冬油菜叶片SPAD的时空分布和氮素诊断的叶位选择

在大田试验条件下测定分析不同施氮水平冬油菜关键生育期SPAD值的时空分布特征,并对不同叶位及叶片不同部位SPAD值与叶绿素含量、叶片含氮量、植株全氮含量及籽粒产量之间的相关性进行分析,探求应用SPAD仪诊断油菜氮素营养状况的最佳测试叶位及位点。结果表明,油菜主茎顶部4片完全展开叶SPAD值存在显著空间差异,增加施氮量能显著提高各叶位叶SPAD值,同时减少叶位间的差异;六叶期、蕾薹期以顶4叶（TL4）SPAD值对氮素的敏感性最大,初花期和盛花期则最低。不同部位间,六叶期和初花期以中部SPAD值对施氮量增加的响应最敏感,盛花期则最迟钝,蕾薹期介于顶部和基部之间。综合分析认为,应用SPAD仪监测油菜氮素营养状况的最佳测试叶位和位点为主茎顶4片完全展开叶中部,该部位SPAD值与叶绿素含量、叶片含氮量和植株全氮含量之间的相关性均达到显著或极显著水平,满足氮素营养快速诊断的要求。     

鲁西南植棉区种植密度对蒜后直播短季棉农艺性状和产量的影响

以鲁棉532为供试棉花品种,研究4个种植密度(7.5万株/hm2、8.25万株/hm2、9万株/hm2、9.75万株/hm2)对直播短季棉农艺性状和产量的影响。结果表明:随着种植密度的增加,棉花生育期延长,第一果枝节位和株高逐渐增高,果枝数、单株结铃数减少,铃重越轻;种植密度9万株/hm2时棉花的铃重、衣分、籽棉和皮棉产量最高,其次是8.25万株/hm2。鲁西南棉区蒜后直播短季棉早中熟棉花品种的种植密度在8.25万株/hm2与9万株/hm2之间为宜。旨在为鲁西南植棉区提高棉花机械化生产水平,降低生产成本和劳动强度,提高植棉的经济效益和棉农的植棉积极性。     

不同基因型棉花品种铃壳重与产量及品质性状的关系

对18个陆地常规非抗虫棉品种铃壳重与7个产量性状、6个纤维品质性状进行了相关性分析与聚类分析。结果表明,铃壳重与全铃重呈极显著正相关,与单铃子棉重、衣指、整齐度指数呈显著正相关,与伸长率呈显著负相关,与皮棉产量、纤维品质综合分值无显著相关。铃壳重较轻与光合产物较多的提供给棉子和纤维的生长发育、促进子棉产量的提高和纤维品质的改善有关。     

氮肥和氮磷钾配比对科棉1号产量和品质的影响

以Bt转基因抗虫棉科棉1号为试验材料．研究了氮肥和氮磷钾配比对皮棉产量和纤维品质的影响。研究结果表明．施氮量375kg／hm^2．氮磷钾配比1：0．4：0．8能够有效增加单株成铃数．提高铃重．提高皮棉产量．获得的皮棉产量最高．这到1650．43kg／hm^2。随着氮磷钾配比的提高．当提高到1：0．8：1．6时。皮棉产量出现下降的趋势。施氮量375kg／hm^2．氮磷钾配比1：0．8：1．6能够有效地促进纤维品质的改善．主要表现为：马克隆值有所优化．更加接近A级．成熟度和长度整齐度均有所提高。断裂比强度显著增加．短绒率有所降低。     

常规棉产量与主要性状的灰色关联度分析

为探索常规棉产量与主要性状的相互关系,以2013年湖北省棉花区域试验19个棉花品种为材料,运用灰色系统理论对影响常规棉产量的12个主要性状进行灰色关联分析。结果表明,主要性状与常规棉产量的关联度大小依次为：籽指（r＝0．491）＞铃期病指（r＝0．430）＞衣指（r＝0．404）＞单株铃数（r＝0．396）＞始果枝着生节位（r＝0．394）＞果枝数（r＝0．390）＞衣分（r＝0．388）＞霜前花率（r＝0．382）＞生育期（r＝0．377）＞单铃重（r＝0．367）＞株高（r＝0．345）。说明在常规棉的选育和高产栽培时,要选择籽指较高、抗病性强的品种,同时注重结铃性和早熟性。     

