Effect of placement of urea and coated urea fertilizers on yield and quality of soybean (Glycine max (L.) Merr.) seeds

The objective of the present study was to record the seed yield and to examine visually the quality of soybean seeds cultivated under different types and placements of urea fertilizers. In addition to the conventional fertilizer application (including ammonium sulfate 16 kg N ha^-1 broadcasting (100 kg N ha^-1 of urea (0B) and X00-d type coated urea CU-100 (CUB), and deep placement (100 kg N ha^-1) of urea (UD) and 100-d type coated urea CU-100 (CUD) was conducted in separate plots in a paddy field converted to an upland field located at Shindori Experimental Station of Niigata University. Soybean plant growth was periodically analyzed and the quality of harvested seeds was also visually examined (hereafter referred to as “visual quality”). It was found that the deep placement treatments were more conducive 1o nitrogen (N₂)fixation, based on the relative mreide N concentration in the xylem sap, which is a good indicator of N~fixation by soybean. Also the total seed yield was the highest in CUD (82 g plant^-1) and 0D (81 g plant^-1), compared to the control (62 g plant^-1), UB (68 g plant^-1), and CUB (68 g plant^-1). The visual quality of harvested seeds showed that CUD enhanced the quality of seeds compared to the other treatments, in which the percentage of good quality seeds, hereafter referred to as "good seeds," based on the dry weight was 51 (control), 65 (K3B), 61 (CUB), 61 (0D), and 6696 (CUD). In terms of diseased seeds, the percentage of turtle wrinkle and broken seed coats was found to decrease by N application compared to the control. Thus, it is suggested that N fertilization management is important for maximum yield of soybean as well as for the enhancement of seed quality.     

Effect of deep placement of calcium cyanamide,coated urea,and urea on soybean (Glycine max (L.) Merr.) seed yield in relation to different inoculation methods

Abstract

The main objective of this study was to increase the productivity of soybean [Glycine max (L.) Merr. cv. Enrei] seed by deep placement of controlled release nitrogen fertilizers and by the application of different methods of inoculation of bradyrhizobia. Ten days old seedlings in an inoculated paper pot (IPP), in a non-inoculated paper pot (NIPP), and those grown in a vermiculite bed without paper pot (DT) were transplanted to an upland field converted from a drained paddy field in Nagaoka. In addition to the basal application of 16 kg N ha^?1 in the surface layer (Control), deep placement of 100 kg N ha^?1 of urea (Urea), 100-day type coated urea (CU-100), and calcium cyanamide (CaCN₂) treatments were applied at the depth of 20 cm. In the IPP method, a significantly higher seed yield was obtained with the deep placement of CaCN₂ and CU-100 compared with the Urea and Control treatments. A similar tendency was observed for the DT and NIPP methods. Among the same N fertilizer treatments, the seed yield for IPP and DT tended to exceed that for NIPP, although the NIPP roots also showed nodulation probably due to infection with indigenous bradyrhizobia. The percentage of nitrogen derived from atmospheric N₂ estimated by the simple relative ureide method was higher in the plants with CU-100 and CaCN₂ compared with those with the Urea and Control treatments at the RI stage, suggesting that the basal deep placement of CaCN₂ or CU-100 for soybean cultivation enabled the supply of N without concomitant depression of N₂ fixation. Thus the deep placement of cheaper CaCN₂ was found to be as effective as that of CU-100 for enhancing the soybean seed yield.     

Effect of placement of coated urea fertilizer on root growth and rubidium uptake activity in soybean plant

Abstract

We reported in the previous paper (Takahashi et al. 1991) that the deep placement of slow release N fertilizer (coated urea) contributed to a stable increase of soybean (Glycine max L. Merr.) yield. In the previous study we observed that the deep placement of coated urea did not depress appreciably the nitrogen fixation by root nodules although fertilizer N was efficiently utilized. We assumed that the N absorbed from the roots in the deep layers did not cause nodule senescence, contributed to the maintenance of the leaf activity during the maturation stage, and that the increase in the availability of carbohydrate and N improved seed production. In the current report the effects of placement of coated urea fertilizer on the root growth and activity were studied by measuring the root dry weight and Rb absorption activity.     

