Physiology and productivity of sugarcane with early and mid-season water deficit

An analysis of the physiological consequences of water deficit during the first half of the season on sugarcane productivity, can aid the evaluation of yield expectations under rainfed systems and the opportunities for saving irrigation water early in the season. Four field experiments were conducted at Ayr in the semi-arid tropics of Australia. Irrigation was withheld at different stages of crop development to investigate timing and severity of water deficit on crop development, biomass accumulation and partitioning of biomass to millable stalk and sucrose, both during the season and at final harvest. Deficits imposed during the tillering phase, while having large impacts on leaf area, tillering and biomass accumulation, had little impact on final yield. This was primarily due to the length of time required to impose significant water deficit when the canopy is small, the comparatively small amount of biomass accumulation lost through water deficit, and the ability of the crop to produce leaves and tillers at a rapid rate during subsequent well-watered conditions. On the other hand, water deficit imposed when the canopy was well-established (leaf area index >2) had a more deleterious impact on final yield of total biomass, stalk biomass, and stalk sucrose. Reductions in millable stalk biomass, could be solely explained by reductions in total biomass. Similarly, >97% of the variation in final cane or sucrose yield could be explained by variation in stalk biomass. While there were transient effects of water deficit on stalk sucrose and dry matter concentration, significant impacts at final harvest did not occur until stalk biomass levels fell to ca. 50% of that of the well-watered control.     

Changes in the components of cane and sucrose yield in response to drying-off of sugarcane before harvest

In irrigated sugarcane production, water is usually withheld prior to harvest to dry the field and to raise the sucrose content of the cane. Past research has provided conflicting results on the optimum length of drying-off. An analysis was conducted of pooled data from 37 experiments on drying-off in Southern Africa to: (1) determine the range of responses in sucrose yield and cane sucrose concentration that have been attained under various drying-off regimes; (2) quantify the trade-off between the loss in cane yield under drying-off and any possible gain in sucrose yield and cane sucrose fresh weight (FW) concentration; and (3) identify which components of sucrose yield and sucrose concentration are most sensitive to late-season water deficit, as a means of developing functions for crop simulation models. In only 22% and 61% of the drying-off treatments was there a significant increase in sucrose yield or sucrose FW concentration, respectively. For both sucrose yield and sucrose FW concentration, the average increase attained by drying-off was 8% and the maximum increase was about 15%. Increase in sucrose yield occurred when the decrease in stalk dry mass was no greater than about 10%. This relationship could form the basis for determining the trade-off between reduction in stalk mass and sucrose yield under varying drying-off regimes, and developing economic optima for drying-off severity. Increase in sucrose FW concentration occurred due to an increase in soluble solids and dehydration. Small reductions in fresh yield of cane under drying-off (up to 10%) can be attributed equally to dehydration and reduction in stalk dry mass.     

Dry matter partitioning of sugarcane in Australia and South Africa

Partitioning of dry matter (DM) in sugarcane is of interest for two fundamental reasons. Firstly, sugar production depends directly on partitioning of crop biomass to the stalk and then to sucrose stored largely in stalk parenchyma. Secondly, various DM components of the stalk and particularly sucrose concentration are used to calculate the value of cane consignments delivered to the mill. In this study we review data from serial harvesting experiments in South Africa and Australia to discover similarities and differences in DM partitioning of sugarcane grown in a wide range of conditions and to gain a better understanding of the factors influencing DM partitioning as a basis for improving functional responses in sugarcane simulation models. Firstly, climatic and genetic variations in DM partitioning to various above ground plant components of sugarcane and to sucrose within the stalk component, are examined at a broad level. We then assess the robustness of sucrose partitioning rules used in the two international sugarcane models (APSIM and CANEGRO) and provide enhancements on predictions of sucrose content (SC) on a DM basis in sugarcane stalks.Well-adapted cultivars in widely different climatic conditions were similar with respect to partitioning of biomass to various above ground organs. The trash component (dead leaves and dead stalks) was one that varied most between cultivars and growing conditions. The stalk fraction of green biomass (biomass less trash) reached a maximum of about 0.85 when green biomass yield exceeded 60 t ha⁻¹ regardless of cultivar or extremes of water regime. Opportunities for further improvements of this trait through breeding were not obvious but harvesting could be delayed to ensure that stalk fraction is as high as possible.Variations in SC with respect to age, biomass and seasonal variation in climate, were explained by a simple conceptual model of cane stalk segments which are rapidly filled with sucrose when young and may remobilise sucrose when carbohydrate is required for rapid expansive growth. Season and age effects on whole stalk SC are due to varying proportions of young segments with low SC and older segments with high SC. A mechanistic model capturing these concepts is required but as an interim measure an empirical model based on stalk mass, leaf number per stalk, leaf area index and temperature accounted for a large proportion of the variation in SC across Australian and South African cultivars and conditions. Uses for this model together with CANEGRO or APSIM include improved SC through manipulating irrigation and the harvest schedule and more realistic targets for cane quality.     

