Soil Aluminum Effects on Growth and Nutrition of Cacao

In acid soils, Al toxicity and nutrient deficiencies are main constraints for low yield of cacao (Theobroma cacao L.). A controlled growth chamber experiment was conducted to evaluate the effect of three Al saturations (0.2, 19, and 26%) adjusted by addition of dolomitic lime on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area (total leaf area/total leaf dry wt), and leaf area ratio (total leaf area/shoot+root wt). Increasing soil Al saturation decreased uptake of elements. Nutrient influx (IN) and transport (TR) decreased significantly for K, Ca and Mg, and showed an increasing trend for S and P as soil Al saturation increased. However, increasing soil Al saturation significantly increased nutrient use efficiency ratio (ER, mg of shoot weight produced per mg of element in shoot) of Ca, Mg and K and decreased ER for other elements. Reduction of soil acidity constraints with addition of lime and fertilizers appear to be key factors in improving cacao yields in infertile, acidic, tropical soils.     

Iron Sources Effects on Growth,Physiological Parameters and Nutrition of Cacao

Productivity and sustainability of cacao (Theobroma cacao L.) in tropical soils are affected by levels of iron. Information is lacking on the cacao response to various sources of iron (Fe). A greenhouse experiment was conducted to evaluate the effects of five iron sources iron sulfate heptahydrate, ferric ethylenediamine-N,N’-bis(2-hydroxyphenylacetic acid), ferric diethylenetriaminepentaacetic acid, ferric ethylenediaminetetraacetic acid, fiesta herbicide (FeSO₄ · 7H₂O, FeEDDHA, FeDTPA, FeEDTA,) at 10 mg Fe kg^?1 soil on growth, photosynthesis, content of photosynthetic pigments and starch and macro- and micronutrient nutrition of cacao. The various iron sources had significant effects on shoot and root dry biomass accumulation, leaf chlorophyll a and b content, carotenoid levels, SPAD index and P_N. These parameters were significantly correlated with concentration, uptake, influx, and transport and use efficiency of Fe. In cacao net photosynthesis, stomatal conductance, internal carbon dioxide (CO₂)_, and transpiration in leaf level responded differently to the sources of Fe. Invariably, macro and micronutrient uptake, influx, transport, and use efficiency showed differential responses to sources of iron but significant effects were only observed for copper (Cu), Fe, manganese (Mn), and zinc (Zn). Overall, FeDTPA, FeEDTA and FeHEDTA could be the best sources of Fe in improving, growth, photosynthesis and macro and micro nutrition of cacao.     

Interactive Effects of Nitrogen Source and Salinity on Growth Indices and Ion Content of Indian Mustard

ABSTRACT

The interactions between salinity and different nitrogen (N) sources nitrate (NO₃ ^?), ammonium (NH₄ ⁺), and NO₃ ^? + NH₄ ⁺ were investigated on Indian mustard (Brassica juncea cv. RH30). Treatments were added to observe the combined effect of two salinity levels (8 and 12 ds m^{? 1}) and three nitrogen sources (NO₃ ^?, NH₄ ⁺, and NO₃ ^? + NH₄ ⁺) on different growth parameters and mineral composition in different plant parts, i.e., leaves, stem, and root. Salinity has been known to affect the uptake and assimilation of various essential nutrients required for normal growth and development. Different growth parameters, i.e., leaf area, dry weight of different plant parts, absolute growth rate (AGR), relative growth rate (RGR), and net assimilation rate (NAR) declined markedly by salinity at pre-flowering and flowering stages. All growth indices were less sensitive to salinity (12 d s m^{? 1}) with the nitrate form of nitrogen. It is pertinent mention that a high dose (120 kg ha^{? 1}) of nitrogen in ammonium form NH₄ ⁺, acted synergistically with salinity in inhibiting growth. Plants fed with combined nitrogen (NO₃ ^? + NH₄ ⁺) had an edge over individual forms in ameliorating the adverse effects of salinity on growth and yield. Under salt stress, different nutrient elements such as N, phosphorus (P), potassium (K⁺), and magnesium (Mg^{2 +}) were decreased in different plant parts (leaves, stem, and root). The maximum and minimum reduction was observed with ammoniacal and combined form of nitrogen, respectively, while the reverse was true of calcium (Ca^{2 +}), sodium (Na⁺), chloride (Cl^?), and sulfate (SO₄ ^2?) at harvest. Nitrogen application (120 Kg ha^{? 1}) in combined form had been found to maintain highest concentrations of N, P, Mg^{2 +}, and Ca^{2 +} along with reduced concentrations of Na⁺, Cl^?, and SO₄ ^{2 ?}. However, reverse was true with ammoniacal form of nitrogen.     

