Evaluating second year cropping on jhum fallows in Mizoram,north-eastern India—Phytomass dynamics and primary productivity

Cropping on jhum fallows in north-eartern India is predominantly done for one year in a jhum cycle. If second year cropping is done, expanse of the forest land required for slashing and burning could be reduced significantly. We tested this hypothesis in a young (6 yr) and an old (20 yr) jhum fallow. We also evaluated if the productivity during second year cropping could be alleviated by auxiliary measures such as tilling the soil or application of fertilizers (chemical or farm-yard manure or both in combination). The results demonstrate that the ecosystem productivity (total dry matter production) and economic yield (rice grain production) decline with shortening of jhum cycle. Second year cropping causes a further decline in ecosystem productivity in old jhum field, but not in young jhum field. Economic yield from second year cropping in its traditional form (without any fertilizer treatment) is not much lower than that in the first year, and can be improved further by manuring the soil. Tilling of soil improves neither ecosystem productivity nor economic yield. Different fertilization treatments respond differently; while inorganic manuring enhances ecosystem productivity, a combination of inorganic and organic manuring improves economic yield     

Evaluating second year cropping on jhum fallows in Mizoram, north-eastern India: Soil fertility

Changes in soil fertility were evaluated on young (6 year) and old (20 year) jhum fields in Mizoram, north-eastern India in response to various operations involved injhum such as slashing and burning of vegetation, cropping period, and intervening fallow period between first and second year cropping. The results demonstrate that the soil is richer in nutrients in old than young field prior to the start of jhum cultivation. Slash burning depletes soil acidity, carbon and nitrogen but elevates phosphorus and cations. Soil fertility declined during first cropping phase, and further declined during second cropping phase. After two cropping years, soil fertility of old field was almost at par with that of young field, signifying that the loss of soil fertility was more in old than young field. A short intervening fallow period between first and second year of cropping did not show any pronounced improvement in soil fertility, though it provided some biomass for second burning. Tilling caused maximum loss to soil fertility. The fertilizer treatments ended with comparable or better soil fertility in comparison to no-treatment plot. There seems to be none of the fertilizer treatments superior over others from the standpoint of ending soil fertility. The unifying conclusions of this series of investigations support the hypothesis that the second year cropping holds promise to reduce the demand for forested land for jhum, and lengthen the jhum cycle substantially.     

Age related changes in ovarian follicular kinetics in the Indian skipper frogRana cyanophlyctis (Schn.)

Changes in ovarian follicular kinetics were studied in relation to aging in the Indian skipper frog Rana cyanophlyctis.Age was determined by skeletochronology, by counting the number of growth rings and lines of arrest of growth from the cross sections of 4th phalange of 4th toe. For follicular kinetics study oocytes were counted under binocular using 10% of Bouin’s fixed ovary and they were classified into first growth phase, medium-sized second growth phase, large-sized second growth phase and atretic follicles. Analysis of phalangeal cross sections indicated that frogs ranging 14–54 g in body weight and 4.9–8.9 cm in body size showed 1–7 year rings. Frogs that weighed 14–16 g showed 1 year ring, and contained immature ovaries; those with 18 g body weight had one to two year rings, in which second growth phase oocytes appeared for the first time in the primiparous ovary. Frogs with 20–54 g body weight showed 2–5 year rings in which ovary contained 5–24% of second growth phase oocytes. Further, body weight, body size, ovarian weight, number and size of second growth phase oocytes and total number of oocytes showed a significant (P < 0.05) positive correlation, while, the number of first growth phase and atretic follicles showed a poor correlation with age. The results suggest that in nature, the age of Rana cyanophlyctis ranges between 1–7 years. Phalangeal growth rings are formed annually. Females attain sexual maturity in 2nd year. Frogs with 2–5 years of age may constitute breeding females. Body weight, body size, ovarian mass, number of second growth phase and total oocytes, and egg size increase with age up to 5 years.     

