Effects of planting density on flower production in carnation crop

The influence of density of planting on flower production of carnation plants grown in vinil houses, was studied. Planting densities of 233,333; 175,000 and 116,667 plants per hectare were obtained by using planting spacings of 0.20 m between rows and 0.15 m, 0,20 m and 0.30 m between plants. Data were taken on total number of flowers per plant and per hectare. As far as planting densities are concerned, there was an increase of total flower production per hectare and a decrease of slower production per plant.

Performance of 'Rocha' and 'Santa Maria' pears as affected by planting density

The objective of this work was to evaluate the performance of 'Rocha' and 'Santa Maria' pears at two planting densities. The experiment was carried out during the 2011/2012, 2012/2013, and 2013/2014 growing seasons, in one-year-old orchards (2011/2012) of 'Rocha' and 'Santa Maria' pears, trained in a central-leader system and planted in two densities (2,000 and 4,000 trees per hectare). The assessed parameters were: production per hectare, production per tree, yield efficiency, number of fruit per tree, average fruit weight, trunk diameter increment, fruit firmness, and soluble solid contents. The cumulative yield of 'Rocha' is greater at the higher planting density, whereas the yield efficiency of 'Santa Maria' increases at the lower planting density, as the trees get more mature. Trunk diameter of 'Rocha' also increases at the lower planting density. However, fruit quality parameters in both cultivars are little affected by planting density.

Planting density and initial growth of two tree species adapted to the semi-arid region

Planting densities influence several aspects of forest formation, including management practices, timber yield, quality, and extraction, and consequently its production costs. The objective of this study was to evaluate Mimosa caesalpiinifolia and Gliricidia sepium growth as a function of planting density (400, 600, 800, 1000, and 1200 plants ha-1) and plant age. The species were evaluated every 90 days for plant height (PH), crown diameter (CD) and root collar diameter (RCD) (10 cm above the ground), with the first evaluation performed at 90 days and the last at 720 days. When plants were one year of age and beyond, evaluations were conducted also for stem diameter at breast height (DBH) (1.30 m above the ground). A randomized block design with split-plots and three replicates was adopted. Species were assigned to plots, planting densities were assigned to subplots, and evaluation ages were assigned to subsubplots. The four traits in both species had their values decreased as planting density increased, but continually increased as plant age increased. For PH and RCD there was an alternation between species superiority, with gliricidia being superior to sabiá at some ages, while the opposite occurred at other ages. As to CD the species only differed in the last measurement, gliricidia being superior. With regard to DBH, gliricidia was superior starting from the second measurement. There was an effect of the species × ages interaction for the four traits and also an effect of the densities × ages interaction for CD and DBH.

Biomass of tree species as a response to planting density and interspecific competition

Planting trees is an important way to promote the recovery of degraded areas in the Caatinga region. Experiments (E1, E2, and E3) were conducted in a randomized blocks design, with three, three, and five replicates, respectively. The objectives were to evaluate biomass of the shoots of: a) gliricidia (G) and sabiá (S), as a response to planting density; b) G, S, and neem (N) in competition; c) G, and S in agroforestry. E1 was conducted in split-plots, and planting densities (400, 600, 800, 1000, and 1200 plants ha-1) as subplots. E2 consisted of a factorial comprising the following plots: GGG, NGN, SGS, NNN, GNG, SNS, SSS, GSG, NSN (each letter represents a row of plants). E3 was conducted with G and S in agroforestry experiment. The trees were harvested after 54, 42, and 27 months old, in E1, E2 and E3, respectively. In E1, G presented higher green biomass of the stems and leaf at smaller densities than S, but lower green biomass of branches at most densities. The species did not differ for mean stem dry biomass and leaf dry biomass, but G showed higher branch dry biomass at most densities. Higher planting densities increased green and dry biomass of stems, branches, and leaves in S, but decreased those characteristics in G, with the exception of leaf dry mass, which was not influenced by density. In E2, the behavior of each species was identical in plots containing the same or different species. Griricidia showed the highest green biomass of stems and branches, and the highest values for geren biomass of the leaf were observed for gliricidia and neem. The highest stem, branch, and leaf dry biomass values were obtained for G, S, and N, respectively. In E3, G was superior for stem and leaf green biomass, and for stem and branch dry biomass. There were no differences between species for the other biomass values.

