Roberta Boselli, N. Anders, A. Fiorini, C. Ganimede, N. Faccini, A. Marocco, M. Schulz, V. Tabaglio
{"title":"Improving weed control in sustainable agro-ecosystems: role of cultivar and termination timing of rye cover crop","authors":"Roberta Boselli, N. Anders, A. Fiorini, C. Ganimede, N. Faccini, A. Marocco, M. Schulz, V. Tabaglio","doi":"10.4081/IJA.2021.1807","DOIUrl":null,"url":null,"abstract":"Alternative strategies to control weeds are required at field level to reduce herbicides and derived pollution. Rye (Secale cereale L.) cultivation as cover crop is adopted mainly because of its allelopathic weed control, which takes place throughout a strong inhibition of germination and seedling growth in several grass and broad-leaved weeds. The present study consisted of: i) a field trial, focused on evaluation of biomass production and allelochemical concentration in the biomass, and in situ weed control at 30 days after termination (with two termination timings: T1 heading phase and T2 10 days later) of 8 rye varieties; ii) a pot experiment, focused on the inhibition effect of mulches derived by those 8 rye varieties on four summer weeds: velvetleaf (Abutilon theophrasti Med.), lambsquarters (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), and common purslane (Portulaca oleracea L). Results showed that biomass production was the highest with Protector, closely followed by Primizia, Sito 70, Hellvus, Forestal, and Hymonta. In any case, rye mulching always reduced the weed biomass, especially with Fasto and Forestal. The allelochemical concentration in the biomass was the highest with Fasto and Forestal, and decreased on average from T1 to T2 (-38% for total BX and -57% for isovitexin). Conversely, the rye biomass production increased (on average + 77%) passing from T1 to T2. We found also that the reduction of weed biomass, compared with the control, is highly Ac ce pt ed p ap er correlated with the allelochemical content in rye biomass in the case of T1 termination, while with the biomass production in the case of T2. In pots, a strong inhibitory effect on seedling growth due to rye mulching was observed for C. album (-76%), A. retroflexus (-56%), and P. olearcea (-84%), while not for A. theophrasti. We concluded that, whatever the variety, adopting rye as cover crop may be considered as a suitable practice to reduce weed pressure at the field level. Among all the varieties tested, Forestal and Protector showed the greatest weed suppression potential, as a consequence of high amount of allelochemicals production for Forestal, and high biomass production for Protector. Introduction Weed control strategies based on the use of herbicides are expensive and may affect negatively the quality of soil, water and air (Felsot et al., 2011). The excessive use of chemical herbicides in the last decades led to the development of herbicide resistance: 262 species of herbicide-resistant weeds have been detected on 93 crops in 70 countries (Beckie, 2020). Consequently, a growing interest in alternative strategies for weed management has been stimulated worldwide to address current economic and environmental challenges of crop production (Kumar et al., 2020). In addition, the European Commission recently stated ambitious goals for reducing the herbicide use (-50%) at the field level by 2030 (European Commission, 2021). The use of cover crops (CCs) has long been indicated as a good solution for limiting weed development in a broad series of agro-ecosystems, thus reducing herbicide use and cost (Barnes and Putnam, 1983). It was shown that selected CC species (e.g. gramineous plants) may suppress weeds due to their high competitiveness for space, light, water and nutrient use (Hiltbrunner et al., 2007). Also, CC residues that remains onto the soil surface can limit weed germination and development by reducing light transmittance and soil temperature (Wayman et al., 2015). In addition, some CCs produce allelochemical compounds as secondary metabolites [(e.g. benzoxazinoids, flavonoids, alkaloids, etc. (Scavo