Effects of nitrogen and phosphorus nutrition on the growth of asparagus seedlings

N was applied at 50, 100 or 150 mg l^?1 in factorial combination with P at 7.5, 15 or 22.5 mg l^?1 to asparagus seedlings. There were 6 successional harvests. N and P increased shoot dry weight by increasing mean dry weight and number of shoots. Increasing P had no effect on shoot growth at 50 mg l^?1 N. N increased root dry weight (crown and roots) by increasing root number, whereas P decreased root dry weight due to a decrease in mean root dry weight. N increased total plant dry weight, but P had no effect. N and P increased the partitioning of dry weight to the shoots, while partitioning to the roots increased with time. Plant analysis revealed that 2.6–2.7% N and 0.29–0.36% P, on a dry-weight basis, were present in the shoots at the later harvests with the higher concentrations of N and P. 100–150 mg 1^?1 N in combination with 15 mg l^?1 P produced a seedling suitable for transplanting into commercial fields at 6 weeks from emergence.     

The effect of planting date and plant density on nitrogen uptake and nitrogen harvest by Brussels sprouts

Summary

Single and combined effects of three planting dates and three plant densities on nitrogen uptake and nitrogen harvest by Brussels sprouts (Brassica olerácea var. gemmifera) were studied in field experiments. The total amount of nitrogen taken up by the crop at harvest ranged between 220 and 325 kg ha^–1. Although final crop dry matter decreased, total nitrogen uptake was not lower when planting was delayed. This resulted in increased nitrogen concentrations both in the total crop and in the harvested product. Forty to fifty per cent of the nitrogen taken up by the harvest was removed from the field with the product. Within the range of 2.7 to 4.4 plants per m², plant density had no effect on final nitrogen uptake nor on the amount of nitrogen harvested with the product. The results indicate that nitrogen fertilizer recommendations should take planting date into account, because with delayed planting less dry matter will be accumulated with a corresponding lower nitrogen requirement. There was no interaction of effects of planting date and plant density on nitrogen uptake.     

The effect of plant density and day-length on growth and development in the carnation

Carnation plants cultivar ‘White Sim’ were grown in containers arranged to simulate the aerial environment of bed-grown crops. The effects of 2 plant densities (9 plants and 100 plants m^?2) and 2 day-lengths (natural days and continuous light) were recorded on the growth of individual plants. The reduction in yield of flowers per plant at high density was greater than could be accounted for simply by a reduction in light intensity. An interaction between light intensity and intra-plant competition is proposed as an explanation of this effect. Continuous light had little effect on the growth and flowering of 2nd and 3rd generation shoots grown at high density.     

Suitability of wood fiber substrates for production of vegetable transplants II.: The effect of wood fiber substrates and their volume weights on the growth of tomato transplants

The influence of wood fiber substrates (WFS) and their volume weights (VW) on the growth of tomato transplants (Lycopersicon lycopersicum (L.) Karst. ex Farw.) were examined. No significant differences were observed for the absolute and relative growth rate of tomato transplants cultivated in WFS as compared to white peat (WP). Particularly in WFS plants showed a well developed root system. When the tomato transplants were cultivated in spring increases of VW led to a reduction of root growth, but no significant differences were observed for other plant parameters. In summer differences between weakly and strongly compacted substrate treatments for fresh mass of leaf and stem for both WFS were found. The coarse WFS also showed a significant difference in leaf area for these two treatments. Weakly compressed substrate had a faster decrease of matric potential in summer.WFS are suitable for cultivation of vegetable transplants and are a good alternative for peat-based substrates. When filling containers, moderate compression of WFS is recommended.     

The effect of nitrogen fertilization on plant growth and the nitrate content of leaves and roots of parsley in the Mediterranean region

Curly-leafed and turnip-rooted parsley have recently been introduced to Greece as alternative herbs within the programme for crop diversification. Because the response of these subspecies to nitrogen (N) application under the warm climatic conditions of the Mediterranean region is unknown, both were cultivated over three consecutive years in order to evaluate their yield potential and quality (in terms of nitrate content) in relation to nitrogen application in comparison with the traditionally cultivated plain-leafed subspecies. Nitrogen was applied as ammonium nitrate in the form of liquid feeds at rates of 30–450 mg kg⁻¹. Foliage and root yield increased with N application up to a level of 150 mg kg⁻¹ and the nitrate content of the tissues was low. Increasing N application rates to 300 or 450 mg kg⁻¹ did not cause a further increase in yield, but the nitrate content of the tissues increased. In view of health concerns with respect to human nitrate intake and environmental threats posed by excessive N application, it is concluded that the optimum level of ammonium nitrate application under local conditions should be 150 mg kg⁻¹. Overall, all three subspecies responded to N in a similar way in terms of yield and nitrate content.     