Growth of sugarcane under high input conditions in tropical Australia. I. Radiation use,biomass accumulation and partitioning

There is little detailed information on yield accumulation in sugarcane under high-input conditions, which can be used to quantify the key physiological parameters contributing to yield variation. Sugarcane is grown under plant and ratoon crop conditions. This study analysed canopy development, radiation interception and biomass accumulation of two contrasting cultivars of sugarcane under irrigation during the same season under plant and ratoon crop conditions. Over the 15 month season, 11 crop samplings were conducted. Biomass partitioning to stalk was also measured to determine to what extent differences in partitioning between cultivars under ratoon and plant crop conditions contribute to differential productivity. The key findings were: (1) The ratoon crop accumulated biomass more quickly than the plant crop during the first 100 days of growth due to higher stalk number, faster canopy development and greater radiation interception. For similar reasons, cultivar Q138 had higher early biomass production than cultivar Q117 in the plant crop. (2) Early differences in biomass accumulation due to crop class became negligible at about 220 days because maximum RUE of the plant crop (1.72 ± 0.01 g MJ⁻¹) was 8% higher than in the first ratoon crop (1.59 ± 0.08 g MJ⁻¹). The higher maximum RUE in the plant crop was consistent with a higher crop growth rate (35.1 ± 2.3 versus 31.0 ± 3.4 g m⁻² d⁻¹) during the linear phase of biomass accumulation. (3) Biomass accumulation, which ceased about 300 days after planting/ratooning and 140 days before final harvest, attained similar levels of 53–58 t ha⁻¹ in all four crops. (4) The plateau in biomass was associated with loss of live millable stalks, and not a cessation in the growth rate of individual stalks. The crops continued to intercept radiation while on the biomass plateau, so that average RUEs at final harvest were much lower than the maximum values. (5) There was no effect of crop class or cultivar on the fraction of biomass in the leaf and millable stalk components. This study emphasizes that maximising early radiation interception and biomass accumulation will not necessarily lead to higher yield in an environment where biomass production reaches a plateau well before final harvest. Loss of live millable stalks late in the crop cycle results in poor utilisation of intercepted radiation.     

Simulation of seasonal stalk water content and fresh weight yield of sugarcane

Stalk water content is an important variable for a sugarcane simulation model as sugar industries in many countries use cane yield and sucrose content on a wet mass basis for payment and yield reports. The prime objective was to develop a stalk water content module (SWCM) that can be incorporated into a sugarcane simulation model. SWCM starts from consideration of the dynamics of water concentration (ρ, g water g⁻¹ dry matter) along stalks and through seasons. The quantities of stalk water were modelled separately for the top and basal sections of the millable stalks. Field observations showed that the stalk water concentration (ρ) declined from 7.8 to 11.8 in the top internodes to 1.6–2.9 g water g⁻¹ dry matter in bottom internodes. In the basal section, ρ ranged from 1.98 in winter to 2.83 g water g⁻¹ stalk dry matter in summer. A two-parameter equation was used to model ρ and resulted in a range of coefficients of determination from 0.8 to 0.97 for six varieties. The SWCM was developed to simulate both the effects of seasonal variation and the age of internodes on the quantity of stalk water. The module was incorporated into a process oriented model of sugarcane growth for validation against field observations in tropical and subtropical areas of Australia and Hawaii, USA. Comparison of observed yields with cane yield simulated by the model that included the SWCM, gave an average of R² of 0.95, compared with the average of R² of 0.97 for simulation of stalk dry matter. The average relative root mean squared error (RMSE) was 15.2% in simulation of cane yield and 15.1% for simulation of cane dry weight. The module can be readily incorporated into a model that simulates sugarcane dry matter so that commercial crop yield can be estimated.     