et al., 2019)], which are released both by living or decaying plant tissues, and Ac ce pt ed p ap er exert a strong control on weeds (Liebman and Davis, 2015). A plant species considered as a reference for the allelopathic weed control is rye (Secale cereale L.) (Tabaglio et al., 2008). Rye is one of the most commonly used winter cover crops, due to high biomass production, soil and climate adaptability, nitrous oxide emission mitigation, and weed suppression potential (Gavazzi et al., 2010; Fiorini et al., 2020). After termination, rye mulch can be left on the soil surface (i.e. in the case of no-till soil management) to ensure a persistent inhibitory effect on weed germination and development (Mirsky et al., 2013; Tabaglio et al., 2013). Beyond the suppressing effect of rye mulch on weeds, which highly depends on the thickness of the mulch layer (Teasdale and Mohler, 2000), rye residue maintained on the soil surface was reported to release the benzoxazinoids 2,4-dihydroxy-1,4 (2H)-benzoxazin-3-one (DIBOA) and benzoxazolin-2(3H)-one (BOA) (Schulz et al., 2013). Those allelochemical compounds strongly inhibit the germination and seedling growth of several grass and broad-leaved spontaneous plants (Macías et al., 2019). Under field conditions, the amount of benzoxazinoids (BX) released by rye is estimated to range between 0.5 and 5 kg ha-1, depending on variety and date of phenological phase of termination (Reberg-Horton et al., 2005). Rice et al. (2005) reported that BX concentration consistently decreases in rye tissues from tillering to flowering. However, previous studies did not consider the component of benzoxazinoids bound to the cell wall: this component is probably not available immediately after rye termination, but it can be released gradually afterwards, affecting the long-term allelochemical potential. Besides benzoxazinoids, also flavonoids have a high allelopathic potential: isovitexin was isolated in flavonoid fraction of oat (Avena sativa L.) (de Bertoldi et al., 2009), which demonstrated a good control of weeds. A clear assessment on relationships between rye varieties and allelochemical concentration under field conditions is missing in our soil-climate conditions and only few studies previously compared the effect of termination time on allelochemical concentration in different rye varieties, evaluating the effect on weed development under both field and greenhouse conditions. In addition, previous Ac ce pt ed p ap er studies did not assess the concentration of cell wall-bound BOA, which may contribute to a long-term allelopathic effect. The present study aims to: (i) identify the best rye varieties for benzoxazinoids and isovitexin concentrations and production in order to improving sustainable weed control, (ii) find the combination rye variety × termination timing that can exert the highest and lasting level of weed suppression. We hypothesized that terminating the cover crop early (at the heading phase) may enhance the alleochemical content and, consequently, the control of weeds. Materials and methods Field experiment The field trial was carried out at CREA Institute, located in Fiorenzuola d’Arda, Piacenza, Northern Italy (lat. 44.926383 N; long. 9.890661 E), from October 2014 to July 2015. Soil characteristics (0-30 cm soil depth) at the beginning of the experiment are reported in Table 1. The climate is temperate; mean annual rainfall and temperature are 774 mm and 12.8° C, respectively. Climatic data during the experiment were collected from an automated meteorological station situated close to the experimental field (Fig. S1). The experiment compared 8 treatments, corresponding to 8 rye varieties (6 cultivars: Dukato, Fasto, Forestal, Primizia, Protector, and Sito 70; 2 hybrids: Hellvus and Hymonta), each one replicated 4 times, for a total of 32 main plots (plot area of 10.2 m2). Then, each plot was divided into two subplots (sub-plot area of 5.1 m2) according to the two selected rye termination timings (i.e. at heading phase [T1] and 10 days after the full