烯效唑对罗汉果试管苗生长的影响

将罗汉果试管苗接种于添加不同浓度烯效唑(S-3307)的改良MS培养基中，结果表明：合适浓度(0．01～0．1mg／L)的S-3307能有效延缓罗汉果试管苗的伸长，使苗矮化增粗；同时促进不定根发生，根系发达，苗健壮。但高浓度的S-3307使苗的生长受到过度抑制，植株过于矮化，表现不正常。     

The effect of temperature on growth and dry matter production of lychee seedlings

In lychee (Litchi chinensis Sonn.), high day/night temperatures ($\text{30}\text{25}$, $\text{25}\text{20}$, $\text{20}\text{15}\text{°}\text{C}$ compared to $\text{15}\text{10}\text{°}\text{C}$) increased stem extension, node and leaf production and plant dry weight in seedling selections of 6 cultivars (‘Bengal’, ‘Haak Yip’, ‘Kwai May’, ‘Gee Kee’, ‘Tai So’ and ‘Wai Chee’). The mean daily base temperature for shoot growth (node production) was estimated by linear correlation to be 11.0°C for the seedlings. High temperatures also increased the proportion of leaf and decreased the proportion of root in the total dry weight. There was a strong effect of cultivar on all aspects of growth, but the responses to temperature were similar.This experiment shows that temperatures in many tropical and warm sub-tropical areas where lychees are grown are too high to induce satisfactory vegetative dormancy prior to floral initiation. The assessment of lychee seedlings for low vigour in a heated glasshouse appears to be a useful technique for the initial screening of adapted genotypes (which flower and fruit under warm conditions) prior to field evaluation.     

The effect of salinity and porosity of sewage sludge compost on the growth of vegetable seedlings

Salinity and porosity of composted sewage sludge (CSS) were studied to evaluate their effect on vegetable seedlings, specifically on vegetable seedling performance and toxicity threshold of soluble salts. For the evaluation, CSS was mixed with different proportions of leached CSS to control the salinity. Soluble salt content of 1.45% or higher in growth media inhibited the growth of cucumber, tomato, and pepper seedlings, while that of 1.1% was relatively safe. Different porosities of CSS media were prepared by mixing CSS (<10 mm) with ground CSS (<1 mm) in different proportions (CSS and ground CSS were leached beforehand to prevent salt stress). The vegetable seedlings grew well in CSS media without showing symptoms of growth inhibition if the total porosity ranged from 66% to 81% and the water holding porosity ranged from 48% to 59%. However, the best seedling performances were achieved with the coarser media with high total porosities. The study indicated that when salt content was appropriate, CSS can be used alone as a vegetable seedling growth medium without the need for grinding or blending with other materials.     

An investigation on the effect of different plant growth regulating compounds in in vitro shoot tip and node culture of lemon seedlings

The possible application of some less commonly used in vitro growth regulating compounds is outlined. A number of treatments were applied to determine the best way of inducing in vitro shoot proliferation and rooting on a modified Driver–Kuniyuki [HortScience 19 (1984) 507] basal medium of lemon (Citrus limon (L.) Burm, f. cv. Interdonato) seedlings. 6-Benzyladenine (BA) alone (1, 2 and 4 mg l⁻¹) and in combination with either orange juice (10%, v/v), silver nitrate (3 mg l⁻¹), gibberellic acid (GA₃) (0.1 mg l⁻¹ at the establishment stage and 0.5 mg l⁻¹ at all combinations during the proliferation stage) or abscisic acid (ABA) (0.2 mg l⁻¹ only at the establishment stage) were used to stimulate shoot formation during the establishment and the proliferation stage. The combination of BA with ABA gave a high rate of shoot formation, while GA₃ and silver nitrate enhanced shoot elongation. When these shoots were transferred to the rooting stage, the effect of application of two different auxins (indole-3-butyric acid (IBA) and α-napthaleneacetic acid) was examined, as well as different methods of application (auxin added to the basal medium and auxin application by dipping the base of the explant in auxin solution). Dipping the base of the explants in a 50% ethanol solution of IBA at 1000 mg l⁻¹ for 5 s resulted in 80% rooting with subsequent 90% survival of these explants, during acclimatization under mist.     

不同栽培基质对温室茭白幼苗生长及光合特性的影响

为筛选出以椰糠为基础并适合茭白幼苗的栽培基质,以茭白浙茭2号为试材,以普通土壤、粗粒椰糠、细粒椰糠、珍珠岩为基质原料,按照不同体积配比设置5种栽培基质:普通土壤(CK)、粗粒椰糠(T1)、V粗粒椰糠:V珍珠岩=3:1(T2)、细粒椰糠(T3)、V细粒椰糠:V珍珠岩=3:1(T4),探究不同栽培基质对茭白幼苗生长及光合特...     

