High night temperature stimulates photosynthesis,biomass production and growth during the vegetative stage of rice plants

Abstract

The effects of night temperature on biomass accumulation and plant morphology were examined in rice (Oryza sativa L.) during vegetative growth. Plants were grown under three different night temperatures (17, 22 and 27°C) for 63 days. The day temperature was maintained at 27°C in all treatments. The final biomass of the plants was greatest in the plants grown at the highest night temperature. Total leaf area and tiller number were also the greatest in this treatment. Growth analysis indicated that the relative growth rate in the 27°C night-temperature treatment was maximal between days 21–42 and this was caused by increases in leaf area ratio, leaf weight ratio and specific leaf area. Plant total nitrogen contents did not differ among treatments. However, nitrogen allocation to the leaf blades was highest and the accumulation of sucrose and starch in the leaf blades and sheaths was the lowest in the 27°C night-temperature treatment by day 42. Despite this, dark respiration was also highest, and both the gross and net rates of CO₂ uptake at the level of the whole plant at day 63 were the highest in the 27°C night-temperature treatment. Thus, high night temperature strongly stimulated the growth of leaf blades during the early stage of rice plant growth, leading to increased biomass during the vegetative stage of the rice plants. As the CO₂ uptake rate per total leaf area was higher, photosynthesis at the level of the whole plant was also stimulated by a high night temperature.     

Effects of Temperature during Seedling Stage on Growth and Nutrient Absorbance of Gerbera jamesonii Growing in Organic Substrate

The effects of different temperature treatments during the seedling stage on growth and nutrient absorbance of Gerbera jamesonii cv ‘Sunshine Coast’ growing in the organic substrate were investigated. The temperature treatments were conducted in growth chamber where the day/night temperature were set to 15/10, 20/15, 25/20, and 30/25°C individually. The results showed that the fresh and dry weight of aboveground part and that of roots, average number of leaves and lateral roots were greater at 30/25°C than other treatments. The highest level of macro elements nitrogen (N), phosphorus (P), and potassium (K) in the leaf samples were also detected at 25/20°C and 30/25°C. However, there was no significant influence of different temperatures on zinc (Zn) levels in leaves. In general, the day temperature 25～30°C and night temperature 20～25°C are thought to be the better temperature condition for gerbera growth as well as the nutrient uptake and accumulation in the plants during the seedling stage.     

The influence of temperature on the growth and sulfur uptake of oats (Avena sativa L.)

Abstract

Oats were grown in perlite and nutrient solution at temperatures varying from 10/5°C (day/night) to 36/31°C. The optimum temperature for growth of tops was found to be 27°C day/22°C night over an eight week period. Plant S content showed an inverse relationship with yield.

Uptake of S was low at low temperature (10/5, 15/10°C), but was balanced by retarded growth at this temperature. Hence, uptake did not restrict growth at low temperature.     

Root‐zone temperature affects nutrient uptake and growth of snapdragon

Nutrient uptake by snapdragon (Antirrhinum majus L. ‘Peoria') was compared at five root‐zone temperatures: 8, 15, 22, 29, and 36°C. Uptake of nitrate (NO₃ ^‐‐N), ammonium (NH₄ ⁺‐N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), iron (Fe), manganese (Mn), and zinc (Zn) responded quadratically to increasing root‐zone temperature. Greatest nutrient uptake temperature varied with nutrient but ranged from 15 to 29°C. Uptake of copper (Cu) and molybdenum (Mo) were unaffected by root‐zone temperature. Dry weight gain and stem length also responded quadratically to increasing root‐zone temperature. Optimal temperatures for nutrient uptake and growth were similar, averaging 22°C. These results indicate increasing or maintaining root‐zone temperatures near 22°C maximizes growth and nutrient uptake of snapdragons.     

