Direct-seeded Plants Research Articles

The characteristics of hill-drop and potting techniques for growing different bean varieties in the protected ground

The research has been conducted in the experimental greenhouses of Scientific Center of Vegetable and Industrial Crops, RA in 2020-2021. Bean varieties were grown without heating during the spring vegetation period. It has been empirically established that per all growing and development indices the best results have been recorded in the local bean varieties of Zepyur (control), Gohar, Ghapan variety-population and in the foreign variety White Ruler cultivated through potting and hill-drop technique. Throughout research activities it has been disclosed that in unheated greenhouse conditions (in the spring vegetation period) the application of pot planting method has been more feasible and effective than hill-drop planting (direct-seeded plants) technique, since the former technique promotes long-lasting fruiting of plants, development of a powerful root system, foliage improvement and, ultimately, a higher yield capacity (the yield surplus was 0.9-1.2 kg/m2).

Arbuscular mycorrhizal fungi inoculation and phosphorus application improve growth, physiological traits, and grain yield of rice under alternate wetting and drying irrigation

Climate change and agricultural malpractices are exacerbating drought in many parts of the world causing a substantial agricultural production loss. The improvement of drought tolerance in rice is crucial for maintaining productivity and ensuring global food security. Alternate wetting and drying (AWD) irrigation along with plant-microbe interaction through arbuscular mycorrhizal fungi (AMF) is a potential approach for enhancing rice production through AMF-induced up-regulation of tolerance and resilience against drought stress. Therefore, the ameliorative role of AMF inoculation and phosphorus (P) application on growth, physiological traits, and grain yield of rice was evaluated under water stress imposed through AWD irrigation. A factorial experiment consisting of four fertilizer treatments where the P percentage varied along with the recommended dose of nitrogen (N) with or without AMF inoculation (P100 as the control, P100 + AMF, P75 + AMF, and P50 + AMF), three soil water potential levels (0, −15, and −30 kPa), and two cultivation methods (wet direct seeding and transplanting) was conducted in a polyhouse. The subscript values of 100, 75, and 50 under P represent 100%, 75%, and 50% of the recommended field application dose. Data were collected on selected growth parameters, physiological traits, levels of mycorrhizal colonization, yield and its components, and water productivity of rice. The results revealed that P100 + AMF inoculated plants had 11%, 14%, 74%, and 54% higher leaf greenness, leaf relative water content, net photosynthetic rate, and grain yield, respectively, for wet direct-seeded plants at reduced soil water potential (−30 kPa) compared with non-inoculated plants (P100). Free proline accumulation gradually enhanced with decreasing soil water potential, and it was maximized by 77% at −30 kPa compared with 0 kPa for P50 + AMF (for transplanted plants). Free proline accumulation was also higher with decreasing soil water potential in AMF-inoculated plants than non-inoculated plants regardless of cultivation methods. Leaf osmotic potential was reduced by −0.5 to −1.2 MPa at −30 kPa compared with 0 kPa under different fertilizer doses. However, AMF inoculation (P100 + AMF and P75 + AMF) improved leaf osmotic potential of plants under severe water stress (−30 kPa) maintained through AWD irrigation resulting in better osmotic adjustment than non-inoculated plants. AMF inoculation improved the response of most of the evaluated physiological traits of rice and enhanced grain yield with higher P availability (even with a 25% reduction in its recommended dose) in the rhizosphere under drought stress. Thus, it can be concluded that AMF inoculation coupled with judicious P management is a promising approach for improving physiological and biochemical traits, grain yield, and water productivity of rice under AWD irrigation regardless of cultivation methods.

Tomato Transplant Production Method Affects Plant Development and Field Performance

ABSTRACTIn addition to direct seeding of tomato (Solanum lycopersicum L.), several plant establishment methods are used, with each presenting its own set of advantages and limitations. Transplant production methods including normal plug tray, bare root transplants with known plant density, and broadcast seeded bare root transplants were evaluated in peat : perlite 60:40 (v/v) or compost : field soil 1/3:2/3 (v/v) substrates against direct seeding of tomato in the field. The highest plant establishment percentage and leaf number before the first truss were for plug transplants; earlier fruit ripening was from bare root transplants. Broadcast seeded bare root transplants and direct-seeded plants had the greatest first yield. Fruit production increased following the second harvest toward maximum potential yield in transplanted seedlings, regardless of production method. Compared to direct seeding, greater total yield was from transplants due to more possible harvests.