Light Intensity Effects on Growth and Micronutrient Uptake by Tropical Legume Cover Crops

ABSTRACT

Cover crops are important components of a sustainable crop-production system in plantation crops such as cacao (theobroma cacao), coffee (Coffee arabica), oil palm (Elaeis Spp.), and banana (Musa Spp.). Optimal growth of cover crops in plantation agriculture is determined by adaptability of crop species, light intensity reaching their leaf canopies, and their nutrient-use efficiencies, including those of micronutrients. An experiment was conducted in a climatically controlled growth chamber to evaluate the influence of levels of light intensity on growth and micronutrient [boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn)] uptake parameters in legume cover crops. Two photosynthetic photon flux density (PPFD, 200 and 400 μmol m^?2 s^?1) light treatments were imposed on nine legume species (joint vetch (Aeschynomene americana), sunhemp (Crotalaria juncea L.), Crotalaria rchroleuca, showy crotalaria (crotalaria spectabilis), hairy indigo (Indigofera hirsute L.), lab-lab (Lablab purpureus), sesbania (Sesbania microcarpa), Brazilian stylo (Stylosanthes guianensis), and cowpea (Vigna unguiculata)). Overall, light intensity significantly affected growth, micronutrient uptake, and use-efficiency ratios; with few exceptions, interactions between cover crop species and PPFD were also significant. Such PPFD × crop species interactions show that the cover crops used in this study differed in growth and nutrient-uptake parameters under the conditions imposed. Sunhemp, cowpea, sesbania, and lab-lab species were superior in producing shoot dry weight and in nutrient accumulation compared with other species at lower as well as at higher PPFD levels. Interspecific differences in nutrient influx and transport were observed. Influx and transport of micronutrients was in the order Mn > B > Fe > Zn > Cu. Overall, growth, nutrient uptake, and use-efficiency ratios were higher at higher PPFD than at lower PPFD. Results of this study indicate that the use of proper crop species at adequate light intensities is an important component of successful cultivation of cover crops in plantation agriculture.     

土壤改良剂对土壤紧实度及燕麦生长状况的影响

研究了不同土壤改良剂(聚丙烯酸钾,聚丙烯酰胺,腐殖酸钾,聚丙烯酸钾十腐殖酸钾,聚丙烯酰胺十腐殖酸钾)对土壤紧实度及燕麦生长状况的影响.结果表明,各改良剂处理均能减小土壤紧实度,表现为:聚丙烯酸钾十腐殖酸钾＞聚丙烯酰胺十腐殖酸钾＞聚丙烯酸钾＞聚丙烯酰胺＞腐殖酸钾＞对照,土壤紧实度均随着土壤深度增加而增加;土壤改良剂对燕麦株高和干物质量具有显著的提高作用,复配处理株高优于其他单施处理;土壤改良剂处理下籽粒产量均显著高于对照,其中聚丙烯酸钾十腐殖酸钾和聚丙烯酰胺十腐殖酸钾籽粒产量较其他处理高,分别为4 694.2和4 566.9 kg/hm2,较对照增产21.66％和18.36％,生物产量的增产效果表现同籽粒产量;各土壤改良剂处理水分利用效率均显著高于对照,其变化趋势与产量变化趋势一致,复配处理效果更佳.     

