Effects of nitrogen form,nighttime nutrient solution strength,and cultivar on greenhouse tomato production

Higher greenhouse tomato (Lycopersicon esculentum Mill.) yield is obtained by using 25% of NH₄‐N in solution compared to using NO₃‐N as the sole nitrogen (N) source. However, blossom‐end rot (BER) may occur in tomato fruit when NH₄‐N was present in nutrient solutions. High nutrient solution strengths improve tomato fruit quality, but can also increase BER. Two NH₄‐N concentrations in solution (0 and 25%), and two nighttime solution strengths (NSS) (1X and 4X Steiner solution strength applied at 7 p.m.) were used to grow five indeterminate type greenhouse tomato cultivars: Caruso, Jumbo, Match, Max, and Trust. A significant interaction occurred between NH₄‐N concentration and NSS factors: 0% NH₄‐N and high NSS increased marketable yield and fruit:whole plant ratio, and reduced BER. In contrast, a concentration of 25% NH₄‐N and high NSS reduced marketable yield and the fruit:whole plant ratio, and increased BER incidence. Max, Match, and Trust tomato cultivars produced high marketable yield and high dry weight of stem and leaves, but were susceptible to BER. Use of NH₄‐N in solution reduced vegetative growth, and high NSS increased stem and leaf dry weight of the tomato plants. Fruit firmness was greater for the Max cultivar, and was unaffected by NH₄‐N and NSS at the mature green, breaker, and red ripe fruit development stages. However, at the fully ripe stage, fruit firmness was higher with high NSS and with 25% NH₄‐N.     

Dry Matter and Nutrient Partitioning of Selected Pineapple Cultivars Grown on Mineral and Tropical Peat Soils

The pineapple cultivars ‘Moris’ (Queen cultivar), ‘N‐36’ (‘Sarawak’ × ‘Gandul’ hybrid), ‘Gandul’ (Singapore Spanish cultivars), and ‘Josapine’ (‘Singapore Spanish’ × ‘Smooth Cayenne’ hybrid) are mostly grown on peat soils in Malaysia, whereas ‘Sarawak’ (‘Smooth Cayenne’ cultivar) is more commonly grown on mineral soils. To obtain good yields of fruit of high quality, it is important to understand the differences in nutrient requirements for these cultivars in the different soils in which they are grown. Therefore, the objectives of the study were to determine the biomass and nutrient partitioning of the different pineapple cultivars and to determine the plant variables affecting fruit yield and quality. Plants of each of the pineapple cultivars were randomly sampled from different locations of the major pineapple‐growing areas in Malaysia. Only plants having A‐grade fruit of marketable quality at harvest were selected. The cultivars and respective field sites were as follows: ‘Sarawak,’ Bukit Tandak farm, Kelantan (5° 55.274′ N, 102° 00.608′ E); ‘Moris,’ ‘N‐36,’ and ‘Gandul,’ Peninsula Pineapple Plantations, Simpang Renggam, Johor (1° 49.909′ N, 103° 14.053′ E); and ‘Josapine,’ Goh Swee Eng Pineapple Farm, Simpang Renggam, Johor (1° 48.441′ N, 103° 11.935′ E). Plants were partitioned into roots, stem, leaves, peduncle, fruit, and crown, and fresh and dry weights were recorded. Total biomasses for the different cultivars were 733.46 ± 22.83 g for ‘Gandul,’ 842.34 ± 43.26 g for ‘N‐36,’ 927.38 ± 53.10 g for ‘Moris,’ 434.77 ± 16.82 g for ‘Josapine,’ and 2446.94 ± 156.00 g for ‘Sarawak.’ Leaves accounted for the greatest proportion of dry matter (48.5%), followed by fruit (22.9%) and stem (21.6%), and a smaller proportion (1.2–2.5%) was roots, peduncle, and crown. The proportions of the dry‐matter accumulation in leaves and stem for the cultivars were 53.5 ± 0.7 and 16.7 ± 0.9% for ‘Gandul’; 45.1 ± 0.5 and 17.7 ± 0.7% for ‘N‐36’; 51.9 ± 1.6 and 16.8 ± 0.6% for ‘Moris’; 56.5 ± 1.0 and 12.0 ± 0.9% for ‘Josapine’; and 54.2 ± 5.1 and 27.7 ± 4.4% for ‘Sarawak.’ The proportion of the macro‐ and micronutrients in pineapple parts differed widely between cultivars. Potassium (K) showed the greatest proportion (7.96 ± 0.6 to 29.73 ± 1.17%) in leaves and (4.46 ± 0.70 to 9.35 ± 0.28%) in fruit followed by nitrogen (N) and phosphorus (P) with lower proportions. Most pineapple cultivars grown showed variation in nutrient‐use efficiency (NUE) with respect to the elements measured with values of <1.0 g dry matter g^?1 nutrient. The NUE values of >1.0 g dry matter g^?1 nutrient were observed for magnesium (Mg) in ‘Gandul’ and ‘N‐36’ and for calcium (Ca) and copper (Cu) in ‘N‐36.’ Total nutrient accumulation in the plant components differed approximately according to their cultivar origins (‘Smooth Cayenne,’ ‘Queen,’ ‘Singapore Spanish’). It is interesting that the results for the ‘Singapore Spanish’ × ‘Smooth Cayenne’ hybrid Josapine were more similar to the ‘Singapore Spanish’ cultivars than being between the parents. Partitioning of biomass and nutrients in pineapple provides a means to categorize them and makes it possible to use a cultivar‐based fertilization program.     