Planting density of gliricidia when intercropped with corn for weed control

Reduced use of herbicides that cause environmental pollution problems is of great interest in modern agriculture. Soil mulching with gliricidia (Gliricidia sepium) branches does not have an allelopathic effect on corn, but decreases weed populations. The objective of this study was to evaluate the effects of gliricidia planting density, when grown as an intercrop, on weed control and corn yield parameters. A randomized block design with split-plots and ten replicates was adopted. Corn cultivars AG 1051 and BM 3061 were grown without hoeing, with two hoes (at 24 and 44 days after planting), and intercropped with gliricidia (planted simultaneously with corn, between crop rows, using two seedlings/pit, spaced at 30, 40, or 50 cm). Twenty-one weed species were found in the experimental area. Increased gliricidia planting density reduced weed biomass, but no difference was found between weed biomass in the intercrop and weed biomass in non-hoed corn. Gliricidia intercropped with corn, planted at a row spacing of 30 cm, did not significantly differ from hoed corn in most characteristics considered to evaluate green corn yield, although mean values were smaller. As to the number and weight of marketable green ears, reductions of 5% and 13%, respectively, were observed. Intercropping caused a 17% reduction in grain yield, reducing the losses (36%) observed in non-hoed corn by more than 50%. The highest green ear yield and grain yield values were obtained with two hoeings, while the lowest values were observed for non-hoed corn. The cultivars did not differ regarding green ear yield and grain yield.

Predicting the effects of nitrogen and planting density on maize water use in semi-arid Kenya

Models are important tools to assess the scope of management effects on crop productivity under different climatic and soil regimes. Accordingly, this study developed and used a simple model to assess the effects of nitrogen fertiliser and planting density on the water use efficiency (q) of maize in semi-arid Kenya. Field experiments were undertaken at Sonning, Berkshire, UK, in 1996 (one sowing) and 1997 (two sowings). The results from the field experiments plus soil and weather data for Machakos, Kenya (1 degree 33'S, 37 degree 14'E and 1560 m above sea level), were then used to predict the effects that N application and planting density may have on water use by a maize crop grown in semi-arid Kenya. The increase in q due to N application was greater under irrigated (15%-19%) than rainfed (7%-8%) conditions. Also, high planting density increased q (by 13%) under irrigation but decreased q (by 17%) under rainfed conditions. The current study has shown the significance of crop modelling techniques in assessing the influence of N and planting density on maize production in one region of semi-arid Kenya where there is high variability of rainfall.

Effects of planting density and nitrogen application on seed yield and other morphological traits of the leafy vegetable kale (Brassica oleracea).

The relationship between food security and sustainable land use is considered to be of the uttermost importance to increase yields without having to increase the agricultural land area over which crops are grown. In the present study nitrogen concentration (25 and 85 kg ha-1) and planting density (6.7, 10 and 25 plants m-2) were investigated for their effect on whole plant physiology and pod seed yield in kale (Brassica oleracea), to determine if the fruit (pod) yield could be manipulated agronomically. Nitrogen concentration did not significantly affect seed yield and it is therefore recommended that the lower concentration be used commercially. Conversely planting density did have a significant effect with increases in seed yield observed at the highest planting density of 25 plants m-2, therefore this high planting density would be recommended commercially to maximise area efficiency, highlighting that simple agronomic changes are capable of increasing crop yields over a set area.