Interactions between Soil,Leaves and Beans Nutrient Status and Dry Biomass of Beans and Pod Husk of Forastero Cacao: An Exploratory Study

ABSTRACT

In cacao crop the understanding of the multiple relationships between bean and pod husk dry biomass and mineral nutrition in the soil-plant system is scarce. The main objective of this work is to verify the linear, bivariate and multivariate correlations between the mineral nutrient concentrations in the soil, leaves and beans of 53 cacao trees with known dry biomass of cacao beans and pod husk, and further graphically identifying the consistency of these information. For this study, soil samples, leaves and fruits (pod husk and beans) were collected from each cacao trees, for the analysis of nitrogen-N, phosphorous-P, potassium-K, calcium-Ca, magnesium-Mg, iron-Fe, manganese-Mn, zinc-Zn and cooper-Cu mineral nutrient concentrations. The interpretation of the results by the exploratory analysis technique linked to the linear correlation analysis proved to be an essential tool to support studies related to mineral nutrition in the soil-plant system. Foliar N concentration were directly related to the high and very high dry biomass classes of cacao beans. Levels of exchangeable Ca and Mg in the soil were inversely correlated with the dry biomass of cacao pod husk (DBCH), in contrast to results with the positive correlations of these nutrients in the leaves and cacao beans data sets. The foliar concentrations of Zn, Mn, Fe and Cu are shown to be more positively associated with DBCH than dry biomass classes of cacao beans. The concentrations of Fe, Mn and Cu in dry cacao beans show such similar pattern of association with dry biomass of pod husk and beans.     

不同肥料和N减量施用对旱作玉米生产的影响

通过在山西寿阳旱农试验区进行玉米地不同肥料和N减量处理试验，得出：普通肥、增效肥以及增效肥减量施用后对玉米出苗率、株高生长以及产量的影响效果不同；其增产、增效作用的排序为：增效复合肥〉普通复合肥〉增效尿素〉普通尿素，施用增效复合肥对植株生长、植株N和K含量状况有所改善；增效复合肥和增效尿素的N利用率为13．1％～27．3％和0．9％～14．2％，优于普通肥料；N减量15％施用后，玉米产量不但没有显著减少，而且增效肥的N利用效率最高，尿素的N利用效率与N100％施用差异不大。N减量30％和45％施用的产量之间没有显著差异，减量越大，N的利用效率反而越高。通过氮肥合理减量施用，可以达到提高氮肥利用率、节本增效和减少养分向环境流失的目的。     

Growth and nutrient uptake of peach seedlings with varying magnesium concentrations at low pH 1

Soils of the peach growing region of the Southeastern Coastal Plain are highly leached and excessively acid, with inherently low concentrations of subsoil magnesium (Mg). A greenhouse experiment was conducted to determine the effects of varying Mg concentrations at low pH on growth and Mg uptake of three peach seedling cultivars commonly used as rootstock in the region. Seedlings of ‘Lovell’, ‘Elberta’, [Prunus persica (L.) Batsch] and ‘Nemaguard’ [Prunus persica (L.) Batsch X Prunus davidiana Carriere] were grown for 36 days in nutrient solution containing 9, 21, 42, 84, 167, 333, and 667 μM Mg. Magnesium concentration in solution did not increase lateral length, number of laterals, trunk cross‐sectional area, or root volume. All terminal growth responses were cultivar related. Magnesium concentration in the leaves, stems, and roots were increased either by quadratic or cubic relationship with solution Mg concentration while Mg uptake rate was increased linearly with solution Mg concentration with all three seedling cultivar. Uptake rates of calcium, manganese, and zinc, and tissue concentrations of phosphorus, manganese, and zinc decreased with increasing Mg concentrations in nutrient solution. Predicted Mg uptake rates by‐regression analysis revealed a cubic uptake isotherm for Nemaguard and a quadratic isotherm for Elberta. Predicted tissue Mg concentration followed similar patterns of accumulation for leaves and stems, but root Mg concentration followed a cubic uptake isotherm for all three seedlings. The linear Mg uptake at low pH may be an important physiological characteristic that enables Lovell seedlings to outperform either Elberta or Nemaguard when used as a rootstock in the southeastern soils.     

