Effect of planting date,ventilation and soil temperature on growth and nutrition of tomato in high tunnels

Growth rates and tissue nutrient concentrations were measured in tomato (Lycopersicon esculentum Mill) grown in unheated high tunnels in the spring in the northeast USA. Two weeks after transplant on 3 April, seedlings had low concentrations of Nitrogen, Magnesium and other nutrients, while later plantings on 17 April and 1 May had adequate nutrition. The low yield and small fruit of the 3 April planting, compared to the later plantings, was likely related to this nutrient stress soon after transplant. Air and soil temperatures were less than 10°C at planting on 3 April. Air and soil were warmed during the day to different extents in tunnels vented at different temperatures. Over all plantings and ventilation regimes, relative growth rates over the two weeks after transplant were correlated to average air temperature. However, there was little uptake of P, N and Mg, when soil was cooler than 12°C. Nutrient concentrations in the shoot became very low because shoot growth continued when soil temperature limited nutrient uptake.     

Effect of crop and soil management practices on soil compatibility in maize and groundnut plots in a Paleustult in Southeastern Nigeria

Frequent occurrences of soil compaction damage resulting from high raindrop impact energy, and from human and animal trafficking during field operations pose a problem to farmers around the tropics. We studied the effect of some crop and soil management practices (manure, mulch, NPK applications, tillage and crop type) on some soil compactibility indices (dry bulk density, cone index, total soil porosity, gravimetric soil water content) in a Typic Paleustult in southeastern Nigeria. The study was carried out for three consecutive planting seasons using two tillage systems and four other soil management practices (poultry droppings + NPK, mulch + NPK, NPK alone and no amendment). These were laid out as split-plot in a RCB design replicated three times and using maize (Zea mays L.) and groundnut (Arachis hypogea) as test crops. Results indicate that the different soil management techniques adopted influenced dry bulk density, penetration resistance, total soil porosity and gravimetric soil water content at 44 and 66 days after planting (DAP) whereas only gravimetric soil water content was affected at 90 DAP. The dry bulk density of tilled maize and groundnut plots increased significantly (P<0.05) by between 2 and 14% relative to no-till plots at 44 and 66 DAP. In both maize and groundnut plots, dry bulk density decreased significantly (P<0.05) in plots amended with poultry droppings +NPK relative to the control plots by 3–10% at 44 and 66 DAP. Tilled maize and groundnut plots had 37–45% lower (P< 0.05) penetration resistance than their corresponding no-till plots at both 44 and 66 DAP. Penetration resistance measurements were lower by 16.5–25% in plots amended with poultry droppings + NPK relative to unamended plots at 44 and 66 DAP. Cumulative (1996, 1997, 1998) data indicate that gravimetric soil water content in maize and groundnut plots generally increased significantly (P<0.05) in no-till plots relative to tilled plots by 18–27% at both 44 and 66 DAP. Plots amended with poultry droppings + NPK had between 24 and 111% increase (P<0.05) in soil gravimetric soil water content at both 44 and 66 DAP. Results are indicative that all soil compactibility indices measured were not affected at 90 DAP except for soil gravimetric soil water content in 1996 and 1998. Results from this work demonstrate that some crop and soil management practices could be used to reduce soil compactibility problems thus increasing productivity of such soils.     

甘蔗—大豆间作对大豆鲜荚产量和农艺性状的影响

为探讨甘蔗-大豆间作模式对大豆鲜荚产量和农艺性状的影响,于2009—2011年连续3年在广州市华南农业大学农场进行大田试验,试验设置2种施氮水平(常规施氮(525kg·hm-2)和减量施氮(300kg·hm-2))和3种种植模式(甘蔗-大豆(1∶1)、甘蔗-大豆(1∶2)、单作大豆)。结果表明:甘蔗-大豆间作(1∶2)模式下,2009年减量施氮水平的大豆鲜荚产量较常规施氮水平提高了33%,2010和2011年不同施氮水平间均无显著差异;甘蔗-大豆间作模式对大豆的单株鲜荚重、多粒荚数和百粒鲜重无显著影响;大豆单株鲜荚重与多粒荚数在不同种植模式下均呈显著相关(P<0.05),在常规施氮间作模式下与大豆单株荚数呈显著相关(P<0.05)。甘蔗-大豆间作没有降低大豆的单株鲜荚产量,也没有对大豆的农艺性状产生负面影响,从增产增收、提高土地生产力来考虑,减量施氮模式下甘蔗-大豆间作具有一定的可行性。     