The response of autumn and spring sown sugar beet (Beta vulgaris L.) to irrigation in Southern Italy: Water and radiation use efficiency

The Apulia region in Southern Italy is an important area for sugar beet cultivation. It is characterised by clay soils and a hot-arid and winter-temperate climate. The capability of sugar beet to exploit solar radiation, water use and irrigation supply in root yield, total dry matter and sucrose production was studied and analysed in relation to two experimental factors: sowing date – autumn (October–December) and spring (March) – and irrigation regime – optimal and reduced (respectively with 100 and 60% of actual evapotranspiration). Data sets from three experiments of spring sowing and three of autumn sowing were used to calculate: (1) water use efficiency in the conversion in dry matter (WUE_dm, plant dry matter at harvest versus seasonal water use ratio), in sucrose (WUE_suc, sucrose yield versus seasonal water use ratio); (2) irrigation water use efficiency in the conversion in dry matter (IRRWUE_dm), in sucrose (IRRWUE_suc) and fresh root yield (IRRWUE_fr); and (3) radiation use efficiency (RUE, plant dry matter during the crop cycle and at harvest versus intercepted solar radiation ratio).Autumnal beet was more productive than spring for fresh root, plant total dry matter, sucrose yield and concentration; also WUE_suc and IRRWUE_s were higher in the autumnal sugar beet, but no difference was observed in WUE_dm (on average, 2.83 g of dry matter kg⁻¹ of water used). An average saving of about 26% of seasonal irrigation supply (equivalent to about 100 mm) was measured in the three years with the earliest sowing time. The optimal irrigation regime produced higher root yield, plant total dry matter and sucrose yield than the reduced one; on the contrary the IRRWUE_fr and IRRWUE_dm were higher in the reduced irrigation strategy. WUE_s and IRRUWE_s correlated positively with the length of crop cycle, expressed in growth degree days and, in particular, to the length of the period from full soil cover canopy to crop harvest, the period when plant photosynthetic activity and sucrose accumulation are at maximum rates. Seasonal RUE was higher in the spring than in the autumn sowing (1.14 μg J⁻¹ versus 1.00 μg J⁻¹). The RUE values during the crop cycle reached the maximum in the period around complete canopy soil cover. The results showed the importance for better use of water and radiation resources of autumnal sowing time and of reduced irrigation regime in sugar beet cropped in a Mediterranean environment.     

不同月份播种对红壤甘蔗干物质与养分积累的影响

甘蔗是广西重要的经济作物.为促进甘蔗高效生产,以甘蔗品种'桂糖42号'为材料,在田间条件下,依据广西甘蔗主要播种月份,设置2月15日、3月15日、4月15日及5月15日4个播种期,分析新植蔗和宿根蔗干物质积累、养分积累及养分经济效率.结果表明,随播期推迟,新植蔗各器官干物质积累量减少;宿根蔗根、叶干物质积累量增加,茎干...     

遮光对玉米干物质积累及产量性能的影响

选用玉米品种郑单958与先玉335,在大田条件分别于7叶全展期（T1）、13叶全展期（T2）、吐丝期（T3）、吐丝后15 d（T4）进行50%遮光处理,研究不同时期遮光对玉米干物质积累与产量性能的影响。结果表明,不同时期遮光均导致玉米终极生长量（a）、干物质积累速率最大时的生长量（W_max）、最大干物质积累速率（G_max）、平均叶面积指数（MLAI）、平均净同化率（MNAR）和收获指数（HI）降低,致使干物质积累与产量不同程度降低,吐丝后15 d遮光对干物质与产量影响最大。在产量构成因素中,遮光处理对穗粒数与千粒重影响较大,穗粒数减少占主导,其次是千粒重的降低。     