应用多元回归模型预测红茄梨单叶面积、鲜重和干重的方法

以红茄梨为试材,应用多元回归模型探讨单叶长度(L)、宽度(W)、SPAD值(S)与单叶面积(LA)、单叶鲜重(FW)和单叶干重(DW)之间的关系,结果分析得到3个作用显著的回归方程:Y_(LA)=-10.84102+6.52299X_W+0.55063W_(LW)-0.62566X_W~2(R~2=0.9149);Y_(FW)=0.40273-0.16328X_L+0.06057X_(LW)+0.00311X_S-0.03973X_W~2(R~2=0.9439);Y_(DW)=0.15305-0.07116X_L+0.02439X_(LW)+0.00199X_S-0.01582X_W~2(R~2=0.9126)。模型验证结果显示,3个模型预测值均与实测值呈现显著线性相关关系。     

The effect of combined Azospirillum inoculation and nitrogen fertilizer on plant growth promotion and yield response of the blanket flower Gaillardia pulchella

The investigation was carried out to examine the performance of Azospirillum isolates on growth and N uptake of Gaillardia pulchella with two nitrogen levels. Azospirillum strain OAD-2 inoculation significantly increased plant height, number of leaves per plant, branches per plant and total dry mass accumulation in G. pulchella than other inoculations and/or uninoculated control. The application of 150 kg N ha⁻¹ further enhanced the above plant growth parameters significantly over application of 112 kg N ha⁻¹. The N uptake of G. pulchella was enhanced due to Azospirillum strain OAD-2 inoculation, which was further augmented in the presence of nitrogen. The combination of Azospirillum strain OAD-2 and 150 kg N ha⁻¹ showed the highest N uptake at 120 DAT. Plant growth and yield parameters also increased when inoculated with the non-diazotrophic, but efficient IAA producing, Azospirillum strain OAD-57. From this investigation, it can be concluded that Azospirillum strains OAD-2 and OAD-11 can play an important role in the N nutrition of G. pulchella.     

植物生长调节剂对紫果西番莲离体培养的影响

以紫果西番莲的茎段为外植体，以1／2MS为基础培养基，添加ZEA2－3mg/l，外植体萌芽率高达100％。不定芽在1／2MS培养基中，附加B A1.0 NAA0.1mg/l，其增殖系数最高。芽苗不定根的诱导培养基1／2MS＋IBA1.5-2.3mg/l，其生根率较高，当IBA为2.5mg/l时芽苗生根率达100％。     

The influence of tree training and plant density on growth,yield components and yield of Arabica coffee cv. Ruiru 11

Assessment of tree growth and yield components of Coffea arabica L. cv. Ruiru 11, as influenced by tree training on single or two-stem systems at densities between 1600-4800 trees per ha during the first production cycle was carried out at Ruiru, Kenya over three years. Trees trained on the two-stem system tended to be taller than those on singlestems. Although the results were not clear, trees at low plant densities had thicker stems irrespective of the training system. The total number of primary branches was significantly higher on trees trained on the two-stem system. However, bearing primaries and productive wood were higher on the single-stem system during the first year of production. The number of bearing primaries and productive wood increased in subsequent production years on the two-stem system. Training trees on the two-stem system significantly depressed yields in the first production year by 245 to 842%, irrespective of plant density. Yields of clean coffee increased significantly with tree density irrespective of the tree training method. Yields over the production period increased by 33, 45,27 and 9% with increases in planting densities from 1600 to 2400, 2400 to 3200, 3200 to 4000 and 4000 to 4800 trees per ha, respectively. However, yields increased at a decreasing rate at densities above 3200 trees per ha. The proportions of the large grade ‘A’ sized coffee beans were not significantly affected by the treatments. It was concluded that it is possible to raise two stems during the first production cycle of ‘Ruiru 11’, although this might not be economical. Single stems would be preferred and a high plant density of between 3200-4000 trees per ha would be optimum during the first coffee production cycle.     

The effect of intermittent irrigation with cold nutrient solution on the growth of tomato seedlings propagated in rockwool

Seedlings of tomato, cv. Counter, propagated in rockwool blocks were irrigated five times every 24 h with nutrient solution at 10°C or 18°C for up to three weeks. The mean block temperature was lowered by 3.5-4.0 degrees C by irrigation at 10°C. One week of irrigation at the lower temperature caused the seedlings to develop a characteristic dark purplish colour. This treatment reduced fresh weight and leaf area but not dry weight which suggests that water uptake was also reduced. Dry weight was reduced following two or more weeks of irrigation at 10°C. When seedlings which had been irrigated at 10°C were returned to irrigation at 18°C, the purple colour slowly disappeared and the percent dry matter decreased. When plants were grown on, the total yield of fruit was unaffected by these seedling treatments.     

