Carbon assimilation,leaf area dynamics,and grain yield in contemporary earlier- and later-senescing maize hybrids

Maize breeding during the past 50 years has been associated with a delay of leaf senescence, but it is not clear whether this trait is likewise associated with higher grain yield in modern hybrids. Post-silking growth, leaf area dynamics, photosynthetic parameters and yield were compared in modern maize hybrids differing in canopy senescence rate. In the first two experiments, four hybrids were grown in the field at Balcarce, Argentina (37°45′ S, 58°18 W). In spite of differences in chlorophyll retention and photosynthesis of the ear leaf, post-silking growth and grain yield were very similar in all four hybrids while kernel N concentration was lower in the later-senescing hybrids. In a third experiment, a later-senescing (NK870) and an earlier-senescing (DK682) hybrid were grown to analyze the potential photosynthetic contribution of delayed leaf senescence. Leaf area and chlorophyll content were larger in NK870, especially at the lower canopy level (0.75 m above the ground). However, hybrids did not differ for canopy light interception. Because photosynthetic photon flux density below 1 m above the ground was less than 10% of incident radiation and photosynthesis quantum yield did not change during senescence, the potential photosynthetic output of lower leaves below 1 m was very low. Lower leaves of NK870 had N concentrations higher than those needed to sustain photosynthesis at the light conditions below 1 m. Therefore, we show that delayed senescence does not necessarily improve post-silking C accumulation because: (i) canopy light interception is not reduced by senescence except at very late stages of grain filling; (ii) contrasting hybrids show more pronounced senescence differences at canopy levels receiving less than 10% of incident radiation; (iii) delayed senescing hybrids present lower kernel N concentrations while extra N is retained in leaves exposed to a light limiting micro-environment. Delayed senescence at lower canopy levels may be unproductive, at least under non-stressing conditions.     

不同熟期夏玉米品种籽粒灌浆脱水特性和激素含量变化

本文旨在研究不同熟期夏玉米品种籽粒灌浆与脱水特性和内源激素含量与平衡的变化,以期为黄淮海夏玉米机械化收获籽粒和高产高效品种筛选提供理论依据。以早熟玉米品种登海518(DH518)、衡早8号(HZ8)和晚熟玉米品种郑单958(ZD958)、登海605(DH605)为试验材料,研究玉米籽粒形成过程中干物质积累、水分含量及内源激素含量变化。结果表明,早熟品种较晚熟品种灌浆期短,籽粒开始脱水早,脱水速率高,生理成熟期粒重低,产量低,但早熟品种中DH518的产量显著高于HZ8。不同熟期玉米品种籽粒内源激素含量及其变化模式不同,但同一激素含量随籽粒发育的变化趋势一致。两早熟品种籽粒的ABA含量高于两晚熟品种,尤其表现在灌浆中后期。各品种籽粒灌浆、脱水速率均与内源激素含量有关,两早熟品种的籽粒脱水速率与玉米素核苷(ZR)含量呈显著正相关。     

施氮水平对不同种植模式小麦旗叶衰老和产量的影响研究

摘要：①氮素水平与小麦后期旗叶衰老有着密切关系。中氮和高氮处理与低氮和无氮处理相比,显著提高了SOD和POD的活性,相对改善了细胞中活性氧产生与清除之间的平衡,减少了细胞内过氧化物的积累,减缓了叶片衰老;但平作栽培小麦264 kg .hm-2水平（N3处理）与165kg .hm-2水平（N2处理）间的SOD、POD活性、MDA含量以及叶绿素含量等生理指标差异不显著,表明施氮量达到一定水平后继续增加施氮量对延缓小麦旗叶衰老无显著效应。②通过对垄作和平作两种栽培模式的比较发现,小麦旗叶衰老进程分为两个阶段;平作小麦以花后14天,垄作小麦以花后21天为拐点,前期为缓慢衰老期,后期为急剧衰老期。在缓慢衰老期,旗叶POD、SOD活性,叶绿素含量会略有上升;而进入急剧衰老期后,上述三个生理指标都急剧下降。平作小麦比垄作小麦提前进入急剧衰老期。③氮素水平为165kg .hm-2时,两种栽培模式均可以获得中产以上产量;264 kg .hm-2水平下能够获得更高的产量,且垄作栽培小麦的增产优势较平作小麦更明显。     

