The commercial and ornamental potential of three apple-berry polyculture systems was ascertained by monitoring the above-ground performance of component species in plots of `GoldRush' apple (Malus ×domestica Borkh.) trees on M.7 rootstock cropped with either blackberry (Rubus spp. L. `Navaho'), edible honeysuckle (Lonicera caerulea L. `Blue Belle' and `Blue Velvet'), or jostaberry (Ribes nidigrolaria Bauer `Josta') as understory plants. Polyculture plots and corresponding monoculture controls were established in 1999, with berry plants at recommended (R) or close [(C), half-recommended] spacings. Blackberries and jostaberries planted in monoculture at recommended spacings [i.e., control (R) plots] amassed dry weights >1 kg/plant by Fall 2001; the dry weight of edible honeysuckle from comparable plots was slightly >0.3 kg/plant. In 2001, blackberry yield (3.1 kg/plant) and fruit weight (3.4 g) were typical of `Navaho' plantings of similar age, whereas jostaberry was only moderately productive (yield = 286 g/plant; fruit weight = 1.4 g). Edible honeysuckle productivity (yield = 13 g/plant, fruit weight = 0.5 g) was minimal, due to disparate flowering phenology between cultivars. `GoldRush' apple growth and productivity (yield = 25 kg/tree; fruit weight = 158 g) was consistent with values expected for trees of similar age. Blackberry plant dry weights were reduced by 20% to 33% when planted at close spacing, whereas blackberry yields were reduced 35% to 38% when grown in polyculture with apple. Both polyculture and plant spacing significantly reduced jostaberry dry weights (i.e., 12% and 24%, respectively) relative to the control, but neither significantly affected jostaberry yield. Conversely, both close-spaced planting and the presence of an apple tree improved the yield of edible honeysuckle. Apple performance was not affected by the presence of an edible honeysuckle understory, but apple growth factors were reduced in blackberry and jostaberry polycultures by as much as 65%. Apple bloom, fruit set, and yield were also significantly reduced in apple-blackberry and apple-jostaberry plots, with fruit numbers/tree averaging <5 in all except the apple-blackberry (C) treatment. None of the polyculture treatments studied were suitable for profitable fruit production. However, each of the polyculture constituents exhibited unique, beneficial attributes with respect to their use as components within an edible landscape.
Tina M. Rivera, Martin F. Quigley, and Joseph C. Scheerens
Michael K. Bomford
Polycultures are thought to offer yield advantages over monocultures when net competition between plants of different species is less than that between plants of the same species. Planting density and crop ratios may both alter these competitive effects. To observe such effects, dicultures of basil (Ocimumbasilicum L.), brussels sprout (Brassica oleracea L.), and tomato (Lycopersicumesculentum Mill.) were grown organically at a range of ratios and densities (1–47 plants/m2) over two field seasons. Relative land output (RLO) values were calculated from field data and from modeled yield-density-ratio surfaces. Both methods showed yield advantages from polyculture at high planting densities (RLO = 2.20 @ top density), but not at low densities. Dicultures offered a 19% yield advantage, on average. Competition for resources was compared by measuring canopy light interception and soil moisture content, showing tomato to be the most competitive crop, followed by brussels sprout, then basil. Diculture yield advantages were most pronounced when individuals of a less competitive species outnumbered those of a more competitive species. Yield advantages were 36% and 20% for dicultures dominated by basil and brussels sprout, respectively.
Dicultures dominated by tomato offered no yield advantage. The results are discussed in terms of the current ecological understanding of plant interactions, and possible advantages to be derived from small-scale intercropping, popularly termed companion planting.
