 55% of the C _tot. A larger proportion (63%) of applied C was stabilized in the passive pool of SOC. Of the analysed pools, C _{frac 1}, C _mic, C _p and C _min were influenced most by the treatments imposed and explained higher per cent variability in the yield of the crops.     

Variation of early growth and nutrient content of no‐till corn and soybean in relation to soil phosphorus and potassium supplies

Abstract

Knowledge of relationships between variation in early plant growth and soil nutrient supply is needed for effective site‐specific management of no‐till fields. This study assessed relationships between soil test phosphorus (STP) and potassium (STK) with early plant growth and P or K content of young corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] plants in eight no‐till fields. Composite soil (0–15 cm depth) and plant (V5‐V6 growth stages) samples were collected from 400‐m² areas at the center of 0.14‐ha cells of a 16‐cell square grid and from 2‐m² areas spaced 3 m along each of two 150‐m intersecting transects. Correlation, regression, multivariate factor analyses were used to study the relationships between the variables. Variability was higher for samples collected from the transects. Plant dry weight (DW), P uptake (PU), and K uptake (KU) usually were correlated with STP and STK but the correlations varied markedly among fields. Relationships between soil and plant variables could not always be explained by known nutrient sufficiency levels for grain production. Plant P concentration (PC) was not always correlated with STP and sometimes it increased linearly with STP, but other times increased curvilinearly until a maximum was reached. Plant K concentration (KC) usually was correlated with STK, however, and increased linearly with increasing STK even in fields with above‐optimum STK. The results suggest greater susceptibility of early growth to STP than to STK and greater plant capacity to accumulate K compared with P over a wide range of soil nutrient supplies. Variation in STK likely is a major direct cause of variation in KC over a wide range of conditions but variation in STP is not likely a major direct cause of variation in PC when high STP predominates.     

Spatial variation of soil δ13C and its relation to carbon input and soil texture in a subtropical lowland woodland

Spatial patterns of soil δ¹³C were quantified in a subtropical C₃ woodland in the Rio Grande Plains of southern Texas, USA that developed during the past 100 yrs on a lowland site that was once C₄ grassland. A 50 × 30 m plot and two transects were established, and soil cores (0–15 cm, n = 207) were collected, spatially referenced, and analyzed for δ¹³C, soil organic carbon (SOC), and soil particle size distribution. Cross-variogram analysis indicated that SOC remaining from the past C₄ grassland community co-varied with soil texture over a distance of 23.7 m. In contrast, newer SOC derived from C₃ woody plants was spatially correlated with root biomass within a range of 7.1 m. Although mesquite trees initiate grassland-to-woodland succession and create well-defined islands of soil modification in adjoining upland areas at this site, direct gradient and proximity analyses accounting for the number, size, and distance of mesquite plants in the vicinity of soil sample points failed to reveal any relationship between mesquite tree abundance and soil properties. Variogram analysis further indicated soil δ¹³C, texture and organic carbon content were spatially autocorrelated over distances (ranges = 15.6, 16.2 and 18.7 m, respectively) far greater than that of individual tree canopy diameters in these lowland communities. Cross-variogram analysis also revealed that δ¹³C – SOC and δ¹³C-texture relationships were spatially structured at distances much greater than that of mesquite canopies (range = 17.6 and 16.5 m, respectively). These results suggest fundamental differences in the functional nature and consequences of shrub encroachment between upland and lowland landscapes and challenge us to identify the earth system processes and ecosystem structures that are driving carbon cycling at these contrasting scales. Improvements in our understanding how controls over soil carbon cycling change with spatial scale will enhance our ability to design vegetation and soil sampling schemes; and to more effectively use soil δ¹³C as a tool to infer vegetation and soil organic carbon dynamics in ecosystems where C₃–C₄ transitions and changes in structure and function are occurring.     

Pattern of iron distribution in the soil‐plant system and its possible relation to iron‐chlorosis

Abstract

The frequent concentration‐ranges of various nutrient elements in soils and in plants are compared. Iron is different from almost all other nutrient elements in the fact that its optimal concentration range in plants is much lower than its frequent concentration range in soils. It is suggested that this observation is related to a chemical‐physiological mechanism of control on the uptake of iron by plants which in turn may explain the situations in which iron deficiency conditions in plants arise.     