不同熟期类型玉米品种籽粒灌浆和脱水特性

根据自然生态条件及玉米品种的熟期、籽粒灌浆与脱水特性和产量潜力等进行科学品种布局,是实现玉米高产优质和资源高效利用的重要途径。本试验选用中早熟、中熟和中晚熟3个熟期类型,共13个玉米生产主栽品种,通过测定籽粒干物质积累和含水率的动态变化,研究并明确了不同熟期类型玉米品种的籽粒灌浆和脱水特性,旨在为生产品种布局提供参考和指导。试验结果表明:产量、籽粒灌浆和脱水特性在不同熟期类型和品种间均存在显著差异。产量表现为中晚熟(13,813.0 kg hm^–2)>中熟(12,970.4 kg hm^–2)>中早熟品种(10,729.0 kg hm^–2),中晚熟分别较中早熟和中熟品种增产28.7%和6.5%。平均灌浆速率表现为中早熟(0.034 g 100-grain^–1℃^–1)>中熟(0.031g 100-grain^–1℃^–1)>中晚熟品种(0.027 g 100-grain^–1℃^–1),生理成熟后的平均物理脱水速率表现为中熟(0.027%℃^–1 d–1)>中早熟(0.025%℃^–1 d–1)>中晚熟品种(0.018%℃^–1 d–1)。中早熟代表性品种京农科728的平均灌浆速率和生理成熟后的物理脱水速率。分别较3个熟期代表性品种郑单958、先玉335、农华101高38.5%和112.5%、28.6%和54.5%、28.6%和13.3%;中晚熟代表性品种京科968产量潜力最大(14,813.0 kg hm^–2),且平均灌浆速率和物理脱水速率分别较同熟期品种郑单958高7.7%和18.8%。产量与灌浆期天数、积温、平均灌浆速率和百粒重呈显著或极显著正相关,收获期籽粒含水率与灌浆期天数和积温显著正相关、与生理降水速率和物理脱水速率极显著负相关,生理降水速率和物理脱水速率与平均灌浆速率相关性不显著。综上,中早熟、中熟和中晚熟3个不同熟期类型及不同玉米品种的籽粒灌浆和脱水特性差异显著,生产中品种布局除考虑熟期外还需兼顾该特性,以更利于实现玉米高产优质和资源高效利用。     

不同熟期类型玉米品种籽粒灌浆和脱水特性

Suitable variety arrangement according to the natural ecological conditions, maturity, grain filling and dehydrating characteristics and yield potential of maize hybrid is an important approach for realizing higher maize yield, quality and photothermal resource utilization. Thirteen hybrids widely planted in maize production with three maturity types [medium-early maturity (MEM), medium maturity (MM) and medium-late maturity type (MLM)] were selected to clarify the grain filling and dehydrating characteristics for different maturity hybrids, by investigating the dynamic changes of grain filling and moisture content. The results showed that yield, grain filling and dehydrating characteristics differed significantly between different maturities and hybrids. Average yield level showed MLM (13,813.0 kg hm^-2) > MM (12,970.4 kg hm^-2) > MEM (10,729.0 kg hm^-2), with MLM was 28.7% and 6.5% higher than that of MLM and MM type, respectively. Average grain filling rate showed MEM (0.034 g 100-grain^-1 ℃^-1) > MM (0.031 g 100-grain^-1 ℃^-1) > MLM (0.027 g 100-grain^-1 ℃^-1), average dehydrating rate after physiological maturity (PM) showed MM (0.027% ℃^-1 d^-1) > MEM (0.025% ℃^-1 d^-1) > MLM (0.018% ℃^-1 d^-1). Average grain filling rate and dehydrating rate after PM of MEM representative hybrid Jingnongke 728 were 38.5% and 112.5%, 28.6% and 54.5%, 28.6% and 13.3% higher than those of representative hybrid Zhengdan 958, Xianyu 335 and Nonghua 101 for three maturity type; the yield of Jingke 968 was the highest (14,813.0 kg hm^-2), average grain filling rate and dehydrating rate after PM was7.7% and 18.8% higher than the same maturity hybrid Zhengdan 958. Yield level was significantly or extremely significantly correlated with grain filling period, corresponding accumulated temperature, average grain filling rate and 100-grain weight; grain moisture content at harvest stage was significantly correlated with grain filling period and corresponding accumulated temperature, but negatively significantly correlated with dehydrating rate before and after PM; there were no significant correlation between dehydrating rate before and after PM with average grain filling rate. Maturity, grain filling and dehydrating characteristics were all important factors for higher maize yield, quality and photothermal resource utilization. This study indicated that maize grain filling and dehydrating characteristics differed significantly between different maturity types and hybrids. Maturity, grain filling and dehydrating characteristics should be well considered for variety arrangement in maize production in order to achieve higher maize yield, quality and photothermal resource utilization.     