Supra‐optimal growth temperature exacerbates adverse effects of low Zn supply in wheat

Rising temperatures are a major threat to global wheat production, particularly when accompanied by other abiotic stressors such as mineral nutrient deficiencies. This study aimed to quantify the effects of supra‐optimal temperature on growth, photosynthetic performance, and antioxidative responses in bread wheat cultivars grown under varied zinc (Zn) supply. Two bread wheat cultivars (Triticum aestivum L., cvs. Lasani‐2008 and Faisalabad‐2008) with varied responsiveness to Zn supply and drought tolerance were cultured in nutrient solution with low (0.1 µM) or adequate (1.0 µM) Zn under optimal (25/20°C day/night) or supra‐optimal (36/28°C day/night) temperature regimes. Supra‐optimal temperature severely reduced root but not shoot biomass, whereas low Zn reduced shoot as well as root biomass. Shoot‐to‐root biomass ratio was reduced under low Zn but increased under supra‐optimal temperature. Supra‐optimal temperature inhibited root elongation and volume particularly in plants supplied with low Zn. In both cultivars, Zn efficiency index was reduced by supra‐optimal temperature, whereas heat tolerance index was reduced by low Zn supply. Supra‐optimal temperature decreased photosynthesis, quantum yield, and chlorophyll density in low‐Zn but not in adequate‐Zn plants. In comparison, low Zn decreased specific activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) and increased glutathione reductase (GR), where supra‐optimal temperature increased SOD, decreased GR and did not change APX activity in leaves and roots. Moreover, supra‐optimal temperature severely reduced shoot Zn concentration and Zn uptake per plant specifically under adequate Zn supply. Overall, supra‐optimal temperature exacerbated adverse effects of low Zn supply, resulting in severe reductions in growth traits viz. shoot and root biomass, root length and volume, and consequently impeded Zn uptake, enhanced oxidative stress and impaired photosynthetic performance. Adequate Zn nutrition is crucial to prevent yield loss in wheat cultivated under supra‐optimal temperatures.     

Investigation of Effects on Nutrient Uptake of Humic Acid Applications of Different Forms to Strawberry Plant

Abstract

The aim of this study was to investigate the effect of humic acid in liquid and solid form on uptake of nutrients for strawberry grown under greenhouse conditions. The experiment was designed in randomized block design with four replications for two years. Solid form of humic acid (Agrolig) that contained 85% humic acid was applied in the amounts of 0, 100, 200, 300, and 400 kg/ha before planting. Liquid form of humic acid (Blackjak) that contained 15% humic acid was applied by drip irrigation system at the concentrations of 0, 2500, 5000, 7500, and 10,000 mL/ha/month. Along with humic acid, 200 kg/ha nitrogen (N), 100 kg/ha phosphorus (P₂O₅), and 400 kg/ha potassium (K₂O) was applied by drip irrigation system after transplanting. According to the results, N, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), and copper (Cu) contents of the leaves were not affected significantly by the applications of solid and liquid humic acid forms. Applied liquid humic acid had a significant effect on the zinc (Zn) content of the leaves causing a decrease in the Zn content. Because of having excessive calcareous soil in the experimental area, uptake of nutrients in strawberry plants was not affected significantly. Applications of humic acid at high concentrations had an inhibitory effect on some of the nutrients.     

Effect of Zinc × Boron Interaction on Plant Growth and Tissue Nutrient Concentration of Corn

ABSTRACT

A pot experiment was conducted in a greenhouse on a calcareous soil (fine, mixed, mesic, Fluventic Haploxerepts) to study the interaction of zinc (Zn) and boron (B) on the growth and nutrient concentration of corn (Zea mays L.). Treatments consisted of a factorial arrangement of seven levels of B (0, 2.5, 5, 10, 20, 40, and 80 mg kg^{? 1}as boric acid), two sources of Zn [zinc sulfate (ZnSO₄ · 7H₂O) and zinc oxide (ZnO)], and three levels of Zn (0, 5, and 10 mg kg^{? 1}) in a completely randomized design with three replications. Plants were grown for 70 d in 1.6 L plastic containers. Applied Zn significantly increased plant height and dry matter yield (DMY) of corn. Source of Zn did not significantly affect growth or nutrient concentration. High levels of B decreased plant height and DMY. There was a significant B × Zn interaction on plant growth and tissue nutrient concentration which were rate dependent. In general, the effect of B × Zn interaction was antagonistic on nutrient concentration and synergistic on growth. It is recommended that the plants be supplied with adequate Zn when corn is grown in high B soils, especially when availability of Zn is low.     

