Spear Weight Research Articles

Effects of Cultivar and Cropping Type on the Growth and Yield of Female and Male Asparagus Plants

Asparagus (Asparagus officinalis L.) is a dioecious perennial plant. Male plants have a higher yield than female plants; therefore, all-male cultivars are more commonly produced. In contrast, female plants have a higher spear weight than that of male plants. To increase profitability, selective cultivation of only female plants would increase the yield of asparagus with a thick spear, which has a higher unit price. However, the effects of cultivar and cropping type on the growth and yield of male and female asparagus plants have rarely been examined. This study compared the growth and yield of female and male plants of three cultivars grown under various cropping types: a rootstock planting forcing culture; a long-term harvest production system in an open field; and a semi-forcing culture. As a measurement of growth, the rootstock weight was significantly higher for female plants compared with that of male plants with the rootstock planting forcing culture. Regarding yield measurements, the spear weight and yield were not significantly different with the rootstock planting forcing culture. However, with the long-term harvest production system in the open field and semi-forcing cultures, the weight and yield of female plants were equivalent to or significantly higher than those of male plants, regardless of the cultivar, except during some harvest periods. These results indicated that the selective production of female plants may be advantageous in terms of growing heavier spears with a higher unit price in a long-term harvest production system in the open field and semi-forcing cultures in Japan. Additionally, the development of a simple and low-cost method for sex identification would be beneficial.

Response of Chosen American Asparagus officinalis L. Cultivars to Drip Irrigation on the Sandy Soil in Central Europe: Growth, Yield, and Water Productivity

The aim of this study was to verify the response of 13 American asparagus cultivars cultivated for green spear on surface postharvest drip irrigation. Irrigation, used to compensate for periodic deficiencies in precipitation, allows for high- and good-quality crops for many species. The field experiment was carried out in 2006–2008 on a very light sandy soil in central Europe (Poland). Irrigation treatments were applied using the tensiometer indications. Water requirements of asparagus were calculated on the base of reference evapotranspiration and crop coefficients. The following evaluations were made: Height, diameter, and number of summer stalks, as well marketable yield, weight, and number of consumption green spears. Drip irrigation applied for 2 years (2006–2007) in the postharvest period had a positive effect on all studied traits in both summer stalks and green spears in 2007–2008. A significant increase in the height, number, and diameter of summer stalks, as well an increase in the marketable yield, weight, and number of green spears was observed for most of the cultivars. In general, postharvest drip irrigation of asparagus cultivated in very light sandy soil significantly contributes to the increase in productivity of American cultivars of this species.

Comparison of spear yield and quality between male and female asparagus plants in protected mother fern culture

A higher yield of spears is generally obtained from male asparagus plants than females in outdoor culture. However, recently in Japan, it was reported that the spear weight and yield of female plants was generally greater than those of males in rootstock-planting forcing or mother fern culture. 'UC157' plants were grown in large black polyethylene pots. Spears were harvested daily and their weight and external appearance were recorded for four and two years, respectively. Spear numbers were not significantly different between male and female plants in spring, and tended to be greater per male plant than per female plant from summer to autumn. Mean spear weights per female plant were significantly higher than those per male plant in spring and from summer to autumn. Spear yields per female plant were also significantly higher than those per male plant during spring, whereas no significant differences were found from summer to autumn. Spearhead tightness, an important external quality indicator, was significantly better in female plants than males. From these results, we concluded that in spring, the spear yield and quality of female plants would be better than those of male plants without causing a difference in the annual yield. Therefore, a choice of all-male varieties seems to be not necessary and all female cultivation could be profitable for protected mother fern culture in Japan, since the price of spears in spring and heavier spears is higher in the Japanese asparagus market.