Effect of increasing potassium levels for alleviating sodium chloride stress on the growth and yield of tomato

Abstract

The efficacy of using various levels of potassium (K) (4, 8, and 16 mM) under saline conditions to alleviate the detrimental effects of salt‐stress were studied using five tomato (Lycopersicon esculentum Mill) cultivars, ‘Strain 19’, ‘Pearson’, ‘Montecarlo’, ‘Maruthuam’, and ‘Pusa Rub’. Results of the study revealed that 50 mM sodium chloride (NaCl) in a Hoagland nutrient solution significantly reduced stem height, fruit weight, and whole plant dry weights, but increased number of fruits/plant and improved fruit quality by increasing total soluble solids. It did not significantly affect leaf count, percent fruit set, or dry weight. The addition of 4, 8 and 16 mM potassium nitrate (KNO₃) to the nutrient solution containing 50 mM NaCl resulted in sodium/potassium (Na/K) ratios of 12.5, 6.3, and 3.1, respectively. The Na/K ratios of 12.5 and 6.3 produced significant improvement in stem height, percent fruit set, number of fruits/plant, fruit weight, and whole plant dry weight. The Na/K ratio of 3.1 was found to be detrimental as it resulted in sharp reduction of plant dry weight compared to the control. Percent total soluble solids was not significantly affected by the addition of any level of K to the saline nutrient solution. The performance of the tomatoplant grown under saline conditions supplemented with K in the nutrient solution indicated a higher response at the lowest K concentration used in this study.     

Influence of root restriction on two cultivars of summer squash (Cucurbita pepo L.)

Variable root restricting conditions were imposed on summer squash (Cucurbita pepo L.) cultivars ‘Senator’ and Dixie’ using container sizes of 0.35, 2.00, and 7.60 liters. Nondestructive and destructive plant sampling were conducted to evaluate leaf area production, dry weight accumulation and partitioning, crop growth rate and net assimilation rate, and flower and fruit development. Within 10 days after transplanting (DAT), ‘Senator’ exhibited declining leaf area production under increased root restriction, and within 17 DAT leaf area was diminished for both cultivars under increased root restricting conditions. Dry weight accumulation in leaves, stems, roots, and fruit was reduced for both cultivars over time and level of root restriction severity. There was a tendency for greater vegetative growth reductions with ‘Senator’ than with ‘Dixie’ at comparable levels of root restriction. Root‐to‐shoot ratio, timing and duration of flowering, and sex of flowers were not significantly impacted by root restriction level or cultivar. Fruit dry weight was greatest for Dixie’ early on, but by 28 DAT, total fruit dry weight produced did not differ for the cultivars except under the most severe root restricting conditions. Fruit dry weight production was limited for both cultivars as container volume became smaller.     