Rapid and reversible nitrate inhibition of nodule growth and N2 fixation activity in soybean (Glycine max (L.) Merr.)

Nodulated soybean (Glycine max. (L) Merr. cv. Williams) plants were hydroponically cultured, and various combinations of 1-week culture with 5 or 0 mm nitrate were applied using 13-d-old soybean seedlings during three successive weeks. The treatments were designated as 0-0-0, 5-5-5, 5-5-0, 5-0-0, 5-0-5, 0-5-5, and 0-0-5, where the three sequential numbers denote the nitrate concentration (mm) applied in the first-second-third weeks. The size of the individual nodule was measured periodically using a slide caliper. All the plants were harvested after measurement of the acetylene reduction activity (ARA) at the end of the treatments. In the 0-0-0 treatment, the nodules grew continuously during the treatment period. Individual nodule growth was immediately suppressed after 5 mm nitrate supply. However, the nodule growth rapidly recovered by changing the 5 mm nitrate solution to a 0 mm nitrate solution in the 5-0-0 and 5-5-0 treatments. In the 5-0-5 treatment, nodule growth was completely inhibited in the first and the third weeks with 5 mm nitrate, but the nodule growth was enhanced in the second week with 0 mm nitrate. The nodule growth response to 5 mm nitrate was similar between small and large size nodules. After the 5-5-5, 5-0-5, 0-0-5, and 0-5-5 treatments, where the plants were cultured with 5 mm nitrate in the last third week, the ARA per plant was significantly lower compared with the 0-0-0 treatment. On the other hand, the ARA after the 5-0-0 and 5-5-0 treatments was relatively higher than that after the 0-0-0 treatment, possibly due to the higher photosynthate supply associated with the vigorous vegetative growth of the plants supplemented with nitrate nitrogen. It is concluded that both soybean nodule growth and N₂ fixation activity sensitively responded to the external nitrate level, and that these parameters were reversibly regulated by the current status of nitrate in the culture solution, possibly through sensing of the nitrate concentration in roots and / or nodules.     

Variation of nitrogen accumulation and yield in response to phosphorus nutrition of soybean (Glycine max L. Merr.)

Phosphorus (P) is essential macronutrient for soybean [Glycine max (L.) Merr.] growth and function. The objective of this study was to determine effect of phosphorus nutrition (including phosphorus nutrition level and interruption of phosphorus supply) on nitrogen accumulation, nodule nitrogen fixation and yield of soybean plants by ¹⁵N labeling with sand culture. The results showed that they all presented a single peak curve with improvement of phosphorus nutrition level, when phosphorus concentration of nutrient solution was about 31 mg/L, they all reached the maximum and effect of phosphorus nutrition level on nodule nitrogen fixation was lower than that on yield formation level. Interruption of phosphorus supply during soybean growth period, nitrogen accumulation and nodule nitrogen fixation were seriously inhibited, and yield was decreased significantly when interruption of phosphorus supply during V₃-R₁ and R₁-R₅ period, while interruption of phosphorus supply during R₅-R₇ period had no significant effect on nitrogen accumulation, nodule nitrogen fixation and yield. So soybean nitrogen metabolism and yield were sensitive to phosphorus nutrition in the V₃-R₅ period, those were not sensitive to phosphorus nutrition after R₅ period.     