Commercial Productivity in the Fourth International Asparagus Cultivar Trial at Azul, Argentina (2016)

A field trial was carried out at Azul (36°48',lat.S-59°51',long.O) consisting of asparagus hybrids ‘Italo’, ‘Vittorio’, ‘Eros’, ‘Ercole’, ‘Giove’, ‘Franco’, ‘Chino’, ‘Early-California’, ‘UC-157’, ‘Patron’, ‘NJ-1189’, ‘NJ-1123’ and ‘NJ-1192’, planted on 16/11/2011 with density 23.810 plants.ha(-1). Characters scored between 19/8/2016-17/11/2016 were: total fresh commercial productivity (TFCP), long and short spear fresh commercial productivity (LSFCP-SSFCP), total commercial spear number (TCSN), long and short commercial spear number (LCSN-SCSN), mean spear weight (MSW) and calibre distribution, CD (J: Jumbo; XL: Extra-Large; L: Large; M: Medium; S: Small y A: Asparagina). Spears were cut, selected (long: 22cm, short: 17cm), weighed, counted, washed and calibrated, and ANOVA-LSD (P≤0.05) employed. Overall mean values were: TFCP:5117,10 t ha-1, TCSN:284910 spears and MSW:18 g spear-1. For TFCP, ‘Vittorio’:6072, ‘UC-157’:6006, ‘Eros’:5885, ‘Franco’:5745, ‘NJ-1123’:5573, ‘Early-California’:5359 and ‘NJ-1192’:5284 kg ha(-1) exceeded the mean. For LSFCP, ‘UC-157’:4250(a), ‘Vittorio’:4134(ab), ‘Franco’:4056(ab), ‘Eros’:3978(ab), ‘NJ-1192’:3861(abc) and ‘Early-California’:3744(abc) excelled and for SSFCP, ‘NJ-1123’:1985(a), ‘Vittorio’:1983(ab), ‘Eros’:1907(abc), ‘Italo’:18174(abcd), ‘UC-157’:1755(abcde), ‘Franco’:1688(abcde) and ‘Early-California’:1615(abcde). For TCSN, ‘UC-157’:356343, ‘Patron’:341991, ‘NJ-1192’:324675, ‘NJ-1123’:308022, ‘Franco’:307671, ‘Early-California’:307359, ‘Vittorio’:306306, ‘Ercole’:300027 and ‘Eros’:289497 exceeded the mean. For LCSN, ‘UC-157’:230334(a), ‘Patron’:219336(ab), ‘NJ-1192’:216996(ab) and ‘Franco’:200343(abc) excelled and for SCSN, ‘NJ-1123’:129012(a), ‘UC-157’:126009(a), ‘Patron’:122655(a), ‘Early-California’:111345(ab), ‘Eros’:110175(ab), ‘Ercole’:110019(ab), ‘Vittorio’:109317(ab), ‘Italo’:108342(ab), ‘NJ-1192’:107679(ab) and ‘Franco’:107328(ab). For CD, 48% were larger calibres and 43% smaller; the following performed well for J: ‘NJ-1189’(a), ‘Eros’(ab), ‘Giove’(abc), for XL: ‘Eros’(a), for L: ‘Franco’(a), ‘Eros’(a), ‘Ercole’(a), ‘Vittorio’(ab), ‘UC-157’(ab), ‘Early-California’(abc), ‘NJ-1123’ (abc), for M: ‘Ercole’(a), ‘UC-157’(a), ‘Patron’(ab), ‘NJ-1123’ (abc), ‘Franco’(abc) and for S: ‘Patron’(a). From these results, it can be discerned that (i) a group of five hybrids (‘Vittorio’, ‘Eros’, and ‘Franco’ =Italian), and ‘UC-157’ and ‘Early-California’ =USA) were high performing for all three productivity measures (TFCP-LSFCP-SSFCP); (ii) an additional hybrid, ‘Patron’, gave high spear number for all three measures (TCSN-LCSN-SCSN); (iii) the hybrids varied considerably in their calibre distribution; and (iv) the hybrids provided a range of different production options for existing and potential growers.