熏蒸条件下有机肥部分替代化肥对西瓜生长及养分利用的影响

基于田间大棚试验,采用等量养分原则,分析生物有机肥、蚯蚓粪、鸡粪等不同有机肥部分替代化肥对西瓜生长、产量、品质以及养分利用的影响。结果表明,与单施化肥相比,有机肥部分替代化肥均不同程度提高了西瓜叶绿素含量、光合性能、产量及品质,其中以蚯蚓粪与化肥配施效果最佳,其光合性能显著高于单施化肥,产量提高了33.63%,可溶性糖、可溶性蛋白及维生素C含量分别增加了14.07%,14.47%和17.52%。有机肥部分替代化肥施肥处理的肥料利用率高于单施化肥,土壤养分元素依存率低于单施化肥,以蚯蚓粪配施化肥作用效果最为显著,氮、磷、钾肥利用率分别为26.02%,5.67%和29.89%,土壤氮、磷、钾素依存率分别为20.96%,20.32%和31.55%。熏蒸处理的西瓜枯萎病发病率整体低于未熏蒸处理,其中熏蒸条件下蚯蚓粪部分替代化肥施肥处理西瓜发病率最低,仅为4.76%。     

有机-无机配施对盐渍土壤水稻生长及养分利用的影响

针对滨海盐渍化土壤水稻种植过程中根系生长受盐碱胁迫,导致养分利用率低的问题。采用田间试验研究了有机肥与磷肥配施对滨海盐渍化土壤水稻不同生育期根系生长、水稻产量及养分利用率的影响。试验采用双因素设计,3个碳水平:(1)C0,无碳;(2)C1:低碳,450 kg/hm~2;(3)C2:高碳,900 kg/hm~2;3个磷水平:(1)P0:无磷;(2)P1:低磷,P_2O_5 64 kg/hm~2;(3)P2:高磷,P_2O_5 128 kg/hm~2。结果表明,在水稻成熟期,低碳低磷(T5)处理时根系总表面积显著高于高碳低磷(T7)和高碳高磷(T8)处理,分别增加25.2%和30.2%;低碳处理(T5、T6)时根系总体积显著高于高碳处理。T5处理时水稻产量、生物量显著高于其他处理,分别为10 245,9 550 kg/hm~2。结实率较高是低碳低磷(T5)处理水稻产量最高的原因。低碳低磷(T5)处理时糙米P积累量最高,显著高于T6、T7、T8处理,分别高出13.9%,27.8%,31.2%。T5处理的磷肥贡献率和农学效率显著高于其他施磷肥处理。磷肥偏生产力表现为低磷投入显著高于高磷投入。综上所述,与单独施用无机肥相比,有机肥与磷肥配施能够显著促进滨海盐渍化土壤水稻根系生长,提高水稻产量及磷肥农学效率,其中低碳低磷(T5,C 450 kg/hm~2+P_2O_5 64 kg/hm~2)处理最有利于盐渍化土壤水稻根系生长。     

酸铝胁迫对栝楼根系生长及铝积累的影响

针对南方酸性红壤对作物的生长造成的不利影响,采用水培方式,研究酸铝环境0、100、300、500、1000μmol·L-1Al3＋pH4.5,处理7d对长兴栝楼根系生长及铝积累的影响。测定指标包括根系活力、质膜透性、抗氧化酶类活性（过氧化物酶POD、过氧化氢酶CAT、抗坏血酸过氧化物酶APX、愈创木酚过氧化物酶GPX、超氧化物歧化酶SOD）及其同工酶、过氧化氢（H2O2）含量、根尖铝含量的影响。结果表明：随着铝处理浓度升高,根系活力增大,根系质膜透性无显著变化;POD、CAT、APX酶活升高,GPX和SOD活性降低,多种抗氧化酶都有多条同工酶谱带出现;根尖相对铝含量升高,桑色素染色情况显示,荧光梯度与铝含量测定结果一致,并观察到根尖以上根毛处细胞凸起较之平整排列的根细胞更容易积累铝。栝楼对南方酸性红壤具有较强的适应能力,其体内抗氧化酶系统及根尖吸收、积累铝的机制对缓解铝毒害起着重要作用。     

