Breeding for improved drought tolerance in Chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is an important legume crop as a protein source across the world. It is mostly grown on arid and marginal lands where it faces drought stress at different growth stages. Drought stress exerts drastic effects on nutrient uptake, hinders the nodule formation and adversely affects yield and yield components. Generally drought at any growth stage and organizational level is responsible for reduction in economic yield. Significant variability in chickpea germplasm is present on the basis of responses to drought stress in the form of drought escape, drought avoidance and drought tolerance; these mechanisms prevent chickpea crop from harmful effects of drought. Improvement in chickpea germplasm against drought stress could be made by using several breeding approaches, that is introduction, hybridization, mutation breeding, marker‐assisted breeding and omic techniques. These breeding approaches, especially marker‐assisted breeding and omics, are further strengthened with the availability of the chickpea genome sequence. This review highlighted the significance, status and advances in different breeding strategies for improvement of drought tolerance in chickpea.     

持续性温强和土壤水分对玉米发育进程的影响及其模拟

作物的发育进程对产量形成有重要影响,在作物生长模型中也起着时间指针的重要作用。但目前逐日累积温度的发育模式无法解释作物播期不同而成熟期差距很小或基本相同的现象;目前对土壤湿度影响作物发育进程的规律也不十分清楚,多数作物生长模型也未予考虑。本研究以华北夏玉米为研究对象,首先对几种常用的作物发育模式进行稳定性比较,然后再分别探讨持续性温度强度和土壤湿度对夏玉米发育进程的影响规律,并构造相关模式。结果表明,积温(TSUM)、发育单位(CHU)和热量单位(THU)等发育模式中以THU的稳定性最高。夏玉米发育进程不仅由累积温度或热量单位决定,而且受持续性温度强度（某一发育阶段的平均温度）的明显影响。平均温度较高时,完成该发育进程需要累积更多的温度。据此建立的模式对夏玉米分期播种的发育进程模拟有明显改善。土壤水分对夏玉米发育进程有明显影响,水分增加将促使夏玉米营养生长阶段的发育加速,导致抽雄期提前。由此建立的模式对区域上夏玉米发育进程的模拟有一定改善。     

Effect of Sulphur and Foliar-applied Chemicals on Cold Tolerance in Chickpea (Cicer arietinum L.)

In a field study it was observed that sulphur fertilization of chickpea at 100 kg S ha⁻¹ imparted cold tolerance under low temperature stress conditions. Further, foliar sprays of DMSO, H₂SO⁴, KCl and H³BO³ proved effective in alleviating cold injury. Glucose spray also showed efficacy in this regard. The effects of sulphur fertilization and foliar applied DMSO and H²SO⁴ were largely associated with improved sulphur nutrition of plants, while improvement in K content under KCl treatment and B content under H₃BO₃ treatment was responsible for cold tolerance effects. Improvement in overall soluble carbohydrate and protein status of plants was held responsible for glucose effects possibly associated with osmoregulation.     

Inheritance of Seed Coat Thickness in Chickpea (Cicer arietinum L.) and its Evolutionary Implications

The desi and kabuli chickpeas are characterized, among other things, by their seed coats being thicker in the desi than in the kabuli type. The inheritance of seed coat thickness, and its relation to flower colour and seed size, was studied. Seed coat thickness exhibits monogenic inheritance, the thin kabuli seed coat being the recessive character. Linkage was found between seed coat thickness and flower colour, the recombinant fraction being 0.19. No relationship was found between seed coat thickness and seed size. The role of these characters in the evolution of the chickpea is discussed.     

Modelling Biomass Accumulation and Partitioning in Chickpea (Cicer arietinum L.)