专项整治对综合医院抗菌药物使用强度的影响

??????? 目的 探讨抗菌药物临床应用专项整治活动对综合医院住院患者抗菌药物使用强度的影响。方法 以限定日剂量（DDD）为单位,对某综合性医院在实施专项整治前、后住院患者抗菌药物使用强度（AUD）进行统计、分析。结果 专项整治活动降低了住院患者累计AUD值,大环内酯类等药物AUD明显下降,第二代、第三代和第四代头孢菌素和不同管理级别抗菌药物AUD均下降。但还存在用药集中、注射用头孢哌酮钠舒巴坦钠AUD下降不明显等问题。结论 专项整治有效降低了综合医院住院患者AUD,但与卫生行政部门标准仍存在差距,应进一步加强管理。     

Evolutionary conservation of angiosperm flower development at the molecular and genetic levels

Flowers consist primarily of four basic organ types whose relative positions are universally conserved within the angiosperms. A model has been proposed to explain how a small number of regulatory genes, acting alone and in combination, specify floral organ identity. This model, known widely as the ABC model of flower development, is based on molecular generic experiments in two model organisms,Arabidopsis thaliana and Antirrhinum majus.Both of these species are considered to be eudicots, a clade within the angiosperms with a relatively conserved floral architecture. In this review, the application of the ABC model derived from studies of these typical eudicot species is considered with respect to angiosperms whose floral structure deviates from that of the eudicots. It is concluded that the model is universally applicable to the angiosperms as a whole, and the enormous diversity seen among angiosperms flowers is due to genetic pathways that are downstream, or independent, of the genetic programme that specifies floral organ identity.     

Soil nutrient status of hill agro-ecosystems and recovery pattern after slash and burn agriculture (Jhum) in north-eastern India

Summary The present study deals with fertility changes in agro-ecosystems where vegetation is removed by slash and burn procedures, the land is planted to crops (cultivated) for one year, and then left to revegetate naturally for upto 50 years (forested fallow, here after referred to as ‘fallow’) before the entire cycle (locally called ‘Jhum’) is repeated. A comparison has been made between three jhum cycles of 30, 10 and 5 years. Depletion in soil carbon continued throughout the cropping period of one year and extended upto a 5 year fallow. This could be one of the reasons against a short jhum cycle, alongwith a similar pattern in depletion of nitrogen. Available phosphorus build up in the fallows also starded only beyond a 5 year fallow period with rapid increase in 10, 15 and 50 year fallows. Cationic concentration in the soil also rapidly declined in the early phases of regrowth of vegetation. This decline was most pronounced for potassium due to the fact thatDendrocalamus hamiltonii is a heavy accumulator of this nutrient. Since this bamboo species dominates the fallow upto about 20 years, potassium build up in the soil was observable only at this stage. It is suggested that this species plays an important role in conservation of this nutrient. In a 50 year fallow, low levels of calcium and magnesium were maintained with rapid depletion of both with depth which is in contrast to that of potassium and phosphorus. In general, short jhum cycles of 5 year permit only low levels of soil fertility with very poor recovery during the fallow period. The significance of these results are discussed.     

Quantitative study of cellular and volumetric growth of magnocellular and laminar auditory nuclei in developing chick brainstem

Development of the second and third order auditory nuclei—nucleus magnoscellularis (NM) and nucleus laminaris (NL) respectively—was studied using Nissl stained serial sections from brain specimens between 8 day of incubation and posthatch day 1, at every two day interval. Reconstruction of these nuclei from three incubation ages showed progressive growth of both nuclei in a rostrocaudal direction. The volume, total neuron, dead cell and glial cell numbers were estimated using stereological quantitation methods. Both nuclei, while undergoing an overall gradual increase in volume up to 20 days registered a transient drop in volume; earlier for NM at 10 days and later for NL at 18 days. From day 20 the two nuclei showed accelerated growth in volume. The total neuron count rapidly declined up to 12 days with 43% loss of neurons in NM followed by a rise and later stabilization within a certain range. The NL, however, showed a continuous fall in neuron numbers throughout the incubation period with 20% cell loss by day 12 and an overall loss of 52%. Cell death in both nuclei was maximal at 16 days and spanned the entire period of incubation. Glia showed a biphasic increase with peak at 14 days for both NM and NL followed by a subsequent rise at day 20 for both nuclei. These data would help in planning further experimental studies of auditory manipulation.     