Yield of Two Hydroponically Grown Tomato Cultivars as Affected by Transplanting Stage or Direct Seeding

Direct seeding or transplanting younger seedlings should reduce costs in hydroponic systems. A 2-year study (2011–12 and 2012–13) was conducted to determine yield of two hydroponically grown tomato cultivars using transplanted seedlings at different growth stages vs. direct seeding. An open bag, using 10-L plastic bags filled with sawdust, was used for direct seeding and transplanting of seedlings at two-, four- or six-leaf stages. Data were collected on early marketable, early total, total, total marketable and cull yield as well as plant fresh and dry mass. In 2011–12, there was increased early marketable and total yields from direct-seeded plants or plants transplanted at the two- or four-leaf stage. Cultivar FA593 produced a higher early marketable yield and total yield compared with ‘Linares’. In 2012–13, the highest early marketable and total yields were for plants developed from those transplanted at the two-leaf stage or from those developed from direct seeding. There was no difference between cultivars on marketable and total yield. Cultivar Linares produced the highest plant fresh and dry mass. Early yield can be induced by direct seeding or transplanting seedlings at the two-true leaf stage with no significant effect on total yield and marketable yield. Direct-seeded plants, or transplanting seedlings at the two-leaf stage, will benefit growers by producing tomatoes earlier for the market while eliminating or reducing transplant shock.

Artificial regeneration with Quercus ilex L. and Quercus suber L. by direct seeding and planting in southern Spain

The limited ability of Quercus species to regenerate naturally in Mediterranean forests has led to the development of various artificial regeneration methods; however, there is no general consensus as to what specific method is the best one for this purpose. In this work, we assessed morphology, growth and survival of two Quercus species (Quercus ilex ssp. ballota and Quercus suber) using two different methods of artificial regeneration (viz. direct seeding and planting) and two seedling ages (1-year-old seedlings and 3-year-old seedlings) in southern Spain. The 1-year-old seedlings of both species were found to exhibit the highest survival percentages and direct-seeded plants intermediate survival values. For direct-seeded plants, seed mass was found to have a significantly positive effect on the establishment success in both species. No clear-cut trend in survival was detected in the 3-year-old seedlings. The survival of the 3-year-old Q. suber seedlings and the direct-seeded plants was similar, but not in Q. ilex, where the survival of the 3-year-old seedlings was the lowest. The latter result may have been a consequence of cultivation in smaller containers leading to root deformation and limiting plant access to water. Differences in survival could not be ascribed to morphological and growth variables or stomatal conductance. Based on the results, all three artificial regeneration methods can be similarly effective provided appropriate nursery cultivation conditions are used and seeds are protected against predators, the best choice in each case being dictated by the particular restoration goals.

Direct seeding is more cost effective than container stock across ten woody species in California

Abstract The planting of native woody plants is a cornerstone of many habitat restoration projects. Current techniques for revegetating disturbed or reclaimed plant communities often consist primarily of planting trees and shrubs from container stock, which can be costly to buy or produce, time-consuming to plant (an additional cost), and logistically difficult for large-scale restoration projects. We tested whether direct seeding woody species was more cost effective than planting container stock. During fall 2004, we planted 3 sites encompassing the ecotone of foothill riparian and woodland habitats in northern California with 10 native species of woody plants, both as container stock and direct seed. Data on survival were collected over a 2-y period. Across species, the planting success of direct-seeded plants, but not container plants, increased significantly with increasing mean seed size. Although seeds generally had lower individual planting success than did container stock, this was always offset by the higher costs of purchasing and planting container stock. Direct seeding was up to 29 times more cost effective than planting container stock when considering base costs (not including fixed costs of tubes, irrigation, and herbicide). Including these additional costs reduced the cost advantage, but direct seeding remained more cost effective per surviving plant across all species, and especially so for large-seeded species.