A combined flamer-cultivator for weed control during the harvesting season of asparagus green spears

Weed competition during spears harvesting reduces asparagus yields. The application of herbicides during this period is illegal, and alternative non-chemical practices are needed. This research tested the effectiveness and efficiency of a custom-built combined flamer-cultivator to control weeds (both in the inter- and intra- spears production bands) during the spears harvest season. It also analysed the effects of various liquefied petroleum gas (LPG) doses on total asparagus yield, mean spear weight, and total number of marketable spears. In both years, the asparagus spears were generally not damaged by flame weeding using LPG doses of between 43 to 87 kg/ha. The same LPG doses were effective in controlling weeds, showing the same total marketable yields as the weed-free control. At high LPG doses (e.g. 130 and 260 kg/ha), yields decreased as a consequence of the damage caused to the spears, resulting in a lower number of marketable spears. Flaming did not affect the mean spear weight, and can be applied repeatedly during harvesting to maintain the weeds at a level that does not lead to a yield reduction. The repeated use of the combined flamer-cultivator (every seven days) led to higher yields than plots where weed control was not conducted. The new machine can be used in a period when herbicides are not possible. Flaming could be introduced by asparagus producers as an alternative, or in addition to herbicides applied in the pre-emergence and post-harvest of spears.

Suitability Of Sixteen Asparagus Cultivars For Growing In Polish Environmental Conditions

Abstract Green spear yield of 16 asparagus cultivars originating from six countries was assessed from 2011 to 2013. There were considerable differences in total, marketable and early yields between the cultivars. The quality of harvested spears also varied remarkably. On average, the highest mean total and marketable yields from 3 years of investigation came from Dutch cultivars ‘Gijnlim’ and ‘Cumulus’ and German cv. ‘Mondeo’. The lowest yields were found in New Zealand cultivars ‘Pacific Challenger’ and ‘Pacific 2000’. The greatest mean marketable spear weight was recorded for ‘Cumulus’, whereas the smallest spear weight was obtained from ‘Pacific 2000’, ‘H666’ and ‘NJ 953’. Cultivars ‘Gijnlim’, ‘Cumulus’ and ‘Mondeo’ produced the highest early yields, while ‘Pacific 2000’ and ‘Pacific Challenger’ produced the lowest. In order to determine the dependence between summer stalks size of tested cultivars in the preceding year and their yields in the following year, regression equations and their correlation coefficients were estimated. The size of summer stalks was expressed as plant growth index, which was the multiplication of height and total cross-sectional area of summer stalks. There was a significant and positive correlation between plant growth index of tested cultivars and their yields in the next vegetation period. The correlation coefficients between these two parameters amounted to 0.62 and 0.68 in 2011/2012 and 2012/2013, respectively

Changing oxygen concentration around the rootstock alters spear elongation and sprouting of white asparagus

We investigated the effects of manipulating the atmospheric oxygen (O2) concentration around white asparagus rootstocks planted in pots to evaluate the applicability of this technique for growth regulation in white asparagus production. The O2 concentrations around the pots were adjusted to 5%, 10%, 20%, 40%, 60%, and 80%, and plants were exposed to these conditions over a 38-d period. We found that the time of both initial sprouting (i.e., when the length of the first emerging spears reached >30mm) and harvesting were delayed when the O2 concentration around the pots was 5%; moreover, decreases in the soluble solids contents (SSCs) of the storage roots were inhibited at 5% O2 relative to the control (20% O2). These delays were likely due to a hypoxic effect, which inhibits the metabolism of some respiratory substrates such as sugars and/or organic acids. Under the 5% O2 treatment, the O2 concentration during the gaseous phase of the soil in the pot was estimated to be 12.4–14.4%; therefore, sprouting should be delayed when the O2 concentration around the roots is <15%. Our results also showed that the rate of spear elongation decreased when the O2 concentration around the spears was within the range of 60–80%. Considering that the 40% O2 concentration did not affect the rate of spear elongation, it appears that the threshold for this phenomenon is an O2 concentration of 40–60%. When the rootstocks grown under each O2 treatment were replanted and cultured under normal atmospheric conditions for 25d, no significant differences were found in growth and yield ability, such as the time of initial harvesting, number of harvested spears, yield, and spear weight. Therefore, the effects of different atmospheric O2 concentrations did not continue after cessation of the experimental treatments. Our results suggest that controlling the O2 concentration around rootstocks may be a new method for the growth regulation of white asparagus. We also expect that the new method can be applied in a closed cultivation system as well as in a plant factory.