heading phase [T2]), thus obtaining a total number of 64 subplots. As a result, a split-plot (SP) experimental design was obtained, where the main factor was the rye variety, and the secondary factor was the rye termination timing. Rye was sown on 29th October 2014, using an 8-row plot-seeder (mod. Wintersteiger), the seeding rate was 110 kg ha-1. Four more plots (one for each block) without rye were used as a control. In the Ac ce pt ed p ap er control plots the vegetation was let to grow spontaneously. Fertilization was carried out twice: (1) before sowing using a ternary fertilizer (15-15-15) applying 45 kg ha-1 of N, 20 kg ha-1 of P and 37 kg ha-1 of K; (2) at the end of the tillering using ammonium nitrate (26% N) distributing 52 kg ha-1 of N. The phenological and yield data were determined in the sub-plot area according to the following termination timing: (T1) at the heading phase and (T2) 10 days after. The aboveground biomass production was obtained cutting manually the whole sub-plots biomass at the two termination timings. Prior to each cut, plant height was determined by measuring 20 randomly chosen plants from the ground level, for each subplot. After cutting, rye aboveground biomass was weighted in the field. A sub-sample of about 800 g was collected to be used (i) as rye mulch for the pot trial (only for subplots harvested at T1, as described below), and (ii) for the allelochemical analyses on a dry matter basis, after being oven-dried at 65 °C to constant weight. The remaining biomass was left onto the soil as mulch for evaluating the effect on weed development directly into the field. Weed density was measured in each sub-plot placing twice randomly a circle of 0.125 m2 30 days after both rye termination timing. Weeds in each sampling area were collected and oven-dried at 105 °C for 48 hours for calculating the total dry weight per plot. Greenhouse pot experiment A greenhouse experiment was set up using rye biomass harvested at T1. The experiment was conducted immediately after rye harvest and it was designed as a randomized complete block (RCB) with 8 treatments and 6 replicates. The 8 treatments were represented by the 8 rye varieties used in the field trial. 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引用次数: 7
Abstract
Alternative strategies to control weeds are required at field level to reduce herbicides and derived pollution. Rye (Secale cereale L.) cultivation as cover crop is adopted mainly because of its allelopathic weed control, which takes place throughout a strong inhibition of germination and seedling growth in several grass and broad-leaved weeds. The present study consisted of: i) a field trial, focused on evaluation of biomass production and allelochemical concentration in the biomass, and in situ weed control at 30 days after termination (with two termination timings: T1 heading phase and T2 10 days later) of 8 rye varieties; ii) a pot experiment, focused on the inhibition effect of mulches derived by those 8 rye varieties on four summer weeds: velvetleaf (Abutilon theophrasti Med.), lambsquarters (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), and common purslane (Portulaca oleracea L). Results showed that biomass production was the highest with Protector, closely followed by Primizia, Sito 70, Hellvus, Forestal, and Hymonta. In any case, rye mulching always reduced the weed biomass, especially with Fasto and Forestal. The allelochemical concentration in the biomass was the highest with Fasto and Forestal, and decreased on average from T1 to T2 (-38% for total BX and -57% for isovitexin). Conversely, the rye biomass production increased (on average + 77%) passing from T1 to T2. We found also that the reduction of weed biomass, compared with the control, is highly Ac ce pt ed p ap er correlated with the allelochemical content in rye biomass in the case of T1 termination, while with the biomass production in the case of T2. In pots, a strong inhibitory effect on seedling growth due to rye mulching was observed for C. album (-76%), A. retroflexus (-56%), and P. olearcea (-84%), while not for A. theophrasti. We concluded that, whatever the variety, adopting rye as cover crop may be considered as a suitable practice to reduce weed pressure at the field level. Among all the varieties tested, Forestal and Protector showed the greatest weed suppression potential, as a consequence of high amount of allelochemicals production for Forestal, and high biomass production for Protector. Introduction Weed control strategies based on the use of herbicides are expensive and may affect negatively the quality of soil, water and air (Felsot et al., 2011). The excessive use of chemical herbicides in the last decades led to the development of herbicide resistance: 262 species of herbicide-resistant weeds have been detected on 93 crops in 70 countries (Beckie, 2020). Consequently, a growing interest in alternative strategies for weed management has been stimulated worldwide to address current economic and environmental challenges of crop production (Kumar et al., 2020). In addition, the European Commission recently stated ambitious goals for reducing the herbicide use (-50%) at the field level by 2030 (European Commission, 2021). The use of cover crops (CCs) has long been indicated as a good solution for limiting weed development in a broad series of agro-ecosystems, thus reducing herbicide use and cost (Barnes and Putnam, 1983). It was shown that selected CC species (e.g. gramineous plants) may suppress weeds due to their high competitiveness for space, light, water and nutrient use (Hiltbrunner et al., 2007). Also, CC residues that remains onto the soil surface can limit weed germination and development by reducing light transmittance and soil temperature (Wayman et al., 2015). In addition, some CCs produce allelochemical compounds as secondary metabolites [(e.g. benzoxazinoids, flavonoids, alkaloids, etc. (Scavo et al., 2019)], which are released both by living or decaying plant tissues, and Ac ce pt ed p ap er exert a strong control on weeds (Liebman and Davis, 2015). A plant species considered as a reference for the allelopathic weed control is rye (Secale cereale L.) (Tabaglio et al., 2008). Rye is one of the most commonly used winter cover crops, due to high biomass production, soil and climate adaptability, nitrous oxide emission mitigation, and weed suppression potential (Gavazzi et al., 2010; Fiorini et al., 2020). After termination, rye mulch can be left on the soil surface (i.e. in the case of no-till soil management) to ensure a persistent inhibitory effect on weed germination and development (Mirsky et al., 2013; Tabaglio et al., 2013). Beyond the suppressing effect of rye mulch on weeds, which highly depends on the thickness of the mulch layer (Teasdale and Mohler, 2000), rye residue maintained on the soil surface was reported to release the benzoxazinoids 2,4-dihydroxy-1,4 (2H)-benzoxazin-3-one (DIBOA) and benzoxazolin-2(3H)-one (BOA) (Schulz et al., 2013). Those allelochemical compounds strongly inhibit the germination and seedling growth of several grass and broad-leaved spontaneous plants (Macías et al., 2019). Under field conditions, the amount of benzoxazinoids (BX) released by rye is estimated to range between 0.5 and 5 kg ha-1, depending on variety and date of phenological phase of termination (Reberg-Horton et al., 2005). Rice et al. (2005) reported that BX concentration consistently decreases in rye tissues from tillering to flowering. However, previous studies did not consider the component of benzoxazinoids bound to the cell wall: this component is probably not available immediately after rye termination, but it can be released gradually afterwards, affecting the long-term allelochemical potential. Besides benzoxazinoids, also flavonoids have a high allelopathic potential: isovitexin was isolated in flavonoid fraction of oat (Avena sativa L.) (de Bertoldi et al., 2009), which demonstrated a good control of weeds. A clear assessment on relationships between rye varieties and allelochemical concentration under field conditions is