JL-DRGs在综合医院管理中的应用探讨

目的 探讨JL-DRGs在综合医院管理中的应用。方法 对2012年和2013年运行JL-DRGs管理前后的全部出院病例进行统计分析。结果 2013年开始全面运行JL-DRGs后平均住院日下降17.74%,均次费用下降13.49%,医保超支年度累计减少1 866万元,平均每月医保超支额度下降39.23%,医疗质量、效率均显著提升。结论 JL-DRGs在大型综合医院管理中应用效果好,可以积极促进医院提质升效并降低运营成本。     

Genome analysis of amaranths: Determination of inter- and intra-species variations

Amaranths are an important group of plants and include grain, vegetable and ornamental types. Despite the economic importance of the amaranths, there is very little information available about the extent and nature of genetic diversity present in the genus Amaranthus at molecular level. We now report the randomly amplified polymorphic DNA (RAPD) profiles of different species of Amaranthus as well as different accessions of the species. These RAPD analyses have been carried out using 65 arbitrary sequence decamer primers. From the RAPD data, an UPGMA dendrogram illustrating the inter-as well as intra-species relationships has been computed. The putative hybrid origin of A.dubious from A. hybridus and A. spinosus is also ruled out by the RAPD data. The trends of species relationships amongst the amaranths determined by RAPDs is consistent with their cytogenetic and evolutionary relationships that have already been determined. NBRI Communication No:464 (N.S.).     

Ethyl methanesulphonate induced changes in the differentiation, structure and functions of spermatozoa of the house rat,Rattus rattus L.

Intraperitoneal administration of 500 mg/kg and 625 mg/kg doses of the germ cell mutagen, ethyl methanesulphonate (EMS) in 5 consecutive days to the house rat,Rattus rattus caused a dose-dependent reduction in its body weight, cauda epididymides weight, concentration, motility and percentage of live spermatozoa with simultaneous increase in the percentage of their abnormal forms. Compared to 0·65% spermatozoa with abnormal heads in the cauda epididymidis of untreated control rats, 24·86% and 65·72% such spermatozoa were observed in rats on day 14 post treatment with 500 mg/kg and 625 mg/kg doses of EMS respectively. On day 28 post treatment corresponding values for abnormal spermatozoa were 16·21% and 14·32%. Similarly, spermatozoa with abnormal flagella increased from 0.78% in control rats to 9·25% and 5·75% on day 14 post treatment of 500 and 625 mg/kg doses of EMS respectively and declined to 2·91% and 2·40% on day 28 post treatment. Abnormality in the sperm head was mainly due to acrosomelessness and in the flagellum due to bending at proximal region. However, the main effect of EMS was the development of spermatozoa without or deformed acrosomes which may impair the fertility of rats. Analysis of various stages of differentiation of spermatozoa inthe testis revealed that population of preleptotene and pachytene spermatocytes and of round spermatids showed a gradual decline which became significantly less than controls on day 28 of EMS treatment. Occurrence of abnormal heads of testicular spermatids indicated that the sperm head abnormalities originated in the testis during late spermiogenesis.     

Conformation of the C-terminal pentapeptide—the ‘message sequence’—of tachykinins as determined by consensus dynamic

The tachykinins are a family of gastrointestinal peptides comprising eight members: substance P, neurokinin A, neurokinin B, eledoisin, physalemin, uperolein, kassinin and phyllomedusin. Consensus dynamics was carried out on an ensemble of seven tachykinins to determine the binding conformation of the common C-terminal fragment: Phe-X-Gly-Leu-Met-NH ₂ ,the ’message sequence’ of tachykinins. Three binding modes for the C-terminal pentapeptide were determined. The first binding conformation is folded due to an intramolecular H-bond between the NH of the variable residue (X) and CO of Met. Other features include γ-bends at both the variable amino acid (X) and at Gly. The global minimum of the simulation has this conformation for the C-terminal pentapeptide. The other two binding modes have slightly higher energies. The second is chiefly characterized by a β-turn around the segment X-Gly-Leu-Met, with additional β-bends at the variable amino acid (X) and Met. The final binding conformation is composed of β-bends around the variable amino acid (X) and Leu, and a ’pseudo’ γ-bend at the terminal Met. This paper was presented at the MBU Silver Jubilee Symposium on Structural Biology and 24th Annual Meeting of the Indian Biophysical Society held at Indian Institute of Science, Bangalore, Dec. 9–12, 1996.     