Effect of liming on dry matter yield of wheat in pots of low humic gley soil

Summary This experiment was carried out with the aim of verifying the effect of liming on three wheat cultivars, IAC-5, Alondra and Anahuac, in lowland hydromorphic soils (Low Humic Gley) rich in organic matter. The treatments consisted of five levels of liming using two recommended methods. These treatments were: control without liming; liming by the aluminium method and 1/3, 2/3 and 4/3 of the liming recommended by the buffer method of Shoemaker, McLean and Pratt (SMP buffer method). Adequate levels of calcium and magnesium in the plants were obtained with higher doses of calcium than those indicated by the aluminium method. With the aid of curves adjusted to the experimental data it was verified that the maximum yields of dry matter of 15.86, 15.88 and 12.53 g/pot for the cultivars IAC-5, Alondra and Anahuac, respectively, occurred with higher quantities of calcium at 2/3 of liming indicated by the SMP method at pH 6.0 At this rate of liming aluminium levels in the soil were not totally neutralized and the levels of calcium and magnesium adequate for maximum yield were estimated in 4.6, 4.08 and 4.7 meq/100 g of soil.The results indicate that for Low Humic Gley soils with a high level of organic matter, the level exchangeable aluminium does not constitute an adequate criterion for indicating liming requirements for wheat.     

开放式增温下非对称性增温对冬小麦生长特征及产量构成的影响

在江苏南京(2007-2009年)设置了全天增温(AW)、白天增温(DW)和夜间增温(NW)3种处理,研究冬小麦生长及产量构成的响应差异.结果表明:非对称性增温条件下,冬小麦的无效分蘖减少,有效分蘖增加.对照(CK)处理的无效分蘖分别是AW、DW和NW处理的2.6、1.7和3.5倍,但有效分蘖却比3个增温处理分别减少13.7%、3.2%和0.5%.AW、DW和NW处理小麦株高分别较CK提高了5.6%、4.5%和1.3%.旗叶面积分别提高了45.7%、39.4%和26.1%,开花期总绿叶面积分别提高了25.1%、29.8%和17.3%,同期绿叶比分别提高了37.7%、43.3%和38.7%.穗部性状中,AW、DW和NW处理的每穗颖花数平均比CK提高了4.1%、5.7%和1.7%,每穗实粒数分别提高了2.2%、5.3%和2.6%.AW、DW和NW处理冬小麦的粒叶比平均分别较CK降低了15.3%、8.5%和11.3%,但千粒重平均分别提高了6.9%、6.2%和11.8%,单位面积产量平均分别提高了27.0%、40.1%和18.3%.表明预期增温条件下华东地区冬小麦生产力将可能进一步提高.     

Effects of Bradyrhizobium strain and host genotype,nodule dry weight and leaf area on groundnut (Arachis hypogaea L. ssp. fastigiata) yield