missing in our soil-climate conditions and only few studies previously compared the effect of termination time on allelochemical concentration in different rye varieties, evaluating the effect on weed development under both field and greenhouse conditions. In addition, previous Ac ce pt ed p ap er studies did not assess the concentration of cell wall-bound BOA, which may contribute to a long-term allelopathic effect. The present study aims to: (i) identify the best rye varieties for benzoxazinoids and isovitexin concentrations and production in order to improving sustainable weed control, (ii) find the combination rye variety × termination timing that can exert the highest and lasting level of weed suppression. We hypothesized that terminating the cover crop early (at the heading phase) may enhance the alleochemical content and, consequently, the control of weeds. Materials and methods Field experiment The field trial was carried out at CREA Institute, located in Fiorenzuola d’Arda, Piacenza, Northern Italy (lat. 44.926383 N; long. 9.890661 E), from October 2014 to July 2015. Soil characteristics (0-30 cm soil depth) at the beginning of the experiment are reported in Table 1. The climate is temperate; mean annual rainfall and temperature are 774 mm and 12.8° C, respectively. Climatic data during the experiment were collected from an automated meteorological station situated close to the experimental field (Fig. S1). The experiment compared 8 treatments, corresponding to 8 rye varieties (6 cultivars: Dukato, Fasto, Forestal, Primizia, Protector, and Sito 70; 2 hybrids: Hellvus and Hymonta), each one replicated 4 times, for a total of 32 main plots (plot area of 10.2 m2). Then, each plot was divided into two subplots (sub-plot area of 5.1 m2) according to the two selected rye termination timings (i.e. at heading phase [T1] and 10 days after the full heading phase [T2]), thus obtaining a total number of 64 subplots. As a result, a split-plot (SP) experimental design was obtained, where the main factor was the rye variety, and the secondary factor was the rye termination timing. Rye was sown on 29th October 2014, using an 8-row plot-seeder (mod. Wintersteiger), the seeding rate was 110 kg ha-1. Four more plots (one for each block) without rye were used as a control. In the Ac ce pt ed p ap er control plots the vegetation was let to grow spontaneously. Fertilization was carried out twice: (1) before sowing using a ternary fertilizer (15-15-15) applying 45 kg ha-1 of N, 20 kg ha-1 of P and 37 kg ha-1 of K; (2) at the end of the tillering using ammonium nitrate (26% N) distributing 52 kg ha-1 of N. The phenological and yield data were determined in the sub-plot area according to the following termination timing: (T1) at the heading phase and (T2) 10 days after. The aboveground biomass production was obtained cutting manually the whole sub-plots biomass at the two termination timings. Prior to each cut, plant height was determined by measuring 20 randomly chosen plants from the ground level, for each subplot. After cutting, rye aboveground biomass was weighted in the field. A sub-sample of about 800 g was collected to be used (i) as rye mulch for the pot trial (only for subplots harvested at T1, as described below), and (ii) for the allelochemical analyses on a dry matter basis, after being oven-dried at 65 °C to constant weight. The remaining biomass was left onto the soil as mulch for evaluating the effect on weed development directly into the field. Weed density was measured in each sub-plot placing twice randomly a circle of 0.125 m2 30 days after both rye termination timing. Weeds in each sampling area were collected and oven-dried at 105 °C for 48 hours for calculating the total dry weight per plot. Greenhouse pot experiment A greenhouse experiment was set up using rye biomass harvested at T1. The experiment was conducted immediately after rye harvest and it was designed as a randomized complete block (RCB) with 8 treatments and 6 replicates. The 8 treatments were represented by the 8 rye varieties used in the field trial. The experiment was conducted using plast