Effect of phosphorus,copper, and zinc addition on the phosphorus/copper and phosphorus/zinc interaction in lettuce

The effect of phosphorus (P), copper (Cu), and zinc (Zn) addition on the P‐Cu and P‐Zn interaction in lettuce (Lactuca sativa L.) was analyzed following a factorial design. The experiment was conducted in a greenhouse. Two levels of P (62 and 224 ppm), three levels of Zn (0, 0.17, and 0.34 ppm), and three levels of Cu (0, 0.03, and 0.06 ppm) were applied in all combinations to lettuce grown in perlite. The influence of the different treatments on the leaf P concentration suggests that the P‐Cu interaction was positive, whereas P‐Zn was negative. An increase in root absorption and retention and a decrease in translocation to leaves were observed for Zn and Cu when the nutrient solution was supplied at a luxurious consumption level of P.     

Foliar application of zinc alleviates the heat stress of pakchoi (Brassica chinensis L.)

Abstract

Experiments were conducted to examine whether the foliar application of zinc (Zn) could mitigate the adverse effects of heat stress on pakchoi plants. Two varieties of pakchoi (Aikangqing and Wuyueman) were foliar applied with ZnSO₄·7H₂O (0%, 0.02%, 0.05%, 0.10%, 0.20%, 0.40%, 0.60%, and 0.80%), and then subjected to two temperature levels (22°C/16°C, day/night; 40°C/30°C, day/night). Heat stress decreased the net photosynthetic rate (P_n) (50.65% and 62.14% for Aikangqing and Wuyueman, respectively), chlorophyll content, chlorophyll fluorescence ratio (F_v/F_m), and effective quantum yield of PSII photochemistry (ΦPSII) of the leaves. Foliar application of ZnSO₄·7H₂O (0.02%–0.40%) effectively alleviated the heat stress in pakchoi by enhancing shoot Zn concentration, superoxide dismutase (SOD) activity, chlorophyll content, F_v/F_m, and ΦPSII. P_n increased by 12.61%–46.19% and 45.73%–119.01% in Aikangqing and Wuyueman compared with those without Zn treatments, respectively. Fuzzy comprehensive evaluation and the extreme model showed that Aikangqing and Wuyueman treated with 0.1218%–0.1220% ZnSO₄·7H₂O (approximately 0.004?M Zn²⁺) and 0.2178%–0.2744% ZnSO₄·7H₂O (approximately 0.008?M Zn²⁺) exhibited the most heat resistance, respectively. Furthermore, Zn (0.02%–0.80% ZnSO₄·7H₂O) application had no significant effect on most physicochemical parameters under normal temperature, which only increased shoot Zn and SOD. The results suggest that additional Zn would be required to fully protect plant growth from heat stress. Foliar application enhanced Zn concentration in leaves, thereby maintaining the SOD activity and membrane stability and protecting photosynthesis against heat damage.     

Effect of shade and level of fertilizer application on nutrient uptake and dry matter partitioning in cocoyam (Xanthosoma sagittifolium L.)

