Yield of bolting winter beet (Beta vulgaris L.) as affected by plant density,genotype and environment

Winter beet roots and shoots might be a favorable substrate for biogas production in Central Europe. However, detailed information about the attainable yield of this crop is lacking. Thus, the impact of plant density, genotype and environmental conditions on total dry matter yield of winter beet crops that bolt after winter was investigated. A significant increase of the dry matter yield (esp. shoot) was expected by harvesting the 1st shoot after flowering in June followed by a final harvest of the whole plant in July. In 2009/10, 2010/11 and 2011/12, three series of field trials with (i) 3 target plant densities (148, 246, 370 thousand plants ha⁻¹) and (ii) 3 different sugar beet genotypes were conducted at Göttingen (Lower Saxony, GER) and Kiel (Schleswig-Holstein, GER); (iii), additional field trials with 5 different sugar beet genotypes cultivated at 2 target plant densities (148, 246 thousand plants ha⁻¹) were conducted in 2011/12, to investigate the relation between maximum taproot diameter and the shoot and taproot yield of bolting winter beet. The total dry matter yield considerably varied between 4 and 23 t ha⁻¹. It was predominantly affected by the environment and to a substantially lower extent by plant density. Increasing plant densities increased the total dry matter yield, resulting in a significantly higher total dry matter yield at plant densities ≥300,000 plants ha⁻¹ compared with lower plant densities. Genotypic differences in total dry matter yield were negligibly small. Pruning in June substantially increased the total dry matter yield in July by ca. 8 t ha⁻¹ only in one out of three environments.Final yield in June (without pruning) and July (pruning in June) was positively related with cumulated temperature and global radiation, but also with taproot dry matter yield before winter. The taproot, shoot (1st, 2nd) and total plant yield were positively correlated with maximum taproot diameter.In conclusion, high dry matter yields close to yields of established energy crops grown over winter were obtained with winter beet roots and shoots only under very favorable conditions (climate, single plant size). High yields can be achieved after good pre-winter development. However, for sufficient frost tolerance the taproot size of plants must be rather small. Hence, the cultivation of bolting winter beet under Central European climate conditions has to face a severe conflict of goals concerning winter survival and yield formation.     

Sugar beet rotation effects on soil organic matter and calculated humus balance in Central Germany

In order to quantify the influence of land use systems on the level of soil organic matter (SOM) to develop recommendations, long-term field studies are essential. Based on a crop rotation experiment which commenced in 1970, this paper investigated the impact of crop rotations involving increased proportions of sugar beet on SOM content. To this end, soil samples were taken in 2010 and 2012 from the following crop rotation sequences: sugar beet–sugar beet–winter wheat–winter wheat (SB–SB–WW–WW = 50%), sugar beet–sugar beet–sugar beet–winter wheat (SB–SB–SB–WW = 75%), sugar beet–grain maize (SB–GM = 50%) and sugar beet-monoculture (SB = 100%); these were analysed in terms of total organic carbon (TOC) and microbial biomass carbon (MBC) content, MBC/TOC ratio and the TOC stocks per hectare. In addition, humus balances were created (using the software REPRO, reference period 12 years) in order to calculate how well the soil was supplied with organic matter. In the field experiment, harvest by-products (WW and GM straw as well as SB leaves) were removed. After 41 years, no statistically significant differences were measured between the crop rotations for the parameters TOC, MBC, MBC/TOC ratio and the TOC stock per hectare. However, the calculated humus balance was significantly affected by the crop rotation. The calculated humus balance became increasingly negative in the order SB–SB–WW–WW, SB–SB–SB–WW, SB monoculture and SB–GM, and correlated with the soil parameters. The calculated humus balances for the reference period did not reflect the actual demand for organic matter by the crop rotations, but instead overestimated it.     