需要在田间一级采用其他控制杂草的策略,以减少除草剂和衍生污染。采用黑麦(Secale cereale L.)作为覆盖作物的主要原因是它具有化感作用,对几种禾本科和阔叶类杂草的萌发和幼苗生长都有很强的抑制作用。本研究包括:1)田间试验,重点评价8个黑麦品种的生物量产量和生物量中的化感化学浓度,并在终止后30天(有两个终止时间:抽穗期T1和10天后T2)进行原位杂草控制;ii)通过盆栽试验,研究了8个黑麦品种的地膜对4种夏季杂草的抑制效果,分别是绒叶(Abutilon theophrasti Med.)、羊蹄草(Chenopodium album L.)、红根藜草(Amaranthus retroflexus L.)和马齿苋(Portulaca oleracea L.)。结果表明,保护膜的生物量产量最高,其次是Primizia、Sito 70、Hellvus、Forestal和Hymonta。在任何情况下,黑麦覆盖都减少了杂草生物量,尤其是Fasto和Forestal。生物量中的化感物质浓度以Fasto和Forestal最高,从T1到T2平均下降(总BX -38%,异牡荆素-57%)。相反,从T1到T2,黑麦生物量产量增加(平均+ 77%)。我们还发现,与对照相比,在T1终止下,杂草生物量的减少与黑麦生物量的化感化学含量相关,而在T2终止下,与生物量产量相关。在盆栽条件下,黑麦覆盖对黑麦黑麦种子的生长有较强的抑制作用,对黑麦黑麦黑麦种子的生长有-76%的抑制作用,对黑麦黑麦黑麦黑麦种子的生长有-56%的抑制作用,对黑麦黑麦黑麦黑麦种子的生长有-84%的抑制作用。综上所述,无论何种品种,采用黑麦作为覆盖作物可被认为是减少田间杂草压力的适宜做法。在所有被试品种中,森林和护林表现出最大的杂草抑制潜力,这是因为森林和护林的化感物质产量高,而护林的生物量产量高。基于除草剂使用的杂草控制策略是昂贵的,并且可能对土壤、水和空气的质量产生负面影响(Felsot et al., 2011)。在过去的几十年里,化学除草剂的过度使用导致了除草剂抗性的发展:在70个国家的93种作物上发现了262种抗除草剂杂草(Beckie, 2020)。因此,全球对杂草管理替代策略的兴趣日益浓厚,以解决当前作物生产的经济和环境挑战(Kumar等人,2020)。此外,欧盟委员会最近提出了雄心勃勃的目标,即到2030年减少除草剂的使用(-50%)(欧盟委员会,2021年)。长期以来,使用覆盖作物(CCs)一直被认为是在广泛的农业生态系统中限制杂草发展的一个很好的解决方案,从而减少除草剂的使用和成本(Barnes和Putnam, 1983)。研究表明,某些CC物种(如禾草植物)可能抑制杂草,因为它们在空间、光、水和养分利用方面具有很高的竞争力(hilthbrunner et al., 2007)。此外,残留在土壤表面的CC残留物可以通过降低透光率和土壤温度来限制杂草的萌发和发育(Wayman et al., 2015)。此外,一些cc作为次生代谢物产生化感化合物[如苯并恶嗪类化合物、类黄酮、生物碱等[Scavo等,2019],这些化合物通过活的或腐烂的植物组织释放出来,并且acp对杂草有很强的控制作用(Liebman and Davis, 2015)。黑麦(Secale cereale L.) (Tabaglio et al., 2008)被认为是化感杂草防治的参考植物。黑麦是最常用的冬季覆盖作物之一,因为它具有高生物量、土壤和气候适应性、一氧化二氮排放减缓和杂草抑制潜力(Gavazzi等,2010;Fiorini et al., 2020)。终止后,黑麦地膜可留在土壤表面(即在免耕土壤管理的情况下),以确保对杂草萌发和发育的持续抑制作用(Mirsky et al., 2013;Tabaglio et al., 2013)。黑麦覆盖对杂草的抑制作用高度依赖于覆盖层的厚度(Teasdale and Mohler, 2000),此外,据报道,保持在土壤表面的黑麦残留物还会释放出苯并恶嗪类化合物2,4-二羟基-1,4 (2H)-苯并恶嗪-3-one (DIBOA)和苯并恶唑啉-2(3H)-one (BOA) (Schulz et al., 2013)。这些化感化合物强烈抑制几种禾草和阔叶自发植物的发芽和幼苗生长(Macías et al., 2019)。 在田间条件下,黑麦释放的苯并恶嗪类化合物(BX)估计在0.5至5 kg ha-1之间,这取决于品种和物候终止期的日期(Reberg-Horton et al., 2005)。Rice等人(2005)报道,从分蘖到开花,黑麦组织中BX浓度持续下降。然而,以往的研究没有考虑到苯并恶嗪类化合物与细胞壁结合的成分:该成分可能在黑麦终止后不能立即得到,但可以在之后逐渐释放,影响长期的化感化学势。除了苯并恶嗪类化合物外,黄酮类化合物也具有很高的化感作用潜力:从燕麦(Avena sativa L.)的黄酮类化合物中分离到异牡牡素(de Bertoldi et al., 2009),证明其对杂草有很好的控制作用。我国土壤气候条件下黑麦品种与化感物质浓度之间的关系缺乏明确的评价,比较终止时间对不同黑麦品种化感物质浓度的影响,评估田间和温室条件下对杂草发育的影响的研究也很少。此外,以往的研究没有评估细胞壁结合BOA的浓度,这可能有助于长期的化感作用。本研究旨在:(1)确定苯并恶嗪类药物和异牡荆素浓度和产量的最佳黑麦品种,以提高杂草的可持续控制水平;(2)寻找对杂草抑制效果最高、最持久的组合黑麦品种×终止时间。我们推测,尽早(抽穗期)终止覆盖作物可能会提高异化化学含量,从而控制杂草。现场试验在位于意大利北部皮亚琴察Fiorenzuola d 'Arda的CREA研究所进行。44.926383 N;长。9.890661 E), 2014年10月至2015年7月。试验开始时土壤特性(0 ~ 30 cm土层深度)见表1。气候温和;年平均降雨量为774毫米,年平均气温为12.8℃。实验期间的气候数据由靠近实验田的自动气象站收集(图S1)。试验比较了8个处理,对应8个黑麦品种(Dukato、Fasto、Forestal、Primizia、Protector和Sito 70 6个品种;2个杂交种:Hellvus和Hymonta),每个重复4次,共32个主要地块(地块面积10.2 m2)。然后,根据选择的两个黑麦终止时间(抽穗期[T1]和完穗期后10天[T2]),将每个小区分成两个子小区,子小区面积为5.1 m2,共64个子小区。以黑麦品种为主要影响因素,黑麦终止时间为次要影响因素的裂区试验设计。黑麦于2014年10月29日播种,采用8行畦播机(Wintersteiger),播种量为110 kg hm -1。另外四个地块(每个地块一个)不种植黑麦作为对照。在试验区和对照区,让植被自然生长。施两次肥:(1)播前施用三元肥(15-15-15),施氮45 kg hm -1、磷20 kg hm -1、钾37 kg hm -1;(2)分蘖结束时,施用硝铵(26% N),施氮52 kg hm -1,分样区物候和产量数据按抽穗期终止时间(T1)和抽穗期终止时间(T2)进行测定。在两个终止时间,人工切断整个子地块的生物量,获得地上生物量产量。在每次切割之前,通过测量从地面随机选择的20株植物来确定每个子样的植物高度。刈割后,田间对黑麦地上生物量进行加权。收集了约800克的子样品,用于(i)作为盆栽试验的黑麦地膜(仅用于T1收获的子地块,如下所述),以及(ii)在65°C烤箱干燥至恒重后,用于干物质基础上的化感化学分析。剩余生物量留在土壤中作为地膜,以评估对直接进入田间的杂草发育的影响。在黑麦终止后30 d,每个小区随机放置2次,面积为0.125 m2。收集每个采样区的杂草,在105°C下烘干48小时,计算每块的总干重。以T1收获的黑麦生物量为原料,建立了温室盆栽试验。试验在黑麦收获后立即进行,设计为随机完全区组(RCB), 8个处理,6个重复。 8个处理以大田试验的8个黑麦品种为代表。实验是用塑料进行的
期刊介绍:
The Italian Journal of Agronomy (IJA) is the official journal of the Italian Society for Agronomy. It publishes quarterly original articles and reviews reporting experimental and theoretical contributions to agronomy and crop science, with main emphasis on original articles from Italy and countries having similar agricultural conditions. The journal deals with all aspects of Agricultural and Environmental Sciences, the interactions between cropping systems and sustainable development. Multidisciplinary articles that bridge agronomy with ecology, environmental and social sciences are also welcome.