不同熟期玉米不同粒位籽粒灌浆和脱水特性对密度的响应

研究密度对不同熟期玉米品种不同粒位的籽粒灌浆和脱水特性的调控效应,为陕北灌区春玉米密植高产机械粒收技术提供依据。于2018—2019年以中熟品种先玉335 (Xianyu 335)和晚熟品种东单60 (Dongdan 60)为材料,设置45,000 (D1)、60,000 (D2)、75,000 (D3)、90,000 (D4)株hm–2四个种植密度,分析其不同粒位籽粒灌浆、脱水特性及其与气候因子的相关性。结果表明,密度的增加能显著提高不同熟期品种玉米籽粒产量,其中2018年2个品种均在D4处理下达到最高产量;2019年先玉335和东单60分别在D4和D3处理下达到最高产量,2年平均最高产量分别为18,739 kg hm^-2和17,111 kg hm^-2,较D1处理产量分别提高了32.2%和27.7%。随着种植密度的增加,不同粒位的籽粒灌浆速率降低,粒重减小,脱水速率加快。在D4种植密度下,先玉335下部和上部籽粒平均灌浆速率较东单60分别高0.08 g d–1和0.04 g d–1,粒重较东单60分别高3.6 g和1.6 g。生理成熟时不同...     

Heterosis for leaf photosynthesis,grain yield and yield components in maize

Summary One of the primary avenues of improving the biological efficiency of crop plants is through the improvement of the leaf and canopy photosynthetic rates. However, the question whether the superiority of hybrids in respect of productivity potential could be traced, in retrospective fashion, to the photosynthetic parameters should be answered first. Once established and standardized, such indices could be streamlined in innovative breeding to predict the heterotic combinations for final yield formation. To answer this question, the photosynthetic rate and other components of photosynthetic efficiency were monitored among eight inbred stocks of maize (selected for variable photosynthetic rate from a previous study) and their all possible one-way crosses. The results demonstrated extensive heterosis in respect of photosynthetic rate and other photosynthetic indices which, in turn, was also realized in terms of higher biomass productivity and yield. Nonetheless, high leaf photosynthesis alone did not result in higher grain yield. On the contrary, component interaction among the photosynthetic indices like photosynthetic rate, leaf area/plant, number of leaves and chlorophyll content on one hand and the complementary gene action on the other, could be held responsible for higher yields in hybrids. Since the components of photosynthetic efficiency can predict heterosis for biomass and grain yield upto a reasonable extent, judicious incorporation of such indices in selection parameters for applied genetic protocols can add yet another dimension to the strategies for future yield improvements.     

冠菌素对玉米籽粒灌浆特性与淀粉合成的调控效应

玉米产量与籽粒灌浆特性紧密相关,调控籽粒灌浆特性是实现玉米高产的重要途径之一。本研究采用不同浓度冠菌素对灌浆期玉米(吐丝后10 d)进行叶面喷施处理,研究冠菌素(coronatine, COR)对玉米籽粒灌浆特性、淀粉含量和淀粉合成关键酶活性及其基因表达的调控效应。2年田间试验研究结果表明, COR对玉米果穗性状、产量、籽粒灌浆和淀粉合成的调控具有明显的浓度效应,适宜浓度COR (1.0 mg L~(–1))处理显著降低玉米果穗秃尖长度,增加穗粒数和千粒重,提高籽粒灌浆速率,延长灌浆持续期,提高产量。此外,适宜浓度COR处理显著提高玉米籽粒灌浆过程中淀粉合成相关酶AGPase、SSS、GBSS和SBE的活性,上调淀粉合成关键酶基因ZmSH1、ZmSH2、ZmWX1和ZmAE1的表达量,促进籽粒支链淀粉、直链淀粉和总淀粉的积累,提高了籽粒淀粉含量。研究结果明确了COR对玉米籽粒形态建成与物质积累的调控效应,为玉米增产增效栽培提供了新的技术手段。     

Dynamic change of mineral nutrient content in different plant organs during the grain filling stage in maize grown under contrasting nitrogen supply

