Canavanine distribution in jackbean fruit during fruit growth

Summary Canavanine is an arginine analogue found in the seeds of many common legumes and is known to inhibit protein synthesis and growth in a number of organisms. Yet canavanine may comprise as much as 4% of the seed dry weight of the jackbean (Canavalia ensiformis).Canavanine is accumulated during earlier development in the pod, but disappears upon ripening. A corresponding increase in seed canavanine of about the same magnitude as the loss in the pod takes place during this latter time, but there is a subsequent significant increase of canavanine content of the seed after all detectable canavanine has disappeared from the pod. The first of these changes suggests synthesis of canavanine in the pod and transport into the seeds while the second one indicates a synthesis of canavanine in the seeds themselves, or possibly in the leaf or pod with rapid translocation to the seed.Canavanine was found to be at its highest concentration in the seed coats and pods when they were growing most rapidly and to gradually decline afterwards; however, the canavanine concentration of the seeds was found to be constant throughout fruit development.The pattern of canavanine mobilization in jackbean fruits was quite similar to the known pattern of total nitrogen mobilization typical of other leguminous fruits. This is consistent with a role as a nitrogen transport and storage compound.University of Tennessee, Department of Botany, Contribution N. Ser. No. 279.     

甘蔗—大豆间作对大豆鲜荚产量和农艺性状的影响

为探讨甘蔗-大豆间作模式对大豆鲜荚产量和农艺性状的影响,于2009—2011年连续3年在广州市华南农业大学农场进行大田试验,试验设置2种施氮水平(常规施氮(525kg·hm-2)和减量施氮(300kg·hm-2))和3种种植模式(甘蔗-大豆(1∶1)、甘蔗-大豆(1∶2)、单作大豆)。结果表明:甘蔗-大豆间作(1∶2)模式下,2009年减量施氮水平的大豆鲜荚产量较常规施氮水平提高了33%,2010和2011年不同施氮水平间均无显著差异;甘蔗-大豆间作模式对大豆的单株鲜荚重、多粒荚数和百粒鲜重无显著影响;大豆单株鲜荚重与多粒荚数在不同种植模式下均呈显著相关(P<0.05),在常规施氮间作模式下与大豆单株荚数呈显著相关(P<0.05)。甘蔗-大豆间作没有降低大豆的单株鲜荚产量,也没有对大豆的农艺性状产生负面影响,从增产增收、提高土地生产力来考虑,减量施氮模式下甘蔗-大豆间作具有一定的可行性。     

Comparisons of Earlier- and Later-formed Pods of Chickpeas (Cicer arietinum L.)

In chickpeas (Cicer arietinum L.) flowering and pod developmentproceed acropetally. In plants grown under normal field conditionsat Hyderabad, in peninsular India, and at Hissar in north India,at successively apical nodes of the branches there was a declinein pod number per node, weight per pod, seed number per podand/or weight per seed. The percentage of nitrogen in the seedswas the same in earlier and later-formed pods at Hyderabad;at Hissar the later-formed seeds contained a higher percentage.Earlier- and later-formed flowers contained similar numbersof ovules. The decline in seed number and/or weight per seedin the later-formed pods of 28 out of 29 cultivars indicatedthat pod-filling was limited by the supply of assimilates orother nutrients. By contrast, in one exceptionally small-seededcultivar there was no decline in the number or weight of seedsin later-formed pods, indicating that yield was limited by ‘sink’size. Cicer arietinum L., chickpea, flowering, pod development, seed number, seed weight, nitrogen content     

Periods of Shoot Chilling Sensitivity in Soybean Flower Development, and Compensation in Yield after Chilling

Soybeans [Glycine max (L.) Merr. cv. Ransom] grown at a constant25 °C were placed in a 12-h inductive photoperiod at twoweeks of age. Subgroups were shoot-chilled for one week at aconstant 10 °C during each of the first four weeks of floralinduction. Controls were photoinduced but not chilled. Chillingduring the first week of photoinduction inhibited productionof floral primordia, but did not increase the abscission rateof flowers and pods. Chilling during the second week did notaffect primordium production or abscission rate, but did causea significant increase in numbers of fused and malformed pods.Chilling during the third week caused loss of 77 per cent ofearly flowers and pods by abscission, while fourth week chillingcaused less severe losses by abscission. Inhibition of vegetativegrowth may have been responsible for primordium loss in first-weekplants, while disturbances in the development of flowers wereresponsible for the losses in the other chilling weeks. Althoughchilling during the first and third photoinduction weeks causeda significant reduction in early pod numbers, plants harvestedat 16 weeks of age showed no significant loss in seed yield.Low abscission rates late in pod filling and increased weightof individual seeds compensated for early losses of pods. Thesecompensatory responses to a chilling-induced loss of pods aresimilar to those reported for mechanically depodded soybeans. Glycine max (L.) Merr., soybean, temperature, chilling, floral initiation, anthesis, abscission, yield, compensation     

Photomorphogenesis of the Gynophore, Pod and Embryo in Peanut, Arachis hypogaea L.