아스파라거스 두 전웅 품종의 저온처리에 따른 휴면 타파와 순의 생장에 미치는 영향

Abstract. The aim of this study was to investigate the effect of two male cultivars of asparagus with low different chilling periods on bud breaking, relative spear growth rate, shoot number and yield. Four-month-old plants of two male cultivars of asparagus were dried to impose dormancy and placed in a coldroom at 5℃ to satisfy the chilling requirement for 0, 2, 4, and 6 weeks. After the specified chilling time, the pots were placed in greenhouse. The results showed that mean days to bud break of ‘Jersey Giant’ significantly decreased with an increasing chilling period from 0 to 6 weeks, but ‘Jersey Supreme’ was not affected. The relative spear growth rate of ‘Jersey Supreme’ was significantly stimulated by chilling compared to non-chilled plants. Shoot production and total spear weight of ‘Jersey Supreme’ tended to be greater than ‘Jersey Giant’ irrespective of chilling treatments. Following low temperature treatment, ‘Jersey Supreme’ showed shorter dormant period than ‘Jersey Giant’, faster growth of spear. The present study showed that asparagus male cultivar at duration of chilling treatment had an affirmative effect on bud breaking, spear growth rates, shoot number and yield of asparagus.

Exploring the potential of wild food resources in the Mediterranean region: natural yield and gathering pressure of the wild asparagus (Asparagus acutifolius L.)

In the Mediterranean region, some wild edible species such as Asparagus acutifolius L. are still harvested and even marketed. Considering the great interest of this species, including its recreational, commercial and agronomic uses, we aimed to study its natural supply and its current scale of harvesting. Nearly 50 plants were monitored in two sites of Central Spain. An experimental harvest of 100% of spears was conducted during spring 2008-2009 to estimate spear production per plant and per hectare. Plants were also monitored but not harvested in 2010-2011 at Site 1 to document real gathering practices and its influence on yield. Spear production ranged from 5.0 to 12.8 g per plant and from 4.0 to 8.9 kg ha-1, reaching the top-ranked values in May (30-60% of total yield). Between-site variations on yield were mainly related to spear number rather than to spear weight, whereas weather conditions influenced annual yields. The percentage of plants harvested by local foragers varied from 26 to 47%. A slight but not significant trend for collecting the largest spears was recorded. According to spear number in harvested (1.8-2.5 spears) and non-harvested plants (1.3-1.5 spears), gathering seemed to promote the growth of new spears, although further research is needed to assess its influence in the long term. Results suggest that foraging is a time-consuming practice, thus social and cultural factors may explain its high appreciation in present times.

Variability of Economic Traits of 28 Cultivars of Asparagus (Asparagus officinalis L.)

Variability of Economic Traits of 28 Cultivars of Asparagus (Asparagus officinalis L.) The research which aim was to characterise variability of economic traits of 28 asparagus cultivars was carried out in the Marcelin Experiment Station in the years 2004-2008. Variability of total and marketable yields, the mean weight of green spears as well as plant survival of all the 28 cultivars and separately of nine German and Dutch cultivars was evaluated. In addition, variability between harvest years of individual cultivars for total and marketable yields, mean spear weight in five and spear thickness in three selected harvest years was characterised. Variability between cultivars was found greater with respect to marketable and total yields expressed in the weight of harvested spears and smaller with respect to mean spear weight and total yield expressed in the number of harvested spears. Less productive cultivars exhibited the least consistent yields between individual harvest years and the worst plant survival. Higher yield consistency, mean spear weight and plant survival were observed in the group of German and Dutch cultivars.

Plant age effect on asparagus yielding in terms of carbohydrate balance

Abstract In order to examine the effect of plant age on asparagus yielding, the number and weight of spears were analyzed. The experiment was carried out on 1-, 4- and 7-year-old plants in the aeroponic system with recirculation. The results showed that the spear number and thus also the yield were not plant age dependent, while spear diameter and their weight were. Taking into account both crown weight and the age of plants, a 26% variation in spear diameter and a 27% variation in mean spear weight were explained. Determination of dry weight and carbohydrate contents in storage roots showed these traits to be independent of asparagus plant age, except for total carbohydrate content per plant. During harvest dry weight, % Brix, sucrose, fructan and total carbohydrates contents losses were also recorded.