外源铁对不同品种番茄光合特性、品质及镉积累的影响

【目的】在人工模拟镉污染土壤条件下,讨论了叶面喷施Fe对番茄Cd积累及化学形态的影响,旨在为镉污染土壤上番茄的安全生产提供理论依据。【方法】采用土培试验研究了在重金属Cd(10 mg/kg)污染条件下,叶面喷施不同浓度Fe(0、200和400μmol/L,Fe SO4·7H2O)对2个番茄品种(‘4641’和‘渝粉109’)生长、光合特性、品质及果实Cd形态和Cd积累量的影响。【结果】叶面喷施Fe提高了番茄的根、茎、叶、果实干重及植株总干重,增幅分别为20.4%~48.6%、13.3%~56.0%、16.0%~63.1%、9.8%~16.5%和21.6%~40.3%,随着喷施Fe浓度的增加,番茄各部位干质量及总干质量呈先增加后降低的趋势,比较两个番茄品种,‘4641’耐Cd性更强,而‘渝粉109’对Fe的反应更为敏感;随着喷施Fe浓度的增加,2个番茄品种的叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)呈先增加后降低趋势,在Fe 200μmol/L时最大,品种‘4641’的Pn、Gs和Tr较对照分别增加了8%、11%和2.9%,而‘渝粉109’较对照分别增加了28.7%、15.5%和18.8%。而喷Fe处理却降低了番茄叶片胞间CO2浓度(Ci),比较2个供试番茄品种,‘4641’光合作用和蒸腾作用强度均高于‘渝粉109’;喷Fe提高了2种番茄果实的硝酸盐含量以及渝粉‘109’还原糖含量,降低了‘渝粉109’果实氨基酸含量,喷施高浓度Fe(400μmol/L)能提高2种番茄果实Vc含量,与对照相比,‘4641’和‘渝粉109’果实硝酸盐增加的幅度分别为18.1%~22.2%、2.3%~22.0%,Vc较对照分别增加了8.2%和13.2%;番茄果实中Cd的主要存在形态为残渣态,其次为盐酸提取态,去离子水提取态和乙醇提取态所占比例较小,残渣态Cd(FR)和盐酸提取态Cd(FHCl)为活性偏低形态Cd,占Cd提取总量的70.8%,去离子水提取态(FW)和乙醇提取态(FE)为活性较高形态Cd,仅占Cd提取总量的11.8%,有效地抑制了Cd的毒害作用。叶面喷施Fe降低了番茄果实各形态镉含量;番茄中Cd主要积累在叶和茎中,而果实和根的积累量较少;喷Fe降低了番茄叶、根、茎、果实的Cd含量,降低幅度分别为7.1%~21.9%、35.6%~50.4%、13.0%~37.0%和2.8%~8.2%,但喷施高浓度Fe(400μmol/L)相比低Fe(200μmol/L)时的番茄各部位Cd含量有所增加,无论是非否喷施Fe,叶、茎、果实中的Cd积累量以及总Cd积累量总是以‘4641’‘渝粉109’,表明在Cd污染土壤上种植‘4641’较‘渝粉109’风险更大。【结论】叶面喷施适量Fe能够促进番茄的光合作用和蒸腾作用,提高了番茄各部位的干重,降低了Cd对番茄的毒害效应,同时减少了番茄各部位Cd含量。     

磷肥对日光温室番茄磷营养和产量及土壤酶活性的影响

采用盆栽方法进行了不同施磷（P2O5）水平下,日光温室番茄产量、不同生育期番茄磷素分配、干物质积累、土壤速效磷含量和酶活性研究,并确定了适宜番茄生长的最佳施磷量与土壤速效磷含量。结果表明,随着磷肥施用量的增加,土壤速效磷含量及番茄各组织含磷量相应增加;当施用P2O5达到0.53 g/kg（处理5）,土壤速效磷含量在60～77 mg/kg时,较适宜番茄生长,番茄产量和单果重达最高,根系和茎叶干物质积累也达到最好水平。当施磷量超过0.53 g/kg时,造成土壤和植株磷累积过高,易引起土壤盐害,降低土壤酶活性,从而降低干物质积累和番茄产量,影响土壤的可持续利用。     

Tomato and eggplant scions influence the effect of rootstock under Na2SO4 salinity