Planting Method, Plastic Mulch, and Fumigation Influence Growth, Yield, and Root Structure of Watermelon

A 2-year field study was conducted to determine the influence of planting method, i.e., transplanting or direct seeding, black plastic mulch, and soil fumigation on the vine growth, yield, and root structure of diploid hybrid watermelon. The experiment was a split-plot design with fumigation as the main plot and there were four replications. Methyl bromide (337 L·ha−1) was applied to the soil, which was then tarped. Black plastic mulch, 0.61 m wide × 2 mil (Visqueen 4020™) was applied to appropriate rows. Vine growth was measured during the season and yield was determined by the number and weight of fruit from each treatment. After fruit harvest, plant roots were excavated so that root structure was maintained with minimal damage and roots were photographed. Root systems were scored for tap root dominance and overall root distribution. Direct-seeded watermelon had more vine growth and higher yields in both years than transplanted watermelon. The advantage of direct seeding was likely the result of the growth and root expansion that occurred for these plants while the transplants were still in the greenhouse. Direct-seeded plants also displayed greater tap root dominance in each year than transplanted watermelon. Roots of both direct-seeded plants and transplants had a greater range in size distribution in both years under plastic mulch than those grown on bare ground. In late-planted watermelon, direct-seeded plants had more favorable vine growth and yield without the aberrant roots systems produced by transplants.

Impact of Corn Gluten Meal on Direct-Seeded Vegetable Seedling Establishment

Corn gluten meal (CGM) may be used as a preemergent or preplant-incorporated herbicide for organic weed control of young developing or emerging weed seedlings. Unfortunately, CGM can also adversely impact seedling survival of certain direct-seeded vegetable crops. Various vegetable crop seedlings respond differently to CGM applications, and the impact of CGM applications on direct-seeded cucurbit crops or dry beans has not yet been determined. Field research was conducted in southeast Oklahoma (Lane, OK) to determine the phyto-toxic impact of CGM application and incorporation methods on seedling establishment of black and pinto bean (both Phaseolus vulgaris L.), cantaloupe (Cucumis melo L.) and watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]. A factorial experiment was repeated twice during the 2001 growing season with 5 CGM application rates, 3 incorporation methods, 4 crops, and 4 replications. The Bernow fine-loamy, siliceous, thermic Glossic Paleudalf soil was prepared for planting by plowing, fertilizing, and forming raised beds. CGM was applied by hand at 1,000, 2,000, 4,000, and 8,000 kg·ha−1. An untreated control was included. Three incorporation methods included tilling prepared beds to a depth of 2.5 to 5.0 cm either before or after application of CGM, or leaving the beds undisturbed. ‘Black Knight’ black bean, ‘Apache’ pinto bean, ‘Magnum 45’ cantaloupe, and ‘Allsweet’ watermelon were direct-seeded on raised beds. Stand data were collected 14,20, and 31 days after planting. CGM applications adversely affected seedling establishment of all direct-seeded vegetable crops. Injury and morality occurred prior to seedling emergence. In all but 2 isolated instances the lowest CGM rate significantly decreased seedling establishment. Seedling mortality percentages at 1,000 kg·ha−1, averaged across evaluation dates and incorporation methods, were 66% (black bean), 58% (pinto bean), 50% (cantaloupe), and 58% (watermelon) increased as CGM application rate increased. Although all of the CGM applications rates significantly decreased seedling survival for these crops, the potential usefulness of CGM as an organic herbicide should encourage additional research to develop safer application methods for CGM. Once seedlings of these crops are established, as transplants or emerged direct-seeded plants, CGM may be safe to use. Research should investigate the impact of application rates below 1000 kg·ha−1 on direct-seeded vegetables, CGM applications on other cucurbit crops, different application methods, and weed control efficacy of CGM when used with these vegetable crops.

Comparison of Direct Seed versus Transplant Yield and Fruit Quality of Processing Tomatoes in the Southern Sacramento Valley

Canning tomato transplants were compared to direct seed in field trials to evaluate fruit yield and quality. Trials were conducted either at the University of California at Davis Long Term Research on Sustainable Agriculture field facility or in a commercial direct-seeded tomato field near Woodland. To closely match harvest dates of both propagation methods, transplants were mechanically planted after direct-seeded plants approached the 2 to 3 true-leaf stage. Trial design was replicated, factorial with propagation method and with plant population comparisons. Populations were 8712, 6534, 5227, and 4356 planting units per acre. Direct-seeded plots were thinned to clumps of three plants centered on 12, 16, 20, or 24 inches between clumps within the seed line. Transplants were 6-week-old, commercial, greenhouse-grown plants that were mechanically planted to match the direct-seed spacing. Plant rows were single lines per bed centered on 5 feet. The entire 100-foot plot length was mechanically harvested into specially designed portable weigh trailers to measure yield. Fruit yield between direct-seed and transplants were similar in two of the 3 years. In one of the 3 years, production problems were encountered resulting in low overall yield, but significantly lower with the transplants. `Halley', a cultivar common in the region, was used in all of the test years. Transplant yields were slightly reduced linearly as spacing between plants increased while yield from direct seed was less affected. Fruit quality tended to be similar among the treatments.