Quantitative information regarding biomass accumulation and partitioning in chickpea (Cicer arietinum L.) is limited or inconclusive. The objective of this study was to obtain baseline values for extinction coefficient (K_S), radiation use efficiency (RUE, g MJ^?1) and biomass partitioning coefficients of chickpea crops grown under well‐watered conditions. The stability of these parameters during the crop life cycle and under different environmental and growth conditions, caused by season and sowing date and density, were also evaluated. Two field experiments, each with three sowing dates and four plant densities, were conducted during 2002–2004. Crop leaf area index, light interception and crop biomass were measured between emergence and maturity. A K_S value of 0.5 was obtained. An average RUE of 1 g MJ^?1 was obtained. Plant density had no effect on RUE, but some effects of temperature were detected. There was no effect of solar radiation or vapour pressure deficit on RUE when RUE values were corrected for the effect of temperature. RUE was constant during the whole crop cycle. A biphasic pattern was found for biomass partitioning between leaves and stems before first‐seed stage. At lower levels of total dry matter, 54 % of biomass produced was allocated to leaves, but at higher levels of total dry matter, i.e. under favourable and prolonged conditions for vegetative growth, this portion decreased to 28 %. During the period from first‐pod to first‐seed, 60 % of biomass produced went to stems, 27 % to pods and 13 % to leaves. During the period from first‐seed to maturity, 83 % of biomass was partitioned to pods. It was concluded that using fixed partitioning coefficients after first‐seed are not as effective as they are before this stage. Environmental conditions (temperature and solar radiation) and plant density did not affect partitioning of biomass.     

Interactive Effects of Salinity and Biological Nitrogen Fixation on Chickpea (Cicer arietinum L.) Growth

The effect of salinity on the nodulation, N-fixation and plant growth of selected chickpea- Rhizobium symbionts was studied- Eighteen chickpea rhizobial strains were evaluated for their growth in a broth culture at salinity levels of 0 to 20 dS m⁻¹ of NaCl + Na₂SO₄. Variability in response was high. Salinity generally reduced the lag phase and/or slowed the log phase of multiplication of Rhizobium. Nine chickpea genotypes were also evaluated for salt tolerance during germination and early seedling growth in Petri dishes at five salinity levels (0–32 dS m⁻¹). Chickpea genotypes ILC-205 and ILC-1919 were the most salt-tolerant genotypes. The selected rhizobial strains and chickpea cultivars were combined in a pot experiment aimed at investigating the interactive effect of salinity (3, 6 and 9 dS m⁻¹) and N source (symbiosis vs. inorganic N) on plant growth. Symbiotic plants were more sensitive to salinity than plants fed mineral N. Significant reductions in nodule dry weight (59.8 %) and N fixation (63.5 %) were evident even at the lowest salinity level of 3 dS m-¹. Although nodules were observed in inoculated plants grown at 6 dS m-¹, N-fixation was completely inhibited. The findings indicate that symbiosis is more salt-sensitive than both Rhizobium and the host plant, probably due to a breakdown in one of the processes involved in symbiotic-N fixation. Improvement of salinity tolerance in field grown chickpea may be achieved by application of sufficient amounts of mineral nitrogen.     

Low Temperature Effects during Seed Filling on Chickpea Genotypes (Cicer arietinum L.): Probing Mechanisms affecting Seed Reserves and Yield