A short-term experiment was conducted to investigate whether the effect of rootstock on plant response to salinity depends on the solanaceous species used as scion. Tomato cv. ‘Ikram’ and eggplant cv. ‘Black Bell’ were grafted onto two tomato interspecific hybrids (‘Beaufort’ and ‘He-Man’). Plants were grown in an open soilless cultivation system and supplied with two nutrient solutions: non-saline control and a saline solution (adding 15 mM Na₂SO₄, 3.7 dS m^?1). Plant dry biomass production and partitioning were influenced by salinity, but its effect was depending on the rootstock/scion combination. ‘Beaufort’ eliminated the deleterious effect of salinity when tomato was used as scion, but reduced (?29.6%) the shoot biomass of eggplant. ‘He-Man’ had a different effect on scion growth under saline conditions: shoot biomass was less reduced in eggplant (?20.6%) than in tomato (?26.8%). Under salt stress, ‘Beaufort’ reduced the accumulation of Na⁺ in tomato leaves more than in eggplant, whereas no differences were observed between tomato and eggplant grafted onto ‘He-Man’. Stem Na⁺ accumulation followed a different pattern. The increase of Na⁺ in the stems was similar for tomato and eggplant grafted onto ‘Beaufort’, whereas stems of tomato accumulated more Na⁺ compared to eggplant grafted onto ‘He-Man’. The opposite response of the tested rootstocks to salt stress when the scion was either tomato or eggplant seems to be partially related to the capacity of the rootstock and scion to exclude Na⁺ from the shoot. However, the results of nutrient accumulation within plant tissues imply that other mechanisms in addition to ion competition are involved in the salt resistance of grafted plants.     

Effect of preharvest application of calcium on the postharvest physiology of apricot fruit

The effect of preharvest calcium (Ca) foliar application on ethylene (C₂H₄) production, respiratory rate, soluble polyuronides, and fruit firmness of ‘Bebekou’ apricot fruits was determined. The study was carried out in two experimental years, 1991 and 1992. Calcium was applied 21, 17, and 13 days before harvest for 1991 at the concentration of 0.5% calcium chloride (CaCl₂) each time and 16 and 12 days before harvest for 1992 at the concentrations of 0.8 and 0.7% CaCl₂, respectively. Calcium treatment resulted in a 30–76% increase in the Ca content of fruit flesh. Treated fruits had significantly lower C₂H₄ production rates than control during (i) four (1991) or five days (1992) at 21°C out of the 7‐day period examined immediately after harvest, and (ii) one (1991) or two days (1992) at 21°C out of the seven‐day period examined immediately after a 3rd‐ (1991) or 4th‐week (1992) storage period at 0°C. After harvest, Ca‐treated fruits displayed one day delay to reach the peak rate of C₂H₄ production. Respiratory rate was significantly suppressed over a five‐day period at 21°C out of the seven‐day period examined immediately after harvesting. However, after four weeks of storage at 0°C, there was not any significant effect of Ca on the respiratory rate. The respiratory peak rate occurred earlier in the control fruits compared to that of the Ca‐treated fruits at harvest time. Calcium‐treated fruits were about 70% firmer than the untreated ones at harvest time. Furthermore, this difference persisted after four weeks of storage at 0°C. Foliar‐applied Ca produced a 29% decrease in the soluble polyuronide content of the fruits at harvest time, but not after four weeks of storage. Fruit firmness was positively correlated to the Ca content of fruits while the soluble polyuronide content of the fruit was negatively correlated to fruit Ca.     

Drought pretreatment increases the salinity resistance of tomato plants

Agricultural productivity is worldwide subjected to increasing salinity problems. Various strategies are applied to overcome the deleterious effects of salinity on plants. This study was conducted in order to determine whether drought pretreatment of seedlings or seed pretreatment with NaCl increases the long‐term salinity resistance of tomato (Solanum lycopersicum L.) and whether the adaptive response to salinity is accompanied by physiological changes throughout the plant‐growth cycle. When plants were pretreated at the five‐leaf growth stage, the plant dry weight was significantly higher in drought‐pretreated than in non‐pretreated plants after 50 d of salt treatment. The positive effect of drought pretreatment applied at the five‐leaf stage was maintained throughout the entire growth cycle, as fruit yield of drought‐pretreated plants was 40% higher than that of non‐pretreated plants at the end of the harvest period (150 d of 70 mM NaCl treatment). Moreover, the most productive plants maintained lower Na⁺ and Cl^– accumulation in their leaves until the end of the growth cycle, which shows that adaptation is a long‐term response during which the plants adjust their physiology to the environmental conditions. Salt resistance was also improved through seed pretreatment with NaCl. In conclusion, drought pretreatment applied at the five‐leaf stage or seed pretreatment with NaCl provide an alternative way to enhance salt resistance in tomato, and the increase in yield is associated with physiological changes throughout the plant‐growth cycle.     