超高产水稻的干物质生产特性研究

 以我国近年育成的超高产水稻品种为材料, 在福建龙海和云南涛源研究分析了超高产水稻品种的高产生理特性。结果表明超高产水稻品种积累了高额的生物量。 稻谷产量随干物质积累总量的增加而提高，产量主要取决于生物产量的高低，而收获指数对稻谷产量的贡献较小。超高产水稻干物质生产优势在中期和后期，产量随中期和后期干物质净积累量的增加而提高。中期和后期的群体生长率(CGR)与产量呈高度正相关，而前期CGR与产量的关系不密切。茎叶干物质输出量构成籽粒产量平均为24％（福建龙海）和33％（云南涛源），茎叶干物质输出量和抽穗后干物质积累量均与稻谷产量呈极显著正相关。在同一地点，对干物质积累的作用，CGR显著大于生长日数。     

Population density and row spacing effects on dry matter yield and bark content of kenaf (Hibiscus cannabinus L.)

Efforts to bring kenaf from experimental crop status to an accepted alternative in established cropping systems have been ongoing for years. To compete with existing crops and maximize monetary returns, the effects of agronomic practices on yield and crop quality must be better understood. Row spacing and population density are implicated in dry matter yield, and therefore, bast fiber production. Four row spacings, four population densities, and two cultivars were examined to determine these effects on dry matter accumulation and bark content. Of all factors evaluated, only row spacing significantly affected dry matter yield. Yield was greatest at the 35.5-cm row spacing, and lowest at the 71- and 101.6-cm row spacings. With regard to bast yield, calculated as a percentage of total sample dry weight, a significant cultivar × row spacing interaction occurred. However, data indicate that manipulating row spacing to maximize total stalk yield per hectare resulted in the highest bast fiber yield for the two cultivars tested. The narrowest row spacing of 35.5 cm, gave the greatest biomass yield as well as the highest bark yield per hectare.     

The influence of environment and season on stalk yield in kenaf

Kenaf is an important fiber crop worldwide. It was recently introduced to South Africa as a commercial fiber crop. The aim of this study was to determine how different environments and seasons influence stalk yield. Nine kenaf cultivars from various countries were analysed in two environments, over two consecutive seasons, where one location was irrigated and the other not. Data were recorded for total fresh yield, defoliated stalk yield and dry stalk yield. Yield stability was analysed with four different statistical models. The dry stalk yield varied from 15.33 to 17.78 ton/ha. El Salvador and Tainung 2 had high dry stalk yields in the favourable environments, but Tainung 2 did not have stable yield across all trials. Everglades 41 and El Salvador were the most stable of the varieties across both environments and seasons. El Salvador was the cultivar that had the highest and most stable dry stalk yield in the two seasons and two locations in South Africa, and should perform well in commercial production.     

Accumulation of reducing sugars by sugarcane: effects of crop age,nitrogen supply and cultivar

Sugarcane was grown under full irrigation in Australia, South Africa and Hawaii. N fertiliser was supplied at a high rate and was non-limiting to biomass accumulation in all but one dataset, where zero and high nitrogen (N) supply regimes were imposed. Crops were sampled for biomass, sucrose, glucose and fructose content of stalks. In one study, the biomass and sugar content of all green crop components were also determined. The objective was to compare the accumulation of reducing sugars, glucose and fructose, with sucrose, and how this responds to agronomic manipulations of crop duration, cultivar and nitrogen supply. Such knowledge can be used to assess the scope for maximising, by agronomic or genetic means, the partitioning of biomass to the economic product, sucrose and maximising the purity of juice for efficient sucrose extraction at the mill. At 12 months growth, 30–50% of reducing sugars was present in the stalk component, but at earlier stages was higher at 50–80%. Stalk yields of reducing sugars for 12 month crops were less than 100 g m⁻², which was less than 5% of total sugars in the stalk. There were strong effects of N supply and cultivar on the amounts and concentration of reducing sugars in the stalk at low yields, but little effect when stalk biomass exceeded about 4000 g m⁻² suggesting that, agronomic or genetic manipulation of levels of reducing sugars will only be effective early in the season. For a given level of stalk biomass, cultivar effects on partitioning to reducing sugars were due either to differences in partitioning of stalk biomass to total sugars, or differences in the partitioning between sucrose and reducing sugars. On the other hand, variation in N supply only altered the partitioning between sucrose and reducing sugars. Calculations suggested that high concentrations of reducing sugars in stalks harvested at a young age or from high N supply treatments, were not expected to lower the polarimetric estimate of sucrose concentration in the juice by more than 6%. This study provides a framework to assess the impact of cultivar, crop duration, and N supply on the accumulation of reducing sugars in different production systems.     