First Report of Bacterial Blight of Four O'Clock (Mirabilis jalapa), Caused by Xanthomonas campestris in California.

Four o'clock (Mirabilis jalapa) is an ornamental used in California as a landscape plant. In 2000 and 2001, four o'clock transplants produced in commercial greenhouses in coastal California were severely affected by a foliar disease. Initial symptoms were small (2 to 5 mm diameter), angular, water-soaked leaf spots that often developed first on leaf edges. Spots enlarged, rapidly turned brown to dark brown, coalesced, and caused transplants to take on a blighted appearance. When leaf spots were macerated and streaked onto sucrose-peptone agar, a yellow, mucoid bacterium was consistently isolated. Based on morphological, physiological, and biochemical characteristics, we identified the bacterium as Xanthomonas campestris (2). Furthermore, Biolog GN profiles identified five Mirabilis strains as X. campestris pv. campestris with similarity values of 79.7 to 87.6%. Fatty acid analyses identified them as the same pathovar with similarity values of 75.8 to 82.1%. These strains also used cellobiose and arabinose as carbon sources and produced acid from arabinose, which are characteristic features for this pathovar. Pathogenicity was demonstrated by growing inocula of six strains in nutrient broth shake cultures for 48 h and misting 30 ml of the broth cultures (106 CFU/ml) on sets of 12 potted four o'clock plants. Control plants were misted with sterile broth. After inoculation, plants were incubated in a dew chamber (100% relative humidity at 18°C) for 24 h then maintained in a greenhouse (24 to 26°C). After 7 to 10 days, leaf spots similar to those originally observed developed on all inoculated plants. Bacteria reisolated from these plants were characterized and found to be the same as those used for inoculation. Control plants remained symptomless. Because of the biochemical similarity between Mirabilis strains and the black rot pathogen of crucifers (X. campestris pv. campestris), we inoculated sets of six cauliflower (Brassica oleracea var. botrytis cv. White Magic) plants with five Mirabilis strains and two X. campestris pv. campestris strains using the same method. After 14 days, cauliflower plants inoculated with Mirabilis strains were symptomless, while plants inoculated with the black rot pathogen developed symptoms typical of this disease. X. campestris was only reisolated from the cauliflower plants inoculated with the crucifer strains. Because the four o'clock transplants from the commercial greenhouse were produced in close proximity to vegetable hosts of other Xanthomonas pathogens, we inoculated pepper (Capsicum annuum), tomato (Lycopersicon esculentum) and four o'clock transplants with four Mirabilis strains using the method described. The four o'clock strains failed to cause any disease on pepper and tomato but resulted in typical leaf spots on four o'clock. Bacteria reisolated from four o'clock plants and characterized were the same as the original strains. All inoculation experiments were repeated and results were the same. To our knowledge, this is the first report of X. campestris on four o'clock in California and the United States. Occurrence of this disease on direct-seeded plants in enclosed greenhouses provides circumstantial evidence that the pathogen might be seedborne. This pathogen may be related to the Xanthomonas sp. reported on four o'clock in India (1). Reference: (1) J. C. Durgapal and B. M. Trivedi. Curr. Sci. 45:111, 1976 (2) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria, 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001.

Brown Bead of Broccoli. II. Relationships of the Physiological Disorder with Nutritional and Meteorological Variables