Effects of inoculating four Arachis hypogaea ssp. fastigiata cultivars with 17 Bradyrhizobium spp. strains were studied in a glasshouse experiment using a sandy soil devoid of an indigenous Bradyrhizobium population. Firstly, a wide range of parameters, indicative of symbiotic performance, were assessed for their influence on seed yield, by correlation and statistical analyses. It was found that nodule dry weight and leaf area were relevant parameters concerning seed yield. Secondly, the effects of host and strain genotype on those parameters were described.Variations in nodule dry weight did not have an effect on seed yield, except for cultivar Natal Common at lower nodule dry weight values. Therefore, it was concluded that the quantity of nitrogen fixing tissue met the demand for combined nitrogen and did not limit seed yield. This conclusion was further supported by the observation that at low nodule numbers per plant the nodule size increased to generate sufficient nitrogen fixing tissue.Leaf area, which comprises components for both photosynthetic capacity and plant development, was found to correlate well with seed yield. An increase in leaf area resulted in significant seed yield increases for all three spanish-type cultivars, but not for the valencia-type cultivar. Leaf area, thus, appeared as a factor limiting seed yield of spanish-type groundnuts.Cultivar performance concerning seed yield was significantly better for Natal Common compared to the other three cultivars, while Natal Common had a significantly lower plant (biomass excluding seed) dry weight value.Inoculation with different strains of Bradyrhizobium resulted in significantly different nodule dry weight values, but hardly led to significant differences in seed yield. This agreed with the finding that the amount of nitrogen fixing tissue appeared not to limit the availability of combined nitrogen.A large quantity of nitrogen was partitioned to the groundnut seeds: 62% to 76% of total accumulated nitrogen was located in the seeds.This study showed that testing for symbiotic effectiveness in the groundnut Bradyrhizobium symbiosis should include assessment of final (seed and biomass) yield, because parameters measured at stages prior to maturity, like nodulation parameters, may lead to flawed effectiveness ratings.     

寄主植物与温度对大豆食心虫滞育期间糖类和脂质含量的影响

【目的】本文探究了大豆食心虫Leguminirora glycinioorella(Mats.)Obraztsov进入滞育以后体内糖类、脂质和水分含量的变化,以及不同寄主植物和滞育诱导期温度对大豆食心虫体内糖类、脂质和水分含量的影响。【方法】通过蒽酮硫酸法和氯仿甲醇分离法测定了滞育前后、以大豆Glycine max(L.)Merr和野大豆Glycine soja Sieb.et Zucc.两种植物为寄主以及不同滞育诱导温度下的大豆食心虫体内脂质、水分、总糖、糖原和海藻糖的含量,结果利用SPSS17.0数据分析软件进行分析。【结果】进入滞育阶段的大豆食心虫体内脂质、总糖、海藻糖和糖原含量显著增加,含水量显著下降。以大豆为寄主的大豆食心虫在滞育阶段体内水分含量、总糖和糖原含量较野大豆寄主的高,海藻糖含量较野大豆的低,差异均显著。不同滞育诱导温度下的大豆食心虫体内生化物质含量基本一致。【结论】滞育前后大豆食心虫体内各种生化物质变化明显,以栽培大豆为寄主和以野大豆为寄主的大豆食心虫体内生化物质含量不同,而滞育诱导温度对大豆食心虫体内生化物质含量影响不大。     

Effect of Bradyrhizobium, VA mycorrhiza and fertilisers on seed composition of groundnut

A field experiment was carried out to investigate the effect of Bradyrhizobium and mycorrhizal (Glomus sp.) inoculation compared to adding urea and super phosphate on proximate composition, in vitro protein digestibility (IVPD) and tannin content of groundnut. The results showed that mycorrhizal inoculation and/or superphosphate significantly (P≤ 0.05) increased both oil and protein content of groundnut seeds. Bradyrhizobium and/or nitrogen fertiliser significantly (P≤ 0.05) increased protein content and significantly decreased the oil content. Bradyrhizobium and/or mycorrhizal inoculation significantly (P≤ 0.05) increased the ash, crude fibre, IVPD and tannin content. Biological and chemical fertilisers significantly (P≤ 0.05) increased IVPD. Superphosphate fertilisers significantly (P≤ 0.05) increased the tannin content. The moisture content was not affected by any treatment.     

The effect of root temperature on rose plants in relation to air temperature

Rose plants (Rosa hybrida ‘Sonia’=‘Sweet Promise’) were grown in heated (minimum night temperature 17°C), and unheated greenhouses with or without root heating to 21°C. These trials covered 6 growth cycles extending over two winter seasons. In the heated greenhouse, root heating did not increase yield, flower quality or plant development. In the unheated greenhouse, root-heated plants grew as well as those in the air-heated greenhouse as long as the air temperature did not fall below 6°C. When minimum night temperatures fell below 6°C, growth, yield and quality were reduced, irrespective of root temperature. Daytime plant water relations were studied in plants growing at 6 different root temperatures in the unheated greenhouse. Leaf resistance to water diffusion was lowest at optimal root temperature. Total leaf water potential was not significantly affected by root temperature.     