Missing self by heterogeneous natural killer cells

Some murine (YAC, P815 and SP20) and human (Molt4, Raji and HR7) tumour cell lines were (i) treated with IFN-γ for inducing enhanced expression of MHC class I antigen, or (ii) given a brief treatment with citrate buffer (pH 3.0), which resulted in denaturation of class I MHC antigens on these tumour cells. IFL-γ or acid treated tumour cells were used as unlabelled competing targets in cold target inhibition assays. The results indicated that the competing ability of acid-treated tumour cells remained unaltered, whereas IFN-γ treated tumour cells competed with significantly less efficiency. These results have been evaluated in light of the current view of NK cell development and the expression of inhibitory receptors for MHC class I molecules (IRMs), on NK cells. A modified view on NK cell heterogeneity based upon IRM expression has been proposed which reconciles several apparently discordant observations about the activity and role of NK cells. Two classes of NK cells have been proposed. Type I NK ceils have target recognition receptors which do not recognize autologous normal cells, lack IRMs, and may participate in first line of defence against transformed cells in vivo. Type II NK cells have target recognition receptors for autologous normal cells and express at least one self-reactive IRM in order to prevent auto-killing. Type II NK cells participate in killing those transformed cells which down-regulate their MHC class I expression in order to escape cytotoxic T-cell surveillance. It is also postulated that mechanism of inverse correlation of target cell MHC class I expression levels and their susceptibility to NK cells, involves interference model of missing self hypothesis for type I NK cells and inhibitory signal model of missing self hypothesis for type II NE cells. Finally, it is proposed that acid treatment of tumour cells enhances their lysis susceptibility by making them additionally susceptible to type II NK cells, rather than enhancing their killing by type I NK cells. This proposition would explain the lack of effect of acid treatment on the competing ability of tumour cells, when target cells are only lysed by type I NE cells.     

Mammotrope heterogeneity in the pituitary gland of European ferret,Mustela putorius furo: An immunoelectron-microscopic study

Employing the superimposition technique of electron-microscopic immunocytochemistry ultrastructural heterogeneity of the mammotropes in the pituitary gland of the European ferret,Mustela putorius furo,was studied. On the basis of the size of their secretory granules, the mammotropes were classified into three subtypes, type-I, type-II and type-Ill, which may correspond to different developmental or physiological states of a single cell type. Simultaneous study of mammotropes and somatotropes in several pairs of serial semithin sections demonstrated the occasional occurrence of bihormonal somatomammotropes /mammosomatotropes which may represent a transitional stage of the progenitor stem-somatotrope during its differentiation into mammotrope; alternatively it may be a functional intermediate during the cross-transformation of somatotrope into mammotrope or vice versa.     

Substances interfering with phosphatidyl inositol signalling pathway affect ultradian rhythm ofDesmodium motorium

The ultradian rhythm of the lateral leaflets ofDesmodium motorium}(Houtt.) Merril. was recorded with a picture analysis method using a video camera and a computer. The periods are in the minute range and depend strongly on temperature. The phosphatidyl inositol signal chain might be involved in the ultradian rhythm of the lateral leaflet movement of Desmodium motorium:Myoinositol shortens the period length and reduces the known period lengthening effect of lithium ions. Neomycin, which inhibits the hydrolysis of phosphatidylinositol-4,5 -biphosphate to inositol-4-phosphate and diacylglycerin, lengthens the period of the rhythm at low concentrations (0.2 mM). Higher concentrations shorten the period, perhaps by activating G protein. Mastoparan, which activates G protein, shortens period likewise. The G protein agonists fluorid ion and ethanol are toxic for the lateral leaflets and could therefore not be used to test the involvement of G protein. The intracellular Ca ²⁺ antagonist 3,4,5-trinietlioxybeiizoic acid 8-(diethylamino)octylester lengthens the period of the rhythm. This indicates, that release of Cas ²⁺ from intracellular stores is important for the lateral leaflet movement rhythm.     

Nitrogen-15 balances for urea and neem coated urea applied to lowland rice following two cowpea cropping systems