Potassium nutrition for improving stubble bud sprouting,dry matter partitioning,nutrient uptake and winter initiated sugarcane (Saccharum spp. hybrid complex) ratoon yield

A field experiment was conducted for two crop cycles during 2003–2005 and 2004–2006 at Indian Institute of Sugarcane Research, Lucknow to improve bud sprouting, dry matter accumulation (DMA), nutrient uptake and ratoon yield by using potassium fertilizer. Potassium (K) fertigation in standing plant cane increased the number of buds per stubble and number of stalks in ratoon cane. K content of stubble increased by 16.7% with K fertigation. The content of reducing sugars in buds at the time of ratoon initiation improved significantly with K fertigation. It improved dry matter accumulation, number of millable canes, individual cane weight, ratoon cane and sugar yields. Thus, it could be concluded that application of 66 kg K ha^?1 with irrigation water in standing plant cane before harvest improved bud sprouting, dry matter accumulation and nutrient uptake in ratoon crop. Irrigation in standing plant cane increased ratoon cane (69.9 t ha^?1) and sugar yields (7.6 t ha^?1). This increase for ratoon cane and sugar yield was 8.7 and 5.55%, respectively over the control. Further, it increased ratoon cane yield by 15.21% (74.1 t ha^?1) and sugar yields by 13.9% (8.2 t ha^?1) with K fertigation over the control. Thus, K nutrition holds great promise for improving growth of ratoon cane and sugar yields.     

Yield decrease in sugar beet caused by reduced tillage and direct drilling

In a long-term series of on-farm tillage trials (10 loessial sites in southern and eastern Germany; annual mouldboard ploughing 0.25–0.3 m deep, mulching with a rigid-tine cultivator 0.1–0.15 m deep, direct drilling with no tillage except seedbed preparation for sugar beet solely) sugar beet yield was significantly decreased by direct drilling compared to ploughing. This study was conducted to (i) show that the lower plant density caused by mulching and direct drilling contributes to yield decrease but explains effects just partially, and (ii) determine the relation between soil structural properties and sugar beet yield. In 2003–2005 plant density experiments (53,000, 65,000 and 82,000 plants ha^?1) were introduced to tillage plots on five selected environments. Yield and soil structural properties of four layers representing 0–0.43 m soil depth were determined.White sugar yield (WSY) significantly declined with direct drilling compared to ploughing treatment, whereas mulching treatment diminished WSY less pronounced. Moreover, decreasing plant density significantly lowered WSY. No interactions between tillage and plant density occurred, revealing that both factors additively affected WSY.Decreasing tillage depth increased penetration resistance (PR) and dry bulk density (DBD), and diminished air filled pore volume (AFPV) in the topsoil down to 0.27 m depth. Several soil structural parameters were closely correlated with each other as well as WSY. Variation of single parameters explained up to 60% of WSY variance attributed to tillage. Combining DBD from 0.03 to 0.07 m depth, average PR from 0.03 to 0.27 m and AFPV from 0.03 to 0.18 m soil depth explained 77% of the tillage effect. Nevertheless, multi-collinearity of soil physical parameters allowed no clear conclusions on the cause-and-effect mechanisms.Conclusively, lowered plant density and soil structure degradation due to reduced tillage may independently decrease sugar beet yield. When grown on loessial soils this crop requires mechanical loosening down to 0.15–0.20 m depth to produce high yields.     

Performance of winter cereals grown on field-stored soil moisture only

According to climate change projections, winter cereal production will likely be exposed to increasing air temperatures and prolonged summer droughts. During the 2009/10 and 2010/11 growing seasons at Braunschweig, Germany, four cultivars each of barley (Hordeum vulgare L.), rye (Secale cereale L.), triticale (Triticosecale Wittmack), and wheat (Triticum aestivum L.) were grown in a mobile rain-out shelter with a nearby irrigated control to determine the maximal impact of water shortage on phenology, physiology, and yield. The rain-out shelter plots were subjected to severe drought stress by withholding rain during tillering to harvest. Permanent prevention of water supply caused an average 2 day earlier heading and flowering and a 19 day earlier loss of green leaves. Midday thermal images revealed consistently higher canopy temperatures under drought stress than under well-watered conditions. The drought related temperature increase was 3.7 K across crops and years. Contrary to canopy temperature, the spectral moisture stress index and the normalized difference water index did not clearly separate the dry from the wet environment. The drought-induced yield loss averaged 5.9 t ha⁻¹ (63%) for grain dry matter and 9.2 t ha⁻¹ (51%) for above-ground dry matter. Among the four cereal species, rye produced the highest grain and above-ground dry matter under both dry and wet conditions, and also had the coolest canopy. Based on the results of the present study, it is expected that rye will cope best, and barley second-best with the drier conditions of the changing climate.     