EFFECT OF VARIOUS TYPES AND RATES OF ORGANIC MANURES ON VEGETATIVE GROWTH, PIGMENTS AND CHEMICAL COMPOSITION OF LEAVES, YIELD AND SPEAR PIGMENTS OF BROCCOLI.

Two Field experiments were conducted at the Experimental Farm of the Faculty of Agriculture, Suez Canal university during the winter seasons of 2004-2005 and 2005-2006 to study the effect of three types of organic manures, i.e poultry manure, cattle manure and sheep manure in comparison with conventional fertilization (cattle manure + mineral NPK) on broccoli vegetative growth, leaves chemical composition, leaf pigments, yield and its components and spear pigments. The organic manures and conventional fertilization (cattle manure + mineral nitrogen fertilizer) were applied according to their content of nitrogen at three rates: 100, 140 and 180kg N/feddan. The obtained results indicated that conventional fertilization gave the highest values of stem length; stem diameter; stem weight; number of leaves per plant; both fresh and dry weights of leaves; chlorophyll a and b, total chlorophyll and carotenoids contents of leaves, N, P and K contents of leaves; main spear diameter; main spear weight; main spear yield (Ton/Fed); average side spear diameter; number of side spear per plant; side spears yield per plant; side spears yield (Ton/Fed); total yield; chlorophyll a, chlorophyll b, total chlorophyll and carotenoids contents of main spear. The second fertilizer with positive increase in the previous parameters was poultry manure followed by cattle manure then sheep manure. The previous parameters except number of leaves per plant were increased with increasing the rate of manure application providing N-level from 100 to 180Kg/Fed. The conventional fertilization containing 180kg N/Fed recorded the highest values of stem length; stem diameter; stem weight; number of leaves per plant; both fresh and dry weights of leaves; chlorophyll a, chlorophyll b, total chlorophyll and carotenoid, contents of leaves; N, P, and K contents of leaves and chlorophyll a, chlorophyll b, total chlorophyll and carotenoids of main spear, while conventional fertilization containing 140kg N/Fed gave the highest values of yield and its components.

Effects of plant density in broccoli on yield and radiation use efficiency

Abstract The effects of plant density on broccoli (Brassica oleracea L. var. italica Plenck) commercial characteristics are well determined. However, it is not completely clear how the broccoli plant respond to changes in plant shading as a result of different plant densities. The objective of this experiment was to determine the effect of plant density on intercepted photosynthetically active radiation (PAR), plant architecture, and plant growth and production. “Legacy” broccoli plants were grown in pots in a greenhouse in the seasons of 2002 and 2003 at 2, 4, 6 or 8 plants m−2 (temperatures: between 10.0 and 16.1 °C, average incident PAR: 12 mol m−2 day−1). Plant density affected the intercepted and accumulated PAR. There were not effects on the length of the vegetative and reproductive periods, the total and final number of leaves, and the spear diameter and fresh weight. The magnitude and evolution of leaf area (LA) was independent of plant density up to 70 days after transplant (dat). Since then on, LA increased linearly with plant density. The highest intercepted PAR was 70–72% with 6–8 plants m−2. With the increase in plant density: the erectness of the upper leaves and stem length increased, the extinction coefficient decreased and commercial spear (inflorescence plus a portion of stem 10 cm long) weight decreased (but it was due to the stem portion of the spear and not to the edible portion). On an area basis, the decrease in commercial spear weight with plant density was more than compensated by the higher number of plants. The radiation use efficiency (RUE) increased proportionally with the leaf area index (LAI) up to a LAI of about 3, and then stabilized. The only effect of plant density on dry weight partitioning was to decrease the dry weight allocated to the stem portion of the spear. As plant density increased, and consequently the degree of shading increased, the net assimilation rate (NAR) decreased and the leaf area ratio (LAR) increased. This compensatory change between NAR and LAR, kept the relative growth rate (RGR) for individual plants almost constant.