Chickpea is sensitive to cold conditions (<15 °C), particularly at its reproductive phase and consequently it experiences significant decrease in the seed yield. The information about the effects of cold stress on chickpea during the seed filling phase is lacking. Moreover, the underlying metabolic reasons associated with the low temperature injury are largely unknown in the crop. Hence, the present study was undertaken with the objectives: (i) to find out the possible mechanisms leading to low temperature damage during the seed filling and (ii) to investigate the relative response of the microcarpa (Desi) and the macrocarpa (Kabuli) chickpea types along with elucidation of the possible mechanisms governing the differential cold sensitivity at this stage. At the time of initiation of the seed filling (pod size ∼1 cm), a set of plants growing under warm conditions of the glasshouse (temperature: 17/28 ± 2 °C as average night and day temperature) was subjected to cold conditions of the field (2.3/11.7 ± 2 °C as average night and day temperature), while another set was maintained under warm conditions (control). The chilling conditions resulted in the increase in electrolyte leakage, the loss of chlorophyll, the decrease in sucrose content and the reduction in water status in leaves, which occurred to a greater extent in the macrocarpa type than in the microcarpa type. The total plant weight decreased to the same level in both the chickpea types, whereas the rate and duration of the seed filling, seed size, seed weight, pods per plant and harvest index decreased greatly in the macrocarpa type. The stressed seeds of both the chickpea types experienced marked reduction in the accumulation of starch, proteins, fats, crude fibre, protein fractions (albumins, globulins, prolamins and glutelins) with a larger decrease in the macrocarpa type. The accumulation of sucrose and the activity levels of the enzymes like starch synthase, sucrose synthase and invertase decreased significantly in the seeds because of the chilling, indicating impairment in sucrose import. Minerals such as calcium, phosphorous and iron as well as several amino acids (phenylalanine, tyrosine, threonine, tryptophan, valine and histidine) were lowered significantly in the stressed seeds. These components were limited to a higher extent in the macrocarpa type indicating higher cold sensitivity of this type.     

Genotypic Variation in Root Systems of Chickpea (Cicer arietinum L.) across Environments

Root systems of various chickpea genotypes were studied over time and in diverse environments, – varying in soil bulk density, phosphorus (P) levels and moisture regimes. In a pot study comparing a range of chickpea genotypes, ICC 4958 and ICCV 94916‐4 produced higher root length density (RLD) and root dry weight (RDW), which were better expressed under P stress conditions. In two field experiments in soils of intermediate and high soil bulk densities, ICC 4958 also had greater RLD and RDW, particularly under soil moisture stress conditions. The expression of greater rooting ability of ICC 4958 under a wide range of environmental conditions confirms its suitability as a parent for genetically enhancing drought resistance and P acquisition ability. The superiority of ICC 4958 over other genotypes was for root proliferation expressed through RLD. Thus, the variation in RLD can be the most relevant root trait that reflects chickpea's potential for soil moisture or P acquisition.     

Exogenous Application of Abscisic Acid Improves Cold Tolerance in Chickpea (Cicer arietinum L.)

Chickpea suffers cold stress (<10 °C) damage especially during reproductive phase resulting in the abortion of flowers and pods, poor pod set, and reduction in seed yield and seed quality. One of the ways in modifying cold tolerance involves exogenous treatment of the plants with chemicals having established role in cold tolerance. In the present study, the chickpea plants growing under optimum temperature conditions (28/12 °C, as average maximum and minimum temperature) were subjected to cold conditions of the field (10–12/2–4 °C; day/night as average maximum and minimum temperature) at the bud stage. Prior to exposure, these plants were treated exogenously with 10 μm abscisic acid (ABA) and thereafter again after 1 week of exposure. The stress injury measured in terms of increase in electrolyte leakage, decrease in 2,3,5-triphenyl tetrazolium chloride reduction %, relative leaf water content and chlorophyll content was observed to be significantly mitigated in ABA-applied plants. A greater pollen viability, pollen germination, flower retention and pod set were noticed in ABA-treated plants compared with stressed plants. The seed yield showed considerable improvement in the plants treated with ABA relative to the stressed plants that was attributed to the increase in seed weight, greater number of single seeded pods and reduction in number of infertile pods. The oxidative damage measured as thiobarbituric acid-reactive substances was lesser in ABA-treated plants that was associated with greater activities of superoxide dismutase, catalase, ascorbate peroxidase, ascorbic acid, glutathione and proline in these plants. It was concluded that cold stress effects were partly overcome by ABA treatment because of the improvement in water status of the leaves as well as the reduction in oxidative damage.     

Evaluation of Yield Criteria for Drought and Heat Resistance in Chickpea (Cicer arietinum L.)