Jacqueline Cormier, Robert Heyduck, Steven Guldan, Shengrui Yao, Dawn VanLeeuwen, and Ivette Guzman
A decrease in available farmland worldwide has prompted interest in polyculture systems such as intercropping where two or more crops are grown simultaneously on the same land to increase the yield per farm area. In Alcalde, NM, a year-round intercropping system was designed to evaluate organically produced blackberry cultivars (Rubus, subgenus Rubus) and winter greens in a high tunnel over a 2-year period. Two floricane fruiting blackberry cultivars, Chester Thornless and Triple Crown, were grown intercropped with ‘Red Russian’ kale (Brassica napus) and ‘Bloomsdale’ spinach (Spinacia oleracea) in a high tunnel. In an adjacent field, the planting of blackberry was repeated with no winter intercrop and no high tunnel. Both cultivars of blackberry were harvested July to September, and fresh weights were measured to determine suitability to the intercropping system in the high tunnel. Both species of winter greens were harvested January to April, and fresh yield weights were measured to discern fitness as possible intercrops in this system. Row covers were used for kale and spinach, and air temperatures were monitored November to April inside the high tunnel. High tunnel temperatures were within acceptable ranges for the production of greens with the use of rowcovers. Yield data from this study indicates that ‘Triple Crown’ blackberry outperformed ‘Chester Thornless’ blackberry in both the high tunnel and field trials with significant difference in the second season. Additionally, blackberry yields from both cultivars were observed to be higher in the field than in the high tunnel for both years. High temperature damage to high tunnel berry canes was noticed for both cultivars, with observed yield decreases in the second year in the high tunnel. Overall, this study indicates that the phenology and climate needs of the two winter greens and blackberry cultivars were not compatible for sustaining year-round organic high tunnel production.
Francis M. Itulya, Vasey N. Mwaja, and John B. Masiunas
Field experiments were conducted in 1992 and 1993 to determine the effect of N fertility, cropping system, redroot pigweed (Amaranthus retroflexus L.) density, and harvesting frequency on collard (Brassica oleracea var. acephala D.C) and cowpea [Vigna unguiculata (L.) Walp.] growth. The N fertilization regimes were 0, 80, 160, and 240 kg·ha-1, applied as urea in a split application. Four weeks after crop planting, redroot pigweed was seeded at 0, 300, and 1200 seeds/m2. Between weeks 6 and 12, collard leaves were harvested at 1- to 3-week intervals. Year, N fertility, and cropping system interacted to determine collard leaf number and mass. For example, in 1992, with N at 160 kg·ha-1, collards intercropped had more total leaf mass than those monocropped. Pigweed density had no effect on collard yields, which were greatest from the 3-week harvest frequency. Cropping system and pigweed density interacted to determine cowpea vine length, shoot dry mass, and branching. The high density of pigweed caused a 56% reduction of cowpea dry mass in 1992.
Ana Regia Alves de Araújo Hendges, Jose Wagner da Silva Melo, Marcelo de Almeida Guimaraes, and Janiquelle da Silva Rabelo
The aim of this work was to evaluate arthropod diversity and levels of population growth in Myzus persicae (Sulzer) under kale (Brassica oleracea L. var. acephala DC) intercropped with green onion (Allium fistulosum L.), coriander (Coriandrum sativum L.), basil (Ocimum basilicum L.), and parsley [Petroselinum crispum (Mill.) Nym.]. The following characteristics were evaluated under both monocrop and intercrop systems: 1) arthropod diversity and abundance, 2) population growth rate in the M. persicae aphid, 3) average number of aphids per kale leaf, and 4) total fresh weight of produced kale. The experiment was carried out in Fortaleza, in the state of Ceará, Brazil, in a design of randomized blocks, with five treatments and five replications. The family Aphididae was the most abundant, represented by M. persicae. Thirty-nine spiders were the most abundant predators. The intercrop with basil gave the greatest diversity of arthropods. The aphid population showed slower growth under the intercrop systems with cilantro and with parsley. Fresh weight production in the kale was inversely proportional to the number of aphids on the plants. The results suggest that intercropping kale with culinary herbs is a promising strategy to reduce aphid populations and losses occasioned by them.
Kathryn E. Brunson and Sharad C. Phatak
Cantaloupe (Cucumis melo L., cv. Hiline) were planted following over-wintering cover crops. In replicated field trials, stand development for 7 different cover crops and their effects on incidence of weeds, insects, diseases, and nematodes was assessed. Effects of cover crops on yield and quality of cantaloupe were evaluated. Cover crops evaluated were rye, crimson clover, lentils, subterranean clover, `Vantage' vetch, mustard, a polyculture of all cover crops and control-fallow. No insecticides were applied and only two applications of fungicides were made. Fertilizer applications were significantly reduced. No differences among cover crops for any of pest nematodes were observed. Significant differences in populations of beneficial and pest insects were observed. Polyculture had the highest plant vigor rating. The highest marketable yield occurred following crimson clover.
