A experimentação do sisal: parte I - experiências de espaçamento

This study aimed to measure maize (Zea mays) plant nutrient content and nutrient removal in grain, and to evaluate the residual soil nitrogen, phosphorus, and potassium as impacted by planting date and density. Field experiments were conducted to evaluate six plant densities and seven planting dates using a split-split plot design with three replications. Besides the crop growth and yield parameters, six plants were collected at the maturity and soil was sampled from each plot for nutrient analysis. Plant N, P, and K concentrations varied with planting date and density and within the ranges of 0.6-1.024%, 0.054-0.127%, and 0.75-1.71%, respectively. Grain N, P, and K concentrations decreased with plant density and varied from 1.059 to 1.558%, 0.20 to 0.319%, and 0.29 to 0.43%, respectively. Soil residual nutrient varied with depth, planting density and date. Residual N concentration in the topsoil varied from 0.6 to 37.2 mg kg-1 in 2019 and from 1.5 to 11.2 mg kg-1 in 2020 and was high under the last two planting dates. Soil residual N concentration was higher in the second layer than in the topsoil. The N concentration in the third layer varied from 0.1 to 33.2 mg kg-1 and was impacted by plant density. Topsoil P did not vary among planting dates and densities. The second and third soil layers P concentration was not affected. There was 83% increase in topsoil K in 2020 compared to 2019, and a decrease of 65 and 23% in soil K was observed in the second and third soil layers, respectively. For maize production system sustainability, future research should use a holistic approach investigating the impact of planting date, plant density on crop growth, yield, nutrient uptake and remobilization, and soil properties under different fertilizer rates to develop the fertilizer recommendation for maize while reducing the environmental impact of the production system.

Yield, quality and leaf senescence of cotton grown at varying planting dates and plant densities in the Yellow River Valley of China

Irrigated wheat response to different population densities and planting dates when it is planted on raised beds is not well defined. A field study was carried out at the Yaqui Valley Agricultural Experimental Station in Sonora, Mexico during fall-winter 1992–1993, in a split plot design with three planting dates: Nov 10, Dec 10 and Jan 10; and six population densities: 50, 100, 150 200, 250 and 800 thousand plants per hectare (TPPH), in a complete randomized block design, with four replications. The fertilization used was 150-40-0 kg ha −1 of N-P 2 O 5 -K 2 O; the wheat variety used was Altar C85. Results indicated that wheat response to population density (PD) was different at different planting dates. At an early date, the plants grew taller and more vigorous and the field area could be covered with a small number of plants. The optimal PD was around 150 TPPH (15 plants m −2 ) when planted on Nov 10, which represents less than 10 kg ha-1 of seed. After this date, it was required to increase the PD as th...

Supplementary irrigation is one of the most effective field management practices to improve water productivity and crop yield in rainfed conditions. Time of supplementary irrigation is another important parameter affecting the enhancement of yield. In order to study the effect of supplementary irrigation time as well as planting date, two factors, namely: 1) supplementary irrigation (No irrigation as control (T1), single irrigation at grain filling stage (T2), and single irrigation at pod filling stage (T3)); 2) Planting date (planting on April 4 (D1) vs. 14 (D2)) were considered and a field experiment carried out at the Research and Training Farm of Imam Khomeini International University, Qazvin, Iran in spring 2011. The field experimental design was a factorial one based upon RCBD of six treatments and three replications. Treatments consisted of: D1T1 (Planting date on 4th April – without irrigation as control), D1T2 (Planting date on 4th April – single irrigation at grain filling stage), D1T3 (Planting date on 4th April – single irrigation at pod filling stage), D2T1 (Planting date on 14th April – non-irrigated), D2T2 (Planting date on 14th April – single irrigation at grain filling stage), D2T3 (Planting date on 14th April – single irrigation at pod filling stage). The effect of single irrigation time on yield, biomass and number of grains in unit area was significant as planting on 4th April and single irrigation at grain filling stage resulted 280 and 210 percent increase in yield and in biomass respectively, as compared to single irrigation at pod filling stage. The planting date factor showed a significant effect on yield and yield components as the yield decreased from 1057.6 (kg/ha) for a single irrigation at grain filling stage and planting on 4th April to 190.93 (kg/ha) for a single irrigation at the same stage and planting on 14th April. This means that the delay in planting date caused a reduction of 82 percent in yield for a single irrigation at grain filling stage. This reduction for single irrigation at pod filling was equal to 82 percent and the amount of yield decreased from 371.6 (Kg/ha) for planting on 4th April to 68.2 (Kg/ha) for planting date of 14th April.