Effects of ozone on sugar beet grown in open-top chambers

Sugar beet (Beta vulgaris cv. Patriot) plants were grown on field plots and in open-top chambers (OTCs) in two successive years. In the OTC treatments, plants were exposed to charcoal filtered air, unfiltered air or unfiltered air enriched with additional ozone (O₃). Ozone exposure continued for almost 5 months and the 8-h average concentration was raised from 34 to 39 nL L⁻¹ in the ambient air chambers to 62 nL L⁻¹ in the ozone enriched chambers. In both years, the AOT40 exposure index in the ozone enriched chambers exceeded 30 μL L⁻¹ h during the 5-month exposure period compared to 6.5 and 2.9 μL L⁻¹ h in ambient air in 2003 and 2004, respectively. Visible symptoms in the form of small white necrotic flecks appeared in both seasons in the ozone enriched chambers. When the data for both years were analysed statistically, a significant reduction of root yield of 6% and a slight reduction of sugar content were detected. These changes resulted in an overall reduced sugar yield ha⁻¹ of about 9%. Although the sensitivity of sugar beet to ozone is highly variety-dependent, in general this biennial crop appears less sensitive than annual crops such as wheat and potato. Ozone has limited effects on quality parameters in sugar beet, although an increase in α-amino-N content was observed, in agreement with the increased nitrogen content resulting from ozone exposure of wheat and potato.Enclosure within the OTCs increased aboveground biomass but decreased root yield (fresh biomass) and sugar content. These effects were most likely caused by a reduction of radiation by the chamber walls and annulus. The increased temperature in the chambers reduced yield quality by increasing mineral content.     

Effects of best management practices on dry matter production and fruit production efficiency of oil palm

Enhancing dry matter production with higher partitioning to fruit bunches is important for sustainable intensification of oil palm. A series of best management practices including site-specific nutrient management, canopy management, and harvesting has been developed for oil palm plantations. However, the effects of these practices on dry matter production and partitioning, and how the effects vary with climatic and soil conditions of plantation sites, remain largely unknown. We established a four-year field trial including 30 paired commercial blocks across Sumatra and Kalimantan, Indonesia. The paired treatments included site-specific best management practices, and standard estate practices as the control. The annual production of aboveground dry matter was 30.0 ± 0.5 t ha⁻¹ yr⁻¹ (mean ± se) under best management practices, higher than 28.8 ± 0.5 t ha⁻¹ yr⁻¹ under standard estate practices. The bunch index, an indicator of the fruit production efficiency, increased by 12% under best management practices compared to standard estate practices. Partitioning of dry matter to the fronds decreased by 8% under best management practices, compared to standard estate practices. The positive effect of best management practices on the annual production of total aboveground dry matter was stronger in the plantation site with higher annual rainfall. These results are useful for optimizing management practices to improve sustainable intensification of oil palm.     