Effect of liming using a partial mixing technique on reductions in the seed cadmium levels for soybeans (Glycine max (L.) Merr.) under field conditions

To reduce the availability of soil cadmium (Cd) to soybeans (Glycine max (L.) Merr.), we employed a liming by partial mixing (PM) technique in two drained paddy fields on Gray Lowland soils, which had 0.1 mol L^–1 hydrochloric acid-extractable Cd concentrations as high as 1.08 and 1.40 mg kg^–1. Among the different application methods tested, PM application (PM2) using a width of 20 cm and a depth of 20 cm was found to be most appropriate for reducing the seed Cd concentration and to obtain the optimum yield at Site A. Under PM2, a liming rate of 38% of that for broadcast incorporated into the surface 15 cm layer (Bc) was suitable to reduce the seed Cd concentration at Site A, whereas the lime rate with PM2 was set at 50% of that for Bc (PM2-50) at Site B due to the higher availability of soil Cd. The root system was limited within the range of lime and fertilizer application for PM2 as well as PM2-50; thus, the lime and fertilizer were supplied successfully to the rooting zone. The soil pH value was lower under PM2 at Site A and PM2-50 at Site B compared with Bc, whereas the seed Cd concentration was lower for PM2 and PM2-50. This may be explained by the intensive uptake of calcium and magnesium with PM2 as well as PM2-50. The seed Cd concentration in the cultivar “Ryuhou” at the target pH of 6.5 was approximately 30% lower with PM2-50 than Bc at Site B. In addition, the average seed Cd concentrations in one cultivar and two lines, characterized by the lower Cd uptake with higher retention in roots and higher accumulation in leaves, were approximately 40% lower compared with “Ryuhou.” Thus, the combination of liming with PM2-50 at the target pH of 6.5 and a low-Cd cultivar (or lines) minimized the seed Cd concentration. The highest seed Cd concentration was found in the first year of soybean cultivation, which was considered to be caused by the release of Cd from organic nitrogen compounds during the nitrogen mineralization process.     

Effect of nodulation with Bradyrhizobium japonicum and Shinorhizobium fredii on xylem sap composition of Peking (Glycine max L. Merr )

Five barley cultivars were grown together in complete, low-P·low-pH and high-Al medium containing only NO₃, only NH₄ or both NO₃ and NH₄ as N sources, respectively using an automatic control system of pH for water culture, and the relationship between the differential Al tolerance and the plant-induced pH change of medium among the barley cultivars was investigated.

The pH of the medium containing only NO₃ as N source tended to increase, whereas the pH of the other media containing only NH₄ or both NO₃ and NH₄ as N sources tended to decrease, but the fluctuations of the medium pH could be maintained within the value of 0.2 pH in the complete medium and within the value of 0.1 pH in the high-Al medium.

Barley cultivars still differed in their Al tolerance in the medium which was continuously stirred and circulated at a constant pH. The pattern of Al tolerance was not affected by the N sources in the medium. The plant-induced pH change of medium for each cultivar was influenced by the N sources in the medium, and was not correlated positively with Al tolerance. The contents of Al and Ca or other nutrient cations in roots were positively correlated with Al tolerance and positive correlations were recognized also between the contents of Al and Ca or some other nutrient cations in the roots.

In conclusion, the following mechanisms are proposed. Al tolerant barley cultivars exclude Al actively outside the plasmalemma of the root cells, and the excluded Al may polymerize and or react with P to form Al precipitates. Consequently, in the Al tolerant barley cultivars the Al content may be low in the root protoplasts, high in the whole root tissues and the contents of Ca or other nutrients may be high in the roots. The plant-induced pH change of medium is not considered to be the cause of the differential Al tolerance among barley cultivars.     