The effect of shade and fertilizer application on nutrient uptake and dry matter (DM) partitioning in cocoyam was evaluated by growing the plant under different levels of shade and fertilizer application at Forest and Horticultural Crops Research Centre, Kade, within a period of 9 months. The shade levels used were 80%, 70%, and 50% shade, and full sunlight exposure. The fertilizer rates used were 112 kg/ha nitrogen, phosphorus and potassium (NPK) (15-15-15 120 kg/ha NPK (15-15-15) in a form) of mineral fertilizer, 112 kg/ha NPK organic fertilizer and no fertilizer (control). The split-plot design was used with shade levels as the main plot factor and fertilizer levels as the sub plot factor. The interaction effect of shade and fertilizer had a significant effect (p ≤ 0.05) on DM of cocoyam leaves, petioles, corm, and cormels as well as nutrient accumulation in plant parts. Cocoyam leaves of plants grown under 50–70% shade stored significantly higher (p ≤ 0.05) quantities of nutrients (1.51 ppm of N, 6.61 ppm of P, and 53.10 ppm of K) and accumulated more DM (71.30 g) than leaves of plants grown under full sunlight exposure which accumulated 1.37 ppm of N, 4.31 ppm of P, 26.06 ppm of K, and 30.7 g DM, at the two rates of the chemical fertilizer application. Under full sunlight exposure, significantly higher amounts of DM were accumulated in the corms and cormels at mineral fertilizer level of 112 kg/ha. At mineral fertilizer rate of 120 kg/ha, nutrient accumulation was significantly higher (p ≤ 0.05) in the corm and cormels (1.72 ppm of N and 7.72 ppm of P) of plants grown under full sunlight exposure than those grown under 70% shade level (0.6 ppm of N and 2.94 ppm of P). Nitrogen and phosphorus accumulation was significant in the petioles of plants grown under the 70% shade level at fertilizer rate of 120 kg/ha. It is recommended that cocoyam be grown under 50–70% shade at a fertilizer rate of 112–120 kg/ha for leaf production and under full sunlight exposure at 112 kg/ha (NPK) for cormel production.     

施锌对小麦开花后氮、磷、钾、锌积累和运转的影响

为明确大田条件下施锌对小麦地上部器官氮、磷、钾、锌的积累量和转移量的影响,2001～2002年开展了田间试验。试验以专用强筋小麦(8901-11)和普通小麦(4185)两个冬小麦品种为材料,包括4个施锌水平(分别为施ZnSO4.7H2O.0、11.25、22.5和33.75.kg/hm2)。结果表明,各器官中Zn的含量变化在4.14～54.18.mg/kg,刚开花时及灌浆前期的含量以子粒>穗壳>叶片>茎秆,至接近成熟时则以子粒>叶片>穗壳>茎秆。每生产100.kg小麦子粒需要吸收Zn的范围在4.40～5.20.g之间。小麦成熟时吸收的Zn约为N或K2O的1/800～1/700,为P2O5的1/500～1/300。施锌后小麦各器官氮、磷、钾、锌的积累量及开花后向子粒的运转量增加,但施锌过多,这些营养元素的吸收、积累和运转反而受到抑制。4185开花前吸收氮和磷的能力较强,而8901-11开花后吸收氮和磷的能力较强;而吸收钾和锌的能力与吸收氮和磷的情况相反。8901-11氮、磷、钾、锌的积累量基本随施锌量增加而提高,以施硫酸锌22.5～33.75.kg/hm2的积累量最高;而4185以施硫酸锌11.25.kg/hm2的积累量最高。因此,在施用大量元素的基础上,普通小麦以施硫酸锌11.25.kg/hm2为宜,而强筋小麦以施硫酸锌22.5～33.75.kg/hm2为宜。     