Comparison of asparagus (Asparagus officinalis L.) cultivars and the effect of covering beds

Five hybrid cultivars ('Boonlim', 'Cipres', 'Dariana', 'Franklim' in 'Steline') of white asparagus were tested on 4 locations in Slovenia (Celje, Logarovci, Nova Gorica and Novo mesto). The plantations were 7 years old when some of the raised beds were covered with black PE mulch and the yield was compared to the yield of uncovered beds. The planting space was 2.2 m between rows and 0.33 m between crowns in the row. Each cultivar had 2 covered and 2 uncovered repetitions with 15 plants (11 m2). The yield and number of spears were measured. For 6 days, white spears were divided into 4 groups based on their thickness (4-8 mm; 8-12 mm; 12-16 mm; over 16 mm), counted and weighed in order to determine the proportion and quality of marketable yield. 'Steline' (3.44 t/ha) had the lowest average yield and 'Boonlim' (6.78 t/ha), which was the best performing cultivar in Logarovci and Nova Gorica, the best. In Novo mesto there were no significant differences among cultivars and in Celje, earlier cultivars 'Franklim', 'Cipres' and 'Dariana' performed better. 'Franklim' had more spears on average but the weight of the spears was best with 'Boonlim' (46.24 g) and worst with 'Steline' (32.03 g). The mulch influenced the yield, which was 5.27 t/ha on uncovered beds and 6.25 t/ha on covered ones. It also influenced the average weight of spears, which increased from 38.15 g to 40.88 g. The mulch did not increase either the number of spears or their thickness.

EFECTO DE NIVELES DE NITRÓGENO Y DENSIDADES DE POBLACIÓN EN LOS RENDIMIENTOS DE LOS PRIMEROS AÑOS DE UNA ESPARRAGUERA

Nitrogen fertilization in asparagus has been studied using plant populations of around 22.000 plants per hectare, not having information of its use in higher populations, which is the tendency nowadays. Results for the first four years of harvest of a trial that employs two plant densities (22.222 and 44.444 pl/ha) and five levels of N (0, 50, 100, 150 and 200 kg/ha) are analyzed. Total and commercial yield of the traditional plant density (22.222 pl/ha), for the first four years of harvest, were not statistically lower than that for the higher population, except for the third season; nevertheless, if for the four year period the general average yield is considered, the higher plant density gave higher total and commercial yields both for weight and number of spears. Similarly, the number of spears and yield per plant increased through the seasons with the lower plant population; likewise, with the higher population they seem to diminish in the fourth harvest, showing an apparent effect of plant competition. Response to nitrogen fertilization was similar for both plant populations tending to lower yields, both in number and weight of spears, when the nitrogen rate applied was over 100 kg/ ha, what would indicate that plant density in asparagus is not a factor of higher N demand.

Caracteres agronómicos en el cultivo de espárrago de diferentes edades y manejos

El objetivo del trabajo fue evaluar el efecto de la edad de la planta y la respuesta a los manejos en 11 híbridos de espárrago (Asparagus officinalis L.). Se utilizó un diseño en bloques completos aleatorios con tres repeticiones de 20 plantas por parcela, con tres y cuatro años de edad, según dos sistemas de manejo: con surcos alomados para la producción de espárrago blanco y surcos sin alomar para espárrago verde. Con el manejo para espárrago blanco se obtuvieron mayores valores promedio para días a brotación, rendimiento de mercado, rendimiento total, número de turiones y peso promedio del turión. Sin embargo, la tasa de incremento del primer al segundo año de cosecha para rendimiento de mercado y rendimiento total resultó superior en el manejo verde debido a una tasa de incremento superior para número de turiones. Para días a brotación y peso promedio del turión, la respuesta debida al efecto del manejo y de la edad del cultivo fue similar, mientras que días al 50% de parcela brotada se vio afectada principalmente por la edad de la planta.