Impact of pyrochar and hydrochar on soybean (Glycine max L.) root nodulation and biological nitrogen fixation

The aim of this study was to identify effects of carbonized organic material (“biochar”) on soybean growth, root nodulation and biological nitrogen fixation, and to elucidate possible underlying mechanisms. Soybean (Glycine max L.) was grown in four arable soils amended with carbonized organic material produced from wood or maize as feedstocks, by pyrolysis (“pyrochar”) or hydrothermal carbonization (“hydrochar”). Nodulation by Bradyrhizobium , biological nitrogen fixation (BNF) assessed by ¹⁵N techniques, plant growth, nutrient uptake and changes in chemical soil properties after soil amendment were determined. Data were analyzed by means of a three way ANOVA on the factors soil, carbonization technique and feedstock. It turned out that soybean root nodulation and BNF was influenced by the carbonization technique used to prepare the soil amendment. Hydrochar, in average and across all soils, increased nodule dry matter and BNF by factors of 3.4 and 2.3, respectively, considerably more than pyrochar, which led to 1.8 and 1.2 fold increases, respectively. Nodule dry matter and BNF correlated positively with available soil sulfur and negatively with available soil nitrogen. Hydrochars provided more available sulfur than pyrochars, and hydrochars caused a decrease in nitrogen availability in the soil solution, thereby exerting a positive influence on nodulation and BNF. Pyrochar amendment increased soil pH but had no effect on nodulation and BNF. Plant growth was affected by the soil and by the feedstock used for the “biochar”, and increased slightly more in treatments with pyrochar and hydrochar made from maize, which was richer in nitrogen and potassium. The results show that carbonized organic materials, and specifically hydrochar, have the capacity to increase BNF in soils. We suggest that this enhancement in BNF in response to soil amendments with carbonized organic materials is due to an increase in available sulfur and a reduction of available soil nitrogen.     

无机包膜肥料在提高小麦氮素利用率和产量效应的研究

A field experiment with winter wheat （Triticum aestivurn L.） was conducted on a silt loam calcaric endorusti-ustic Cambosols derived from the Yellow River alluvial deposits in Henan, China, from 2001 to 2002 to evaluate N recovery and agronomic performance of different mineral coated fertilizers （MiCFs） compared to normal urea used in wheat cropping systems under field conditions. Five treatments, including CK （check, no N fertilizer）, urea and three different MiCFs at an equivalent N application rate were established in a randomized complete block design. N release from MiCFs in soil was more synchronous with the N requirement of wheat throughout the growth stages than that from urea, with grain yield of the MiCF treatments significantly higher （P 〈 0.05） than that of the treatment urea. Correspondingly, the N recovery rate was greater for all MiCFs compared to urea, increasing from 32.8% up to 50.1%. Due to its high recovery and low cost, use of the mineral coated N fertilizers was recommended instead of the polymer coated N fertilizers.     

Phenolic composition and antioxidant activity in seed coats of 60 Chinese black soybean (Glycine max L. Merr.) varieties

Phenolics in black soybean seed coat (BSSC) are considered to be responsible for the health benefits of black soybean. BSSCs of 60 Chinese varieties were examined for phenolic contents, anthocyanin profiles, and antioxidant activity. Total phenolic and condensed tannin contents ranged from 512.2 to 6057.9 mg gallic acid equivalents/100 g and from 137.2 to 1741.1 mg (+)-catechin equivalents/100 g, respectively. Six anthocyanins (delphinidin-3-glucoside, cyanidin-3-galactoside, cyanidin-3-glucoside, petunidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside) were detected by HPLC. Total anthocyanin contents (TAC) were from 98.8 to 2132.5 mg/100 g, and cyanidin-3-glucoside was the most abundant anthocyanin in all varieties, with a distribution of 48.8-94.1% of TAC. Antioxidant properties detected by DPPH, FRAP, and ORAC methods all showed wide variations ranging from 4.8 to 65.3 μg/100 mL (expressed as EC(50)), from 17.5 to 105.8 units/g, and from 42.5 to 1834.6 μmol Trolox equivalent/g, respectively. Sixty varieties were classified into four groups by hierarchical clustering analysis, and group 4 consisting of nine varieties had the highest phytochemicals content and antioxidant activity.     

