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Open access

R. F. Korcak, G. J. Galletta, and A. Draper

Abstract

The growth and elemental composition of a range of blueberry (Vaccinium sp.) progenies was greenhousetested on 5 unmulched soils. Three of the soils, low in pH and fertility, represented the physiographic regions of the eastern United States; Coastal Plain, Piedmont, and Appalachian Highlands; also included were a high-pH, high-fertility Piedmont soil and a commercial blueberry Coastal Plain soil. Two studies, 10 and 20 weeks in duration, were made with seedlings of crosses of blueberry clones of hybrid origin. Growth was significantly higher for seedlings grown on the commercial blueberry soil in both studies. V. ashei (rabbiteye) seedlings grew significantly larger than all others when measured over all soil types in one experiment but not the other. There were no significant differences in growth among the 4 progenies when averaged over all soil types. Percent sand was positively correlated with growth while both percent silt and clay were negatively correlated with growth. Plant composition was generally within acceptable levels for Ca, Mg, K, Fe, and Zn. Plant Mn and Al, although variable, tended to be higher than reported values. Soil Mn was significantly and negatively correlated with growth. It was possible to select individual seedlings which grew well on each of the mineral soils represented in the study.

Free access

W.M. Tilson and H.D. Stiles

The analog output of a portable battery-powered infrared pyrometer capable of nondestructive measurement of blackberry fruit temperatures was collected, formatted, and stored by a Polycorder in the field during the 1996 and 1997 harvest seasons. The program written for the data recorder allowed collection of ≈10 temperatures per plot per minute. Download and analysis of the information gathered during a typical survey of 24 rep × treatment combinations was easily completed prior to subsequent surveys in the field at noon and midafternoon.

Free access

J.M.S. Scholberg, B.L. McNeal, J.W. Jones, S.J. Locascio, S.R. Olsen, and C.D. Stanley

Modeling the growth of field-grown tomato (Lycopersicon esculentum Mill.) should assist researchers and commercial growers to outline optimal crop management strategies for specific locations and production systems. A generic crop-growth model (CROPGRO) was previously adapted to simulate the growth of fresh-market tomato under field conditions. Plant growth and development of field-grown tomato, and fruit yields, will be outlined and compared to model predictions for a number of locations in Florida, nitrogen fertilizer rates, and irrigation management practices. Possible application of the model to quantify effects of crop management on crop production will be discussed using simulated yield values for a wide range of environmental conditions.

Free access

Paul Grun and M.D. Orzolek

Savory Peppers™ (Sp™) is the low heat form of Capsicum chinense from northern South America where it is widely used as a condiment. We are adapting it to northeastern conditions through introgression of genes from adapted C. annum, selection within SP™, and use of improved culture methods. Introgression is progressing in spite of species isolation barriers expressed as failure of F1 seeds to germinate, and F1 and later generation male sterilities. Selection has been carried out on plants of two landraces, producing ten improved strains which were tested at three stations last summer: 1) west PA on sandy soil with long growing season: 2) central PA on clay loam with short growing season, and 3) eastern PA on clay loam with long growing season. Strains of both landraces yielded well in region 1), and poorly in region 2), and one landrace yielded well in region 3), while those of the other yielded poorly as a result of early wilt. Roles of soil and temperatures in producing these results will be discussed.

Free access

Fabián Robles-Contreras, Raul Leonel Grijalva-Contreras, Manuel de Jesus Valenzuela-Ruiz, and Rubén Macias-Duarte

Water is a very limited resource in the Sonoran Desert region of Caborca, Sonora, Mexico. For an efficient use of irrigation water, a method of calculating water requirements of the crops is needed. Potential evapotranspiration (Eto) value obtained with the Penman-Monteith model from a regional weather station was not dependable, since some parameters, such as sensible heat flux in the soil, are estimated from a fixed rate with net radiation (Rn), also an estimated value. The weather station did not have a sensor for heat flux in its network. Studies in northwestern Mexico have indicated that it is feasible to adapt the use of the Makkink model, because a single measurement of solar radiation and temperature would be required. We compared the daily Makkink Eto against the Class A pan method (control) Eto during 75 days and found a value of 0.81 mm/day less with the Makkink model. To fit the Makkink model to regional conditions, we ran the Makkink model varying the value of C constant (from 0.5 to 0.95), and found that a value of C = 0.87 substituted for C = 0.65 (original value) has an daily average difference of 0.09 mm/day less with respect to the control. This could be because there are few clouds in the region, and a greater proportion of global radiation arrives at the surface from the earth or the crops in form of net radiation.