In order to investigate their relationships with brown bead, a data set composed of 48 variables characterizing the developmental rate, climate, and nutrients in the soil and in the tissues of heads of broccoli (Brassica oleracea L., Italica group) was collected from 328 plots (41 experimental fields over 3 year× 4 N fertilization level× 2 blocks). The four N treatments were 85-0-0, 85-54-0, 85-54-54, and 85-54-108, the first number indicating the N level (kg·ha-1) applied before planting; the second, N level applied 5 weeks after planting; and the last, N level applied 7 weeks after planting. Broccoli plants were either direct-seeded (26 experimental fields) or transplanted (15 experimental fields). Whether direct-seeded or transplanted, fast-developing broccoli plants showed a lower incidence of brown bead. More particularly, heads of transplanted broccoli plants experiencing warmer temperatures had a lower brown bead incidence and severity. A regular supply of water decreased the incidence and severity of the physiological disorder in both direct-seeded and transplanted broccoli plants. Low levels of Ca and high levels of Mg and K in mature broccoli head tissues were associated with a higher incidence of brown bead. Multiple-regression models were developed to predict the percentage of broccoli heads with brown bead for direct-seeded plants (R2 = 0.76; n = 104), and for transplanted plants (R2 = 0.69; n = 44). For direct-seeded broccoli, solar radiation between the button stage (head diameter of 2.5 cm) and maturity (head diameter of 10 cm), as well as soil and tissue Mg content, were among the first variables to enter the regression models. In general, more solar radiation and less precipitation translated into more heads showing brown bead symptoms. For transplanted broccoli plants, the minimum temperature from the button stage to maturity was a key variable in the prediction of the percentage of heads with brown bead and the corresponding index of severity.

A Comparison of the Growth, Establishment, and Maturity of Direct-seeded and Transplanted sh2 Sweet Corn

Sweet corn (Zea mays L.) cultivars containing the shrunken-2 (sh2) gene have superior kernel quality but often germinate poorly and display poor seedling vigor. The transplanting of sh2 sweet corn was investigated as a method to improve stand establishment and hasten maturity. Three-week-old plants (sh2 cv. Krispy King) were raised in 200-cell polystyrene trays in either plug-trays (PT), float beds (FB), or ebb-and-flood (EF) production systems and compared with direct-seeded (DS) controls for transplant quality, successful establishment, and early harvest. In 1994, when plants were established in early June, PT plants matured 1 week earlier than DS and FB plants, which had similar mean times to harvest. In 1995, when field planting occurred in July, all plants flowered prematurely when only 60 cm tall. In 1996, the experiment was begun in early May, and survival of all transplants was >85% vs. 54% for DS plants. In 1996, transplants matured 10 to 13 days earlier than DS plants, however, >90% of DS plants produced marketable ears vs. 63%, 49%, and 44% of EF, FB, and PT plants, respectively. The DS plants were also taller with better root development than transplants in all years. Transplants produced smaller, lower-quality ears than did DS plants, thus nullifying the benefits of greater plant populations and earlier maturity. The EF system produced high-quality seedlings because of the greater control of water availability during seedling development. In some areas, the increased value of early sh2 sweet corn may be worth the additional cost of transplanting and greater percentage of unmarketable ears.

Yield, Quality, and Water Use Efficiency of Muskmelon Are Affected by Irrigation and Transplanting Versus Direct Seeding

Restrictions on pumping water from underground aquifers are limiting vegetable production in Southwest Texas. To determine yield, quality, and water use efficiency (WUE) of muskmelon (Cucumis melo L. group Cantalupensis, `Caravelle'), six irrigation systems with varying input levels and their interactions with stand establishment (containerized transplants vs. direct seeding) were examined. Irrigation systems were: 1) pre-irrigated followed by dryland conditions; 2) furrow/no mulch; 3) furrow/mulch (40-μm-thick black polyethylene); 4) surface drip (0 cm depth)/mulch; 5) subsurface drip (10-cm depth)/mulch; and 6) subsurface drip (30-cm depth)/mulch. Field experiments were conducted on a silty clay loam soil during four seasons (1995-98). In 1995, marketable fruit yields were greater for subsurface drip systems at 30-cm depth than for furrow systems, with or without plastic mulch. Transplants grown with surface drip irrigation produced 75% greater yield in the 9-count fruit class size during early harvest than did those grown with subsurface drip (10- or 30-cm depth), but total yield was unaffected by drip tape depth placement. In 1996, the driest season of these studies, direct-seeded plants had higher total yields than did transplants; yield was greatest for direct-seeded plants on subsurface drip placed at 10- or 30-cm soil depth, and for transplants on subsurface drip at 10-cm depth. Soluble solids content was minimally affected by irrigation method, but was higher in fruit from transplants than in those from direct-seeded plants in 3 years. Across all seasons, the average water applied for drip systems was 53% lower than that for conventional furrow systems, and WUE was 2.3-fold as great.