Little is known about whether the high N losses from inorganic N fertilizers applied to lowland rice (Oryza sativa L.) are affected by the combined use of either legume green manure or residue with N fertilizers. Field experiments were conducted in 1986 and 1987 on an Andaqueptic Haplaquoll in the Philippines to determine the effect of cowpea [Vigna unguiculata (L.) Walp.] cropping systems before rice on the fate and use efficiency of¹⁵N-labeled, urea and neem cake (Azadirachta indica Juss.) coated urea (NCU) applied to the subsequent transplanted lowland rice crop. The pre-rice cropping systems were fallow, cowpea incorporated at the flowering stage as a green manure, and cowpea grown to maturity with subsequent incorporation of residue remaining after grain and pod removal. The incorporated green manure contained 70 and 67 kg N ha⁻¹ in 1986 and 1987, respectively. The incorporated residue contained 54 and 49 kg N ha⁻¹ in 1986 and 1987, respectively. The unrecovered¹⁵N in the¹⁵N balances for 58 kg N ha⁻¹ applied as urea or NCU ranged from 23 to 34% but was not affected by pre-rice cropping system. The partial pressure of ammoniapNH₃, and floodwater (nitrate + nitrite)-N following application of 29 kg N ha⁻¹ as urea or NCU to 0.05-m-deep floodwater at 14 days after transplanting was not affected by pre-rice cropping system. In plots not fertilized with urea or NCU, green manure contributed an extra 12 and 26 kg N ha⁻¹, to mature rice plants in 1986 and 1987, respectively. The corresponding contributions from residue were 19 and 23 kg N ha⁻¹, respectively. Coating urea with 0.2g neem cake per g urea had no effect on loss of urea-N in either year; however, it significantly increased grain yield (0.4 Mg ha⁻¹) and total plant N (11 kg ha⁻¹) in 1987 but not in 1986.     

hsp 83 mutation is a dominant enhancer of lethality associated with absence of the non-protein codinghsrω locus inDrosophila melanogaster

Thehrsω or the 93D heat shock locus ofDrosophila melanogaster, which does not code for any protein, has an important role in development since nullosomy of this locus in transheterozygotes for two overlapping deficiencies, viz.,Df(3R) e ^Gp4 (eGp4) andDf(3R)GC14 (GC14), is known to cause a high (∼ 80%) mortality with the small number of escapee nullosomic flies being sterile, weak and surviving for only a few days. We now show that a majority of thehsrω-nulosomics die as embryo and that the 20% escapee embryos develop slower compared to their sibs carrying either one or two copies of thehsrω locus but after hatching survive to pupal/imago stage. Most interestingly, we further show that when onehsp83 mutant allele (hsp83 ^e4A) is introduced ineGp4/GC14 trans-heterozygotes, practically none of thehsrω-nullosomic embryos develop beyond the 1st instar larval stage. The specificity of this interaction betweenhsp83 andhsrω genes was further confirmed by examining the effect of thehsp83 mutant allele on other mutations in the 93D cytogenetic region. Therefore, we conclude that thehsp83 mutation acts as a dominant enhancer of the lethality associated with nullosomy for thehsrω gene. The observed genetic interaction between these two members of the heat shock gene family during normal embryonic development ofDrosophila reveals novel aspects of their biological functions.     

Effect of continuous cropping and fertilizer use on the organic nitrogen fractions in a typic ustochrept soil

Summary The influence of continuous cropping and soil test based fertilizer use on the organic nitrogen fractions in the plough layer has been studied in a Typic Ustochrept soil. Seven years of multiple cropping without manuring caused marked depletion in all the hydrolysable fractions except unidentified hydrolysable N namely, hexosamine (48.8%), hydrolysable ammonium (23.9%) and amino acid (7.3%) as compared to an adjacent fallow. Fertilizer nitrogen application maintained the levels of various forms of N as in the fallow plots and nitrogen in conjunction with phosphorus raised the status of amino acid N. Phosphate improved the contents of hydrolyzable ammonium and total hydrolyzable N whereas farmyard manure enhanced the latter only. The system of intensive cropping followed with appreciably high doses of fertilizers favoured greater immobilization of N in hydrolyzable ammonium and total hydrolyzable fractions. Original not seen     

Effects of nitrogen mineralization on paddy rice yield under low nitrogen input conditions in irrigated rice-based multiple cropping with intensive cropping of vegetables in southwest China