The introduction of new hybrids and integrated crop-soil management has been causing maize grain yield to increase. However, less attention has been paid on the nutrient concentration of the grain; this aspect is of great importance to supplying calories and nutrients in the diets of both humans and animals worldwide. Increasing the retranslocation of nutrients from vegetative organs to grain can effectively increase the nutrient concentration of grain and general nutrient use efficiency. The present study involved monitoring the dynamic change of macro- and micronutrients in different organs of maize during the grain filling stage. In addition, the mobility of different elements and their contribution to grain nutrient content were evaluated in a 2-year experiment under low (LN, no N supplied) and high N (HN, 180 kg N ha⁻¹) supply. Under HN supply, the net remobilization efficiency (RE) of the vegetative organs as a whole (calculated as nutrient remobilization amount divided by nutrient content at silking) of N, P, K, Mn, and Zn were 44%, 60%, 13%, 15%, and 25%, respectively. The other nutrients (Mg, Ca, Fe, Cu, and B) showed a net accumulation in the vegetative organs as a whole during the grain filling stage. Among the different organs, N, P, and Zn were remobilized more from the leaves (RE of 44%, 51% and 43%, respectively) and the stalks (including leaf sheaths and tassels) (RE of 48%, 71% and 43%, respectively). K was mainly remobilized from the leaves with RE of 51%. Mg, Ca, Fe, Mn, and Cu were mostly remobilized from the stalks with the RE of 23%, 9%, 10%, 42%, and 28%, respectively. However, most of the remobilized Mg, Ca, Fe, Mn, Cu, and Zn were translocated to the husk and cob, which seemingly served as the buffer sink for these nutrients. The REs of all the nutrients except for P, K, and Zn were vulnerable to variations in conditions annually and were reduced when the grain yield and harvest index were lower in 2014 compared with 2013. Under LN stress, the RE was reduced in P and Zn in 2013, increased in Cu and unchanged in other nutrients. The concentration of these nutrients in the grain was either unchanged (P, K, Ca, Zn, and B) or decreased (N, Mg, Fe, Mn, and Cu). It is concluded that grain N, P, K, Mn, and Zn, but not Mg, Ca, Fe, Cu, and B concentration, can be improved by increasing their remobilization from vegetative organs. However, enhancing the senescence of maize plant via LN stress seems unable to increase grain mineral nutrient concentration. Genetic improvement aiming to increase nutrient remobilization should take into account the organ-specific remobilization pattern of the target nutrient.     

Effect of panicle nitrogen on grain filling characteristics of high-yielding rice cultivars

The effects of four levels of panicle nitrogen fertilizer on the grain filling characteristics of three rice (Oryza sativa L.) varieties (super japonica rice Ningjing 3, three-line japonica hybrid rice Changyou 3 and three-line indica–japonica hybrid rice Yongyou 12) were analyzed. The results showed that difference in time of maximum filling rate (T_max) was the smallest between the superior and inferior spikelets of Ningjing 3, bigger between those of Changyou 3, the biggest between those of Yongyou 12. Ningjing 3 was of the synchronous grain-filling type, Yongyou 12 the asynchronous type, and the Changyou 3 the medium type. The grain filling rate, the initial filling power (R₀), the maximum filling rate (G_max), and the average filling rate (G) of the superior and inferior spikelets of the three varieties under the treatment of panicle N with the amount of 120 kg ha⁻¹ (middle panicle N, shortened as NM) treatment were higher than those of other treatments. NM treatment led to the highest increase in grain weight at the middle stage of filling for all the three varieties. The treatment shortened the early and late stages of grain filling, but extended the middle stage when the filling rate was the highest. However, the middle stage of grain filling of Changyou 3 and Yongyou 12 was much more extended than that of Ningjing 3, indicating a better effect of N on hybrid rice varieties.     

Evaluation of grain yield and related agronomic traits of quality protein maize hybrids in Southern Africa

Maize is the major staple food in southern Africa with human consumption averaging 91 kg capita^?1 year^?1, and normal maize is nutritionally deficient in two essential amino acids: tryptophan and lysine. Despite the development of quality protein maize (QPM) with high tryptophan and lysine, stunting and kwashiorkor remain high in sub-Saharan Africa due to lack of high yielding and adapted QPM varieties. This study aimed at evaluating a new generation of QPM varieties for yield and related agronomic traits. Before the QPM varieties were validated on-farm, they were simultaneously selected on-station under five different management conditions. In the 2014/2015 season, 10 elite QPM varieties were selected from on-station trials based on high grain yield and stability, and were compared with the best commercial check varieties on-farm. During the 2015/2016 season, some poorly performing QPM varieties were dropped while new ones were added, resulting in 12 elite QPM varieties being evaluated on-farm. Analysis of variance for the 2014/2015 season showed non-significant hybrid × management condition interaction. Mean grain yields across management conditions ranged from 1.5 to 4 t ha^?1 and were higher under mild stress (2.3–5.5 t ha^?1) compared to random stress conditions (1.1–2.9 t ha^?1). Broad sense heritability estimates were low to moderate (11–69%), and thus could still permit effective selection of better genotypes. Yield advantage ranged from 12 to 25% across the 2 years, suggesting effective genetic gains in QPM breeding. QPM hybrids CZH132044Q, CZH142238Q and CZH142236Q were stable and high yielding. Promotion of such QPM hybrids may help reduce protein energy malnutrition.     