Selección de progenitores en espárrago

The principal aim of this experiment was to ascertain what the variables are which best explain the variations among individuals within the populations of asparagus which originates from the cultivar Argenteuil and as a result select better plants to form new populations. The test, using 1,280 plants, was carried out at he experimental farm in the Facultad Ciencias Agrarias de la Universidad Nacional de Rosario, Santa Fe, Argentina, in 1996. During 1997 and 1998 the number of spears per plant (TU), the mean weight of spears (PM), mean diameter of spears (DI) total yield (RE), marketable yield (RM), days to first harvest (DAC), number of stalks (NUTA), plant height (ALT) and fresh weight of the fern (MASAV) were measured. According to an analysis of the principal components, the variables RE, RM, PM, DI and TU were responsible for 60% of the variation that exists within the population evaluated.

Influence of Formononetin and NaCl on Mycorrhizal Colonization and Fusarium Crown and Root Rot of Asparagus.

Replanted asparagus fields commonly fail to produce a profitable stand due to alleopathic residues left behind from the previous asparagus crop, elevated densities of pathogenic Fusarium spp., and low densities of vesicular arbuscular mycorrhizae (VAM). Formononetin, a plant isoflavone that stimulates VAM spores to germinate, and sodium chloride (NaCl), a disease-suppressing amendment, were evaluated alone and in combination for their effect on reestablishing asparagus at two locations in abandoned asparagus fields. Greenhouse studies also were conducted with naturally and artificially infested soils. Formononetin was applied as a crown soak or soil drench, and NaCl was applied as a granular treatment. Feeder roots from soil cores sampled from field plots and from greenhouse transplants were assayed for colonization by VAM and for lesions caused by Fusarium oxysporum and F. proliferatum. Formononetin increased the number of VAM vesicles in roots from the field and greenhouse studies and reduced the percent root lesions caused by Fusarium spp. when compared with the nontreated controls. NaCl was more effective than formononetin in reducing the percentage of root lesions in both field and greenhouse experiment when compared with untreated plants but had no effect on VAM colonization. However, there was evidence that NaCl negated the effect of formononentin on VAM colonization. The NaCl treatment increased the May 2001 spear number by 15% and marketable spear weight by 23%. At one site, treatment with formononetin increased mean number of stalks per plant by 29% in 2000 and 14% in 2001. Both formononetin and NaCl improve growth and reduce disease of asparagus in replanted asparagus and may be useful in reestablishing asparagus in abandoned asparagus field.

INFLUENCE OF PLANTING DEPTH AND PLANT POPULATION ON YIELD AND QUALITY OF GREEN ASPARAGUS

The effect on asparagus yield and quality of three planting depth (10, 20 and 30 cm) and two plant densities (22000 and 33000 plants ha -1 ) was assessed in a volcanic soil in the subhumid Mediterranean climatic zone. The cultivar used was UC-157 F1, and the experimental design was randomized complete block in a factorial arrangement, with four replications. Plots were harvested daily during four seasons (1997-2000), and number, weight and diameter of spears were determined after trimming to 18 cm. Marketable yield was determined as the total yield minus culls, and exportable yield as the marketable 7-17 mm diameter spears. No interaction between plant density and planting depth, and no effect of plant density were detected on cumulative marketable yield and percentage of 7-17 mm diameter spears. The marketable yield declined when crowns were planted at 30 cm, although the individual weight of spears increased. This was explained by a decrease in the number of spears per m 2 . The highest proportion of exportable yield (7-17 mm) was

Early selection of elite plants in Asparagus

In order to establish an efficient selection criterion the variability in three asparagus populations was evaluated defining the most important yield components and analysing its evolution along three growing seasons. The yield components, coefficient of variation (CV) and the proportion of plants contributing to 80% of the total yield were estimated. The elite plants were selected by mean of total yield and clusters techniques. Multiple regression showed that spear number (SN) and spear weight (SW) were the most important yield components. In every population, total yield (TY) and SN showed the highest values of CV, independently of sex. 69% of the plants contributed to the 80% of the total yield in the first year while in the second and third year the contribution was 57%. At the end of the third year, 17 plants were selected by the average of the total yield and 43 by clusters. It is suggested to select for SW in the first year, reducing in 68% the experimental material. In the second year, the selection for SN would reduce to 5% the plants to evaluate for total yield in the third year. In this way the selected plants are the same but the number of plants to evaluate is dramatically reduced along the years, therefore facilitating the breeders work.