Growth and nutrition of pansy as influenced by N‐form ratio and temperature

Abstract

Pansy (Viola xwittrockiana Gams.) producers often observe nutrient disorders among plants grown during warm periods (>18°C) of the growing season. These disorders typically are not seen when production temperatures are optimal (≥18°C) even though fertility regimes may remain the same. Our objectives were to assess the effects of temperature and nitrogen (N) fertility on growth and nutrition of pansy. Pansies cultivar ‘Crown White’ were grown until lateral branches had open flowers. Treatments consisted of two temperatures (12 and 22°C) and three NO₃ ^?:NH₄ ⁺ molar % ratios (100:0, 62:38, and 25:75) with a total concentration of 100 mg N L^?1. A modified Hoagland's solution was used with NO₃ ^?‐N supplied as Ca(NO₃)₂ and KNO₃ and with NH₄ ⁺‐N as (NH₄)₂SO₄. Cumulative nutrient absorption and foliar nutrient content were determined when plant lateral branches flowered. Root and shoot growth were limited when NH₄ ⁺ was present in solutions at high ambient air temperature (22°C), but not at low temperature (12°C). Individual absorption and accumulation of plant nutrients varied with N regimes and temperatures. Overall, pansies absorbed more total N, NH₄ ⁺, NO₃ ^?, calcium (Ca), potassium (K), magnesium (Mg), phosphorus (P), zinc (Zn), and less iron (Fe) and manganese (Mn) at 12°C than at 22°C. In addition, absorption of NO₃ ^? by pansy was negligible if any NH₄ ⁺ was present in solutions at 22°C. Results suggest that pansy growers should adjust fertility programs according to production temperatures to avoid possible nutritional disorders and maximize plant growth. If maximum growth is to be obtained in warm temperatures, the use of NH₄ ⁺‐containing fertilizers should be reduced or eliminated. However, the choice of NO₃ ^?:NH₄ ⁺ ratio for nutrition may be less important under cool growing conditions.     

The relationship between phosphorus and copper concentrations in wheat

Abstract

Poorly managed kaolinitic soils are often too low in P and K for optimum agronomic crop production. Even though many of these soils have relatively high phosphate fixing capacities, P applied at sufficient rates to increase soil P to acceptable levels may induce micronutrient deficiencies. The purpose of this study was to evaluate the effects of applied and residual P on Mn, Zn, and Cu uptake by field grown wheat (Triticum aestivum). Treatments were a one‐time application of P (0, 64, 128, 256, and 384 kg/ha P) and K (0, 110, 220, 440, and 660 kg/ha K) rates arranged in a 5×5 complete factorial. The treatments were applied in October, 1977 and the study was continued through June, 1979. Potassium and P × K interactions did not have a significant effect on Mn, Zn, or Cu uptake. Phosphorus did not affect Mn concentration in the wheat tissue but Zn and Cu concentrations generally decreased as applied and residual soil P levels increased. The tissue Zn concentration at the various plant growth stages did not decrease below defined critical levels. The Cu concentration decreased linearly with applied P and curvilinearly with residual P. The tissue Cu levels often decreased below suggested critical levels. Total Cu in the wheat tissue indicated that the decrease in Cu concentration as P levels increased was not a simple dilution effect resulting from increased plant growth as applied and residual soil P increased.     

Phosphorus-induced zinc deficiency in wheat pot-grown on noncalcareous and calcareous soils of different properties

High levels of phosphorus (P) often induce zinc (Zn) deficiency in plants grown on Zn-poor soils. We investigated P-induced Zn deficiency in durum wheat (Triticum durum L. ‘Carpio’) grown on 16 noncalcareous and 31 calcareous soils differing in levels of available (Olsen) P and available (diethylenetriaminepentaacetic acid (DTPA)-extractable) Zn using micropots. A completely randomized factorial design with two levels of P (0 and 40 mg P kg^?1 soil) and Zn (0 and 3 mg Zn kg^?1 soil), i.e. four treatments (‘control’, + P, + Zn, and + PZn), were used. Grain yield of control plants depended mainly on the Olsen P level. Phosphorus had a negative effect on yield in 6 soils with Olsen P/Zn_DTPA > 25, and Zn a positive one in 5 soils with Olsen P/Zn_DTPA > 50; and the + PZn treatment generally resulted in the highest yield. Grain Zn concentration of control plants was negatively correlated with growth and Olsen P. Calcareous soils were less sensitive to P-induced Zn deficiency than noncalcareous soils because phosphate is sorbed by calcite rather than being co-adsorbed with Zn on the Fe oxides. Co-application of P and Zn to soil at low and application of Zn at high Olsen P ensured both maximum yield and grain Zn bioavailability.     