Effects of phosphorus amended low phosphorus soil on soybean (Glycine max L.) and wheat (Titicum aestivum L.) yield and phosphorus uptake

A major constraint for crop production on disturbed soils is phosphorus (P). A 2-year field study was conducted on a disturbed soil to evaluate broiler litter ash (BLA) as an inexpensive phosphorus fertilizer for soybean. BLA or super phosphate (SP) was applied at four rates and planted with soybean followed by wheat. At soybean growth stage R3, two plants from each plot were removed for tissue analysis. Soybean tissue P concentration distributions were in the order pods?>?leaves?>?stems?>?roots. At maturity, soybean grain and wheat tissue yields were not significantly affected by P source. Except for the high superphosphate rate for the second crop, P concentrations of soybean grain and wheat tissue were not significant between P source. In this study, BLA was as effective as SP for growth of soybean grain and wheat tissue, suggesting that BLA can be used as an inexpensive P fertilizer on low P disturbed soils.     

Growth characteristics,phytate contents,and coagulation properties of soymilk from a low-phytate Japanese soybean (Glycine max (L.) Merr.) line

The phytic acid (myo-inositol hexakisphosphate or InsP₆) content of seed crops is important to their nutritional quality. Since it represents 75?±?10% of the total seed phosphorus (P), phytic acid is also important regarding the management of P in agricultural production. A low-phytate F5 line, No. T-2-250-4-20, was selected from the progeny of a cross between the low-phytate soybean line CX1834 and the Japanese commercial cultivar Tanbakuro. This line and its parents were grown in a field nursery, and the growth characteristics, phytate accumulation, and processing suitability for tofu were evaluated. At full maturity, the weight of seeds per plant of line T-2-250-4-20 was 5.2- and 1.3-fold higher than that of CX1834 and Tanbakuro, respectively. The amount of phytate-phosphorus as a percentage of the total P content in seeds was 23% in line T-2-250-4-20-34, 30% in CX1834, and 69% in Tanbakuro. No significant difference was observed among the three cultivars/lines in their seed magnesium (Mg), potassium (K), crude protein, and sugar. However, the calcium (Ca), crude fat and ash contents in seeds of line T-2-250-4-20-34 and Tanbakuro was lowered compared to that of CX1834. The breaking stress of tofu was estimated employing a rheometer with a decreasing concentration of the coagulant magnesium chloride (MgCl₂), starting at 15.7?mmol?L^?1. In tofu made from Tanbakuro, the concentration of MgCl₂ required to achieve the maximum breaking stress was 12.6?mmol?L^?1; however, it was 9.5?mmol?L^?1 for tofu made from T-2-250-4-20-34 and CX1834. The tofu made from Tanbakuro was soft and broke at 6.3?mmol?L^?1 MgCl₂, but, in line T-2-250-4-20-34, harder tofu was made with lower MgCl₂ concentrations. No difference was observed among the cultivars/lines in the SDS-PAGE patterns of protein in soymilk. These results indicate that we have developed a low-phytate soybean with adequate productivity, and confirmed that tofu made from the low-phytate T-2-250-4-20-34 soybean becomes coagulated and harder at a lower MgCl₂ concentration than that from high-phytate soybean cultivars.     

包膜尿素对温室番茄产量、品质和经济效益的影响

采用田间小区和试验示范研究了包膜尿素对番茄产量、 品质和施肥经济效益的影响,包膜尿素20%的氮混入育苗基质,剩余80%在移栽时条施（总施氮量为常规施氮量的50%）。结果表明,包膜尿素接触施肥的番茄壮苗指数比常规育苗提高了47.9%;与普通尿素底施加3次追肥相比,施用包膜尿素的番茄产量较等氮量普通尿素（N 180 kg/hm2）和常规施氮量（N 360 kg/hm2）处理分别增加了5.1%和9.7%,氮肥利用率提高了9.0~10.2个百分点;相比普通尿素,包膜尿素改善了番茄品质,其中可溶性糖含量提高6.5%9.~4%,Vc含量提高10%~11.3%。与常规施氮相比,包膜尿素在氮肥投入略低的情况下（减少44 Yuan/hm2）,番茄单位面积产值和净收益（扣除肥料投入）比常规施氮量增加了33.8%。施用包膜尿素的表层（020 cm）土壤硝态氮含量相对普通尿素起到了削峰填谷作用,降低了硝态氮的淋失风险。     

Isolation and determination of anthocyanins in seed coats of black soybean (Glycine max (L.) Merr.).