Effect of plant density and nitrogen rates upon the leaf area of seed sugar beet on seed yield and quality

Three-year field trials were set up on eutric brown soil in northwestern Croatia (Zagreb) with the objective to determine the effect of plant density and nitrogen rates on the formation and size of leaf area of seed sugar beet, and on the yield and seed quality in seed production without transplanting. Investigations should also reveal how much the yield and quality of sugar beet seed depend on the leaf area index (LAI). Four plant densities of seed sugar beet were investigated after crop wintering (40 000, 80 000, 120 000, and 160 000 plants/ha) as well as three nitrogen rates (60, 120, and 180 kg/ha) applied in two identical topdressings: at the beginning of the spring growing period and immediately before shooting of inflorescence stalks. Leaf area formation was strongly influenced by weather conditions. An increase of plant density from 40 000 to 160 000 plants/ha led to a decrease of leaf area per plant. Raised nitrogen rates in topdressing caused an increase of leaf area, depending on the precipitation and soil fertility. Maximum LAI, achieved in the flowering stage, grew almost linearly with increasing plant density (LAI: 1.77–4.85 m²/m²), but was statistically significant only up to 120 000 plants/ha. Raised nitrogen rates in topdressing led to a significant increase of the LAI in the stage of inflorescence stalk shooting, though not in full flowering. On the basis of this research, seed yield and germination of seed sugar beet could not be predicted regarding LAI in the flowering stage.     

Effect of free air carbon dioxide enrichment combined with two nitrogen levels on growth,yield and yield quality of sugar beet: Evidence for a sink limitation of beet growth under elevated CO2

The increase in atmospheric CO₂ concentration [CO₂] has been demonstrated to stimulate the growth of C₃ crops. However, little information exists about the effect of elevated [CO₂] on biomass production of sugar beet, and data from field experiments are lacking. In this study, sugar beet was grown within a crop rotation over two rotation cycles (2001, 2004) at present and elevated [CO₂] (375 μl l^?1 and 550 μl l^?1) in a free air CO₂ enrichment (FACE) system and at two levels of nitrogen supply [high (N2), and 50% of high (N1)], in Braunschweig, Germany. The objective of the present study was to determine the CO₂ effect on seasonal changes of leaf growth and on final biomass and sugar yield. Shading treatment was included to test whether sugar beet growth is sink limited under elevated [CO₂]. CO₂ elevation did not affect leaf number but increased individual leaf size in early summer resulting in a faster row closure under both N levels. In late summer CO₂ enrichment increased the fraction of senescent leaves under high but not low N supply, which contributed to a negative CO₂ effect on leaf area index and canopy chlorophyll content under high N at final harvest. Petioles contained up to 40% water-soluble carbohydrates, which were hardly affected by CO₂ but increased by N supply. More N increased biomass production by 21% and 12% in 2001 and 2004, respectively, while beet and sugar yield was not influenced. Concentration of α-amino N in the beet fresh weight was increased under low N and decreased under high N by CO₂ enrichment. The CO₂ response of total biomass, beet yield and white sugar yield was unaffected by N supply. Averaged over both N levels elevated [CO₂] increased total biomass by 7% and 12% in 2001 and 2004, respectively, and white sugar yield by 12% and 13%. The shading treatment in 2004 prevented the decrease in leaf area index under elevated [CO₂] and high N in September. Moreover, the CO₂ effect on total biomass (24%) and white sugar yield (28%) was doubled as compared to the unshaded conditions. It is concluded that the growth of the storage root of sugar beet is not source but sink limited under elevated [CO₂], which minimizes the potential CO₂ effect on photosynthesis and beet yield.     

Effects of base removal and heat treatment on visual and nutritional quality of minimally processed leeks