棉花专用缓释肥在湖北黄冈的适宜用量研究

通过在棉花栽培中施用缓释肥试验，结果表明：棉花施用缓释肥能够延缓植株衰老，增加后期铃重和衣分，同时延长了有效开花成铃期，从而有利于提高产量。黄冈地区适宜施用量1200kg/hm2左右，采用较高施肥量，产量较高。     

Estimation of the N fertiliser requirement of cotton grown after legume crops

In a series of legume-based cropping systems experiments, the economic optimum N fertiliser rate for cotton ranged from 0 to 186 kg N ha⁻¹ depending on the cropping system and soil N fertility. The economic optimum N fertiliser rate was closely correlated with pre-sowing soil nitrate-N (0–30 cm) and petiole nitrate-N (at early flowering). Pre-sowing soil nitrate-N and petiole nitrate-N were also strongly correlated with cotton N uptake at late boll-filling and lint yield of unfertilised cotton.These analyses allow for the estimation of the N fertiliser requirement, providing revised calibrations that more precisely estimate the N-fertiliser requirement of irrigated cotton crops where legume cropping has substantially improved soil N fertility. Such management tools are essential to avoid the problems associated with over- or under-fertilizing cotton crops.The importance of optimising N fertiliser application was demonstrated by examining the effects of crop N nutrition on cotton maturity and fibre quality. Crop maturity (rate of boll opening) was delayed by 1 day for each 83, 16 or 24 kg fertiliser N applied per hectare in the three experiments. Increasing N fertiliser rates generally increased fibre length, and tended to increase fibre strength, whereas micronaire tended to decline.     

SPAD Values and Nitrogen Nutrition Index for the Evaluation of Rice Nitrogen Status

Abstract

Plant-based diagnosis is one of the most important methods to determine nitrogen (N) content of crops. Our objective was to establish the relationship between soil-plant analysis development (SPAD) values and N nutrition index (NNI) during the three developmental stages of rice and apply the SPAD meter as diagnostic tools for predicting grain yield response to N fertilization. We determined the SPAD values of four uppermost fully expanded leaves of two rice cultivars at six N fertilization levels at three growth stages and examined the relationship between SPAD values and NNI. The critical N concentration (N_c) was 5.31 W^–0.5 in Xiushui63, and 5.38 W^–0.49 in Hang43, where W is the total shoot biomass. The correlation between SPAD value and NNI varied with the leaf position, developmental stage, and variety. The lower leaf appeared to be more sensitive to the N level than the upper leaf in the response of biomass, and could be more suitable as a test sample for N status diagnosis, especially in the booting and heading stage. The dependence of grain yield on SPAD values of the fourth fully expanded leaf (L4) was significant at booting stage (R²_L4 = 0.82** in 2011, R²_L4 = 0.72** in 2012). Ratio of SPAD values of L4 to that in the N-saturated plot (RSPAD) (R²_L4 = 0.92** in 2011, R²_L4 = 0.77** in 2012) and NNI (R² = 0.96** in 2011, R² = 0.86** in 2012) at booting stage demonstrated a closer relationship with grain yield.     

Irrigated cotton in the tropical dry season. I: Yield,its components and crop development