微生物土壤活化剂对甘蔗根系及地上部分作用效果

利用大型容器对甘蔗品种ROC22和云蔗06-407进行桶栽种植,探讨微生物土壤活化剂对甘蔗根系及地上部分的作用效果。结果表明:(1)施用微生物土壤活化剂对ROC22、云蔗06-407的根系和地上部分的提高均有一定效果,其中对云蔗06-407效果更显著,云蔗06-407的株高和茎径分别增加12.37%和28.81%;地上鲜重和根系鲜重分别增长32.61%和37.10%,白根根长增长92.57%,白根表面积增长66.08%,以上指标除株高外差异均达显著水平。(2)侧根数量越多,根系平均直径越小。(3)甘蔗地上部分的茎径、株高和地上鲜重均与根系鲜重呈极显著正相关,相关性系数均在0.797 9以上。表明微生物土壤活化剂可促进甘蔗根系的生长,有利于提高株高和茎径,从而提高甘蔗产量。     

Fresh biomass production and partitioning of aboveground growth in the three botanical varieties of Cynara cardunculus L.

Fourteen accessions of Cynara cardunculus were compared with the aim to evaluate the fresh biomass production and its partition, aiming at its potential use for industrial purposes. At anthesis stage, when plants have the maximum vegetative development, stalks, leaves and capitula were weighed separately. The percentage of dry matter per gram of fresh biomass was also calculated. The first capitulum components of each plant: bracts, flowers and remnant receptacle were also weighed separately. The total fresh biomass ranged between 1188 and 3235 g/plant, with variable values within each botanical variety, whereas the partition of the aboveground biomass was strongly affected by botanical variety. In both cardoons varieties, the percentage of dry matter ranged between 30 and 35% for all components of aboveground biomass, whereas in globe artichoke values ranged between 20% for capitula and 40% for leaves. Regarding capitula components, receptacle weight was of greatest importance in globe artichoke and cultivated cardoon. In wild cardoon flowers weight was more important than the other components. Results suggest that Cynara cardunculus var. scolymus and C. cardundulus var. cardunculus, might be considered as double purpose crops if after the capitula (in globe artichoke) or leaves (in cardoon) harvest, the fresh matter remaining is artificially dried and cut. On the other hand, Cynara cardunculus var. sylvestris, might be incorporated into the culture system as an industry or energy crop due the low inputs management that it requires, its adaptability to the local conditions and its aboveground biomass production.     

甘蔗育种经济权重选择指数法的应用研究Ⅰ. 目标性状经济权重模型的构建

选育及推广应用甘蔗良种能带给蔗糖产业最大化的经济效益,从市场经济的角度客观高效地筛选和评价甘蔗品种对蔗糖生产的可持续发展具有重要意义。本研究旨在对甘蔗的多个目标性状进行经济权重模型的构建,客观评价目标性状的相对重要性,为完善甘蔗育种评价体系和甘蔗良种的推广应用奠定基础。依据云南省18家糖厂3个榨季的调查问卷数据和云南省多年从事甘蔗生产的农户及农场管理人员的调研反馈数据,对整个蔗糖产业各个环节进行成本核算,计算不同经济性状的经济权重,获得了如下主要结果：（1）构建了甘蔗11个育种目标性状的经济权重模型,包括3个直接目标性状（蔗茎产量、甘蔗蔗糖分、纤维分）,8个间接目标性状（茎径、有效茎、株高、蒲心、脱叶性、57号毛群、侧芽、芽突起程度）;（2）基于新植产量63 t/hm ²、糖分12.5%、纤维分12.0%和甘蔗1 a新植2 a宿根生产周期总产量170.73 t/hm ²的条件下,每吨糖的总生产成本为4643.99元,蔗农的生产成本占总成本的68.15%,糖厂的生产成本占总成本的31.85%;当每吨甘蔗的收购价格为440元时,蔗农每吨甘蔗的收益为44.38元,当市场糖价突破每吨糖5000元时,糖厂每吨糖的收益超过356.01元;（3）基于目前人工收获生产模式条件下,甘蔗11个目标性状的绝对经济权重值为：蔗茎产量（t/hm ²）37.95元、商业糖分（%）328.44元、纤维分（%）-22.28元、茎径（cm）320元、有效茎（条/m ²）-80元、株高（cm）0元、蒲心（分级）-760元、脱叶性（分级）-320元、57号毛群（分级）-160元、侧芽（分级）-159.82元、芽突起程度（分级）-63.26元;（4）结合性状遗传增益的分析得到11目标性状的相对经济权重值,依次为商业糖分400.99元、蔗茎产量130.51元、茎径36.93元、株高0元、芽突起程度-5.22元、纤维分-8.25元、脱叶性-21.15元、侧芽-24.30元、有效茎-28.61元、毛群-30.72元、蒲心-200.04元。通过对整个蔗糖产业各个环节成本的核算,利用边际效益的方法构建的目标性状经济权重模型可为甘蔗品种选育和推广应用提供参考和依据。     