Source and mode of sulphur application on groundnut productivity

The effectiveness of 20 kg/ha sulphur (S) of the S‐containing compounds iron sulphate (FeSO₄), gypsum, phosphogypsum, elemental S, and pyrite on groundnut (Arachis hypogaea L.) productivity was determined for plants grown on calcareous soil in the field. Plants grown with S compared to those without S had increased plant height, number of flowers, nodule numbers and weight, higher dry matter, seed, haulm (leaves and stems), and oil yields; higher tissue concentrations of nitrogen (N), phosphorus (P), S, iron (Fe), and zinc (Zn); and higher total uptake of mineral nutrients. Elemental S, pyrite, and FeSO₄ were more effective than gypsum and phosphogypsum, with FeSO₄ being the most effective source of S for improving plant growth traits, yield, and nutrient uptake. The most effective method of FeSO₄ application was half to the soil at planting time (basal) followed by the remainder in three equal foliar sprays at 30,50, and 70 days after plant emergence (DAE). Pyrite and elemental S were most effective when applied to the soil only, half as a basal soil dressing, and the remainder in two equal doses at 25 and 50 DAE. Plant concentrations of S, P, and potassium (K) were similar for each source of S, but elemental S, pyrite, and FeSO₄ enhanced N, Fe, manganese (Mn), and Zn uptake. Gypsum and phosphogypsum enhanced calcium (Ca) uptake. Elemental S and FeSCM provided similar results when half was applied to the soil followed by three equal foliar sprays. The best results from pyrite, gypsum, and phosphogypsum were obtained when soil applied.     

Assessment of ZN Interaction with Nutrient Cations in Alkaline Soil and its Effect on Plant Growth

An experiment was conducted to assess the zinc (Zn) availability to wheat in alkaline soils during Rabi 2009–2010. Wheat seedlings in pots having 2 kg alkaline sandy soil per pot were treated with 5, 10 and 15 kg Zn ha^?1 as soil and with 0.5 and 1.0% zinc sulfate (ZnSO₄) as foliar application. Results showed that Zn increasing levels in soil helped in phosphorus uptake up to boot stage but its conversion to grain portion lacked in Zn treated plants. Potassium (K) uptake also increased up to 6.24% in boot stage with treatment of 10 kg Zn ha^?1 + 1.0% ZnSO₄ foliar spray. Zinc (Zn) concentration increased in plant tissues with the increasing level of Zn application but this disturbed the phosphorus (P)-Zn interaction and, thus, both of the nutrients were found in lesser quantities in grains compared to the control. Despite of the apparent sufficient Zn level in soil (1.95 mg kg^?1), improvement in growth and yield parameters with Zn application indicate that the soil was Zn deplete in terms of plant available Zn. The above findings suggest that the figure Zn sufficiency in alkaline soil (1.0 mg kg^?1) should be revised in accordance to the nature and type of soils. Furthermore, foliar application of Zn up to 1.0% progressively increased yield but not significantly; and it was recommended that higher concentrations might be used to confirm foliar application of Zn as a successful strategy for increasing plant zinc levels.     