Silica content in soil solution and its relation with phytolith weathering and silica biogeochemical cycle in Typical Argiudolls of the Pampean Plain,Argentina—a preliminary study

Purpose  

Little is known on the silica biogeochemical cycle in terrestrial environments. The aim of this work is to assess phytolith’s role on the biogeochemical cycle of Si in Typical Argiudolls under different vegetation of the Pampean Plain, Argentina.     

Long‐term acidification of farmland in northern Idaho and Eastern Washington

Abstract

In the past several years many scientists, consultants and growers in northern Idaho and eastern Washington have noticed a decline in the pH of agricultural soils. The purpose of this study was to compile and generate data for the determination of the causes, rate and magnitude of the pH decline in the region. Soil pH records from the past 40 years were collected from the soil testing laboratories at the University of Idaho and Washington State University. An intensive field pH survey was conducted in northern Idaho from 1982–84 and virgin soil samples were acidified under laboratory conditions.

Soils in northern Idaho and eastern Washington have undergone a rapid decline in pH in the past 25 years. These soils, which were near neutral in pH in their virgin state, have been acidified to the point that over 65% of the agricultural soils in the region have soil pH values less than 6.0. By 1984 over 45% of the agricultural soils in northern Idaho had pHs less than 5.6. This pH decline is attributed to the long‐term use of high rates of N fertilizers, as over 1250 kg N/ha have been applied to typical soils in the region since the virgin prairie sod was first broken for agricultural production. Seventy‐five percent of all N has been applied since 1960. Consequently, most soil acidification has occurred in the last 25 years. Field simulation in the laboratory was used to confirm the extent of soil acidification attributable to N fertilizer.     

LC-MS study to reduce ion suppression and to identify N-lactoylguanosine 5'-monophosphate in bonito: a new umami molecule?

In this study a specific taste modulating flavor ingredient, N-lactoylguanosine 5'-monophosphate (N-lactoyl GMP), was determined in bonito (Japanese, Katsuobushi, dried fermented skipjack) and in powdered bonito using liquid chromatography-electrospray ionization (+) mass spectrometry-mass spectrometry (LC-ESI(+)-MS/MS) with a methanol/ammonium acetate or formate gradient. Furthermore, the influence of ion suppression due to sample matrix effect was investigated and was found to substantially influence the total MS response of N-lactoyl GMP; by adjusting the LC conditions the response could be approximately 5-fold-enhanced. The N-lactoyl GMP concentrations in different types of bonito products were between 0.2 and 2.4 microg/g.     

Can integrated watershed management reduce soil erosion and improve livelihoods? A study from northern Ethiopia

The study aimed at evaluating the impact of integrated watershed management on reducing soil erosion and changes in the livelihoods of rural farming households in Ethiopia. The changes in soil erosion for the years between 2002 and 2015 were estimated using the Revised Universal Soil Loss Equation model, while the impacts on livelihoods were assessed by household interviews. During the study period, the overall average annual soil loss was halved. Furthermore, crop productivity, water availability (irrigation and domestic) and fodder availability increased by 22, 33 and 10%, respectively, while an increase in household income (by 56%) was observed. Moreover, 72% of the sampled households were able to cover their 12-month annual expenditure demands in 2015, while only 50% of the households were able to cover these demands in 2002. It can be concluded that the implemented integrated watershed management activities seemingly resulted in reduced soil loss, enhanced vegetation cover, and additional household income. This paper also elaborates on the hurdles for integrated watershed management expansion.     

Salt tolerance of rapid‐cycling brassica species in relation to potassium/sodium ratio and selectivity at the whole plant and callus levels

The potassium/sodium (K/Na) ratio in the shoots of six rapid‐cycling Brassica species was greatly reduced by seawater salinity. It proportionally decreased with increasing salinity from 4 dS/m to 12 dS/m. This decrease was correlated with salt‐induced growth reduction (expressed as the percentage of control) within a species. The change in K/Na ratio with increasing salinity, however, was not correlated with K‐Na selectivity. The change in K/Na ratio at the callus level corresponded to that at the whole plant level. Both K/Na ratio and K‐Na selectivity were not found to be correlated with the relative salt tolerance of these Brassica species, indicating that the maintenance of a high K/Na ratio as a mechanism for salt tolerance in these Brassica species was not operative. These results also suggest that a high shoot K/Na ratio or K‐Na selectivity may not be reliable selection criteria for salinity resistance in some species.