Effect of saline irrigation on the biomass yield,and the protein,nitrogen, phosphorus,and potassium composition of alfalfa in a pot experiment

During 1994–1995, field experiments were conducted in six apple orchards located in the southwest of Finland (the mainland and the Åland Islands). The cultivars were ‘Melba’, ‘Raike’, ‘Red Atlas’, ‘Lobo’, ‘Aroma’, and ‘Åkero’. Fruit samples were picked at about one week before commercial maturity and stored for three to six months at 2 to 4°C and 85–95% relative humidity. During storage the percentage of physiological disorders was visually recorded. Fruit nitrogen (N) and calcium (Ca), firmness, diameter, juice titratable acidity (TA), and soluble solids concentrations (SSC) were determined at harvest. Nitrogen and Ca in the soil and leaves collected during fruit development were determined. The ranges in fruit N were 296–624 and Ca 27–68 mg kg^‐1 fresh weight, and in the leaves N 15–23 and Ca 9–19 g kg^‐1 dry matter. The N/Ca ratio was 5 and 16 and 0.9 and 2.3 in fruit and leaves, respectively. There was more variation between years in N and Ca contents of leaves than that of fruit. Other fruit quality characteristics varied between seasons and cultivars. Leaf N correlated positively with fruit diameter and negatively with fruit dry matter. The incidence of physiological disorders on apples after three month storage was 2 to 13% and after six months 10 to 95%. Fruit with Ca content below 45 mg kg^‐1 fresh weight were susceptible to bitter pit ('Aroma’ and ‘Åkero') and Jonathan spot ('Red Atlas'). The cultivar ‘Melba’ was susceptible to bruising damages and ‘Raike’ and ‘Red Atlas’ were affected more with internal breakdown and core browning.     

Comparison of leaf and fruit metabolism in two tomato (Solanum lycopersicum L.) genotypes varying in total soluble solids

Sink and source activity in two tomato (Solanum lycopersicum L.) genotypes that vary in fruit Brix were investigated to identify differences that potentially underscore this trait. Solara (Brix 9%) accumulated almost twice the glucose, fructose, and sucrose in ripe fruit and had a higher horticultural yield (25% greater) compared to Moneymaker (Brix 5%). 14C-glucose feeding suggested large disparities in sucrose metabolism in ripe fruit between genotypes. Biochemical pathways in the leaf adjacent to a fruiting truss at night were also analyzed since in many species, this is the period when leaf reserves are mobilized to feed the plant. Surprisingly, leaf metabolism, i.e., starch and sugar content, the levels of polar metabolites assayed by GC-TOF MS and 14CO2-pulse-chase fluxes in detached leaves, did not change between the day and night in either genotype. Solara has a higher morphological source-to-sink ratio, and this may contribute to higher Brix in that genotype.     

苗期昼夜温差对番茄产量形成因子的影响分析

为了了解苗期昼夜温差对番茄成株期生长发育和产量形成的影响,试验利用微电脑人工气候箱(SPX-250IC),在20℃平均温度下,研究了昼夜3个不同温差0(昼温和夜温均为20℃)、6(昼温和夜温分别为23和17℃)和12℃(昼温和夜温分别为26和14℃)对番茄苗期物质积累和花芽分化的影响,并观察了定植后的开花、坐果和产量形成状况。结果表明,与0昼夜温差相比,12℃昼夜温差可增加幼苗单株干物质量48.77%～55.73%;可提早花芽分化始期,但苗期处理结束时(28d)减少花芽分化数17.0%～18.2%;前3穗果的开花和坐果时间平均提前2.3和1.9d;但是番茄现蕾数减少了9.2%～19.7%、开花数减少了12.4%～23.3%、坐果数减少了1.5%～30.0%,单株采收果实数减少了5.8%～17.0%,单果质量降低了7.8%～8.3%,前期产量降低了14.3%～16.3%。0昼夜温差不利于番茄干物质积累和后期的持续高产。6℃昼夜温差处理时,番茄幼苗单株干物质量比0昼夜温差时显著增加,前3穗果的开花数、坐果数、单株采收果实数都比12℃昼夜温差时显著增加,单果质量和产量也显著增加。因此,平均温度20℃时,6℃左右的昼夜温差是番茄植株物质积累、花芽分化和产量形成的平衡点,有利于番茄的营养生长和产量形成。该研究可为番茄苗期温度调控提供参考。     