621 Optimizing Marigold (Tagetes erecta L.) Petal and Pigment Yield

Marigold flower pigments can be extracted and used as a natural source of food colorants in the poultry and dairy industry. These pigments impart an orange color to egg yolks and a yellowish color to dairy products. We examined four African marigold cultivars for their ability to be commercially grown and harvested mechanically. `E-1236' yielded the highest quantity of lutein (22 kg/ha), a carotenoid pigment, using a spectrophotometer for quantification. `E-1236' and `A-975' were the earliest flowering cultivars, 11 June 1998 for transplants and 9 July 1998 for direct-seeded, at 8 weeks after sowing regardless of field establishment method. `E-1236' produced the greatest number of flowers in a production season, both as transplants (68 flowers/plant) and direct-seeded (57 flowers/plant) at 363,290 plants/ha. Transplants resulted in two more harvests in a single season than direct-seeded plants. Subsequently, more flowers and petal material were produced for pigment extraction than with direct-seeded plants. A one-time application of ammonium nitrate (28.02 kg/ha) at mid-season did not significantly effect flower number, flower weight, or pigment yield. Experiment was repeated in 1999 with four cultivars, two field establishment methods, seven harvest dates, and five nitrogen applications.

288 Use of Transplants, Rowcovers, and Black Plastic to Improve Yield and Earliness of Butternut and Calabaza Squash

The population of Puerto Ricans and Dominicans in Massachusetts is ≈6% of the total state population. Latinos have begun to request certain commodities native to their culture at Farmers' Markets and retail stores. One of these commodities is a winter squash [Cucurbita moschata (Duchene Poir)] called calabaza in Puerto Rico and auyama in the Dominican Republic. Calabaza has also been found in Asian markets. In order to have the crop ready for market by August in the Northeast, cultural practices which hasten maturity would need to be used. Eight treatments were tested: 1) direct seeded in bare ground, 2) direct seeded in black plastic, 3) direct seeded in bare ground with rowcover, 4) direct seeded in black plastic with rowcover, 5) transplanted in bare ground, 6) transplanted in black plastic, 7) transplanted in bare ground with rowcover, 8) transplanted in black plastic with rowcover. Calabaza was compared to butternut squash. Three weeks after seeding or transplanting, the transplants on black plastic were just beginning to vine and those transplants on black plastic and covered with rowcover were vining and in flower. Direct-seeded plants were in the second- or third-leaf stage. Treatment effects on early growth in the spring translated to differences in earliness and yield at the end of the season. Overall, the use of transplants improved yield by 30%, black plastic improved yield 15%, and the use of rowcover improved yields by 12%. There were no significant differences among the treatments where transplants were used along with plastic, rowcover or both. Significant differences were found in the number of fruit available for harvest in August. Direct-seeded plants on bare ground or on plastic did not have any harvestable fruit in August. The transplant, plastic and rowcover treatment had 300 to 500 boxes/acre depending on the year. Even the use of transplants on bare ground yielded an August-harvested crop.

Maturity of Fresh-market Sweet Corn with Direct-seeded Plants, Transplants, Clear Plastic Mulch, and Rowcover Combinations

Sweet corn (Zea mays L.) growers in the upper midwestern U.S. have used clear plastic mulch to improve early yield and advance crop maturity. Results of this practice have been inconsistent because of early season temperature variability and inadequate information on cultivar adaptation. Our objective was to improve the performance consistency by investigating earliness techniques with the early, sugary-enhancer (se) cultivar Temptation planted at two sites. Treatments were bare soil or clear plastic mulch, rowcovers or none, and direct-seeded or transplanted plants. Transplants were produced in the greenhouse in either 50-cell plastic trays or peat pot strips, 2.3 inches × 4.0 inches deep (6 × 10 cm) and were evaluated according to transplant age and cell size. In the cold springs of 1996 and 1997, the use of clear plastic mulch shortened maturity of sweet corn by 1 and 10 days, respectively, for the silt loam site; but no maturity advantage was observed for the loamy sand site. Clear plastic raised the minimum soil temperature by 3.8 to 4.0 °F (2.1 to 2.2 °C) at both sites. The 2-week-old 50-cell tray transplants matured 6 days earlier than the peat pot strip transplants or direct seeded at both locations in 1997. Marketable yield from the transplants was inconsistent by location and year. Four-week-old transplants did not withstand field stress and performed poorly regardless of type of container. Ear quality as indicated by row number, ear diameter, ear length, and tipfill was lowest with transplants.