Genotypic Differences in Potassium Nutrition in Lowland Rice Hybrids

China imports most of its potassium (K) requirements for crop production. The objective of this study was to evaluate indica rice hybrids for K‐use efficiency. Twenty‐eight indica rice hybrids were evaluated in nutrient solution. The K influx rate was greatest in genotype Weiyou 64 (684.9 nmol K⁺ plant^?1 h^?1) and least in genotype Xie A/909 (457.2 nmol K⁺ plant^?1 h^?1). The K‐use efficiency was greatest in genotype ShanA/909 [81.8 mg dry matter (DM) produced per mg K taken up] and least in genotype Shanyou 64 (55.9 mg mg^?1). The maximum biomass was produced by genotype Shan A/4663‐5 (100.8 mg DM per plant), and the least biomass was produced by genotype Xie A/4663‐4 (59.1 mg DM per plant). These results suggest that K shortage for rice production can be alleviated by using K‐efficient rice genotypes.     

不同遮光度对冬小麦生长发育和水分利用效率的影响

[目的]探究不同程度遮光对冬小麦生长发育和水分利用效率的影响,分析遮光条件下小麦的生长发育状况及耗水特性,为节水灌溉提供新途径。[方法]通过小区试验,设置不遮光(CK)、20%遮光(L_(20))、40%遮光(L_(40))、60%遮光(L60)、80%遮光(L_(80))共5个处理组,分析冬小麦株高、叶面积、干物质、产量和水分利用效率的变化特征。[结果]遮光处理使冬小麦生育期延长,叶面积增加,但各处理间的株高无明显变化;L_(40),L60,L_(80)处理抑制了冬小麦茎、穗干物质的积累;遮光使得光合产物在茎、叶、穗各器官中的分配比例发生变化,但L_(20)处理对冬小麦茎、叶、穗干物质的积累和分配无明显影响;遮光使得土面蒸发量和冬小麦的总耗水量均明显降低,且遮光度越大,降低幅度越大;与CK相比,L_(20)处理的产量下降了4.23%,水分利用效率则提高了10.11%,其他处理的产量和水分利用效率均有所下降。[结论]L_(20)处理对产量无明显影响,但有效提高了水分利用效率,起到了明显的节水作用。     

不同覆盖旱作水稻对后茬大麦生长和土壤氮素的影响

通过田间试验研究水稻不同覆盖旱作栽培方式对后茬大麦生长及土壤氮素动态变化的影响。结果表明，盖草处理后茬大麦表层土壤硝态氮含量最高，而土壤铵态氮含量由高到低依次为：水作〉盖草〉覆膜〉裸露，且硝态氮、铵态氮从表层（0～20cm）到底层（60～80cm）依次降低。具有明显的层次性。各处理都表现出0～40cm土层氮素表观盈余，水作、盖草和裸露处理后茬分别比覆膜处理后茬高40．5％，39．5％和36．1％。大麦籽粒产量以盖草处理后茬摄高，分别比水作后茬和裸露后茬增加837kg／hm^2和251kg／hm^2。后茬大麦各生育阶段对氮素的累积吸收量均以前茬盖草早作处理最高。覆膜、盖草和裸露旱作水稻后茬大麦的氮肥利用率分别比水作稻后茬大麦高16．1％，17．5％和13．8％。土壤氮素转化和大麦产量均表明，半腐解秸秆覆盖旱作水稻-大麦轮作是一种较合理的种植模式。     