Growing cotton during the dry (winter) season avoids many insect pests endemic in the wet season (summer) and could permit the reintroduction of cotton to the semi-arid tropics in Australia. This research addressed the questions: (1) what yield is possible given the lower mid-season radiation and temperature of the dry season, (2) the prediction and management of crop development using a range of sowing months to assess whether cotton can be grown and picked within the dry season. Over three seasons two Gossypium hirsutum L. (upland) cultivars and one Gossypium barbadense L. cultivar were sown from March, to June at the Ord River (15.5°S) in Western Australia. For the upland cultivars, lint yields of 1900–2300 kg/ha for March and April sowings were at the high end of Australian and International benchmarks. High lint yields were linearly correlated with a greater proportion of bolls that were located on outer sites on fruiting branches than for high yielding crops in temperate climates (∼30°lat.). The change in boll position increased the length of the growing season which was also linearly correlated with yield. Future research needs to confirm if low minimum temperatures early in flowering caused the change in boll position and to measure the impact of extreme temperature seasons on yield and time to maturity. The lint yield of the G. barbadense cultivar was highest at a March sowing, at least 87% of the upland cultivars, which is comparable with temperate climates. The frequency of temperatures >35 °C and <11 °C affected time to squaring, requiring modification of existing development models derived in temperate climates. It was concluded sowing during March to April should achieve the dual objectives of high yields and avoidance of rain at maturity. The wide temperature range observed in these experiments improved the prediction of boll period from mean temperature; this function should be applicable outside the semi-arid tropics.     

Impacts of early-season square abscission on the growth and yield of transgenic Bt cotton under elevated CO2

A field study was carried out to quantify the compensation capacity of Bacillus thuringiensis (Bt)-transgenic cotton to simulated damage by manually removing squares during the early growing season in 2004 and 2005 in combination with CO₂ levels (ambient CO₂ and elevated CO₂). Treatments included: initial squares were wholly (100%) removed manually for 1 week (i.e., SR1 treatment) and for 2 consecutive weeks (i.e., SR2 treatment). Plant leaf area was measured every 2 weeks, and plant root, stem, leaf, shatters, boll dry weight and lint yield and maturity were measured at harvest. Significantly higher leaf area per plant was observed on each sampling date for SR1 and SR2 treatments compared with control (SR0) treatment in 2004 and 2005 under elevated CO₂. Significantly higher lint yield and maturity were observed for SR0, SR1 and SR2 treatments under elevated CO₂ in 2004 and 2005. CO₂ concentration and square removal significantly affected plant lint yield and maturity. Moreover, the interaction between CO₂ concentration × square removal had a significant effect on plant leaf dry weight, lint yield and maturity. Our results indicated that transgenic cotton plants can compensate for the manual removal of 100% of the initial squares for 1 and 2 weeks under ambient and elevated CO₂.     

Effects of plant density and nitrogen and potassium fertilization on cotton yield and uptake of major nutrients in two fields with varying fertility

As the most important cultural practices for cotton production, the single effects of plant density and [nitrogen (N) and potassium (K)] fertilization on yield and yield components are well documented but their combined effects on Bt cotton are poorly understood. Using a split–split plot design with four replications, we conducted a two-year field experiment in two fields, one with lower fertility and the other with higher fertility, in the Yellow River Valley of China. The aim was to evaluate both the individual and combined effects of plant density and nitrogen and potassium fertilization on yield, yield components and uptake of major nutrients. The main plots were assigned to plant density (4.5 and 7.5 plants/m²), while nitrogen (0 and 240 kg N/ha) and potassium fertilization (0 and 150 kg K/ha) were assigned to the sub- and sub–subplots. Lint yield was improved with high plant density (7.5 plants/m²) in the lower fertility field, particularly without N and K application, but not in the higher fertility field. Nitrogen or K application also increased lint yield, and a combination of high plant density, N and K application further improved lint yield in the lower fertility field, while only K application increased lint yield in the higher fertility field. Lint percentage was not affected by any of the variables studied. Thus, the yield increase due to plant density, fertilization or their combinations was attributed to increases in boll number or boll weight. The ratio of seed cotton to stalk (RSS) was linearly correlated with harvest index, and thus can be a simple indicator of dry matter allocation to reproductive structures. Increased yield due to plant density and fertilization was mainly attributed to the enhanced biological yield in the lower fertility field, while the yield increase due to K fertilization was mainly due to increased RSS in the higher fertility field. The plants used approximately equal N and P to produce 100 kg lint in both fields, but the uptake of K to produce 100 kg lint in the higher fertility field was about 21% more than that in the lower fertility field. Ratios of N:P:K were 1:0.159:0.604 in the lower fertility field and 1:0.159:0.734 in higher fertility field. This study suggests that K fertilization was extremely important for maintaining high yield, although luxury consumption occurred in the higher fertility field; N was applied more than required in the highly fertile field, and increased plant density would be beneficial to cotton yield in the lower fertility field.     