Expired air temperature during prolonged exercise in cool- and hot-humid environments

The purpose of this investigation was to measure expired air temperature under cool- and hot-humid environmental conditions at rest and during prolonged exercise to: (1) establish if significant increases in body core temperature affected expired air temperature, and (2) to determine if the temperature setting for heating the pneumotachometer in an open-circuit system requires adjustment during prolonged exercise tests to account for changes in expired air temperature. Six male distance runners completed two tests in cool-humid [dry bulb temperature (T _db) 15.5 (SD 1.3)°C, wet bulb temperature (T _wb) 12.1 (SD 1.4)°C] and hot-humid [T _db 31.6 (SD 0.6)°C, T _wb 24.9 (SD 0.6)°C, black globe temperature (T _g) 34.3 (SD 0.3)°C] environments, running at a velocity corresponding to 65% [67.1 (SD 2.82)%] of their maximal oxygen uptake. Rectal temperature and expired air temperatures were compared at rest, and after 30 min and 60 min of exercise for each environment. The main finding of this investigation was a significant (P < 0.05) but small increase in expired air temperature between the 30-min and 60-min measures in the hot-humid environment. No significant differences in expired air temperature were found between the 30-min and 60-min measures in the cool-humid environment. These findings suggest that: (1) expired air temperature is influenced by elevations in body core temperature during prolonged exercise in hot-humid conditions, and (2) that the temperature setting for heating the head of the pneumotachometer (after determining the appropriate temperature through measuring expired air temperature for the set environmental condition) may require adjustment during prolonged exercise trials in hot-humid environmental conditions. Accepted: 27 February 1997     

Effects of P,K, and liming on soil pH,Al, Mn,K, and forage barley dry matter yield and quality for a newly-cleared Cryorthod

Forage barley dry matter yield and quality, as well as soil pH, Al, and Mn were monitored in response to P, K, and lime application on a newly cleared Typic Cryorthod (Orthid Podzol). The overall yearly yield level was affected by precipitation. Without liming soil acidification occurred after three years of production. The liming rate of 2.2 Mg.ha⁻¹ was found optimal for maintaining initial pH levels (5.66) and increasing forage barley yields. It was also found optimum for K and P utilization for these first years of production. Soil pH dropped an average of 0.33 units over the three years on unlimed P plots and 0.46 units over 4 years on K plots. Phosphorus and K fertilization increased N utilization and resulted in decreased soil acidification. Phosphorus availability was greater in the first year of cropping than in subsequent years, this was likely due to the effects of higher available moisture, liming release of native P, and effects of initial fertilization. There was a 148% increase in total dry matter yield and an 85% increase in protein yield of forage barley with P application. Liming increased total forage barley yields an average of 69% and total protein yields 48%. Reduced barley yields in unlimed plots were due to low soil pH. After two years of cultivation, unlimed plots contained exchangeable Al and soluble Mn levels reported toxic for other soils. The higher liming rates of 4.4 and 6.6 Mg.ha⁻¹ reduced soluble Mn to near critically low levels. soil Al and Mn were highly correlated to pH. Soil exchangeable Al, Mn, and soluble Mn along with tissue Al were inversely correlated to percentage yield. The average yield respone to three levels of applied K, increased from zero initially to 67% by the fourth year. Total dry-matter production increased 32% and total protein yield increased an average of 32% and total protein yield increased an average of 15% with K fertilization over four years. About 60% of the yield response occurred between the 0 and 22kg K.ha⁻¹ rates. Initial soil exchangeable K levels were not maintained even at the highest 66kg K.ha⁻¹ treatment. Soil exchangeable Al and soluble Mn were elevated with dropping pH. Soil K reserves and resupply of exchangeable K in these soils over the long term will be an important factor in crop production.     