The effects of maize planting density and weeding regimes on light and water use

Light and water are among essential resources required for production of photosynthates in plants. A study on the effects of weeding regimes and maize planting density on light and water use was conducted during the 2001/2 short and 2002 long rain seasons at Muguga in - the central highlands of Kenya. Weeding regimes were: weed free (W1), weedy (W2), herbicide (W3) and hand weeding twice (W4). Maize planting densities were 9 (D1) and 18 plants m-2 (D2) intercropped with Phaseolus vulgaris (beans). The experiment was laid as randomized complete block design replicated four times and repeated twice. All plots were thinned to 4 plants m-2 at tasseling stage (96 DAE) and thinnings quantified as forage. Soil moisture content (SMC), photosynthetically active radiation (PAR) interception, evapo-transpiration (ET crop), water use efficiency (WUE), and harvest index (HI), were determined. Percent PAR was higher in D2 than in D1 before thinning but higher in D1 than in D2 after thinning in both seasons. PAR interception was highest in W2 but similar in W1, W3 and W4 in both seasons. SMC was significantly lower in W2 but similar in W1, W3 and W4. D2 had lower SMC than D1 in season two. Weeding regime significantly influenced ET crop, while planting density and weeding regime significantly influenced WUE and HI. D2 maximizes water and light use for forage production but results to increased intra-specific plant competition for water and light severely before thinning (96 DAE) that reduce grain yield in dual purpose maize, relative to D1.

Effect of Alternaria cassiae, Pseudocercospora nigricans, and soybean (Glycine max) planting density on the biological control of sicklepod (Senna obtusifolia)

The interactions of two fungal biocontrol agents, Alternaria cassiae and Pseudocercospora nigricans, and soybean planting density on sicklepod mortality and dry weight were studied in the field over 2 yr. The experimental field was divided into three equal areas: one without soybean and two where the soybean was sown in densities of 20 and 36 seeds per meter row with a 0.95-m row spacing. The fungi were sprayed alone or in a mixture at three growth stages of sicklepod plants grown at three levels of crop interference resulting from the three soybean planting densities. The fungal treatments were: an untreated control, A. cassiae (105 spores/m2), P. nigricans (3.3 g mycelium/m2), and the mixture of these two fungi. Sicklepod was at the cotyledonary leaf, two-leaf, and four-leaf stages when treated. Alternaria cassiae was most effective in reducing both sicklepod survival and dry weight. The mixture of P. nigricans and A. cassiae was generally comparable to but not better than A. cassiae alone in killing the weed (mortality) and reducing its growth (dry weight). Soybean density did not have significant effects on the mortality or the dry weight of sicklepod. Thus, there is no advantage to combining the highly effective biocontrol agent A. cassiae with the less effective P. nigricans or with soybean interference to control sicklepod. However, the results validate the efficacy of A. cassiae by itself as a bioherbicide.

Yield gains of coffee plants from phosphorus fertilization may not be generalized for high density planting

Inconclusive responses of the adult coffee plant to phosphorus fertilization have been reported in the literature, especially when dealing with application of this nutrient in high density planting systems. Thus, this study was carried out for the purpose of assessing the response of adult coffee plants at high planting density in full production (in regard to yield and their biennial cycle/stability) to the addition of different sources and application rates of P in the Zona da Mata region of Minas Gerais, Brazil. The experiment with coffee plants of the Catucaí Amarelo 6/30 variety was carried out over four growing seasons. Treatments were arranged in a full factorial design [(4 × 3) + 1] consisting of four P sources (monoammonium phosphate, simple superphosphate, natural reactive rock phosphate from Algeria (Djebel-Onk), and FH 550®), three P rates (100, 200, and 400 kg ha-1 year-1 of P2O5), and an additional treatment without application of the nutrient (0 kg ha-¹ year-¹). A randomized block experimental design was used with three replicates. The four seasons were evaluated as subplots in a split plot experiment. The P contents in soil and leaves increased with increased rates of P application. However, there was no effect from P application on the yield and its biennial cycle/stability regardless of the source used over the four seasons assessed.