对13个杂交棉品种的产量与性状间逐步回归分析

运用逐步回归、通径分析和相关性分析方法,研究了13个杂交棉品种中6个农艺性状对皮棉产量的影响。以及产量与产量性状间的相关性性。结果表明：单株果枝数、铃重和铃数对皮棉产量有显著的负向直接贡献,株高、衣分和籽指对皮棉产量均表现为显著的正向贡献。衣分与皮棉产量间的相关系数最大。     

Effect of introducing Bacillus thuringiensis gene on nitrogen metabolism in cotton

Bacillus thuringiensis (Bt) transgenic cotton has shown changes in vegetative and reproductive growth characteristics. The objective of this study was to investigate the physiological changes in nitrogen metabolism that related closely to growth in Bt cotton cultivars. The study was undertaken on two Bt transgenic cotton cultivars and their parents, one conventional (Xingyang 822) and recurrent parent (Sumian No. 9), the other a hybrid (Kumian No. 1) and female parent (Yumian No. 1), during the 2001 and 2002 growing seasons at the Yangzhou University Farm, Yangzhou, China.In the 2001 study, the results indicated that the Bt cotton cultivars (during peak reproductive growth) possessed greater leaf N, free amino acid and soluble protein than their parents. The biggest increase of total nitrogen was at peak boll period, with 36 and 19% increase for Kumian No. 1 and Xingyang 822, respectively. Similar results were found for free amino acid and soluble protein content. Further in 2002, the nitrate reductase activity increased dramatically at peak squaring and early boll open period, the biggest increase at early boll open period, with Kumian No. 1 and Xingyang 822 exhibiting 88 and 61% greater activity than their parents, respectively. The biggest increase in glutamic-pyruvic transaminase activity was at peak boll period, with Kumian No. 1 and Xingyang 822 having 39 and 29% higher activity than their parents, respectively. However, protease activity of Bt cultivars reduced significantly before flowering and early boll open period, the biggest decrease was before the flowering period. The results suggest that the Bt cotton cultivars have a more intense leaf nitrogen metabolism than their parents during reproductive development. The enhanced N metabolism may lead to excessive vegetative growth. Cultural practices should therefore be aimed at reducing leaf nitrogen metabolic strength and keeping the balance of vegetative and reproductive growth.     

杂交棉F1代主要经济性状的相关及通径分析

以43份杂交棉F1代为研究对象,时各杂交组合主要性状竞争优势、相关系教及通径系数进行分析.结果表明:杂交棉F1代中皮棉产量、单株铃数和表分都有较强的竞争优势;时皮棉产量直接作用较大的性状为单株铃数、衣分和单铃重,对F1代的筛选应注重对这几个性状选择,以获得强优势的杂交组合.     

Chlorophyll meter-based nitrogen management of rice grown under alternate wetting and drying irrigation