To identify the high yield planting date and pinching pattern, we compared the yields of five new varieties (lines) of tea-applied chrysanthemum, the ‘Suju 10’, ‘Suju 12’, ‘Suju 13’, ‘CH1-44’ and ‘CH5-13’. A field experiment with split-split plot design was carried out. The main plot treatments including three (early, middle and late) planting dates, split-plot treatments including 5 new varieties (lines), and split-split-plot treatments including four different kinds of pinching schemes. The results showed that the yield of ‘CH5-13’ and ‘Suju 13’ was relatively higher among the five varieties (lines), followed by ‘CH1-44’ and ‘Suju10’, and ‘Suju 12’ showed the lowest yield. Among the five varieties (lines), planting date on May 27th and two-time pinching treatments showed the highest values of plant height, crown width, flower number, flower diameter, fresh mass, yield per plant and yield per unit area. Compared with the planting date on May 7th and June 13th, the above indexes increased by 16.0% and 19.0%, 18.0% and 22.8%, 36.7% and 42.2%, 11.1% and 2.3%, 13.0% and 4.0%, 47.8% and 36.6%, 48.5% and 36.7%, respectively. With the pinching time postponed, plant height decreased. Compared with the no pinching treatment, plant height of the two-time pinching treatment decreased by 50.2%, and values of crown width, flowers number, the flower fresh mass, the yield per plant and the yield per unit area were highest, with increases of 17.0%, 29.1%, 5.5%, 34.0% and 34.8%, respectively. The impact performance of three main factors on the growth and yield of the tea-applied chrysanthemum was in order of planting date>varieties>pinching time.

In order to evaluate the performance of double-cross maize hybrids in planting dates suitable for fall growing season in the middle region of Iraq, a field experiment was conducted at the fields of the College of Agricultural Engineering Sciences - University of Baghdad - Jadriya for the fall season of 2022 using double-cross maize hybrids selected from fifteen double cross hybrid maize resulted from crossing ten single hybrids resulting from crossing five inbred lines using the half-diallel method. These included Hybrid 1 = (1×4)(3×5) from the crossing of (ZM49W3E x CDCNS) (ZM43WIZE x ZM19), Hybrid 2 = (1×2)(3×5) from the crossing of (ZM49W3E × CDCN5) (ZM43WIZE x ZM60), Hybrid 3 = (1×5)(2×4) from the crossing of (ZM60 × ZM19) (ZM43WIZE ×CDN5), Hybrid 4 = (1×2)(4×5) from the crossing of (ZM19 × CDCN5) (ZM43WIZE ×ZM60), and Hybrid 5 = (1×4)(2×3) from the crossing of (ZM60 × ZM49W3E) (ZM43WIZE × ZM19), and their comparison with the synthetic variety IPA5018, and testing them under three planting dates: July 1st, July 15th, and August 1st. The experiment used a randomized complete block design with four replications arranged in a split-plot design. The main plots included the three planting dates, while the subplots included the five double-cross maize hybrids and the control variety. Yield and yield components were studied. The results of the experiment showed high significant effects for the third planting date for all traits except for the number of ears per plant, where the third planting date was superior in the number of grains per ears 660.4, weight of 100 grains 37.83 g , days to physiological maturity 99.67 days, crop growth rate 5.644 g plant-1 day-1, and yield per unit area 14.95 ton ha-1. The superiority of the hybrid (1×2)(3×5) in the number of grains ear-1 and the weight of 100 grains was 542.3 and 36.37, respectively., and this was reflected on the yield per unit area, which reached 11.69 ton ha-1, while hybrid (1×2) (3×5) outperformed in number of ears per plant 1.400 and the same hybrid was the earliest to reach physiological maturity at 97.50 days. The response of the double-cross maize hybrids varied with different planting dates and gave significant interaction for all studied traits except for the number of ears per plant.

Influence of planting distance and density on the yield and photosynthetic traits of sweet potato (Ipomoea balatas L.) under an intercropping system with walnut (Juglans regia) saplings

To determine the effects of seed priming, date and density of planting on the silage yield of corn (Ks.c704 cultivar) in summer delayed planting, an experiment was carried out as a split-split plot in a randomized complete block design with four replications in 2015 and 2016. Treatments were examined including two planting dates (July 27 and August 13) as main plots, two planting densities (7 and 9 plants per m2) as sub plots and four levels of seed priming (without priming, distilled water, 0.5% KNO3 and 10% PEG(8000)) as sub-sub plots. The results showed maximum of the speed and percentage of seedling emergence at the first year. The number of days decreased from planting date until 8- and 12- leaf stages in seed priming by the distilled water method. The silage yield decreased (26.69%) with the late planting (13 August), but the speed of seedling emergence increased. The planting density (9 plants/m2) yielded the highest percentage of lignin, speed of seedling emergence, plant height and silage yield. The highest ratio of the ear fresh weight to the total silage weight was obtained by the late planting date (13 August) and seed priming with the PEG method. The maximum value of the silage yield (45,566.41 kg/ha) was produced by the early planting date (27 July) and higher planting density (9 plants/m2). Thus, to increase seedling emergence speed and to obtain maximum silage yield, early planting date (27 July), higher planting density (9 plants/m2) and seed priming by the distilled water method are recommended.