Comparisons among cultivars of wheat,hulless and hulled oats: Dry matter,N and P accumulation and partitioning as affected by N supply

A better understanding of the impact of fertilizer nitrogen (N) on biomass and N accumulation, and their partitioning into different plant components is needed to optimize crop yield and quality. A field experiment with spring wheat (Triticum aestivum), hulless (Avena nuda), and hulled (Avena sativa) oats was conducted for 3 years in Ottawa, ON, Canada, to determine the crop responses to N addition (0, 75, and 150 kg N ha^–1). Biomass, N, and phosphorus (P) accumulation and partitioning into different plant components were examined during the growth season. Lodging score was determined for all crops when it occurred and again at harvest. During the growth season, both hulless and hulled oats and the wheat cultivar showed almost similar patterns of N and P accumulation with maximum contents at late grain filling or at harvest. Plant N concentration was up to 60 g kg^–1 during the seedling stage, decreased gradually with advancing growth stages, and was lowest at harvest. Nitrogen treatments significantly increased plant N and P contents. At heading stage, N treatments enhanced dry matter (24%–45%), N (35%–135%), and P (27%–45%) contents in plant components (i.e., culm, leaf, and head), but also enhanced crop lodging, especially in oats. Both hulled and hulless oats had higher total plant N (5%–35%), N : P ratio, and dry‐matter content in leaf (6%–43%) and head (0%–129%) along with higher P (up to 27%) in culm than the wheat cultivar. The wheat cultivar accumulated greater dry matter and higher N content in kernels than both hulled and hulless oats at harvest. Both hulled and hulless oat cultivars exhibited similar lodging susceptibility to N addition (75 or 150 kg N ha^–1), produced lower dry weight and lower kernel N, and hence lower grain yield than the wheat cultivar. The larger vegetative dry‐matter accumulation at heading coupled with higher P content in culms under high‐N‐supply conditions may be related to severe lodging in oat cultivars.     

Effects of NaCl salinity on miniature dwarf tomato ‘Micro‐Tom’: II. Shoot and root growth responses,fruit production,and osmotic adjustment 1

The growth and production of miniature dwarf tomato selection Lycopersicon esculentum ’Micro‐Tom’ plants grown from seedling to harvest in solution batph culture’ at four different NaCl salinity levels (2.4 [control, no NaCl], 7.6, 12.8, or 18 dS‐m^‐1 solution conductivities) was monitored. Incremental reductions in canopy extent and shoot area of ‘Micro‐Tom’ were observed with increasing solution NaCl level. Root growth and shoot height were somewhat less responsive to imposed salinity. Fruit number, fruit size, and leaf tissue osmotic potential decreased as NaCl concentration increased. Fruit yield was highly correlated with total canopy and shoot area, but not with tissue osmotic or total water potential. ‘Micro‐Tom’ plants survived and continued fruit production at higher salinity levels despite reduced canopy growth. Treatment effects on vegetative growth and fruit production became more pronounced later in the growth cycle.     

Boron partitioning in B‐sprayed and unsprayed fruiting twigs of hazelnut

Abstract

Following B sprays, fruit set increase in ‘Barcelona’ hazelnut was accompanied by a decrease in dry‐matter accumulation for the entire fruiting twig. In unsprayed controls prior to 5 June, leaves constituted 80% of the total dry weight of a fruiting twig. Later in the season (5 Aug.) the percent dry weight was maximum in the nut tissue (66%), followed by leaves (17%), and then husks (13%). Leaves contained 87% of the total B in a fruiting twig early in the season, indicating that the leaf was a major sink for B at that time. Of the net B increases over a 2 months period, 24% was in the leaves, 38% in the nuts, and 37% in the husks. By 5 Aug., compared to other tissues, stem dry matter (3%) and B content (32) was negligible; hence, the stem was of little importance in overall partitioning. Boron sprays did not alter B partitioning in the fruiting twigs.     