Effect of two-week heat stress during grain filling on stem reserves,senescence, and grain yield of European winter wheat cultivars

To examine the extent to which heat stress during grain filling impacts on the development and yield of winter wheat (Triticum aestivum L.), a 3-year field experiment was conducted on a loess soil with high water holding capacity in the North German Plain. Thirty-two mostly European winter wheat cultivars were exposed to heat stress in a mobile foil tunnel with maximum air temperatures of 45.7, 45.4, and 47.2°C in 2015, 2016, and 2017, respectively. The 14-day post-anthesis heat stress treatment caused an average 57.3% grain yield reduction compared to a close-by non-stressed control. The proportion of green crop area after the heat stress phase varied from 7% to 98% in 2016 and from 37% to 94% in 2017. The green crop area percentage did not significantly correlate with grain yield, indicating that the delayed senescence of stay-green phenotypes offers no yield advantage under terminal heat stress. The water soluble carbohydrate (WSC) concentration of the stems at crop maturity varied between 6 and 92 g/kg dry matter, showing that the genotypes differed in their efficiency at using the stem carbohydrate reserves for grain filling under heat stress. The stem WSC concentration correlated positively with the beginning of anthesis (r = 0.704; p < .001) but negatively with the grain yield (r = −0.431; p < .05). For heat tolerance breeding, the stem reserve strategy, i. e. the rapid and full exhaustion of the temporary carbohydrate storage therefore seems more promising than the stay-green strategy.     

Diallel analysis of grain filling rate and grain filling period in tropical maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

Grain yields of maize in the lowland tropics are generally limited by short days and high temperatures that minimize durations of incident light. Little has been published on the effects of this limiting environment on the genetics of grain filling rate (GFR), and grain filling period (GFP) in tropical maize germplasm. This study sought to address these limitations. A set of 8 elite maize inbreds of tropical origin and their 28 diallel hybrids were grown in three seasons at Waimanalo, Hawaii, USA. Seasonal differences included > 100% differences in values of photosynthetic active radiation (PAR) during grain formation. Information was sought on the performance variations and the genotype by season interactions for GFR, GFP, days to mid-silk (DTS), kernel weight, with estimates of general (GCA) and specific combining ability (SCA) and their interactions with seasons. Significant differences occurred for inbreds, hybrids, and genotype by season interactions, GCA and SCA effects and their interactions with seasons, which could be attributed primarily to the differences in PAR values among seasons in Hawaii during grain filling. Additive genetic effects predominated for GFR and GFP. Breeding approaches that take advantage of additive gene effects including hybrid breeding with evaluations in multiple Hawaii seasons may be used to alter GFR and GFP.     

不同氮效率玉米基因型苗期对光和氮响应的研究

对氮效率表现差异显著的三个玉米自交系幼苗采用不同光强和氮浓度处理,比较根冠比、生物产量、硝酸还原酶和谷氨酰胺合成酶的响应差异。结果表明：不同氮效率自交系对不同氮浓度与光照强度处理的响应存在显著差异;氮低效材料在低光低氮条件下的生物产量表现比氮高效材料好,在高光高氮条件下时生物产量表现比氮高效差;氮高效材料随着氮浓度增加比氮低效材料更能保持根的发达性,表明根系是氮高效的保证。不同氮效率自交系生物产量和硝酸还原酶光氮最佳耦合点值不同,氮低效自交系出现光氮最佳耦合点时所需要的氮浓度（或光强）要比氮高效自交系低。因此,玉米基因型氮效率的发挥不但需要适宜的供氮水平,还需要合适的光照强度。     