The farm household responsibility system (FHRS) was adopted in Chinese rural areas during the economic reform in the early 1980s. Since then, many farm households have increased cropping intensity by using large quantities of nitrogen (N) fertilizers in their responsible fields to increase agricultural income. However, intensive cropping systems with low N input are still common in remote places of the southwestern region of China. Maintenance and improvement of soil quality in intensive cropping systems is critical for sustaining agricultural productivity and environmental quality for future generations. The effects of intensive cropping of vegetables on paddy rice (Oryza sativa L.) yield using small quantities of N fertilizers through N mineralization of paddy soil in irrigated rice-based multiple cropping systems were studied in 15 paddy fields in Sichuan Province, China for 3 years. Intensification of vegetable cropping with negative N balance and removal of vegetable crop residues has greatly decreased total N (TN) contents in paddy soil leading to low levels of effective cumulated soil temperature and thickness of plow layer. As a result, the N mineralization in paddy field during paddy rice growing period was decreased. In addition to the low levels of chemical fertilizer N input and residual mineral N input, the lower level of N mineralization in paddy fields and low N recovery efficiency decreased the amount of N accumulated in aboveground biomass of paddy rice at maturity, resulting in limited rice yields. The amount of mineralized N only correlated with TN (partial correlation analysis). Therefore, in paddy fields with very low N input, the N mineralization in paddy soil during the paddy rice-growing period was the major limiting factor affecting the total yield increases. In addition, a decline in soil fertility can be determined using TN as an indicator. To improve paddy rice yield and avoid soil deterioration, the development and adoption of rational soil management programs are needed. These include input of plant residues, conscientious soil tillage for the maintenance of soil temperature and thickness of the plow layer, and the split application of fertilizer for the improvement of N recovery efficiency.     

Plant regeneration from protoplasts ofCapsicum annuum L. cv. California Wonder

Plant regeneration from mesophyll protoplasts of pepper,Capsicum annuum L. cv. California Wonder has been demonstrated via shoot organogenesis. Protoplasts isolated from fully expanded leaves of 3-week-old axenic shoots when cultured in TM medium supplemented with 1 mg l ⁻¹ NAA, 1 mg l ⁻¹ 2,4-D, 0 5 mg l ⁻¹ BAP (CM 1) resulted in divisions with a frequency ranging from 20–25 %. Antioxidant ascorbic acid and polyvinylpyrrolidone (PVP) in the medium and incubation in the dark helped overcome browning of protoplasts. Microcalli and macrocalli were formed in TM medium containing 2 mg l ⁻¹ NAA and 0.5 mg l ⁻¹ BAP (CM II) and MS gelled medium containing 2 mg 1 ⁻¹ NAA and 0 5 mg 1 ⁻¹ BAP (CM III), respectively. Regeneration of plantlets was possible via caulogenesis. Microshoots, 2–5 percallus appeared on MS gelled medium enriched with 0.5 mg l ⁻¹ IAA, 2mg l ⁻¹ GA and l0mg l ⁻¹ BAP (CM IVc). Rooting of microshoots was obtained on half strength gelled medium containing 1 mg l ⁻¹ NAA and 0.5mg l ⁻¹ BAP. Protoplasts isolated from cotyledons failed to divide and degenerated eventually.     

等量蚕豆鲜秆还田配施不同比例化肥对单季晚稻的影响

2012年4-11月在浙江省丽水市碧湖镇下季村进行田间试验,研究等量蚕豆鲜秆还田配施不同比例常规用量化肥对单季晚稻养分吸收、养分利用率和产量的影响.试验设置不翻压蚕豆鲜秆和不施化肥(CK)、常规用量化肥(CF)及翻压15 t·hm^-2(GM₁₅)蚕豆鲜秆配施0、20%、40%、60%和80% CF共7个处理.结果表明： 在所有的蚕豆鲜秆还田配施化肥处理中,GM₁₅+60%CF和GM₁₅+80%CF处理的水稻N、P、K养分的总吸收量高于其他处理,但GM₁₅+40%CF和GM₁₅+60%CF处理的水稻N、P、K养分的农学利用效率最高.水稻稻谷产量与N、P、K的养分农学利用效率和养分生理利用效率之间均有显著的相关性,因此养分农学利用效率和养分生理利用效率2个指标可以用来准确综合评价N、P、K养分的肥效.与CK相比,CF和蚕豆鲜秆还田配施化肥处理的稻谷产量分别提高25.0%和6.1%～29.2%.在蚕豆 单季晚稻耕作制中,蚕豆鲜秆异地还田量15 t·hm^-2不会使单季晚稻苗期产生僵苗现象.本试验条件下,从提高水稻产量、水稻养分利用率及降低环境风险的角度出发,蚕豆鲜秆异地还田量为15 t·hm^-2时,以配施常规用量化肥60%为宜.