Seasonal growth and composition and accumulation of N‐P‐K in dryland and irrigated pumpkins

Growth and N‐P‐K uptake in pumpkin (Curcubita moschata Poir.) cv ‘Libby‐Select’ were studied in dryland and irrigated culture. In both moisture regimes, maximum rates of dry matter accumulation occurred between the early and mid‐fruiting developmental stages. Higher total dry matter production with irrigated than dryland culture was primarily associated with increased shoot growth. Concentrations of N, P, and K in foliage generally decreased as pumpkin age increased. Irrigated pumpkins in conjunction with higher total vegetative dry matter accumulated more N, P, and K than dryland pumpkins. Up through early fruit development, N, P, and K accumulation was primarily in leaves and vines and by the late growth stages was almost entirely in the fruit. Total N, P, and K uptake at late fruiting was estimated at 219, 32, and 228 kg/ha in irrigated pumpkins and 180, 21, and 177 kg/ha in dryland pumpkins. Approximately 58% of the N, 52% of the K, and 68% of the P accumulated by late‐fruiting was absorbed by the plant after the early‐fruiting stage in both moisture regimes. Potassium redistribution from vegetative tissues during late fruit development decreased foliar K contents 32% in dryland pumpkins and 21% in irrigated pumpkins.     

不同剂量外源纤维素酶对设施土壤生物活性与番茄生长的影响

【目的】土壤纤维素酶活性在一定程度上反映土壤生物化学过程的强度及土壤肥力水平。本研究主要探讨了添加外源纤维素酶对设施土壤环境及栽培作物的积极影响,以期为设施土壤改良和质量提升提供参考。 【方法】以番茄‘芬达’为试材进行了盆栽试验。在设施土壤上设置添加外源纤维素酶:0、3、6、9、12、15 kg/hm2,分别用CK、T1、T2、T3、T4和T5表示,共6个处理。结果初期测定了番茄叶片光合指标,结果初期、结果盛期、采收盛期分别取土样测定了土壤脲酶、蔗糖酶、SOD、碱性磷酸酶活性,以及土壤细菌、真菌、放线菌数量,果实成熟期分批测产。 【结果】同一生育期,随酶制剂用量的增加,土壤微生物数量及酶活性均先增加后降低。与CK相比,细菌、真菌、放线菌最高分别增加了996.8% (结果盛期的T4)、801.4% (采收盛期的T3) 和314.6% (坐果初期的T3);坐果初期T3的土壤脲酶、蔗糖酶、SOD及采收初期T3的碱性磷酸酶活性提高较多,分别较CK增加了214.3%、424.3%、254.0%和44.0%;同时添加外源纤维素酶对番茄株高、茎粗以及Pn、Tr、Gs、Ci等光合指标的提高有促进作用,增加了番茄产量,T3的番茄产量最高,达到55188 kg/hm2。 【结论】适当添加外源纤维素酶,在提高土壤本身纤维素酶活性的同时也增强了其他土壤酶活性,促进了土壤中微生物的积累和繁殖,从而改善了土壤环境,并促进蔬菜作物健康生长,提高了作物产量。9 kg/hm2为本试验推荐的应用于设施土壤的纤维素酶最佳使用量。     

Fruit nutrient accumulation of four orange varieties during fruit development 1

Evaluation of nutrient accumulation trends in fruit during fruit development and nutrient status in the leaves are important components defining nutrient requirements. Such nutrient demand should be met by nutrient supply in order to develop optimal rate and timing of fertilizer application. In a 3‐year study the citrus (orange) varieties, ‘Valencia’, ‘Parson Brown’, ‘Hamlin’, and ‘Sunburst’ were fertilized with either 168, 224, or 280 kg N ha^‐1 yr^‐1 as a broadcast application of N:P:K dry soluble granular fertilizer. These rates did not significantly affect the fruit nutrient status, juice quality, or nutrients concentrations in the spring flush. The concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in the fruit decreased with their enlargement during June through November. However, micronutrient concentrations in the fruits increased from June through August or September and then decreased. Fruit dry weight was greatest in ‘Valencia’ followed by ‘Hamlin’, ‘Parson Brown’, and ‘Sunburst’ varieties. Soluble solids concentration (SSC) were higher in ‘Valencia’ and ‘Sunburst’ fruit than in the other two varieties. Other juice quality parameters were not significantly different among the varieties. This study indicated non‐significant influence of fertilizer rates on concentrations of various mineral elements in 6‐month‐old spring flush with most of those concentrations within the optimal ranges.     