RESPONSE OF GROUNDNUTS DEPENDENT ON SYMBIOTIC AND INORGANIC NITROGEN TO HIGH AIR AND SOIL TEMPERATURES

Groundnuts (Arachis hypogaea L.) are frequently exposed to high temperatures in the semi-arid tropics. The objectives of the present research were: (i) to determine the response of groundnuts to different nitrogen sources; (ii) to quantify the effects of high air and soil temperatures on nodulation, dry matter production, partitioning and pod yields; and (iii) to discover whether plants dependent on symbiotic dinitrogen are more sensitive to heat stress than those dependent on inorganic nitrogen (N). Plants were grown at optimum air and ambient soil temperatures from sowing until the first flowering. Thereafter, plants were exposed to a factorial combination of two air temperatures [optimum: 28°/22°C (day/night) and high: 38°/22°C], two soil temperatures (ambient: 26°/24°C and high: 37°/30°C) and three N-sources [inoculated with Bradyrhizobium strain NC 92 (symbiotic N₂); inoculated and supplied with 20 ppm inorganic N (symbiotic N₂ plus 20 N); or not inoculated and supplied with 100 ppm inorganic N (inorganic N)]. At optimum air and ambient soil temperature dry matter and pod yields were greatest in plants dependent on inorganic N, intermediate in symbiotic N₂ plus 20 N and least in symbiotic N₂. High air or high soil temperatures significantly (P < 0.001) reduced pod yield to a similar extent and their effects were additive and without interaction. High soil, but not high air temperature, significantly (P < 0.001) reduced nodule numbers, nodule dry weight and 100 seed weight. High air and/or high soil temperature had no effect on pod yield in plants dependent on symbiotic N₂ or symbiotic N₂ plus 20 N, but significantly (P < 0.05) reduced pod yield in plants dependent on inorganic N. This suggest that effectively nodulated plants with small quantities of inorganic N are potentially more adaptable to hot environments than those relying on large quantities of inorganic N.     

Ryegrass Response to Mineral Fertilization and Organic Amendment with Municipal Solid Waste Compost in Two Tropical Agricultural Soils of Mali

Abstract

A pot experiment was conducted to assess the effect of mineral fertilization and compost on the growth and chemical composition of ryegrass (Lolium perenne L.) grown on two Malian agricultural soils coming from Baguinéda, abbreviated as Bgda, (12°23′ S, 7°45′ W) and Gao (16°18′ N, 0°). Treatments included non‐fertilized control, NPK alone, NPK + C₂₅, NPK + C₅₀, NPK + C₁₀₀, PK + C₅₀, NK + C₅₀, NP + C₅₀, K + C₅₀, P + C₅₀, N + C₅₀, and C₅₀ alone, where NPK represents the non modified Hoagland's solution and C₂₅, C₅₀, and C₁₀₀ represent the different rates (25, 50, and 100 T/ha) of compost. Compost and mineral fertilization significantly increased dry matter production. The application of 50 T/ha of compost alone increased the dry matter yield by 10 and 17.5% while mineral nitrogen–phosphorus–potassium (NPK) increased yield by 69.7 and 65% for Gao and Bgda, respectively. The combination of compost and mineral NPK (NPK + C₂₅ for Gao and NPK + C₅₀ for Bgda) affected the highest dry matter yield. For both soils, N concentrations in plants increased significantly with compost rate. Phosphorus and K concentrations in plants varied according to the soil. The application of compost increased the uptake of iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and potassium (K from both soils). Increases in soil organic carbon, available P, calcium (Ca), magnesium (Mg), Fe, Mn, Zn, Cu, K, and pH were observed in treatments receiving compost. Therefore, compost appeared to be a good supplier of nutrients for tropical soils.     

施磷量对小麦物质生产及吸磷特性的影响

在低磷土壤条件下,以中筋小麦扬麦12号和弱筋小麦扬麦9号为材料,研究了施磷量对小麦物质生产和吸磷特性的影响。结果表明,在施磷量(P2O5)0～180.kg/hm2范围内,植株对磷的吸收量、吸收速率和磷的积累量随施磷量增加而上升;以施磷量108.kg/h2处理的叶面积指数(LAI)、植株茎蘖数、茎蘖成穗率、干物质积累量、花后干物质积累量和子粒产量最高。当施磷量超过108.kg/hm2时,相关物质生产指标则呈下降趋势,说明即使在缺磷土壤上,施磷量有其适宜值。小麦一生对磷的吸收存在两个高峰,出苗至越冬始期为第一个吸收高峰,拔节至孕穗期为第二个吸收高峰。植株磷素积累量的70%～75%是在拔节后吸收,表明拔节期施磷对满足小麦第二个吸磷高峰和磷的最大积累期需磷有重要意义。