Anthocyanin pigments in seed coats of black soybean (Glycine max (L.) Merr.) were extracted with 1% HCl-CH(3)OH, and the crude anthocyanin extract was purified by Shepadex LH-20 and Lichroprep RP-18 open-column chromatography. Three major anthocyanins were isolated, and their chemical structures were identified by spectroscopic methods (UV-visible, FABMS, (1)H and (13)C NMR, and by TLC). The complete structures of these anthocyanins were elucidated as delphinidin-3-glucoside, cyanidin-3-glucoside, and petunidin-3-glucoside. Among them, petunidin-3-glucoside was identified as a new anthocyanin in black soybeans. On the basis of RP-HPLC with a UV-vis detector, the contents of delphinidin-3-glucoside, cyanidin-3-glucoside, petunidin-3-glucoside, and total anthocyanins in seed coats of 10 black soybeans were found in the ranges of 0-3.71, 0.94-15.98, 0-1.41, and 1.58-20.18 mg/g, respectively. The results obtained in this study imply that the seed coats of black soybean can be used as a good source for cyanidin-3-glucoside and delphinidin-3-glucoside.     

Lead-Induced Histological and Ultrastructural Changes in the Leaves of Soybean (Glycine max (L.) Merr.)

The seedlings of the soybean ( Glycine max. (L.) Merr.) cv. Polan were investigated by subjecting them to water culture for a period of 14 d. To the Knop nutrient solution, lead was added as PbCl₂ at four concentrations: 0, 10, 20 and 40 mg dm⁻³. Observations of soybean leaf tissues were carried out by light microscopy, transmission electron microscopy and scanning electron microscopy. The Pb levels used in the present study reduced the area of cotyledons and leaf blades of the soybean plants. Pb-induced changes in the leaf epidermis structure involved a reduction in the cell size, more abundant wax coating, and an increase in the number of stomata and trichomes per unit area with simultaneous reduction in the size of the guard cells. The lead treatment resulted in the reduction in the thickness of the leaf blades, reduction in the area of xylem and phloem in the vascular bundles and in the diameter of the xylem vessels. Under Pb stress, the leaf mesophyll cells were characterized by the presence of altered chloroplasts with a reduced lamellar system and multidirectional pattern of the thylakoid system. Burst stroma of the thylakoid system and cracked chloroplast envelopes were also observed. The importance of the increase in the number of stomata and trichomes for plants under the metal stress was examined.     

Influence of lime and phosphorus on soybean (Glycine max (L.) Merrill) yield,leaf and seed composition on a paleudult soil

Abstract

This research was undertaken on a paleudult soil in southern Brazil, 30° south latitude, to quantify lime and P effect upon soybean (Glycine max (L.) Merrill). A lime x P factorial experience with lime treatments of 0, 0.5, 1, and 2 times SMP interpretation to pH 6.5, and 0, 44, 88, 132, and 176 kg P/ha with 3 replications were installed. The experiment was conducted for 2 years (1973–74, 1974–75), with leaf‐N, P, and K; yield; seed‐N, P, and K; Bray P₂ (0.03N NH₄F + 0.1N HC1) avail‐able‐P and soil pH measurements completed each year. Data was evaluated with linear, quadratic, logarithmic, polynomial, segmented line, and multiple regression using the coefficient of determination as goodness of fit.