间作对分蘖洋葱与番茄根际土壤磷转化强度及磷细菌群落结构的影响

【目的】间作分蘖洋葱能缓解番茄连作障碍,提高番茄养分吸收。本试验主要研究间作后分蘖洋葱和番茄根际土壤中磷细菌群落结构及活性的变化,以揭示该间作体系磷细菌改善作物磷营养的生物学机制。【方法】盆栽试验选用茄科连作8年的设施土壤,番茄品种为‘东农708’,分蘖洋葱品种为‘五常红旗社’。设番茄单作、分蘖洋葱单作、分蘖洋葱与番茄间作及无苗对照等4个处理。在定植23 d、30 d和37 d取样,测定植株干重及磷浓度。同时用抖根法取番茄和分蘖洋葱根际土,测定土壤中磷细菌数量及磷细菌的转化强度。采用PCRDGGE方法测定磷细菌的群落结构。【结果】1)间作后,番茄地上和地下干重增加,分蘖洋葱地上和地下干重减少,在37 d差异达到显著水平。2)间作后,番茄根际土壤中无机磷和有机磷细菌的数量增加,在23 d和37d差异达到显著水平;分蘖洋葱根际土壤中无机磷细菌数量在23 d时显著降低,有机磷细菌数量在间作37 d时显著升高。间作期间分蘖洋葱和番茄根际土壤中无机磷和有机磷细菌的数量均显著高于无苗对照。间作23d时,番茄根际土壤中无机磷和有机磷细菌的转化强度均显著升高,分蘖洋葱根际土壤中无机磷和有机磷细菌的转化强度均显著降低;而间作37 d时,分蘖洋葱根际土壤中无机磷和有机磷细菌的转化强度均显著升高,且间作期间番茄和分蘖洋葱根际土壤中无机磷和有机磷细菌的转化强度均显著高于无苗对照。3)间作37 d番茄和分蘖洋葱根际土壤pH显著升高,EC值显著降低,且各处理土壤pH均高于无苗对照,土壤EC值均低于无苗对照。间作30 d时番茄根际土壤中速效磷含量显著升高,间作37 d时显著低于单作。间作期间分蘖洋葱根际土壤速效磷含量变化不显著,番茄根际土壤速效磷含量均低于无苗对照,而分蘖洋葱均高于无苗对照。间作后番茄植株磷浓度和磷吸收量显著高于单作处理,分蘖洋葱植株磷浓度显著高于单作处理,而磷吸收量显著低于单作处理。4)间作后番茄根际土壤中无机磷细菌的条带数、香农多样性指数和均匀度指数显著高于其单作处理,而间作分蘖洋葱显著低于其单作处理。间作后番茄根际土壤中有机磷细菌的条带数、香农多样性指数和均匀度指数前期显著高于单作番茄,后期显著低于单作。而间作分蘖洋葱与对应单作比较差异不显著。【结论】间作分蘖洋葱通过改变番茄根际土壤中磷细菌数量和群落结构,提高了磷细菌的转化强度,增加了番茄根际土壤中速效磷含量,促进植株磷浓度和磷吸收量增加,改善了番茄磷营养。     

Toxicity symptoms and tissue levels associated with excess boron in pear trees

Abstract

High levels of B were applied to the soil around ‘Bartlett’ and ‘d'Anjou’ pear trees in a non‐irrigated orchard. B levels in the soil profile and in the flowers, leaves and fruit were monitored for 6 years. Levels of B in the soil dropped to below 2 ppm within 5 years following the application. By then all visible symptoms of toxicity had disappeared. The B content of ‘Bartlett’ tissues was always higher than that of ‘d'Anjou’ and the symptoms of toxicity were more severe. Under conditions of this research, full bloom blossom cluster levels and levels in the fruit at harvest time were better indicators of toxicity than were the levels in leaves. Boron levels in blossom clusters above 90 and 115 ppm and in fruit above 55 and 45 ppm for ‘d'Anjou’ and ‘Bartlett’ pears respectively were considered to be toxic.