This study was carried out to evaluate the yield and quality of pineapple fruits of the cultivars MD2, Smooth Cayenne, and Cabezona from plants treated with 2‐(3‐chlorophenoxy) propionic acid (CPA) in the humid tropics of Mexico with respect to three planting dates and two planting densities. The experimental design used was a scheme in sub‐subdivided plots with four replications. The pineapple cultivars were established on three planting dates (February 28, April 28, and June 28, 2022) at two planting densities, that is, those typically used at the regional level (Density 1: MD2 and Smooth Cayenne, 36,000 plants ha −1 ; Cabezona, 26,500 plants ha −1 ), and an increase of 28% in the number of plants planted in Density 1 for each cultivar (Density 2). For floral inhibition, 120 g CPA ha −1 was applied at each density and divided into three applications every 10 days beginning on October 20, 2022. The results revealed that the fruit yield and concentration of total flavonoids were not affected by the planting date, but the fruit/crown ratio, pH, °Brix, percentage of citric acid, maturity index, and total polyphenol concentration (TPC) were. The planting density significantly affected the yield, pH, and maturity index. The yield of the cultivars in Density 2 was 33% higher than that in Density 1, even though the fruits weighed 3.5% less and exhibited decreased °Brix and maturity index values. The fruits harvested from October to November (planting date June 28) presented the highest TPC (89.76 mg 100 g FF −1 ). Among the cultivars, MD2 and Cabezona presented the highest TPC. It is concluded that it is possible to produce pineapples in seasons of product shortage by modifying the dates and planting density without affecting the quality of the product.

A field study was conducted in spring of 2011, at Kanipanka and Bakrajo, in the province of Sulaimani to evaluate the impact of planting dates and spacing on growth and yield of oilseed sunflower (Helianthus annuus L.), variety "Flame". The experiment comprised of three planting dates (March15th, 30th and April15th), and three-plant spacing (15, 20, and 25 cm). Seed yields obtained from earlier planting date and narrow plant spacing were significantly higher. The results also showed that the early planting date March15th has a significant positive effect on plant height, stem diameter, head size, and seed weight than the late planting date April15th as an average of both locations. The interaction between planting dates and plant spacing as an average of both locations, showed that March15th planting date and 25 cm plant spacing had significantly higher 1000 seed weight and seed weight per plant, while the highest seed yield gained by the interaction of March 15th and plant spacing 15cm. Percentage seed oil content collected as an average of both locations was significantly higher from plants with late planting date April 15th at 20 cm plant spacing. All the studied characters except seed oil percentage shows higher significant values at Kanipanka location due to the favorable agro- climatic condition compared to Bakrajo location.

Para avaliar a qualidade das hastes florais, a cultivar de crisântemo Snowdon foi conduzida em estufa plástica em oito populações de plantas e duas épocas de plantio. O experimento bifatorial (2 x 8), com parcela subdividida, foi conduzido na Universidade Federal de Santa Maria (Santa Maria, RS) e teve época como parcela principal, sendo a primeira época outono/inverno no período de 05/03/98 à 29/06/98 e a segunda época inverno/primavera no período de 22/07/98 à 11/11/98 e as populações de 40, 48, 56, 64, 72, 80, 88 e 104pl/m², na subparcela para as duas épocas de plantio. As plantas foram conduzidas em haste unifloral. Determinaram-se a altura da planta, o diâmetro da inflorescência e da haste e a massa da matéria fresca. Para obtenção de maiores rendimentos de hastes de classe A (comprimento da haste > ou = 90 cm, diâmetro da inflorescência > ou = 13,5cm, diâmetro da haste > ou = 0,73cm e massa da matéria fresca > ou = 113g) a população indicada está entre 40 e 56plantas/m². Não há diferenças de rendimento qualitativo de classe A entre as épocas de plantio. Para obtenção de maiores rendimentos qualitativos, as populações de plantas não devem ser superiores a 72 plantas/m².