The chickpea (Cicer arietinum L.) is usually grown under rainfed, rather than irrigated conditions, where drought accompanied by heat stress is a major growth constraint. The aim of this study was to select chickpea genotypes having resistance to drought/heat stress and to identify the most appropriate selection criteria for this. A total of 377 chickpea accessions were sown 2 months later than normal for the Antalya region (Turkey) to increase their exposure to the drought and high‐temperature conditions of a typical summer in this part of the world. Interspersed between every 10 test genotypes as benchmark genotypes, were plants of the two known genotypes ILC 3279 (drought‐susceptible) and ILC 8617 (drought‐susceptible), while ICC 4958 (known drought‐resistant) and ICCV 96029 (known very early, double‐podded) were also sown for confirmation. All plants were subsequently screened for drought and heat stress resistance. Soon after the two known susceptible genotypes had died, evaluations of the entire trial were made visually on a scale from ‘1’ (free from drought/heat damage) to ‘9’ (all plants died from drought/heat). Yield loss in many of the test genotypes and in the two known susceptible genotypes (ILC 3279 and ILC 8617) rose to 100 %. The desi chickpeas (smaller, dark seeds) were generally more drought‐ and heat‐resistant than the kabuli chickpeas (larger, pale seeds). Two desi chickpeas, ACC 316 and ACC 317, were selected for drought and heat (>40 °C) resistance under field conditions. Seed weight was the trait least affected by adverse environmental conditions and having the highest heritability, and it should be used in early breeding selections. When breeding drought‐ and heat‐resistant chickpeas, path and multivariate analyses showed that days to the first flowering and maturity to escape terminal drought and heat stresses should be evaluated ahead of many other phenological traits, and harvest index, biological yield and pods per plant for increased yield should also be considered.     

Salinity Effects on the Growth and Ion Contents of Some Chickpea (Cicer arietinum L.) and Lentil (Lens culinaris Medic.) Varieties

The effect of salinity on seed germination, plant yield parameters, and plant Na, Cl and K concentrations of chickpea and lentil varieties was studied. Results showed that in both crops percentage emergence was significantly reduced by increasing NaCl levels (0–8dSm^?1). From the plant growth studies it was found that differences existed among chickpea and lentil varieties in their response to NaCl application. In chickpea, the variety Mariye showed the comparatively lowest germination percentage and the lowest seedling shoot dry weight in response to salinity and was also among the two varieties which had the lowest relative plant height, shoot and root dry weight and grain yield at maturity. Similarly, variety DZ-10-16-2, which was the second best in germination percentage and the highest in terms of seedling shoot dry weight, also had the highest relative plant height, shoot and root dry weights, and grain yield at maturity. In lentil, however, such relationships were less pronounced. Chloride concentration (mg g^?1) in the plant parts at salt levels other than the control was about 2–5 times that of Na. K concentration in the plants was significantly reduced by increasing NaCl levels. Chickpea was generally more sensitive to NaCl salinity than lentil. While no seeds were produced at salinity levels beyond 2dSm^?1 in chickpea (no seeds were produced at this salt level in the most sensitive variety, Mariye), most lentil varieties could produce some seeds up to the highest level of NaCl application. Overall, varieties R-186 (lentil) and Mariye (chickpea) were the most sensitive of all varieties. On the other hand, lentil variety NEL-2704 and chickpea variety DZ-10-16-2 gave comparatively higher mean relative shoot and root dry weights, and grain yield, thus showing some degree of superiority over the others. The observed variations among the varieties may be useful indications for screening varieties of both crops for salt tolerance.     