谷子不同栽培模式对土壤水温环境及水分利用效率的影响

通过大田试验研究了山西中部地区谷子不同栽培模式(覆膜穴播、精量条播、传统穴播)对土壤水温环境、谷子叶片及群体水分利用率的影响。结果表明:覆膜穴播处理与不覆膜的精量条播和传统穴播处理相比,全生育期土壤平均含水量分别增加1.59%和1.84%,土壤平均积温增加182.3℃,为谷子生长提供了良好的土壤环境条件。覆膜穴播与2个不覆膜处理相比,显著提高了谷子各生育阶段的叶片水平水分利用效率(WUEl)和群体水平水分利用效率(WUEc),促进了谷子的生长发育,产量显著增加。精量条播处理与传统穴播处理相比,在部分生育期的WUEl、群体WUEc、部分生长指标及产量上有着更好的表现。不同栽培模式之间的水分利用差异,WUEl提高的主要原因是净光合速率的显著增加,而WUEc提高的主要原因则是产量的显著增加。综合试验研究结果,可以确定覆膜穴播是山西中部地区谷子最适宜的高产高效栽培模式,而在不使用地膜覆盖的条件下,则应当优先选择精量条播栽培模式。     

不同土壤容重条件下水分亏缺对作物生长和水分利用的影响

为探究不同土壤容重和不同程度水分亏缺条件下冬小麦-夏玉米生长指标及产量的变化。采用桶栽土培法,分别设置3种土壤容重(1.2,1.4,1.6 g/cm^3)和3个土壤水分控制下限(低水分50%田间持水量、中水分60%田间持水量和高水分70%田间持水量),研究不同土壤容重和水分亏缺对冬小麦—夏玉米根系、生长指标、耗水量、产量和水分利用的影响。结果表明:随水分亏缺程度的加剧,冬小麦和夏玉米生长指标、生物量、耗水量和产量均呈降低趋势。随土壤容重增加,冬小麦生物量和产量呈先升高再降低的趋势,冬小麦耗水量和水分利用效率呈降低趋势;而夏玉米产量、耗水量和水分利用效率均呈降低趋势。试验中,1.4,1.2 g/cm^3分别为冬小麦和夏玉米生长的最适土壤容重。土壤容重与水分处理互作对夏玉米株高、耗水量和水分利用效率有极显著影响,而对冬小麦和夏玉米生物量及产量无显著影响。研究结果可为黄淮海地区作物绿色增产增效及水土资源高效利用提供理论参考。     

Influence of ca concentration on growth,tissue concentration,and nutrient uptake of in vitro propagated plums and lovell seedlings

Seedlings of ‘Lovell’ peach [Prunus persica (L.) Batsch], and in vitro propagated plums, ‘St. Julien A GF 655–2’ [Prunus institia (L.) Bullace] (655–2), ‘Damas GF 1869’ [Prunus domestica (L.)] (D1869), and ‘Clark Hill Red Leaf’ [Prunus saliciana (Lindl) x Prunus cerasifera (EHRH)] (CH redleaf) were grown in the greenhouse 45 or 51 days in nutrient solutions containing 2, 6, 22, 200, and 400 μM Ca. Terminal length, number of laterals, trunk cross‐sectional area, and root volume were increased by the 22 μM Ca treatments at harvest 1. The CH redleaf and 655–2 plums had the largest increase in growth for harvest 1, but the ‘Lovell’ peach seedlings and D1869 plum had the largest increase in growth for harvest 2. There were no leaf symptoms of Ca deficiency when the leaf Ca concentration in the tissue exceeded 2500 μg/g (dry wt.) Calcium concentration was increased from 1406 to 4109 μg/g (dry wt.) in the stems, and from 540 to 2633 μg/g (dry wt) in the roots by Ca treatments of 400 μM after 45 days of growth. Calcium uptake rate for ‘Lovell’ seedlings was greater than were rates for CH redleaf and 655–2 plums at all solution concentrations during the first 45 days of growth. The Ca uptake rate for D1869 plum was greater than the rate for ‘Lovell’ seedlings during the second growth period. An interaction between Ca concentration and plant species occurred for P, K, and Mg uptake rates at both harvest dates. The in vitro propagated D1869 plum was equal to the ‘Lovell’ seedlings in growth, tissue Ca concentration, and Ca uptake rates.     