'Tommy Atkins' mango trees subjected to high density planting in subhumid tropical climate in northeastern Brazil

The objective of this work was to evaluate the effects of high density planting on 'Tommy Atkins' mango trees cultivated in subhumid warm tropical climate in northeastern Brazil. Treatments consisted of five spacial arrangements of plants (8x5 m, 7x4 m, 6x3 m, 5x2 m and 4x2 m), which resulted in the following plant densities: 250 (control), 357, 555, 1,000 and 1,250 plants per hectare. Plant vegetative and reproductive variables, besides fruit quality parameters, were evaluated at seven and eight years after transplantation to the field. In general, high density planting caused reduction in vegetative and reproductive variables of individual mango trees, but had little influence on fruit quality. Above 555 plants per hectare, a significant decrease was observed in mango tree growth. Furthermore, there were decreases in the percentage of flowering, fruit yield per plant and per area. However, planting density up to 357 plants per hectare, in spite of decreasing plant growth and fruit yield per tree, increases fruit yield per area in 30% in comparison to the control.

Stand density management in rainforest plantations

Trees in plantations established for timber production are usually grown at a sufficiently high density that canopy closure occurs within a relatively short time after planting. The trees then shade and outcompete most herbs, shrubs or grasses growing at the site. The closer the spacing (i.e. the greater the density) the faster this will occur. Subsequently, as the trees grow larger, this between-species competition is replaced by within-species competition. If unmanaged, this competition can reduce the commercial productivity of the plantation. Thus, there are two management dilemmas. One is knowing the best initial planting density. The second is knowing how to management the subsequent between-tree competition in order to optimize overall plantation timber productivity. In this chapter we consider initial spacing and thinning for high value timber trees grown in single and mixed species plantations. From growth studies in stands of different ages recommendations are proposed for managing both types of plantations where the primary objective is timber production. It seems that many rainforest species will require more space to achieve optimal growth than most eucalypts and conifers. On the other hand many rainforest species do not have strong apical dominance. Care will be needed to balance these two attributes.

Planting times and spacing of carrot crops in the São Francisco Valley, Pernambuco state, Brazil.

Climate variations over the year and plant density tend to strongly affect the agronomic performance of carrot crops. Thus, the objective of this work was to evaluate the performance of the cultivar Brasilia in crops under mild (winter) and high (summer) temperatures. An experiment was conducted from May 2011 to February 2012, using a randomized block design and treatments arranged in split plot, with three replications. The plots consisted of planting seasons (winter and summer) and the subplots of plant spacing (4, 6, 8 and 10 cm). The height of plants presented a linear decrease, from 53.4 to 51.0 cm, with an increase in spacing in summer planting, while in winter the greatest height (50.7 cm) was obtained with spacing of 8.0 cm between plants. The lowest commercial yields were found in summer crops and with the widest spacing between plants. The smallest spacing between plants (4 cm) had yields of 45.9 Mg ha -1in summer and of 63.1 Mg ha-1 in winter crops. The winter planting had higher fresh root weight (89.9 g root - 1 ) compared to the summer (81.4 g root - 1 ), reaching higher weight with increasing plant spacing. Higher yields are achieved with plant spacing of 4 cm during winter. The carrot can be grown throughout the year in the Submiddle of the São Francisco Valley.

Role of healthy nursery plants in orange yield during eight years of Citrus Variegated Chlorosis epidemics

The production and commercialization of citrus seedlings inspected and produced in protected screen-houses has become mandatory in Sao Paulo State, Brazil since January 2003. This law was intended to avoid the dispersion of Citrus Variegated Chlorosis (CVC), disease caused by Xylella fastidiosa. Our objective was to compare the yield over 8 years of `Natal` sweet orange trees grafted onto Rangpur lime obtained from healthy nursery plants and from plants artificially inoculated with X. fastidiosa. Yield was evaluated in an orchard planted in February 1999 with two treatments: (i) trees from healthy nursery plant, and (ii) trees from plants artificially inoculated with X. fastidiosa. The mean yield was 21% higher in trees from healthy nursery plants, as compared to trees from inoculated nursery plants. This difference represents a gain of approximately 203 boxes of 40.8 kg each, considering a planting density of 550 plants per hectare. (C) 2011 Elsevier B.V. All rights reserved.