不同覆盖材料土壤水温效应与作物增产效应分析

在位于山西省阳曲县河村的“国家‘十一五’支撑计划农业综合节水研究示范基地”,采用大田试验对不同材料（普膜、降解地膜、秸秆、液膜）覆盖下的土壤水分和温度动态变化以及玉米生长和产量效应、WUE进行了研究,并分析了不同覆盖材料的经济效益。结果表明：供试降解膜和普膜覆盖均具有显著的增温效果和一定的保水作用,秸秆覆盖同时具有显著的降温作用和保水作用,而供试液膜只具有一定的增温效应,无保水作用,不同覆盖材料的增温或降温效应主要表现在玉米生育前期。供试降解膜和普膜覆盖均显著促进了玉米生长发育,玉米产量和WUE以降解膜覆盖最高,普膜覆盖次之,但经济效益以普膜覆盖最好,降解膜覆盖次之。供试液膜对玉米生长也具有一定促进作用,玉米产量、WUE和经济效益也均略好于CK,但差异均不显著。而秸秆覆盖影响了玉米生长发育,产量、WUE和经济效益均显著低于CK。由以上结果可见,在试验区域低温干旱并存的条件下,有效的覆盖材料应同时具备增温作用和保水作用,而且增温作用较保水作用更为重要。因此,秸秆不适合作为低温干旱并存区域的覆盖材料,供试液膜因其效果欠佳也不适宜推广应用,而普膜覆盖的推广应用可获得最大的经济效益,但考虑到普膜的环境污染成本,供试降解膜也具有良好的推广应用价值。     

不同温湿度条件下杨树人工林土壤氮矿化特征研究

为了掌握不同温度和湿度条件下杨树人工林土壤的氮矿化过程,探明土壤在干旱条件下的氮矿化特征,采用室内培养法,将含水量分别为田间持水量的20%(重度干旱处理)、40%(轻度干旱处理)和70%(对照处理)的杨树人工林表层土壤(0~10 cm),分别置于15、20、25、30℃恒温条件下进行了8周培养试验,研究不同温湿度条件下的土壤氮矿化特征。结果表明:(1)土壤净氮矿化量与温度呈极显著正相关关系(P0.01);(2)在较低温度条件下(15、20℃),不同湿度土壤净氮矿化量表现为轻度干旱重度干旱对照,而在较高温度条件下(25、30℃),培养前期的氮矿化量变化规律与低温处理一致,但至培养后期,则表现为对照轻度干旱重度干旱;(3)各种处理土壤矿质氮主要以硝态氮为主;(4)土壤电导率与土壤硝态氮含量、净氮矿化量呈极显著正相关关系(P0.01)。研究表明适度干旱能够促进土壤氮的早期矿化,但适宜的湿度更有利于土壤氮的长期矿化。     

Consistent Variation Across Soil Types in Salinity Resistance of a Diverse Range of Chickpea (Cicer arietinum L.) Genotypes

Chickpea is considered sensitive to salinity, but the salinity resistance of chickpea germplasm has rarely been explored. This study aimed to (i) determine whether there is consistent genetic variation for salinity resistance in the chickpea minicore and reference collections; (ii) determine whether the range of salinity resistance is similar across two of the key soil types on which chickpea is grown; (iii) assess the strength of the relationship between the yield under saline conditions and that under non‐saline conditions; and (iv) test whether salinity resistance is related to differences in seed set under saline conditions across soils and seasons. The seed yield of 265 chickpea genotypes in 2005–2006 and 294 cultivated genotypes of the reference set in 2007–2008 were measured. This included 211 accessions of the minicore collection of chickpea germplasm from the International Crops Research Institute for the Semi‐Arid Tropics (ICRISAT). The experiments were conducted in a partly controlled environment using a Vertisol soil in 2005–2006 and an Alfisol soil in 2007–2008, with or without 80 mm sodium chloride (NaCl) added prior to planting. In a separate experiment in 2006–2007, 108 genotypes (common across 2005–2006 and 2007–2008 evaluations) were grown under saline (80 mm NaCl) and non‐saline conditions in a Vertisol and an Alfisol soil. In 2005–2006 in the Vertisol and 2007–2008 in the Alfisol, salinity delayed flowering and maturity, and reduced both shoot biomass and seed yield at maturity. There was a large variation in seed yield among the genotypes in the saline pots, and a small genotype by environment interaction for grain yield in both soil types. The non‐saline control yields explained only 12–15 % of the variation of the saline yields indicating that evaluation for salinity resistance needs to be conducted under saline conditions. The reduction in yield in the saline soil compared with the non‐saline soil was more severe in the Alfisol than in the Vertisol, but rank order was similar in both soil types with a few exceptions. Yield reductions due to salinity were closely associated with fewer pods and seeds per pot (61–91 %) and to lesser extent from less plant biomass (12–27 %), but not seed size. Groups of consistently salinity resistant genotypes and the ones specifically resistant in Vertisols were identified for use as donor sources for crossing with existing chickpea cultivars.     