W-OH固化剂对玉米生长及土壤养分淋失的影响

采用盆栽试验,研究了不同W-OH喷施浓度(1%,3%,5%)对玉米生长及土壤养分淋失的影响。结果表明:与对照(不喷施W-OH)相比,喷施W-OH对玉米生长有促进作用,且这种作用自玉米生长中期逐渐明显。试验条件下,低、中浓度W-OH(1%和3%)更有利于玉米生长;盆栽3个月后,与对照相比,低、中浓度处理下玉米株高分别增加16%和35%,净光合速率分别增加3%和17%,气孔导度分别增加34%和79%,蒸腾速率分别为对照的2倍和3倍。降雨量对W-OH的保水作用影响不同,小雨和中雨下,3%浓度处理的渗流量最低,保水效果最显著;降雨量达到大雨及以上时,W-OH的保水作用与其喷施浓度成正比。在玉米生长初期W-OH的保肥作用与其喷施浓度成正比,随着后续降雨渗流反复淋溶,其保肥作用趋于稳定;3%和5%浓度的W-OH均能有效减少观测期的土壤养分淋失量,且以硝态氮降幅最大。研究结果为土壤固化剂在坡耕地中的应用提供理论指导。     

土壤秸秆注孔对土壤含水量及作物生长的影响

[目的] 研究土壤秸秆注孔对土壤含水量及作物生长的影响,为旱作农田增加雨水蓄集能力及提高水分利用效率提供理论依据。[方法] 开展玉米-小麦轮作田间试验,设置常规种植(CK)、土壤秸秆注孔2孔/m²(T₁),4孔/m²(T₂),8孔/m²(T₃)4个处理。[结果] 秸秆注孔所有处理均提高了整个试验期表层土壤含水量。T₂,T₃处理提高了收获期深层土壤含水量,试验结束时两者底层土壤(60-80 cm)含水量较CK分别提高了29.19 %和28.18 %。秸秆注孔处理提高了作物株高、经济产量和生物量,以及降水利用效率和水分利用效率,T₂,T₃处理的提高效果最明显,且彼此差异不显著。[结论] 秸秆注孔具有保水性能和增产能力,根据成本和效果综合考虑,推荐秸秆注孔4孔/m²(T₂)作为优选处理。     

施γ-聚谷氨酸对桃树生长发育和15N吸收利用及损失的影响

以1年生桃树盆栽实生苗为试材,底肥为尿素3 g(其中15N标记0.4 g)、磷酸二氢钾3 g,设CK为对照,T1、T2、T3分别添加γ-PGA 10,80,150 mg,探究不同浓度γ-聚谷氨酸(γ-PGA)对桃树植株生长与氮素吸收利用的影响。结果表明:施用中量和高量γ-PGA能显著提高土壤脲酶与过氧化氢酶活性以及土壤碱解氮含量;施用中、高量γ-PGA能促进桃实生苗根系生长,尤其是细根的生长。与对照相比,施用中量γ-PGA桃实生苗根系总长度、分支数、根尖数、交叉数和根系总表面积分别增加51.95%,40.53%,30.72%,35.21%,45.23%;施用中、高量γ-PGA能显著提高植株净光合速率和叶绿素SPAD值,以及干物质积累量。施用中、高量γ-PGA能显著提高桃实生苗根系活力、硝酸还原酶、谷草转氨酶和谷丙转氨酶活性。施用中、高量γ-PGA提高了桃实生苗氮素吸收利用率和氮素残留率,降低了氮素损失率,与对照相比,氮素吸收利用率分别提高27.80%和27.07%,氮素残留率分别提高14.00%和19.04%,氮素损失率分别降低16.43%和19.49%,且差异显著。可见施用γ-PGA可改善桃根区土壤理化性状,提高植株氮素吸收利用率和土壤氮素残留率,降低氮素损失率,促进了桃实生苗的生长。