玉米不同氮素水平下产量与zmAspAT基因表达分析

研究不同氮素水平下导入系L18和Y478产量及相关性状的差异以及与zmAspAT基因表达模式的关系。考察L18和Y478在低氮和正常供氮条件下的产量及相关性状,利用实时定量PCR技术分析zmAspAT基因的表达变化。在正常供氮条件下L18的单穗产量比Y478高17.21%,显著增加,行粒数极显著增加,百粒重显著减小;低氮条件下,L18单穗粒重比轮回亲本Y478显著减少,达到20.64%,行粒数显著增加,百粒重极显著减小。在低氮胁迫条件下,zmAspAT基因在L18中下调表达,在Y478则上调表达,表达模式不同。L18是氮低效的导入系,由于zmAspAT基因在L18与Y478表达模式不同,导致了L18较低的氮素利用效率和产量,zmAspAT是重要的玉米氮利用效率基因。     

小麦旗叶衰老过程不同数学模型拟合比较及衰老特征分析

为了准确了解小麦叶片的衰老特征,筛选适合描述小麦叶片衰老过程的数学模型, 2011年和2012年分别以91个和105个小麦品种(系)为材料,用S型曲线中的Logistic、Gompertz和Richards模型拟合了试验品种叶片的衰老过程,解析了其叶片衰老特征。结果表明,试验品种可分为延绿、中等延绿、中等早衰和早衰4种类型。其旗叶衰老过程可分为衰老起始期、快速衰老期和衰老结束期3个阶段,3个阶段旗叶的衰老速度表现为慢–快–慢,不同延绿类型品种开花后旗叶的绿色叶面积百分比下降主要在衰老过程的中后期。3种模型对不同延绿类型品种旗叶衰老过程均可以拟合,Gompertz和Richards模型拟合度接近,高于Logistic模型。Gompertz模型的拟合度以早衰中等早衰中等延绿延绿类型。不同延绿类型品种旗叶衰老曲线特征参数达到最大衰老速度时间(TMRS)、平均衰老速度(ARS)和绿色叶面积持续期(GLAD)存在显著差异, TMRS和GLAD以延绿中等延绿中等早衰早衰, ARS以早衰中等早衰中等延绿延绿。Gompertz模型对小麦叶片衰老过程的拟合度优于Logistic模型。叶片衰老过程特征参数可以用于品种延绿性差异评价。     

Interspecific hybrids and possible phylogenetic relations in grain amaranths

Summary Phylogenetic relations among the three species in grain amaranth need investigation to provide information for breeding experiments germplasm conservation efforts, and decision on evolutionary patterns in the grain types. Hybrid development from crosses between species was studied to find out genetic relationship between them. Interspecific crosses were made among Amaranthus hypochondriacus, A. caudatus and A. cruentus in the glasshouse. The F₁ plants were relatively easy to obtain but had low pollen fertility (10.3–15.1%) and low seed set. A few of these hybrids did not produce seeds. Only a few F₁ seeds obtained in crosses between A. cruentus and A. caudatus. All the F₁ plants from these crosses died at the seedling stage. Crosses between A. cruentus and A. hypochondriacus produced few seeds. Most of the F₁ plants obtained from the seeds died at the seedling stage with only four plants growing to maturity but were sterile. Based on hybrid development, it was suggested that A. hypochondriacus and A. caudatus were genetically closer than the other two combinations of species studied. A. cruentus seemed to be genetically closer to A. hypochondriacus than it was to A. caudatus.Research was supported by Grand No. AMA-KE-4-83-22. (CRG GRANT) from the National Academy of Science, U.S.A.     

棉花根系生长与叶片衰老的协调性

为探索棉花根系生长和叶片衰老之间的协调性,选用早熟性一致但衰老快慢有明显差异的棉花基因型百棉1号(叶片衰老慢)和DP99B (叶片衰老快),于2011—2012年,在田间条件下研究了其根系生长和活力、叶片衰老和产量。结果表明, 2年间百棉1号的纤维产量(皮棉及霜前皮棉)均显著高于DP99B。百棉1号的叶片光合作用或基于吸收光能的性能指数显著高于DP99B。百棉1号的根系长度密度和根系深层分布比例及根系活力(以伤流液总量和伤流液蛋白质含量表示)显著高于DP99B。2012年结果显示,DP99B根系生长比百棉1号快,并且DP99B根系长度密度及根系活力分别在8月中旬和7月下旬显著高于百棉1号,且伤流液分泌总量是百棉1号的1.7倍。棉花盛花期后,根系密度大、伤流液分泌多和叶片衰老晚具有一致性,证实棉花叶片衰老受后期根系生长和活力的调控。