Farmers have adopted alternate wetting and drying (AWD) irrigation to cope with water scarcity in rice production. This practice shifts rice land away from being continuously anaerobic to being partly aerobic, thus affecting nutrient availability to the rice plant, and requiring some adjustment in nutrient management. The use of a chlorophyll meter (also known as a SPAD meter) has been proven effective in increasing nitrogen-use efficiency (NUE) in continuously flooded (CF) rice, but its use has not been investigated under AWD irrigation. This study aimed at testing the hypotheses that (i) SPAD-based N management can be applied to AWD in the same way it is used in CF rice, and (ii) combining chlorophyll meter-based nitrogen management and AWD can enhance NUE, save water, and maintain high rice yield. Experiments were conducted in a split-plot design with four replications in the 2004 and 2005 dry seasons (DS) at IRRI. The main plots were three water treatments: CF, AWD that involved irrigation application when the soil dried to soil water potential at 15-cm depth of −20 kPa (AWD₋₂₀) and −80 kPa (AWD₋₈₀) in 2004, and AWD₋₁₀ and AWD₋₅₀ were used in 2005. The subplots were five N management treatments: zero N (N₀), 180 kg N ha⁻¹ in four splits (N₁₈₀), and three SPAD-based N-management treatments in which N was applied when the SPAD reading of the youngest fully extended leaf was less than or equaled 35 (N_SPAD35), 38 (N_SPAD38), and 41 (N_SPAD41). In 2005, N_SPAD32 was tested instead of N_SPAD41. A good correlation between leaf N content per unit leaf area and the SPAD reading was observed for all water treatments, suggesting that the SPAD reading can be used to estimate leaf N of rice grown under AWD in a way similar to that under CF. SPAD readings and leaf color chart (LCC) values also showed a good correlation. There were no water × nitrogen interactive effects on rice yield, water input, water productivity, and N-use efficiency. Rice yield in AWD₋₁₀ was similar to those of CF; yields of other AWD treatments were significantly lower than those of CF. AWD₋₁₀ reduced irrigation water input by 20% and significantly increased water productivity compared with CF. The apparent nitrogen recovery and agronomic N-use efficiency (ANUE) of AWD₋₁₀ and AWD₋₂₀ were similar to those of CF. The ANUE of N_SPAD38 and N_SPAD35 was consistently higher than that of N₁₈₀ in all water treatments. N_SPAD38 consistently gave yield similar to that of N₁₈₀ in all water treatments, while yield of N_SPAD35 about 90% of that of CF. We conclude that a combination of AWD₋₁₀ and SPAD-based N management, using critical value 38, can save irrigation water and N fertilizer while maintaining high yield as in CF conditions with fixed time and rate of nitrogen application of 180 kg ha⁻¹. Treatments AWD₋₂₀ and N_SPAD35 may be accepted by farmers when water and N fertilizer are scarce and costly. The findings also suggested LCC can also be a practical tool for N-fertilizer management of rice grown under AWD, but this needs further field validation.     

马铃薯氮素营养状况的SPAD仪诊断

以马铃薯品种克新1号为材料,研究了叶片SPAD值、叶片全氮含量、叶绿素含量以及块茎产量随供氮水平的变化规律及相互关系,旨在为使用叶绿素仪进行马铃薯无损伤氮素诊断和推荐施肥奠定基础。研究结果表明,从马铃薯苗期到块茎淀粉积累各个生育阶段叶片的SPAD测定值均与马铃薯叶片含氮量呈显著正相关关系。除苗期外,块茎形成期、块茎膨大期、淀粉积累期的马铃薯叶片含氮量和叶片SPAD值随土壤施氮量的变化均表现为线形加平台的模式。因此马铃薯块茎形成期后叶片的SPAD读数可揭示马铃薯的氮素营养状况。统计分析结果还表明,叶片SPAD值与块茎相对产量呈线形加平台的数量关系模式,据此确定了应用叶绿素仪SPAD-502进行马铃薯推荐施肥的SPAD临界值为块茎形成期47.3、块茎膨大期45.1、淀粉积累期40.2。     

陆地棉品种间杂种主要性状的遗传相关和通径分析

研究了陆地棉品种问杂种F1代主要经济性状间的相互关系．并对皮棉产量、纤堆长度和霜前花率等3个目标性状进行了遗传通径分析。结果表明，单铃重与皮棉产量遗传相关最密切，对皮棉产量的直接遗传正效应也最大；纤堆长度与霜前花率遗传正相关最密切，而对纤维长度的直接遗传正效应最大的则是皮棉产量；霜前花率与单铃重遗传正相关最密切，对霜前花率直接遗传正效应最大的是衣指。通过研究提出高产、优质、早熟性的杂种F1代选育的主攻方向是以抗病性为前提．首抓铃重，次抓衣指。     

Comparison of petiole nitrate concentrations,SPAD chlorophyll readings,and QuickBird satellite imagery in detecting nitrogen status of potato canopies