地膜覆盖方式对花生田土壤含水量、温度及产量的影响

为探讨半干旱区地膜覆盖方式对花生田土壤水分、温度及植株生长发育动态特征的影响,测定了不同覆盖方式下,垄作花生各生育时期耕层土壤水分(0-40 cm)、土壤温度(0-25 cm)变化情况。结果表明:覆盖方式影响0-40 cm土层土壤含水量变化,随生育期推进,各土层和起垄位置土壤含水量均表现为抛物线变化趋势;各覆盖方式下,花生苗期垄面处0-40 cm土层含水量明显低于垄沟处,且苗期至开花期垄沟处土壤含水量降幅较大。不同覆盖方式主要通过提高日最高温度来影响耕层土壤温度的变化,花生生长前期,地温受覆盖方式影响强烈,多垄覆盖方式的日最高温度较高,达36.2℃;花生生育后期,地温受覆盖方式的影响较小;开花后,覆盖方式对0-10 cm日地温的影响不明显,但对15-25 cm土层14:00—18:00时地温影响较大。覆盖栽培对花生田土壤14:00温度影响强烈,可使花生苗期耕层土壤日平均温度升高0.5~2.4℃,且最高温度出现在15 cm土层的垄面花生行间位置。地膜覆盖可增产16.81%~37.17%,水分利用效率提高17.03%~37.42%。常规起垄覆膜双行栽培花生的覆盖方式是较为经济、高效、易耕作的覆盖种植方式。     

Alterations in Photochemical and Physiological Activities of Chickpea (Cicer arietinum L.) Cultivars under Drought Stress

In this study, some morphological, physiological and biochemical parameters of two chickpea cultivars, cv. Gökçe and Canıtez, were analysed to understand their tolerance to drought stress. Twenty-day-old plants were subjected to three different regimes of drought stress by withholding water for 3, 5 or 7 days, and then rewatering for 2 days after the initial 7 days of drought stress. Drought treatments only reduced shoot elongation in the Canıtez cultivar. Leaf production and fresh biomass decreased in both cultivars under all drought treatments, however to a greater extent in Canıtez. In both cultivars, malondialdehyde, proline and anthocyanin accumulation increased significantly, whereas relative water content declined under drought stress. The total chlorophyll and carotenoid contents of Gökçe were not affected by drought stress, whereas the chlorophyll content of Canıtez increased greatly at the end of the treatments. Using chlorophyll a fluorescence measurements, we found that extended drought treatment caused photoinhibition of PSII activity in both cultivars. However, this was greater in Canıtez, especially under severe drought stress. Although Canıtez recovered quickly from drought stress and exhibited a good ability to overcome drought stress, via activation of many protection mechanisms such as increasing antioxidant enzymes and proline and anthocyanin accumulation during vegetative stage, our results show that Canıtez is less drought tolerant than Gökçe.     

Integrated breeding approaches for improving drought and heat adaptation in chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is a dry season food legume largely grown on residual soil moisture after the rainy season. The crop often experiences moisture stress towards end of the crop season (terminal drought). The crop may also face heat stress at the reproductive stage if sowing is delayed. The breeding approaches for improving adaptation to these stresses include the development of varieties with early maturity and enhanced abiotic stress tolerance. Several varieties with improved drought tolerance have been developed by selecting for grain yield under moisture stress conditions. Similarly, selection for pod set in the crop subjected to heat stress during reproductive stage has helped in the development of heat‐tolerant varieties. A genomic region, called QTL‐hotspot, controlling several drought tolerance‐related traits has been introgressed into several popular cultivars using marker‐assisted backcrossing (MABC), and introgression lines giving significantly higher yield than the popular cultivars have been identified. Multiparent advanced generation intercross (MAGIC) approach has been found promising in enhancing genetic recombination and developing lines with enhanced tolerance to terminal drought and heat stresses.     