Freshly harvested leeks (Allium ampeloprasum L. var. porrum) were trimmed (leaf tips, roots), had the decayed leaves removed, washed with tap water, cut at 50 cm length and subjected to heat treatment at 55 °C for 0 and 17.5 min. They were then trimmed at the root base and leaves to produce stalks 22 cm in length with or without removal of a 2 cm portion of the base. Minimally processed leeks were tray-packaged, wrapped with 16 μm stretch film and stored at 10 °C for 7 days to determine the effects of base removal and heat treatment on visual (leaf growth, fresh weight loss and discoloration) and nutritional quality after storage. CO₂ and ethylene concentrations of packages containing minimally processed leeks showed a wound-induced pattern typical of other fresh cut vegetable tissues. Base removal did not significantly affect respiration but increased ethylene production, while heat treatment increased respiration rate and suppressed ethylene production. Storage of minimally processed leeks at 10 °C for 7 days resulted in a slight decrease of chroma and hue angle of base cross section as well as a decrease of chroma of the upper cross section. Heat treatment prevented the decrease of chroma of the base and upper cross section. Base removal reduced, but did not totally control leaf growth of stored minimally processed leeks. Moreover, it resulted in a decrease of dry matter, soluble solids, total soluble phenols, antioxidant capacity and total thiosulfinates at the end of the storage. A combination of base removal and heat treatment efficiently controlled leaf growth, but these treatments resulted in increased fresh weight and total thiosulfinate loss.     

The effect of wheat straw residue on the emergence and early growth of sugar beet (Beta vulgaris) and oilseed rape (Brassica napus)

The management of straw residue can be a concern in non-inversion tillage systems where straw tends to be incorporated at shallow depths or left on the soil surface. This can lead to poor crop establishment because straw residue can impede or hinder crop emergence and growth. Small container-based experiments were undertaken using varying amounts of wheat straw residue either incorporated or placed on the soil surface. The effects on days to seedling emergence, percentage emergence, seedling dry-weight and soil temperature using sugar beet and oilseed rape were investigated because these crops often follow wheat in a cropping sequence.The position of the straw residue was found to be the primary factor in reducing crop emergence and growth. Increasing the amount of straw residue (from 3.3 t ha^?1 to 6.7 t ha^?1) did not show any consistent trends in reducing crop emergence or growth. However, in some instances, results indicated that an interaction between the position and the amount of straw residue occurred particularly when the straw and seed was placed on the soil surface. Straw placed on the soil surface significantly reduced mean day-time soil temperature by approximately 2.5 °C compared to no residue. When the seed and straw was placed on the soil surface a lack of seed-to-soil contact caused a reduction in emergence by approximately 30% because of the restriction in available moisture that limited the ability for seed imbibition. This trend was reversed when the seed was placed in the soil, but with straw residue still on the soil surface, because the surface straw was likely to reduce moisture evaporation and improved seed-to-soil contact that led to rapid emergence. In general, when straw was mixed in or placed on the soil surface along with the seed, sugar beet and oilseed rape emergence and early growth biomass was significantly restricted by approximately 50% compared to no residue.The consequences of placing seed with or near to straw residue have been shown to cause a restriction in crop establishment. In both oilseed rape and sugar beet, this could lead to a reduction in final crop densities, poor, uneven growth and potentially lower yields that could lower financial margins. Therefore, if farmers are planning to use non-inversion tillage methods for crop establishment, the management and removal of straw residue from near or above the seed is considered important for successful crop establishment.     

Dry matter,nitrogen and phosphorus accumulation,partitioning and remobilization as affected by N and P fertilization and source–sink relations