Nitrogen (N) management is critical in optimizing potato yield and quality and reducing environmental pollution. Six N rates from 34 to 270 kg ha⁻¹, and different timing of N application were used in a 3-year field experiment to contrast SPAD-502 chlorophyll meter and QuickBird satellite imagery data against the conventional petiole sampling technique for assessing canopy N status. Overall treatment variations in SPAD readings were consistent with those in petiole nitrate-nitrogen (NO₃-N) concentrations. However, the ability of the SPAD meter to detect treatment differences varied with growth stage and growing season. Severe N deficiency was detected about 1 month after emergence with SPAD readings, but as early as 2 weeks after emergence with petiole NO₃-N concentrations. Petiole NO₃-N concentrations tended to differentiate more treatment variations than SPAD readings at all growth stages except at hilling. N deficiency was detected with QuickBird image-derived vegetation indices (VIs) at the hilling stage in 2002, but not in 2003. At the post-hilling stage, treatment differences in VI values were minimal and insignificant except very late in the growing season. SPAD meters could be used as an indirect method for detecting N deficiency at the hilling stage when making supplemental N applications, but they are not as sensitive as the petiole sampling method. The sensitivity of QuickBird imagery to canopy N variations needs to be further tested with more pixel data. However, cloud interference and high cost of images could limit the use of QuickBird data in making timely management decisions.     

Improvement of nitrogen management in rice paddy fields using chlorophyll meter (SPAD)

Optimum rate and timing application of nitrogen (N) fertilizer are most crucial in achieving high yield in irrigated lowland rice. In order to assess leaf N status, a semidwarf rice cultivar (Khazar) was grown with different N application treatments (0, 40, 80, and 120 kg N ha⁻¹ splited at transplanting, midtillering, and panicle initiation stages) in a sandy soil in Guilan Province, Iran, in 2003. The chlorophyll meter (SPAD 502) readings were recorded and leaf N concentrations were measured on the uppermost fully expanded leaf in rice plants at 10-day internals from 19 days after transplanting to grain maturity. Regression analysis showed that the SPAD readings predicted only 23% of changes in the leaf N concentration based on pooled data of leaf dry weight (N _dw) for all growth stages. However, adjusting the SPAD readings for specific leaf weight (SPAD/SLW) improved the estimation of N _dw, up to 88%. Specific leaf weight (SLW), SPAD readings, leaf area and weight as independent variables in a multiple regression analysis predicted 96% of the N _dw changes, while SPAD readings independently predicted about 80% of leaf N concentration changes on the basis of leaf area (N _a). It seems that chlorophyll meter provides a simple, rapid, and nondestructive method to estimate the leaf N concentration based on leaf area, and could be reliably exploited to predict the exact N fertilizer topdressing in rice.     

Evaluation of the SPAD Value in Faba Bean (Vicia fabaL.) Leaves in Relation to Different Fertilizer Applications

Abstract

The correlations of the reading of a portable chlorophyll meter (SPAD-502) with the chlorophyll and N contents of leaves of two faba bean (Vicia fabaL.) cultivars, Japanese (Ryousai-issun) and Egyptian (Cairo 241), were examined. The SPAD readings positively correlated (ρ<0.01) with the chlorophyll contents and the r² values were 0.99 and 1.00 for Ryousai-issun and Cairo 241, respectively. A close linear relationship (ρ0.001) was observed between SPAD reading and total leaf N content at the pod development stage of faba bean plants with r² = 0.88 and 0.99 for Ryousai-issun and Cairo 241, respectively. The SPAD reading was the highest in the 2^nd to 4^th leaves counted from the top (the youngest fully expanded leaves). The changes in leaf chlorophyll content of both cultivars from 3 weeks after transplanting to the ripening stage showed an incomplete “M” type curve. SPAD readings were significant¬ly higher in Ryousai-issun than in Cairo 241 throughout the growth season. Organic fertilizers application improved faba bean plant growth. These results suggest that the SPAD-502 chlorophyll meter can be used to measure chlorophyll and nitrogen contents of faba bean leaves for quick screening faba bean genotypes.