季节性干旱下农艺节水措施对甘蔗生长和产量的影响

为探明不同农艺节水措施在甘蔗应对季节性干旱中的作用机制,本研究以‘粤糖94-128’为材料,设置地膜覆盖+有机肥（T1）、保水剂+有机肥（T2）、蔗叶覆盖+有机肥（T3）、蔗叶覆盖+保水剂（T4）4个处理,以常规种植为对照（CK）,研究不同农艺节水处理下土壤水分和出苗率、农艺性状和干物质积累、光合活性和根系指标以及经济性状对季节性干旱的响应。结果表明：干旱胁迫前期土壤含水量表现为地膜覆盖>蔗叶覆盖>无覆盖;T1处理出苗率最高且显著高于CK。2015年,与CK相比,T1处理显著增加株高（18.1%）和+1叶长（30.6%）,T4处理显著增加茎粗（21.8%）,而T2处理的株高、茎粗和叶宽则显著降低;T1处理显著增加+1叶的最大光能利用效率（F_v/F_m）和叶片SPAD值（SPAD-502叶绿素仪测定值）,T3处理显著增加+1叶PSII实际光化学效率（Φ_PSII）,其余各处理与CK之间差异不显著;T1、T2、T3、T4处理的总干物质积累分别增加94.5%、-37.0%、53.4%、79.9%;T3处理显著增加根长密度、根表面积和根数,T2处理各根系指标则显著降低;T2和T3处理单茎重高于T1处理,但有效茎数远低于T1处理,有效茎数高是T1处理高产的主要原因;有机肥处理显著增加田间锤度,T3处理增幅最高。2016年,与CK相比,甘蔗不同处理的农艺性状、生理指标和干物质积累差异不显著;但与2015年相比,T1处理农艺性状指标呈下降趋势,而T2处理则呈上升趋势;各处理+1叶的Φ_PSII均呈下降趋势;T1、T2和T3处理总干物质积累呈下降趋势,而T1和CK则呈上升趋势。T3处理根系生物量和根长密度显著高于CK,主要是由于细根增加所致;T4处理有效茎长显著高于CK,但茎径和单茎重并无显著差异,产量差异源于有效茎数的差异;有机肥处理显著增加田间锤度且各处理的田间锤度与2015年比呈上升趋势。综上,农艺节水措施主要通过在旱季减少土壤水分散失而提高甘蔗出苗率从而增加有效茎数,并通过增加植株干物质积累和促进根系生长以应对季节性干旱,进而保障后期经济性状。     

外源糖和氮对春小麦花后物质生产的影响

为了解花后养分供应对春小麦产量形成的调控效应,以春小麦品种龙麦33为试验材料,分析了叶面喷施糖、氮物质(5%蔗糖和2%尿素)后小麦花后干物质积累、齐穗后群体生长率(CGR)、旗叶SPAD值、净光合速率、可溶性糖含量和全氮含量的变化。结果表明,与对照相比,叶面喷施糖、氮后小麦穗粒数和千粒重均增加,并分别增产 6.86%和15.82%。 外源糖、氮使小麦花后光合物质积累量及其对籽粒产量的贡献率提高,其中外源糖的效果更明显;外源糖、氮对CGR有显著的促进作用;外源氮显著提高收获指数（增幅11.76%）,而外源糖使收获指数略有下降（降幅0.085%）;外源糖、氮分别降低和增加旗叶SPAD值,但均提高旗叶净光合速率和全氮含量,降低旗叶可溶性糖含量和糖氮比值(C/N)。可见外源糖、氮对春小麦花后碳、氮代谢和物质生产有一定的调节作用,可促进小麦高产。     