Durum wheat (Triticum turgidum subsp. durum L.) is being increasingly grown in many areas of the world, but there is a lack of information about the physiological processes limiting grain yield. In this study, different rates of N and P fertilization were applied and the source:sink ratio was manipulated to examine the factor(s) limiting grain filling under rainfed conditions. Plants exposed to four fertilization treatments (control, 80 kg N ha^?1 (N), 50 kg P ha^?1 (P) and 80 kg N ha^?1 and 50 kg P ha^?1 (N–P)) and were artificially modified to obtain a range of different source:sink ratios. The treatments were (I) control; (II) half of the spike was removed; (III) all the spike was removed. The cultivar Cosmodur was used, which is widely grown in Greece and other Mediterranean countries and is quite productive especially under rainfed conditions. The distribution of dry matter, N and P among grains, stems and leaves was analyzed at anthesis and harvesting. Dry matter accumulation and partitioning into different plant parts was different between the fertilization treatments and the control. At anthesis, leaf + culm dry matter was higher than the chaff dry matter. Total aboveground biomass increased after anthesis in both years and at all fertilization treatments. N fertilization affected N concentration at the whole plant level at anthesis and at maturity. There was an average increase of 20% in N concentration with N application at anthesis in both years relative to the control. N content was affected by the fertilization treatments and it was increased by 33% over the 2 years of the study compared with the control. In addition, P fertilization affected P concentration both at anthesis and maturity in every plant organ, and there was also a significant effect of the change of P concentration at the two different growth stages. P accumulation was also affected by the fertilization regime and by the spike halving treatment. Dry matter translocation was an average of 22% higher at the fertilized treatments compared with the control, which indicates that fertilization led plants to translocate higher amount of dry matter. N and P translocation were affected by the fertilization treatment and in some treatments by the sink reduction. The spike reduction treatment increased the pre-anthesis contribution to seed indicating that the N and P remobilization from vegetative tissues were very important for grain development. The present study indicates that N and P fertilization and sink size can affect dry matter, N, and P accumulation, partitioning, and retranslocation of durum wheat which can affect seed yield.     

Can hot water treatments enhance or maintain postharvest quality of spinach leaves?

It has been reported that a short duration hot water treatment, applied as a heat shock, improves subsequent postharvest quality in bagged spinach and rocket leaves. This study has established that the maximum hot water temperature and duration before spinach leaves showed damage, was 45 °C for 60 s. Subsequent detailed studies compared postharvest quality of leaves treated at 45 °C for 60 s immediately after harvest with untreated leaves after 5 and 10 days of storage at 4 °C. Heated leaves were significantly lighter and more yellow suggesting enhanced senescence, but leaf membrane integrity and associated gas composition of the storage atmosphere were not significantly different. Hot water treatment at 45 °C for 60 s applied immediately after harvest had a mixed effect on the biochemical constituents of the leaves; total carotenoid concentration was maintained compared to untreated leaves but the contents of ascorbic acid, dehydroascorbic acid, chlorophyll a and b were not affected. These observations suggest that in contrast to other reports, hot water treatments have limited commercial potential for postharvest quality improvement of spinach leaves.     

The relevance of N fertilization for the amount of total greenhouse gas emissions in sugar beet cultivation

The agricultural sector is highly affected by climate change and it is a source of greenhouse gases. Therefore it is in charge to reduce emissions. For a development of reduction strategies, origins of emissions have to be known. On the example of sugar beet, this study identifies the main sources and gives an overview of the variety of production systems. With data from farm surveys, calculations of greenhouse gas (GHG) emissions in sugar beet cultivation in Germany are presented. Emissions due to the production and use of fertilizers and pesticides, emissions due to tillage as well as field emissions were taken into account. All emissions related to the growing of catch crops during fall before the cultivation of sugar beet were also included. The emissions are related to the yield to express intensity.The median of total GHG emissions of sugar beet cultivation in Germany for the years 2010–2012 amounted to 2626 equivalents of CO₂ (CO₂eq) kg ha⁻¹ year⁻¹ when applying mineral plus organic fertilizer and to 1782 kg ha⁻¹ when only organic fertilizer was applied. The CO₂eq emissions resulting from N fertilization exclusively were 2.5 times higher than those caused by diesel and further production factors. The absence of emissions for the production of organic fertilizers led to 12% less total CO₂eq emissions compared to the use of mineral fertilizer only. But by applying organic fertilizer only, there were more emissions via the use of diesel due to larger volumes transported (126 l diesel ha⁻¹ vs. 116 l ha⁻¹ by applying mineral fertilizer exclusively).As there exists no official agreement about calculating CO₂eq emissions in crop production yet, the authors conclude that there is still need for further research and development with the aim to improve crop cultivation and crop rotations concerning GHG emissions and the therewith related intensity.     