The best model fit between P treatment and Bray P₂ available‐P was a quadratic equation; the model between relative yield and Bray P_2‐P with 54% of the relative yield attributed to Bray P₂ available‐P, a sigmented line. This model indicated point of maximum yield (91% relative yield) was obtained at 7.4 ppm‐P, with no increase in relative yield with increasing levels of soil available‐P. To calculate the P fertilizer necessary to increase available soil‐P to the level of maximum yield of equation Y_p = [1639(7.4 ‐ x_s)]^1/2, where Y_p = kg P/ha fertilizer needed; and x_s = initial Bray P₂ soil available‐P in ppm's. The lime effect upon soil pH was best described as a linear relationship. Yield increase with lime at this site was not significant at the 5% level.

The leaf‐N, P, and K increased significantly with soil available‐P levels. A second degree polynomial with logarithmic function best defined these relationships. The calculated DRIS indices and sum proved useful to evaluate the plant‐N, P, and K balance of each treatment.

Only seed‐P level was directly related to soil available‐P. Both seed‐N and seed‐K were highly correlated with indirect effects of soil available‐P levels.

Results from this study suggest the segmented line model would best interpret soybean yield response to Bray P₂ available‐P for this soil. To obtain maximum yield using this model rather than the second degree polynomial would require less fertilizer P. Foliar analyses interpretation confirmed adequate plant‐P level would be supplied for maximum yield at this level of fertilization.     

Analysis of regulation site and manner of abundant nodulation in a soybean (Glycine max (L.) Merr.) cultivar,kitantusunte, using grafting techniques

To characterize the regulation site and manner of the abundant nodulation in the soybean (Glycine max (L.) Merr.) cv. Kitamusume, three grafting eperiments were carried out as follows: reciprocal wedge grafting and inter-cultivar approach grafting between Kitamusume and a normal nodulating cultivar, Toyosuzu, as well as wedge grafting of scions of the supernodulating mutant En6500 onto either Kitamusume or Toyosuzu rootstock. In the reciprocal wedge grafting, the number of nodules per shoot dry weight and average weight per nodule in the grafted plants were consistent with those exhibited by the genotype of their rootstocks. Approach grafting did not affect the number of nodules per shoot dry weight on either side of the inter-cultivar approachgrafted plant. Although grafting of the mutant scion resulted in the loss of the autoregulatory response from the roots of both cultivars, difference in the number of nodules per g shoot dry weight still remained between the two cultivars. These results suggested that the abundant nodulation in Kitamusume is controlled by the root in a non-systemic manner and is independent of the autoregulation mechanism.     

Effects of deep placement of controlled-release nitrogen fertilizer on soybean growth and yield under sulfur deficiency

Sulfur (S) and Nitrogen (N) metabolisms in plants are interacted and it is known that S deficiency decrease N absorption and metabolism. In leguminous plants S deficiency also decreases N₂ fixation by rhizobia in the nodules. Deep placement of a controlled-release N fertilizer is a good method to provide nitrogen to soybean without inhibiting N₂ fixation; thus, it was hypothesized that this method is able to provide nitrogen effectively to sulfur-deficient soybean plants. In this study effects of deep placement of coated urea on S-N physicological interaction, growth and productivity in soybean plants were examined using pot experiments. Soybean plants were grown with sulfate concentrations of 30, 100, or 1000 μM, with or without deep placement of coated urea. Shoot weights at the developing stage were not affected by S deficiency. SPAD values of leaves during the flowering stage decreased with S deficiency and increased with the deep placement of coated urea. S deficiency decreased seed weight per plant at the harvesting stage, but this decrease was attenuated by the deep placement of coated urea. N and S content in shoots at the developing stage increased with the deep placement of coated urea, whereas in seeds, only the N content increased. N₂ fixation activity based on the relative ureide-N content in xylem sap indicated that the deep placement of coated urea did not inhibit N₂ fixation activity at the early flowering stage. Without deep placement of coated urea, the relative ureide-N content decreased under S deficiency at the seed filling stage. These results suggest that the deep placement of coated urea is an efficient method to supply N to support soybean yield under S deficiency.

Abbreviations: Deep+: with deep placement of coated urea; Deep–: without deep placement of coated urea