Darkened excized gynophores ceased to elongate after 8–10days in vitro and started to form a pod. Gynophore elongationwas inhibited to a greater extent in total darkness than underlow irradiance, while pod and embryo growth was stimulated indarkness only. Intact gynophores, enclosed in transparent vials containingglass beads, continued to elongate in both light and darkness.In light the elongating gynophores thickened as they penetratedbetween the glass beads, forming a seedless pod at the bottomof the vials. In the dark the elongating gynophores producedsmall pods in which the seeds had started to grow. Excized gynophores elongated in vitro under continuous whitelight at a rate similar to that of intact exposed gynophores.The rate of elongation in vitro, was lower under continuousblue or red-enriched light, than under white light, and wasfurther reduced under continuous far-red irradiation. Pods didnot form during any of the continuous irradiation treatmentsbut only after transfer to darkness, the largest pods formingafter continuous far-red irradiation. As little as 10 min daily exposure to red or far-red irradiancehad the same effect on gynophore elongation as continuous irradiation.Pods formed only when the daily periods of far-red irradiationwere 30 min or less. Reducing the daily exposures to 2 min decreasedthe time to onset of pod formation from 30 to 16 days. Far-redfollowing red irradiation was effective in inhibiting gynophoreelongation stimulated by red irradiation. Pod formation in red/far-redirradiation was only 50 per cent of that observed in far-redirradiation. The involvement of light in continual gynophoreelongation and in the concomitant inhibition of proembryo growthis discussed. Arachis hypogaea L., peanut, gynophore, photomorphogenesis, embryo development, pod development, proembryo     

Isolation and characterization of a pea pod cDNA encoding a putative blue copper protein correlated with lignin deposition

Nearly isogenic pea lines were selected to investigate the geneticbasis for lignification of the pea (Pisum sativum) pod endocarp.The development of the pod endocarp in the normal and mutantpea pod pheno-types was examined by light microscopy. A peapod cDNA library representing poly (A)+ RNA purified from L59pea pods (genotype, PV; phenotype, lignified endocarp) was differentiallyscreened with total cDNA probes prepared from total pod RNAfrom L59 and L1390 (genotype, pv; phenotype, no lignificationof endocarp) pods 4-6 d after flowering (DAF). A clone, designatedpLP18, was selected for further characterization on the basisof hybridization to the L59 cDNA probe, but not the L1390 cDNAprobe. Northern blotting was used to show that pLP18 representeda mRNA of 0.95 kb. The predicted polypeptide from the LP18 cDNAencoded a putative blue type 1 copper protein. The expressionpattern of LP18 mRNA in pods of the experimental pea lines wasdetermined using RT-PCR quantitation. Hybridization of the cDNAto pea genomic DNA showed that this protein is probably encodedby a single gene. Key words: Pisum sativum, pod endocarp, lignification, blue copper protein     

Carbon Transfer and Partitioning between Vegetative and Reproductive Organs in Pisum sativum L

Assimilate partitioning was studied in the common pea (Pisum sativum L.) by feeding ¹⁴CO₂ to whole plants and measuring radioactivity in different organs 48 hours after labeling. Two experimental protocols were used. For the first, one reproductive node was darkened with an aluminum foil, to prevent photosynthesis during labeling. The aim was to study assimilate translocation among nodes. The second was carried out to assess any priority among sinks. Whole plants were shaded, during labeling, to reduce carbon assimilation. Various developmental stages between the onset of flowering and the final stage in seed abortion of the last pod were chosen for labeling. When all photosynthetic structures at the first reproductive node were darkened at any stage of development after the formation of the first flower, the first pod was supplied with assimilates from other nodes. In contrast, later developed pods, when photosynthetic structures at their node were darkened, received assimilates from other nodes only when they were beyond their final stage in seed abortion. Reducing illumination to 30% did not change distribution of assimilated carbon between vegetative and reproductive structures, nor among pods. It appears that the relative proportion of ¹⁴C allocated to any one pod, compared to other pods, depends on the dry weight of that pod as a proportion of the total reproductive dry weight. When the plant was growing actively, following the start of the reproductive phase until a few days before the end of flowering, the top of the plant (i.e., all the organs above the last opened flower) had a higher sink strength and a higher relative specific activity than pods, suggesting that it was a more competitive sink for assimilates. The pattern of assimilate distribution described here provides an explanation for pod and seed abortion.     