Absorption of 1-MCP by fresh produce

The capacity of various types of fresh produce to absorb gaseous 1-methylcyclopropene (1-MCP) was compared. The produce, which included potato, parsnip, ginger, green bean, asparagus, tangerine, key lime, melon, apple, plantain, leaf lettuce, and mango, was placed in 1, 2, and 10 L glass jars, depending on the size of produce. 1-MCP gas was added to the headspace at an initial concentration of approximately 10 μl l⁻¹. Gas concentrations were measured after 2, 4, 6, 8, 10 and 24 h. The concentration of 1-MCP in empty jars was stable for the 24 h holding period. All produce absorbed 1-MCP, but the rate of sorption differed markedly. The 1-MCP loss data was fitted with an exponential decay curve to determine the initial rate of sorption and the time to 50% decline in concentration (t_1/2). Under the conditions of the experiment, the initial rate of loss (% h⁻¹) and the t_1/2 varied by as much as 30-fold between commodities. The initial rate of 1-MCP sorption (μl h⁻¹) for each commodity was found to correlate with the fresh weight, dry matter, insoluble dry matter (IDM), and water weight, but not soluble dry matter. The strongest correlation (r² = 0.44) was with insoluble dry matter; this relationship was improved if insoluble dry matter was divided by the shortest radius of the organ (r² = 0.63) to adjust for the length of the diffusion path. The correlation between the rate of sorption and insoluble dry matter content is consistent with previously published data suggesting that cellulosic materials possess a high affinity for 1-MCP.     

Old tall durum wheat cultivars are suited for dual-purpose utilization

The lateness, tallness and high vigour of old tall durum wheat cultivars could be advantageous for dual-purpose use and their high propensity for lodging should be reduced by grazing. A 3-year field trial was performed in Sardinia, Italy, in a typical Mediterranean environment. Crops of the durum wheat cultivar Senatore Cappelli were sown in October, and grazing was simulated by clipping half of the plots at the terminal spikelet stage of development. The forage biomass derived from clipping varied greatly between seasons (from 0.8 to 3.3 t ha⁻¹ dry matter) in response to the notable inter-seasonal variability in weather conditions. Cultivar Senatore Cappelli showed good recovery following clipping, with the ability to attain almost complete radiation interception well before anthesis. The high number of leaves that emerged after clipping might have contributed to this good recovery. Nevertheless, clipping reduced the dry matter produced by anthesis (16 t ha⁻¹ in clipped compared to 21 t ha⁻¹ in unclipped crops) as well as the final dry matter (DM_MAT) (19 t ha⁻¹ in clipped compared to 23 t ha⁻¹ in unclipped crops), although these differences disappeared when the clipped biomass was included. The lower lodging observed at anthesis in the clipped (21%) compared with unclipped crops (63%) likely reduced the difference between treatments. The lower DM_MAT of clipped treatments was reflected in a lower grain yield (GY) (3.4 t ha⁻¹ vs 4.2 t ha⁻¹ in the unclipped treatment). Clipping did not affect the amount of nitrogen present in the biomass, nitrogen uptake efficiency or radiation use efficiency. GY reduction after clipping was mediated by the reduction in spikes m⁻² and kernels m⁻² (KNO). Spike fertility was not affected by clipping, because the same amount of radiation was available for each spike (about 1 MJ). The period with reduced ground cover after clipping was reflected in an increased evaporation and reduced transpiration, which did not alter the total water used and increased the transpiration efficiency in terms of DM_MAT.Old tall durum wheat cultivars manifested good suitability for dual-purpose use in environments with low attainable yields because their low grain yield potential contributed to reducing the negative effects of clipping on GY. Their high straw yield and kernel protein percentage represented an advantage with respect to semi-dwarf cultivars.     

Effect of depth of fertilizer banded-placement on growth,nutrient uptake and yield of oilseed rape (Brassica napus L.)