The root-knot nematode problem in sesbania fallows and scope for managing it in western Kenya

Sesbania (Sesbania sesban), which is promoted as a short-duration-fallow species in eastern and southern Africa, is an alternative host to root-knot nematode (Meloidogyne spp.). Therefore, it is important to know the extent of sesbania infection by the nematode on farms and its effects to crops grown in rotation with sesbania. A survey of 14 farms in western Kenya indicated that sesbania was infected by root-knot nematode in all the farms. The potential to build up the nematode population was much greater on farms where maize (Zea mays) was previously intercropped with a susceptible bean (Phaseolus vulgaris). Screening of 30 single plant accessions of four sesbania provenances (Kakamega, Siaya, Kisumu, and Kisii) from western Kenya in pots indicated limited scope for selecting material resistant to the nematode. All four provenances were infested by the nematode, and they increased its population in soil and root. A rangewide collection of sesbania germplasm needs to be screened to determine the scope of finding nematode-resistant material. Transplanted seedlings produced in heat-sterilized, nematode-free soil showed less nematode infection than direct-seeded plants. However, both direct seeding and transplanting seemed to increase nematode population similarly. A number of Crotalaria spp. that were found resistant to nematodes can be considered as alternatives to sesbania-planted fallows, but further field-scale testing is necessary to select appropriate species based on biomass production. Among other species suitable for short-duration fallows, only pigeonpea (Cajanus cajan) and senna (Senna siamea) showed promise. Species such as neem (Azadirachta indica), casuarina (Casuarina junghuhniana), and grevillea (Grevillea robusta) that are suitable for boundary plantings were free from the root-knot nematode.

Substrate pH and Papaya Seedling Growth

Two studies were conducted to determine the influence of pH on `Waimanalo' papaya seedling growth and morphology. The seedlings were grown in clear, plastic tubes with diameter of 7 cm and length of 21 cm, and substrate was silica sand. The substrate was drenched daily with complete nutrient solution. The solution was adjusted to pH of 3, 4, 5, 6, 7, 8, or 9. We used direct-seeded plants in the first study, and plants were harvested following 9.5 weeks of growth. We used transplants in the second study, and plants were harvested following 4 weeks of growth. Dry mass of plants was relatively unaffected by substrate pH within the range of 4 to 9. In both studies; however, dry mass of plants receiving solution with a pH of 3 was reduced. The response pattern was similar for canopy:root ratio, total root length, root growth rate, lateral root thickness, and root tip density. Unit leaf area per unit root length was greatly increased for plants receiving pH of 3, indicating increased susceptibility to drought conditions.

Preliminary evaluation of the suitability of Enterolobium cyclocarpum for use in intensive feed garden in southwestern Nigeria

The best method of establishment of Enterolobium cyclocarpum (enterolobium) and biomass yields and nutritive value under cutting were determined in three separate trials. Soaking in boiled water for 30 seconds gave the highest percent seed germination (76%) and most vigorous seedlings. Transplanted seedlings out-grew direct-seeded plants with 1.70 and 1.12 m, respectively, at six months after planting. Intra-row spacing did not significantly affect early growth of the plants. Cutting every 12 weeks gave the highest leaf (4.05 t/ha), stem (2.26 t/ha) and total (leaf + stem) dry matter yields. Cutting regimes did not significantly affect the crude protein and neutral detergent fibre content of the leaves which averaged 21.3 and 60.7%, respectively. This initial study suggests that enterolobium has a potential as a forage tree and should be further studied to understand its agronomy and feed value.

EFFECTS OF ROWCOVER AND TRANSPLANT METHODS ON SUMMER SQUASH PRODUCTION

Effects of planting methods and rowcover on the production of yellow crookneck squash, Cucurbita pepo L. var. melopepo Alef., were evaluated over 2 years at the E.V. Smith Research Center, Shorter, Ala. Summer squash was direct-seeded or transplanted in the field with or without black plastic mulch and grown with or without rowcover. Yield of transplanted squash was significantly increased over the same squash direct-seeded. Neither plastic mulch nor rowcover had an effect on summer squash production. Transplants matured 8 to 10 days earlier than the direct-seeded plants.