Avaliou-se o crescimento e a produção de cúrcuma em função de adubação mineral e população de plantas em dois experimentos na Universidade Federal de Goiás, Goiânia (GO). No primeiro, realizado de janeiro a agosto/98, estudaram-se, numa matriz baconiana, doses de uréia, superfosfato triplo e cloreto de potássio (0; 40; 80; 120; 160 e 200 kg/ha de N; 0; 50; 100; 150; 250 e 400 kg/ha de P2O5 e 0; 40; 80; 120; 200; 280 kg/ha de K2O, densidades de plantio (55.556; 41.667 e 33.333 plantas/ha, no espaçamento de 0,60 m entre linhas e 71.428; 47.619 e 35.714 plantas/ha no espaçamento de 0,70 m entre linhas) e parcelamentos da adubação nitrogenada [toda no plantio, 1/2 no plantio e 1/2 aos três meses após o plantio (AP), 1/3 no plantio, 1/3 aos dois meses e 1/3 aos quatro meses AP, 1/4 no plantio, 1/4 a um mês e meio, 1/4 aos 3 meses e 1/4 aos quatro meses e meio AP. No segundo experimento, realizado de dezembro/99 a setembro/00, estudaram-se, num fatorial de 2 x 4, dois espaçamentos entre linhas (0,60 e 0,80 m) e seis espaçamentos entre plantas na linha (0,05; 0,10; 0,15; 0,20; 0,30 e 0,40 m). O delineamento utilizado foi o de blocos ao acaso com quatro repetições. A produtividade de rizomas frescos aumentou, em função do N, de 12.130 kg/ha, com a dose zero, até o máximo de 16.124 kg/ha, com a dose de 130 kg/ha; e em função do P, de 12.799 kg/ha, com a dose zero, até o máximo de 15.763 kg/ha com a dose de 177 kg/ha de P2O5. O K e o parcelamento de N não influenciaram a altura das plantas e a produção de rizomas. A produtividade decresceu de 25 t/ha, obtida com o espaçamento de 5 cm entre plantas, para 18 t/ha com o espaçamento de 40 cm. Os ganhos de produtividade obtidos em espaçamentos menores que 10 cm não superaram as diferenças de gastos de rizomas para os respectivos plantios.

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), has become a major pest of grain sorghum, Sorghum bicolor (L.) Moench, in the United States in recent years. Feeding by large densities of sugarcane aphids causes severe damage, which can lead to a total loss of yield in extreme cases. Our objective was to determine the effect of grain sorghum planting date on sugarcane aphid population dynamics and their potential to reduce yields. We conducted field experiments from 2015 to 2017 in which an aphid-susceptible grain sorghum hybrid was planted at four different dates, which encompassed the typical range of planting dates used in Arkansas production systems. Plots were either protected from sugarcane aphid feeding using foliar insecticide sprays, or left untreated to allow natural populations of sugarcane aphids to colonize and reproduce freely. Planting date impacted both the magnitude and severity of sugarcane aphid infestations, with the highest population densities (and subsequent reductions in sorghum yield) generally occurring on plots that were planted in May or June. Sugarcane aphid feeding reduced yields in the untreated plots in two of the four planting date categories we tested. Earlier planting generally resulted in less sugarcane aphid damage and improved yields compared with later planting dates. While the effect of planting date on sugarcane aphid populations is likely to vary by region, sorghum producers should consider grain sorghum planting date as a potential cultural tactic to reduce the impact of sugarcane aphid.

Corn (Zea mays L.) grain yield is closely related to plant density and is typically maximized in the northern Corn Belt when planting occurs in late April. However, spring rainfall events often result in wet soil conditions that delay planting. From 2008 to 2010, experiments were conducted at two locations in southern Minnesota to determine whether the agronomic responses of corn to plant density differ with planting date. Six plant densities ranging from 38,400 to 107,900 plants ha−1 were evaluated within three planting dates that occurred on 2‐wk intervals beginning in late April to early May. Yield and net return to seed cost were not affected when planting was delayed 2 wk, but were 15 and 18 to 30% lower when planting was delayed 4 wk, respectively. Yield loss due to late planting was associated with a 7% decrease in kernel weight and no change in kernels per square meter. Responses to plant density for stalk diameter, intercepted photosynthetically active radiation (IPAR) and leaf area index (LAI) at silking, lodging, grain yield and components, and net return to seed cost for 25 economic scenarios did not differ with planting date. There was a quadratic‐plateau response of grain yield to plant density with yield maximized at ≥81,700 plants ha−1. These results from a 102‐d relative maturity hybrid over six site‐years in southern Minnesota show that increased plant density may not be able to offset the yield and economic losses associated with late planting.

Effect of rooting depth, plant density and planting date on maize (Zea mays L.) yield and water use efficiency in semi-arid Zimbabwe: Modelling with AquaCrop