应用飞机大面积喷施抗旱型甘蔗増糖增产剂的效果研究

研究应用飞机大规模喷施抗旱型增糖增产剂的实际效果,为在生产上提高甘蔗的抗旱性,实现增产增糖提供依据。本研究在2008/2009和2009/2010两个年度于广西蔗区甘蔗生长后期应用飞机大面积喷施抗旱型甘蔗增糖增产剂共2 400 hm2,以后分别调查其对甘蔗品质及产量构成因素的影响。结果表明:喷施抗旱型甘蔗增糖增产剂后甘蔗绿叶数和叶绿素都有所增加,并提高了蔗汁锤度和重力纯度、甘蔗纤维分和蔗糖分,降低了蔗汁还原糖分,其中以2009～2010年度喷施50 d时表现最为明显,新植和宿根蔗平均甘蔗蔗糖分比对照提高2.23%(绝对值,下同),新植蔗增糖效果优于宿根蔗;不同时期总平均甘蔗蔗糖分比对照提高1.33%。甘蔗株高、茎径、单茎重有一定的提高,平均甘蔗产量比对照增加14.3%,以宿根蔗增产效果优于新植蔗。应用抗旱型甘蔗增糖增产剂可以防止甘蔗叶片早衰,实现增糖增产,节本增效。     

木薯和花生间作模式下2种作物光合与干物质积累特性

为研究木薯和花生间作模式下2种作物光合与干物质积累特性,以木薯和花生间作行数比为2∶4模式为对象,木薯单作（SC）、花生单作（SP）为对照,在大田条件下测定了该间作系统中2种作物（木薯用IC表示,花生用IP表示）不同时期干物质积累特点和光合特性。结果表明：（1）花生实际产量和预期产量均表现出先增后降的趋势,且在定植后92 d之前的实际产量大于预期产量,之后的实际产量和预期产量均开始下降;木薯实际产量从定植后75 d到收获均大于预期产量,且实际产量的增加速度大于预期产量的增加速度。（2）块根形成期和块根膨大期,IC植株叶片的最大净光合速度（P_nmax）和光饱和点（LSP）均显著高于SC;苗期和块根膨大期,IC植株叶片的暗呼吸速度（R_d）小于SC。荚果膨大期,IP植株叶片的光补偿点（LCP）、LSP和R_d均显著低于SP,表观量子效率（α）显著高于SP。（3）IC通过最大干物质积累速率出现时间提前、延长快增期持续天数和提高最大干物质积累速率来达到增加干物质理论最大积累量;IP通过提早快增期开始时间和快增期结束时间来缩短快增期持续天数,并使其最大干物质积累速率出现时间提前,最终使IP的干物质理论最大积累量下降。综上表明,木薯通过提高光能截获和利用效率,同时降低自身消耗来增加干物质积累量,花生后期由于高位作物的遮荫影响其生长发育,但在荚果膨大期IP通过降低LCP和LSP来提高对弱光的利用效率,降低R_d来增加花生体内营养物质的有效积累。     

拔节期追氮对鲜食糯玉米产量和花后养分积累转运的影响

以苏玉糯5号和渝糯7号为材料,2013～2016年于扬州大学实验农场研究拔节期追氮量(0、150、300 kg/hm2)对鲜食糯玉米产量(鲜果穗和鲜子粒)、干物质和氮素积累和转运的影响。结果表明,鲜食糯玉米子粒产量和果穗产量均随追氮量的增加呈先升后降趋势,在追氮150 kg/hm2时产量最高。干物质和氮素积累量随着追氮量的增加表现趋势与产量一致。氮素利用率以子粒作为收获产品时随追氮量增加逐渐降低,以果穗作为收获产品时,在150和300 kg/hm2时无显著差异,低于不追氮处理。在鲜食糯玉米生产中,拔节期适量追氮150 kg/hm2可有效增加鲜食糯玉米产量、后期干物质和氮素积累量以及氮素利用效率,提高产量的同时降低环境风险。