Effect of air and soil temperature on water balance of jojoba growing under controlled conditions

Jojoba [ Simmondsia chinensis (Link) Schneider] cuttings were grown in pots under constant light intensity and vapour pressure deficit at wir temperatures of 18 and 27°C in climate-controlled cabinets. Leaf conductance and transpiration rate decreased exponentially as the xylen water potential (Ψ_x) decreased concurrently with the drying out of the soil. At high Ψ_x'leaf conductance and transpiration rate were much higher at the higher air temperature, and as Ψ_x declined both parameters decreased more rapidly at 27°C than at 18°C. When soil temperatures were decreased from 27 to 13°C, leaf water potential was not affected at either air temperatures, but transpiration rate was reduced. A linear negative correlation was found between transpiration rates and soil temperatures. It is suggested that the low soil temperature may restrict reducion of water flux in turn reduces stomatal conductance and transpiration without affecting the water potential in the shoot. The releavance of the response to changes in soil or air temperature to the performance of the plant in its semi-arid habitat is discussed.     

Effect of gibberellic acid on pod set in soybean

Field-grown soybean plants (Glycine max (L.) Merr. cv. Evans) were treated with gibberellic acid (GA₃; 10gl^–1) and/or (2-chloroethyl)-trimethylammonium chloride (CCC; 0.8gl^–1) in 1983 and 1984, and subsequent anthesis, pod set, seed size, seed number, and seed yield were determined at one node. The treatments were applied to five leaves in the center of each plant (typically leaves 7–11) and reproductive development at the node in the center of those leaves was monitored. Gibberellin A₃ applied Early (about 3d before anthesis of the first flower at the monitored node) had no effect on the number of flowers produced, but decreased the fraction of flowers that set pods in both experimental years (by 32% in 1983 and 76% in 1984). Seed size was slightly decreased by the GA₃ treatment in 1983 but not in 1984. The Middle GA₃ treatment (applied about 3 days after the Early treatment) slightly decreased the number of pods set; and Late treatments (9 days after) had no effect. None of the monitored parameters were affected by CCC.The Early experiments were repeated with two additional genotypes, Lincoln and T210. Genotype T210 is a single-gene, dwarf mutant of Lincoln whose stem elongation and leaf expansion are insensitive to GA₃. Gibberellin A₃ affected the reproductive parameters in Lincoln very similarly to Evans but those in T210 were unaffected. This indicates that GA₃ exerts its effect by increasing the mass of vegetative tissue and thus diverting assimilates away from the pods. However, since the mutation in T210 might affect a receptor that is in flowers as well as shoots, it is possible that GA₃ exerted its effect on the normal genotypes directly on the developing pods, rather than indirectly by diverting photoassimilates.     

Effects of limestone and gypsum application to a Malaysian ultisol on soil solution composition and yields of maize and groundnut

A field experiment was conducted on an Ultisol in Malaysia to assess changes in soil solution composition and their effects on maize and groundnut yields, resulting from limestone and gypsum application. The results showed that soil solution Ca in the lime treatment remained mainly in the zone of incorporation, but in the gypsum treatment some Ca moved into 15–30 cm zone. Al³⁺ and AlSO₄ ⁺ were dominant Al species in the soil solution of nil treatment. Liming decreased Al³⁺ and AlSO₄ ⁺, but increased hydroxy-Al monomer activities. However, gypsum application resulted in an increase of AlSO₄ ⁺ activity and in a decrease of Al³⁺ activity. Relative maize and groundnut yields were negatively correlated with Al³⁺, Al(OH)²⁺ and Al_sum activities. Likewise, relative yields were negatively correlated with Al concentration and the Al concentration ratio and positively correlated with soil solution Mg concentration and Ca/Al ratio.     

Crop residue application increases nitrogen fixation and dry matter production in groundnut (Arachis hypogaea L.) grown on an acid sandy soil in Niger,West Africa

Field experiments were conducted during the rainy reasons of 1989, 1990 and 1991 on an acid sandy soil in Niger, West Africa, to assess the effect of millet straw application (+CR) on growth and N₂ fixation of groundnut (Arachis hypogaea L.).Three years of +CR (4 t ha^–1 yr^–1) increased symbiotic N₂ fixation, total dry matter production (haulm plus pods) by 83% and total nitrogen (N) accumulation by 100%. Concentration of N in the shoot dry matter and total N in the soil were only slightly affected by the +CR treatment.Crop residue application increased the concentration of potassium (K) and molybdenum (Mo) and decreased the concentrations of aluminium (Al) and manganese (Mn) distinctly, both in the plant (shoot and nodule dry matter) and in the soil.The increase in dry matter production and N uptake was mainly due to improved N₂ fixation reflected by enhanced formation and growth of nodules as well as nitrogenase activity. This was attributed to improved chemical soil conditions, particularly to the higher availability of Mo and the lowered content of available Al and Mn.Although with the application of 4 t CR ha^–1, 60 kg K were supplied, increased growth could not be attributed to the additional supply of K.ICRISAT Journal Article No. 1229.ICRISAT Journal Article No. 1229.     