Effect of cocoa pod age on egg distribution and egg parasitism of the cocoa pod borer in Malaysia

The effects of pod age on oviposition, and on egg and larval survival of the cocoa pod borer (CPB), Conopomorpha cramerella (Snellen), were investigated. CPB were allowed to oviposit on a batch of 50 pods for a period of 7 days over several exposure dates. Numbers of CPB eggs/pod and survival to larval emergence from the pods were recorded. Pods were harvested when ripe and analyzed for larval survival within the pod. The oviposition pattern varied with pod age. Older pods less than 7 weeks before ripening (WBR) were preferred, suggesting greater nutritional value or chemical attraction of the older pods. The proportion of eggs parasitized by Trichogrammtoidea bactrae fumata Nagaraja (TBF), the number of eggs lost and the proportion surviving to larval emergence from the pod were independent of pod age. Egg parasitism was low, implying that TBF was not an effective natural enemy. Mass-releases of TBF should be intensified during cropping periods with higher proportions of susceptible pods (<10 WBR). Survival of larvae in the presclerotic layer (preSCL) was high and independent of pod age. Larval mortality at the SCL (sclerotic layer) was dependent on pod age and was high in older pods. Larval density influenced the survival of larvae inside the pod and was dependent on pod age. Larval mortality associated with SCL hardness and thickness is one of the criteria for the selection of CPB resistant cocoa clones.     

The effects of flower removal on the seed yield of pigeonpeas (Cajanus cajan)

In field experiments carried out at Hyderabad, India with early and mediumduration cultivars of Cajanus cajan sown at the normal time, in July, removal of all flowers and young pods for up to 5 wk had little or no effect on final yield. The flowering period of the deflowered plants was extended and their senescence delayed. The plants compensated for the loss of earlier-formed flowers by setting pods from later-formed flowers; there was relatively little effect of the deflowering treatments on the number of seeds per pod or weight per seed. The plants were also able to compensate for the repeated removal of all flowers and young pods from alternate nodes by setting more pods at the other nodes.
The removal of flowers from pigeonpeas grown as a winter crop resulted in yield reductions roughly proportional to the length of the deflowering period, probably because maturation of these plants was delayed and occurred under increasingly unfavourable conditions as the weather became hotter.     

遮光对蚕豆花荚形成和脱落的影响

本文旨在研究蚕豆开花前后不同时期光照强度对花荚形成和脱落的影响。产量补偿能力以及花荚形成和脱落的生理生态原因。蚕豆花前遮光,开花总数和结荚数降低,但花荚脱落率下降,粒重增加。花期和花后遮光,对开花总数没有明显影响,但花荚脱落严重,减产最多。任何时期遮光均使比叶重、遮光后期叶绿素含量、光合生产量、生殖器官干物质分配率,可溶性糖和含N量下降,但成熟期可溶性糖和含N量,营养元素吸收量不受影响。遮光导致花荚形 成和产量减少的主要原因是C／N比值下降,而不是改变营养元素的丰度所致。     

Effects of enhanced UV-B radiation on pea (Pisum sativum L.) grown under field conditions in the UK

A new modulated lamp system is described. This system has successfully provided an ultraviolet-B (UV-B) supplement in proportion to ambient UV-B. The modulated system was used to simulate the UV-B environment resulting from an annual mean reduction of 15% in the stratospheric ozone under UK field conditions, but taking account of seasonal variation in depletion. The effects of this enhanced level of UV-B on the growth, physiology and yield of four cultivars of pea were assessed. Enhanced UV-B resulted in small reductions in the number of stems and total stem length per plant (respectively 4.7 and 8.7%). There were also significant decreases in the dry weight of peas (10.1%), pods (10.3%) and stems (7.8%) per plant. UV-B treatment had no effect on the number of peas per pod or average pea weight, but did significantly reduce (12.1%) the number of pods per plant. This decrease in pod number was partly due to enhanced abscission of pods during the final month of plant growth. UV-B treatment had no significant effect on chlorophyll fluorescence characteristics or CO₂assimilation rate per unit leaf area. These results are consistent with previous controlled environment experiments, and suggest that reduction in yield may be due to direct effects of UV-B on plant growth rather than a decrease in photosynthetic capacity per unit leaf area.     