Free access

K.J. Sauter, G.R. Gingera, and D.W. Davis

Pigeonpea, a subtropical legume, was successfully grown in a high-latitude (≈45°N) environment. Four short-season pigeonpea accessions from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) were subjected to three cycles of pedigree selection. Performance trials (175,000 plants/ha) were conducted on loamy sand with dryland and irrigated sites in 1991 and 1992. Thirty-eight S3-derived lines from ICRISAT ICPL 83004 were used in both years and seven S3-derived lines from ICRISAT P 2125 and ICRISAT ICPL 85010 were added the second year. Differences (P ≤ 0.05) in seed yield (kg·ha–1) were observed among the S3 lines, with a maximum yield of 1468 kg·ha–1. The lines also differed (P ≤ 0.05) for harvest index (HI), calculated as the ratio of seed yield to shoot total dry matter (TDM) with a maximum of 0.48 (line MF-26). Dryland seed yield was strongly correlated with TDM (r 2 = 0.98), HI (r 2 = 0.92), and early bloom (r 2 = 0.76). In a time-of-planting comparison of seven lines in 1992, seed yield was highest (754 kg·ha–1) at the earliest (29 Apr.) planting date and declined progressively to 178 kg·ha–1 at the latest (2 June) planting date, while HI decreased from 0.42 to 0.12. Plants were shorter at maturity in the earliest planting date.

Free access

Juan Carlos Álvarez-Hernández, Javier Zaragoza Castellanos-Ramos, and Cesar Leobardo Aguirre-Mancilla

Grafting Carica papaya plants can have several benefits for productive, phytosanitary, and sexing purposes. However, the literature on the subject of papaya grafting is limited. The tongue approach and cleft grafting techniques seem to be the most adequate for C. papaya, but the quality of grafts depends on several factors. With the objective of developing and adapting a grafting method for papaya, experimental assays were carried out in the Valley of Apatzingan, Michoacan, Mexico. The physical condition of the seedlings was assessed, and the most advantageous time for grafting was determined based on the size and thickness of the stems. Three assays were then carried out. The first assay was a test of the tongue approach and cleft grafting techniques using two clamping devices. The second assay involved the same techniques with modifications and the addition of another treatment. In the third assay, the modified tongue approach grafting method was tested on three containers with papaya plants. Seedling vigor, graft survival, and graft quality were the recorded variables. The results indicated that unwanted tissue should be cut 6 days after grafting. The tongue approach grafting method using tape as the fastening device (T-T) yielded a graft survival of 80%. The modified tongue approach grafting method, in which the tongues were formed just below the stem-site cut and tape was used as the fastening device (M-T-Bc-T), yielded a graft survival of 90%. In the third assay, the previously described modified method, but with seedlings grown in plastic bags (M-T-Bc-T-B), yielded a graft survival of 92.5%. It can be concluded that the modified tongue approach grafting method with seedlings grown in plastic bags (M-T-Bc-T-B), is a reliable grafting method for papaya that does not require special handling conditions.

Open access

Philip Busey, James A. Reinert, and Ray A. Atilano

Abstract

Visual evaluations of a 5-year-old replicated planting of 63 zoysiagrass (Zoysia spp.) genotypes in southern Florida showed highly significant (P < 1%) differences in overall vigor and survival, flight selections and 2 commercial cultivars (‘Emerald’ and ‘Meyer’) were sodded at 2 distant sites. Selected genotypes (FZ-28, FZ-80, FZ-26, and FL-1753) were significantly better adapted, had significantly less weed encroachment and greater vigor and ground coverage, than Emerald or Meyer. The latter commercial cultivars were unacceptable in most evaluations. Furthermore, FZ-28 and FZ-80 had low sting nematode (Belonolaimus longicaudatus Rau) counts and FZ-28 had few eggs of Banks grass mite (Oligonychus pratensis [Banks]). Sod webworm (Crambus spp.) infestation appeared to be another variable closely associated with adaptive differences among genotypes and explained serious establishment problems at some sites. Zoysiagrass was successfully established as a turf only on one site involving fumigated soil and generally proved poorly suited for this subtropical region.

Open access

Renata A. Kraszewski and Douglas P. Ormrod

Abstract

A central composite rotatable design was used to estimate polynomial equations describing the effect of a 2-phase sequence of light levels on growth and flowering of Browallia speciosa L. (browallia), Crossandra infundibuliformis Salisb. (crossandra), and Oxalis vulcanicola L. (oxalis) in controlled environments. Plants were subjected to 9 lighting regime combinations of 30 days at light levels that might be used by a producer (production light phase) and 30 days at levels that might be used by a consumer (postharvest light phase). In the first phase plants received photosynthetically active radiation (PAR) for 12 hr day ranging from 20 to 350 μmol s−1m−2 (400–700 nm) and in the 2nd phase levels of 17 to 300 μmol s−1m−2. Various growth, flowering, and aesthetic response variables were measured at the beginning and at the end of each phase for covariate analysis. The response surface equations were displayed as isometric (3-dimensional) plots with phase 1 and phase 2 light levels as the 2 base axes. If responses were significant in only one phase, 2-dimensional response curves were plotted. The response surfaces evaluated plant response to light level and extent of change in response to light level in the 2nd phase. Browallia increased in size at a wide range of light levels and some change in response to light occurred between phases. Crossandra increased in size and had high quality foliage at low light levels but there were fewer flowers. Oxalis increased in size and flowered profusely only when light levels were high in both phases. There was little evidence of change in light response in crossandra and oxalis with the treatment durations used in this study.