鹰嘴豆锌指蛋白基因ZE1的克隆及表达分析

利用一段从PEG胁迫的鹰嘴豆幼苗叶片所构建的cDNA文库中得到的EST序列,通过3'RACE方法克隆到一个鹰嘴豆C_2H_2型锌指蛋白基因ZF1,该基因不含内含子,编码一条244个氨基酸残基的多肽,含有两个典型的Cys2/His2锌指结构.其氨基酸序列含有一个可能的核定位型号,农杆菌介导的洋葱表皮细胞GFP瞬时表达实验表明,ZF1蛋白位于细胞核内.半定量RT-PCR分析表明,ZF1在鹰嘴豆的根、茎、叶、花、幼荚和幼胚中均有表达,在茎和叶中表达较弱,为组成型转录因子.半定量RT-PCR和实时荧光定量PCR检测结果显示,ZF1不但受高温及干旱诱导,而且还受6-苄基腺嘌呤(6-BA)、脱落酸(ABA)、乙烯利(Et)、赤霉素(GA_3)、吲哚-3-乙酸(IAA)、茉莉酸甲酯(MeJA)、水杨酸(SA)和氧胁迫诱导.这些结果表明,ZF1基因可能作为一个核调控因子参与植物的生长代谢以及多种生物与非生物胁迫的应答.     

玉米不同种植模式下土壤表层温湿度变化研究

采用田间试验,研究了玉米不同覆膜方式(平作不盖膜、平作膜侧、平作全膜、垄作膜侧、垄作全膜、垄作全膜沟栽)对土壤水分、温度的影响。结果表明:从移苗到第1次测定,土壤水分含量为:垄作膜侧垄作全膜沟栽平作全膜垄作全膜平作膜侧平作不盖膜,到第2次测定时土壤水分含量变化为:垄作全膜垄作膜侧垄作全膜沟栽平作膜侧平作不盖膜平作膜侧,从第3次测定土壤水分含量开始,结果差异都不大,到最后一次测定时,土壤水分含量基本一致;在温度方面,在8:00时温度最高的为平作全膜,在14:00和18:00时平作膜侧温度最高,平作不盖膜在8:00、14:00和18:00时温度均最低。     

可降解地膜覆盖对土壤水热及春玉米产量的影响

为探讨可降解地膜在晋东南地区玉米生产中的实际意义,从土壤保温性、土壤保水性、玉米生育进程与产量、田间降解等方面对3种地膜进行分析比较。结果显示：与不覆膜裸地相比,两种降解地膜能显著提高土壤温度和土壤水分,但效果稍逊于普通地膜,两种降解地膜之间差异不显著;地膜覆盖可显著加快玉米生育进程和增加玉米产量,降解地膜使生育期缩短4天,普通地膜使生育期缩短了9天,分别增产9.06%、9.72%、14.54%,普通地膜优于可降解地膜的促进效果,但普通地膜与降解地膜产量之间差异未达显著水平。在地膜降解方面,2种可降解地膜破裂启动期较为一致,发生于覆膜后约40～50天,可基本满足玉米苗期对温度、水分的需要; 覆膜 90～100天后可降解地膜从土壤表面基本消失。以上结果显示,供试的2种可降解地膜不仅具有显著的生物学效应和经济学效果,其降解特性也基本符合玉米生长对环境条件的要求,且较普通地膜既省工省时,并可降低环境污染,所以降解地膜替代普通地膜应用于晋东南玉米生产具有可行性。