Preferential Loss of an Abundant Storage Protein from Soybean Pods during Seed Development

A temporary vegetative storage protein, composed of similar 25 kilodalton and 27 kilodalton subunits, was found to be abundant in soybean (Glycine max (L.) Herr. var Hobbit) leaves, stems, pods, flower petals, germinated cotyledons, and less abundant in roots, nodules and seeds. Total pod protein was highest at 3 weeks after flowering and declined by 37% within 3 weeks during seed development. During this time the vegetative storage protein declined from 18% to 1.5% of the total pod protein and accounted for 45% of the protein lost from pods. This indicates that the vegetative storage protein makes a significant contribution to the pool of nutrients mobilized from pods for transport to developing seeds.     

Physical restriction of pods causes seed size reduction of a brassinosteroid-deficient faba bean (Vicia faba)

BACKGROUND AND AIMS: A brassinosteroid-deficient mutant faba bean (Vicia faba 'Rinrei') shows dwarfism in many organs including pods and seeds. 'Rinrei' has normal-sized seeds together with dwarf seeds, suggesting that dwarfism in the seed may be indirectly caused by brassinosteroid deficiency. The mechanism of seed size reduction in this mutant was investigated. METHODS: The associations between seed orientation in the pod, seed numbers per pod and pod lengths with seed sizes were analysed in 'Rinrei' and the wild-type plant. KEY RESULTS: 'Rinrei' seeds are tightly arranged in pods containing two or three seeds. Seed size decreased as the number of seeds per pod increased or as the length of the pod decreased. Where no physical restriction occurred between seeds in a pod, the wild-type faba bean seeds had a nearly constant size regardless of seed number per pod or pod length. 'Rinrei' seeds in pods containing single seeds were the same size as wild-type seeds. Brassinolide treatment increased the seed size and the length of pods containing three seeds in 'Rinrei'. CONCLUSION: Seed size of 'Rinrei' is mainly regulated through a reduction of pod length due to brassinosteroid deficiency; physical restriction within pods causes a reduction in seed size. These results suggest a possible mechanism for increasing faba bean yields to optimal levels.     

A Physiological Analysis of the Branching Pattern in Sequential Types of Groundnut in Relation to the Fruiting Nodes and the Total Mature Pods Produced

The branching pattern of eight sequential branching types ofgroundnut was studied and the contribution of each node (fruitingpoint) of the n, n+1 and n+2 branches (if present) to the totalnumber of mature pods per plant ascertained. The results indicatedthat n+2 branches were present in several varieties and theircontribution to mature pods was significant in some of them.The first three nodes of the n+1 branches contributed from 50.6per cent (in a variety which had significantly more n+2 branches)to 88 per cent in other varieties. The results also indicatedthat the contribution of the late formed n+1 branches was lowand the total mature pods produced from all nodes decreasedwith each successive (chronologically) n+1 branch in all thevarieties studied. Neither the total number of n+1 branchesnor the number of mature pods per node was related to the podnumber or pod yield, but the total number of fruiting pointsfrom all branches showed a high correlation with pod yield andmature pod number at harvest. The results suggest that for higherpod yield it may be desirable to have only a few n+1 branches(4 or 5) but with more fruiting points on each branch. Arachis hypogaea, branching pattern, sequential types, fruiting points     

The role of auxin in cell separation in the dehiscence zone of oilseed rape pods

Concentrations of both free and conjugated indole-3-acetic acid(IAA) were studied during development of pod wall, dehiscencezone and seeds of Brassica napus pods. A decrease in auxin contentprior to moisture loss in the pods was observed specificallyin the dehiscence zone, which was correlated with a tissue specificincrease in ß-1,4-glucanase activity. Furthermore,treatment of the pods with the auxin mimic 2-methyl-4-chlorophenoxyaceticacid resulted in a delay of 10 d of ß-1,4-glucanaseactivity and con-comitant cell separation in the dehiscencezone. This indicates that the activity of hydrolytic enzymesinvolved in cell separation in the dehiscence zone is regulatedby auxin activity. Comparison of parthenocarpic pods with seeded pods pointed tothe seeds as the source of IAA. Levels in the dehiscence zoneof these pods were low over the entire sampling period, whilecell separation in the dehiscence zone was delayed by about4 d. These results indicate that a low level of auxins in thedehiscence zone is necessary for dehiscence to take place, butother factors may also be important. Key words: Brassica napus, pod dehiscence, auxin, cellulase     

Responses of Kamchatkan fish‐eating killer whales to playbacks of conspecific calls

Killer whales produce repertoires of stereotyped call types that are primarily transmitted vertically through social learning, leading to dialects between sympatric pods. The potential function of these call repertoires remains untested. In this study, we compared the reaction of Kamchatkan fish‐eating killer whales to the playbacks of calls from the same and different pods. After the playback of recordings from a different pod, in three cases whales changed the direction of their movement toward the boat, and in three cases no changes in direction were observed. After the playback of recordings from the same pod (either from the same or a different unit within the pod), in seven cases whales changed the direction of their movement toward the boat, and in only one case no change in direction was observed. Whales remained silent after all six playbacks of recordings from a different pod, even when they changed direction toward the boat. After the playback of recordings from the same pod, however, in all eight cases whales started calling in response. Our playback study shows that killer whales may react to playbacks of conspecific sounds and that reactions are dependent on the type of playback stimuli.     