The effect of root damage caused by simulated white grub attack on the growth,yield and water-use of groundnut plants

White grubs (larval scarabaeids) are now recognized as being important pests of groundnut (peanut) in many parts of the world because of their ability to damage roots. A method of simulating white grub damage to groundnut plants was developed to obtain an indication of how the feeding activity of these insects influences plant growth. The effect of root cutting and drought stress on water uptake and biomass production was evaluated, with roots being cut at three depths in the late vegetative and early podfilling stages. As groundnut plants are often grown under conditions of drought stress, the effects of which would be accentuated by root damage, this factor was introduced into the experiment. Plant water-use measurements indicated that the root systems of plants cut 30 days after emergence (DAE) and watered twice a week became fully functional again after 40 days. Pod and total biomass production were however significantly less than those of the uncut control plants, with drought stress reducing yields below the well-watered controls, particularly when cut at 10 cm below the soil surface. The root systems of plants cut 51 DAE did not regrow to any appreciable extent, and rates of plant water-use remained less than half of the uncut control plants. Over all treatments, there was a strong positive correlation between total (and pod) biomass and plant water-use. It was concluded that the phenological stage of the plant at which root damage occurred had a profound influence on the subsequent recovery in root growth and function, and ultimately on pod yield.     

西双版纳热带次生林林窗干热季气温分布特征的初步分析

利用西双版干热季次生林林窗的温度观测资料,探讨了林窗４方位的气温时空变化特征。由于林窗不同区域所受太阳辐射的影响不同,加之林缘热力效应的综合作用,林窗中存在明显的气温差异,特别是最高气温差异显著;气温最高值和气温日较差最大值不在林窗中央而出现在林窗东侧林缘树冠垂线处。     

Effects of substrate availability on the temperature sensitivity of soil organic matter decomposition

Soil carbon is a major component in the global carbon cycle. Understanding the relationship between environmental changes and rates of soil respiration is critical for projecting changes in soil carbon fluxes in a changing climate. Although significant attention has been focused on the temperature sensitivity of soil organic matter decomposition, the factors that affect this temperature sensitivity are still debated. In this study, we examined the effects of substrate availability on the temperature sensitivity of soil respiration in several different kinds of soils. We found that increased substrate availability had a significant positive effect on temperature sensitivity, as measured by soil Q ₁₀ values, and that this effect was inversely proportional to original substrate availability. This observation can be explained if decomposition follows Michaelis–Menten kinetics. The simple Q ₁₀ model was most appropriate in soils with high substrate availability.     

土壤深层供水对冬小麦干物质生产的影响

采用根系研究装置研究了土壤深层供水对冬小麦干物质生产的影响 .结果表明 ,上层低湿度下层高湿度的处理在小麦灌浆期仍然保持了较高的土壤和叶片含水量 ,具有发达的根系 ,特别是 1m以下的根量在 4个处理中为最高 ,旗叶和穗的干重也最大 ,具有最大的产量潜力 .本研究表明 ,上层土壤较干下层土壤湿润有利于发挥小麦根信号的积极作用 ,平衡水分利用 ,同时通过对土壤水分的合理调节可以促进深层根的发育 ,有利于提高产量和水分利用效率 .     

Effect of brassionosteriods on nodulation and nitrogenase activity in groundnut (Arachis hypogaea L.)

The effect of brassinolide, 24-epibrassinolide and 28-homobrassinolide on nodulation and nitrogenase activity of groundnut was studied. The tested brassinosteroids substantially increased both nodulation and nitrogenase activity.