Influence of plant density and time of fertilizer application on growth characteristics,nutrient uptake and yield of tomato

In a factorial experiment to investigate the combined effects of plant density and time of split application of fertilizer, 4 spacings and 3 fertilizer treatments were employed. Plant populations were varied between 24,000 and 54,000 per ha. Equal amounts of NPK were applied in different split applications and at specific physiological stages.Time to 50% flowering was delayed by fertilizer application as well as by wide within-row spacing. Total leaf N and P content declined with all treatments between flowering and mature-green stage of fruits, but increased again at table-ripe stage. Leaf K content remained constant throughout the growth period.Two-split applications of NPK, one at 2 weeks after transplanting to the field and the other at fruit set, were more beneficial than either no fertilizer or 3-split applications of equal amount of fertilizer, when the third application was at mature-green stage. This was indicated by higher fruit yields with 2-split applications.Highest fruit yields were obtained when tomatoes were planted either at 30.5 cm × 91 cm single-row spacing, or at 45.5 cm × 122.0 cm, double-row spacing, both giving 36,000 plants per hectare. Fruit yields were reduced at lower and higher population densities.     

土壤施入甲基对硫磷降解菌对青菜和黄瓜生长的影响

通过盆栽试验研究甲基对硫磷降解菌对青菜和黄瓜苗鲜重、干重及株高的影响。结果表明,甲基对硫磷降解菌能够在5d内有效地降解喷施在土壤中的甲基对硫磷,解除甲基对硫磷对黄瓜生长的抑制作用,并显著促进黄瓜干物质的生成和积累。甲基对硫磷降解菌对矮脚黄青菜鲜重、干重的影响不明显。     

不同摘心高度和种植密度对番茄生长指标及产量的影响

试验以‘北京圣粉’为材料,通过不同摘心高度和不同种植密度处理,主要对生长指标以及产量进行分析比较。试验结果表明：摘心高度低,有利于番茄植株的生长指标增加,降低发病率。种植密度越大,相应的生长指标都有所降低,发病率也随之提高。综合摘心高度和种植密度来看,适当的摘心高度和种植密度有利于温室番茄的生长和产量增加。处理Ⅲ表现最好,为最佳种植方案,种植密度为8000株／667m2,产量较对照增产26．64％。     

Effects of ages of plug transplants and planting depths on the growth and yield of sweetpotato

Sweetpotato [Ipomoea batatas (L.) Lam. cv. Beniazuma] plug transplants produced from single node leafy cuttings under artificial light in a closed-type growth chamber were planted with roots and substrate of 11- and 15-day old (ca. two to three unfolded leaves with 0.08 m shoot length and three to four unfolded leaves with 0.11 m shoot length, respectively). The plug transplants of both the 11- and 15-day old were planted with one and three nodes depth (ca. 4 and 25 mm deep, respectively) inside the soil ridges (called one- and three-node depth, respectively, hereafter). The conventional vine cuttings (ca. 0.3 m long with seven to eight unfolded leaves) without roots were planted as Control treatment to compare the growth and yield of sweetpotato with each of the treatments of plug transplant. The main objectives of the study were to see the effects of ages of plug transplants and depths of planting for greater growth and yield of sweetpotato in the field. The yield of storage roots 115 days after planting in the field was 33 t ha⁻¹ when using 15-day old plug transplants planted with three-node depth and was 10 t ha⁻¹ greater than that in the Control. The mean storage root length was about 259 mm when using 11-day old plug transplants planted with three-node depth and was 33 mm greater than that in the Control. The mean diameter of storage roots was 70 mm when using 11- and 15-day old plug transplants planted with one-node depth and was 21 mm greater than that in the Control. The plug transplants planted either 11- or 15-day old showed greater overall performances than those of the conventional cuttings. The plug transplants planted with three-node depth showed greater performances than did the plug transplants planted with one-node depth.     

The effect of nitrogen on stolon and ramet growth in four genotypes of Fragaria chiloensis L.

Plant foraging response is a process in which clonal plants proliferate in nutrient-rich sites by shortening stolon length and increasing ramet density. Conversely, stolon length increases and ramet density decreases in nutrient-poor sites. Four genotypes of strawberry (Fragaria chiloensis (L.) Duch.) were grown in a greenhouse for 10 weeks and treated with different concentrations of nitrogen. Genotypes differed in plant size, stolon and ramet production, and nitrogen distribution between parent and ramets. Genotype Q18 were the smallest plants with the greatest number of stolons and ramets, typical of the phalanx morphology. The other genotypes had fewer but longer stolons, typical of the guerrilla morphology. Number of stolons and ramet density increased with increased N more in Genotype Q18 than the other genotypes. Results indicate that vegetative growth changed in response to increasing N treatment of the parent plant by shortening the average stolon length, increasing the number of stolons, and increasing the number of ramets while maintaining total stolon length. Foraging response characteristics were observed in strawberry but varied among genotypes.