Seed dispersal of Acacia erioloba by African bush elephants in Hwange National Park, Zimbabwe

Approximately two-thirds (64%) of all dry season samples of elephant dung analysed during a 3-year study in the Main Camp subregion of Hwange National Park, Zimbabwe, contained seed and/or pod materials from Acacia erioloba . Most seeds were recovered intact and actively germinating seeds were not uncommon. Very little pod mass relative to seed mass was recovered in most instances, with pod fragments recorded from only 56% of all exhaustively sampled elephant dung piles containing A. erioloba fruit materials. Nonetheless, large pod fragments and even entire intact pods were recovered occasionally from elephant dung. Seeds and pods of A. erioloba may comprise 12% or more of total wet-weight dung mass; individual dung piles were found which contained > 5000 A. erioloba seeds. Birds and smaller mammals search out and consume A. erioloba seeds present within elephant dung piles. The findings of this study indicate that potential digestibility of A. erioloba seeds for bush elephants ( Loxodonta africana africana ) may be much higher than expected from previous studies. In controlled feeding trials with captive bush elephants (age 11–15 years old) maintained on predominantly free-range dry season diets, the estimated efficiency of digestion for A. erioloba seeds consumed in pods was 81% to 96%, with a gut-transit time of between 24.5 and 36.0 h. On the basis of throughput times determined in experimental feeding trials, potential elephant-dispersal distances of 20–50 km are predicted for A. erioloba in the Kalahari Sands landscapes of southern central Africa.     

Transmission of the Monocarpic Senescence Signal via the Xylem in Soybean

During monocarpic senescence in soybean (Glycine max [L.] Merrill cv. Anoka) there is a remobilization of nitrogen from the leaves to the seeds, and it has been hypothesized that this loss of nitrogen from the leaves induces foliar yellowing. The phloem in a small segment of the petiole between the pods and the target leaf can be inactivated with a jet of steam. When a plant is depodded except for a single pod cluster in the center of the plant, the pod cluster induces yellowing of the nearest leaf even if the petiole contains a zone of dead phloem, whereas most of the rest of the plant remains green. The nitrogen content of these leaves with a dead phloem zone in their petioles does not decrease greatly, even though the leaves turn yellow. A similar treatment of a single leaf on a fully depodded plant (leaves stay green) does not cause that leaf to turn yellow. Since nutrients would have to be withdrawn from the leaves via the phloem, the pods do not induce yellowing by pulling nutrients out of the leaf and must be able to exert their influence via the xylem.     

DEMOGRAPHIC ASPECTS OF FLOWER AND FRUIT PRODUCTION IN BEAN PLANTS,PHASEOLUS VULGARIS L.

In this paper we assess the relative contributions to total pod yield of cohorts of flowers of known age. Bean plant (Phaseolus vulgaris L.) growth was monitored and 'births' of individual flowers were recorded and their fates followed. For every cohort of flowers an array of yield measures was calculated, including the mean and total cohort dry weight of fruits, and the numbers of viable and aborted seeds and completely undeveloped ovules. When mature, pods were removed from half of the plants. Plants whose mature pods were removed produced significantly greater numbers of flowers, ovules and viable seeds and a greater total weight of pods than did untreated plants. However, the proportion of ovules giving rise to viable seeds and to aborted seeds and undeveloped ovules was the same in plants of both groups. Approximately 50% of ovules of marketable pods, in all plants, yielded viable seeds. The 12 cohorts of flowers contributed markedly different amounts to plant yield. Early and later cohorts contributed much less than did middle cohorts in terms of marketable pod dry weight and numbers of fully developed seeds, aborted seeds, and undeveloped ovules. Peak productivity was therefore obtained from the middle phase of flowering in these annual bean plants. The lower pod yield of later cohorts is interpreted as a result of competition for limited resources between maturing pods and new flowers. We consider possible causes for the various fates of flowers and ovules and discuss flowers as plant modules suitable for demographic examination.