Nancy G. Creamer, Mark A. Bennett, and Benjamin R. Stinner
Polyculture mixtures of several species of cover crops may be the best way to optimize some of the benefits associated with cover crop use. In the first year of a three year study, 16 polyculture mixtures of cover crops (4 species/mixture) were screened at seven sites throughout the state. Five of the mixtures were seeded at two planting dates. Fall evaluation of the cover crop mixtures included ease of establishment, vigor, percent groundcover, plant height, and relative biomass. The two mixtures with the highest percent groundcover were (1): sudex, rye, mammoth red clover, and subterranean clover (62% and 80% groundcover, one and two months after planting respectively), and, (2), annual alfalfa, hairy vetch, ryegrass, and rye (56% and 84% groundcover one and two months after planting respectively). The six mixtures with the highest percent groundcover did consistently well, relative to other mixtures, at all locations. Mixture (1) above also had the highest relative biomass throughout the state. Yellow and white sweet clovers, hairy vetch, winter oats, subterranean clover, red clover, rye and barley established well and maintained high vigor ratings throughout the fall. Ladino clover, timothy, and big flower vetch consistently had poor vigor ratings.
Nancy G. Creamer, Mark A. Bennett, and Benjamin R. Stinner
Planting polyculture mixtures of cover crops can optimize the benefits of their use. Thirteen polyculture mixtures of cover crops were evaluated in Columbus and Fremont, Ohio, to find a species mix that would establish quickly for erosion control, overwinter in Ohio, contribute sufficient N and have a C : N ratio between 20:1 and 30:1 to optimize N availability for subsequent crops, be killable by mechanical methods, and have high weed control potential. All of the mixtures in Columbus had achieved 30% ground cover 1 month after planting, but only four of the mixtures achieved this in Fremont due to poor conditions at planting. Above-ground biomass (AGB) accumulation in the mixtures ranged from 3631 to 13,642 kg·ha-1 in Columbus, and 449 to 12,478 kg·ha-1 in Fremont. Nitrogen in the AGB ranged from 74 to 269 kg·ha-1 in Columbus, and 10 to 170 kg·ha-1 in Fremont. Weed cover in the cover crop plots ranged from 1% to 91% eight weeks after cover crop kill in Columbus, and 12% to 90% seven weeks after cover crop kill in Fremont. Because one or more species in each screened mixture was determined not to be suitable, none of the mixtures was optimum. However, information gained about performance of individual species within the mixtures is also useful. `Nitro' alfalfa (Medicago sativa L.), ladino clover (Trifolium repense L.), subterranean clover (Trifolium subterraneum L.), Austrian winter peas [Pisum sativum ssp. Arvense (L.) Poir], and annual ryegrass (Lolium multiflorum Lam.) did not overwinter dependably in Ohio. Tall fescue (Festuca arundinacea L.), perennial ryegrass (Lolium perenne L.), and orchardgrass (Dactylis glomerata L.) did not compete well with taller, more vigorous species, and were not persistent in the mixtures. Medium and mammoth red clover (Trifolium pratense L.), annual and perennial ryegrass, and white and yellow blossom sweetclover [Melilotus alba Desr., and Melilotus officianalis (L). Desr.], were not killable by mechanical methods. Individual species that established quickly, were competitive in the mixtures, overwintered dependably, and were killed by mechanical methods were rye (Secale cereale L.), barley (Hordeum vulgare L.), crimson clover (Trifolium incarnatum L.), and hairy vetch (Vicia villosa Roth.)
Eric T. Wolske, Bruce E. Branham, and Kevin J. Wolz
Multifunctional polycultures have been theorized to provide a significant array of functions and services including enhanced landscape productivity, ecological services, and economic profitability and stability ( Lovell et al., 2017 ; Wolz et al
Kim E. Hummer
offered genetic resilience in the face of disaster ( Nabhan, 2009 ). The Ethiopian tradition of planting mixtures or polycultures of grains helped in a second situation. A strain of black stem rust ( Puccinia graminis f. sp. tritici ) was found in Uganda