A better understanding of crop growth and nutrient uptake responses to the depth of fertilizer banded-placement in the soil is needed if growth and nutrient uptake responses are to be maximized. A two-year field study covering two rape seasons (2010–2011 and 2011–2012) was conducted to examine the effect of banded-placement of N–P–K fertilizer at various depths on growth, nutrient uptake and yield of oilseed rape (Brassica napus L.). The results showed that fertilization at 10 cm and 15 cm soil depth produced greater taproot length and dry weight than fertilization at 0 cm and 5 cm. 0 cm and 5 cm deep fertilization significantly increased the lateral root distribution at 0–5 cm soil depth, while 10 cm and 15 cm deep fertilization induced more lateral root proliferation at 5–15 cm soil depth. At 36 days after sowing (DAS), 5 cm deep fertilization produced better aboveground growth and nutrient uptake than 10 cm and 15 cm deep fertilization. However, reversed results were observed after 36 DAS. 10 cm and 15 cm deep fertilization produced more rapeseed than 0 cm and 5 cm deep fertilization, moreover, the yield difference was more significant in drought season (2010–2011) than in relatively normal season (2011–2012). In summary, these results preliminarily suggest that both 10 cm and 15 cm are relatively proper fertilizer placement depth when the practice of banding fertilizer is used in oilseed rape production. But from the viewpoint of diminishing the production cost, 10 cm deep fertilization should be recommended in actual farming. Because 15 cm deep fertilization may require higher mechanical power input, and thus resulting in higher cost of production.     

Radiation interception and radiation use efficiency of potato affected by different N fertigation and irrigation regimes

Three years of field experiments were carried out to explore the response of potato dry matter production, accumulated intercepted photosynthetic active radiation (Aipar) and radiation use efficiency (RUE) to five N levels providing 0, 60, 100, 140 and 180 kg N ha⁻¹ and three drip irrigation strategies, which were full, deficit and none irrigation. Results showed that, irrespective of years, dry matter production and Aipar were increased by prolonged N fertigation, even though N fertigation was carried out from middle to late growing season. The highest total and tuber dry matter and accumulated radiation interception in all three years were obtained when potatoes were provided with 180 kg N ha⁻¹. RUE on the other hand was not affected by N regime. Thus, increases in total dry matter production with increasing N levels were essentially caused by higher Aipar. The strongest response to N fertilization occurred when most N was applied early in the growing season and the latest N fertilization should be applied no later than 41–50 days after emergence. Deficit irrigation, which received ca.70% of irrigation applied to full irrigation, did not reduce radiation interception and radiation use efficiency.     

Effects of low temperature storage and sucrose pulsing on the vase life of Lilium cv. Brindisi inflorescences

Lilium cv. Brindisi inflorescences were stored at 2.5 °C for 5, 10, 15 or 20 d, comparing dry storage with storage of the stem ends in water. Prior to storage, inflorescences were treated with 20 or 100 g L⁻¹ sucrose in water, for 20 h at 20 °C. After storage the inflorescences were individually placed in water at 20 °C. The floral buds were still closed at the end of cold storage. In experiments carried out in summer, the time to bud opening was hastened by storage at 2.5 °C in water, more so after a longer period of cold storage. The time to tepal senescence after cold storage in water decreased with the time of storage. The time to tepal abscission was about 1 day longer than the time to tepal senescence. Repeat experiments in late fall and winter additionally showed early leaf yellowing after cold storage. Compared to the experiments in summer, more desiccated floral buds were found in the fall. Pulse treatment with 100 g L⁻¹ sucrose prior to cold storage reduced the number of desiccated buds. However, leaf yellowing was aggravated by the 100 g L⁻¹ sucrose pulse treatment. Compared to cold storage in water, dry storage at 2.5 °C further hastened the time to bud opening and also further hastened tepal senescence and abscission. Dry storage also produced more buds that desiccated or opened poorly. Sucrose treatment (100 g L⁻¹) alleviated the effects of dry storage on tepal senescence and bud desiccation. The data showed that lily cv. Brindisi inflorescences are prone to chilling injury, but can be stored, depending on the treatment, for 5–10 d, during most of the year.