Physiological responses of chickpea genotypes to terminal drought in a Mediterranean-type environment

Two field experiments were carried out to investigate the effects of terminal drought on chickpea grown under water-limited conditions in the Mediterranean-climatic region of Western Australia. In the first experiment, five desi (small angular seeds) chickpeas and one kabuli (large round seeds) chickpea were grown in the field with and without irrigation after flowering. In the second experiment, two desi and two kabuli cultivars were grown in the field with either irrigation or under a rainout shelter during pod filling. Leaf water potential (Ψ_l), dry matter partitioning after pod set and yield components were measured in both experiments while growth before pod set, photosynthesis, pod water potential and leaf osmotic adjustment were measured in the first experiment only.

In the first experiment, total dry matter accumulation, water use, both in the pre- and post-podding phases, Ψ_l and photosynthesis did not vary among genotypes. In the rainfed plants, Ψ_l decreased below −3 MPa while photosynthesis decreased to about a tenth of its maximum at the start of seed filling. Osmotic adjustment varied significantly among genotypes. Although flowering commenced from about 100 days after sowing (DAS) in both experiments, pod set was delayed until 130–135 DAS in the first experiment, but started at 107 DAS in the second experiment. Water shortage reduced seed yield by 50 to 80%, due to a reduction in seed number and seed size. Apparent redistribution of stem and leaf dry matter during pod filling varied from 0 to 60% among genotypes, and suggests that this characteristic may be important for a high harvest index and seed yield in chickpea.     

Reproductive response of two morphologically different pea cultivars to drought

Water use by semi-leafless peas (Pisum sativum L.) is usually less than that of conventional peas because of their reduced surface leaf area, suggesting that semi-leafless peas would be less sensitive to drought because drought develops later. This work aimed to study the reproductive response of peas cv. Solara (semi-leafless) and cv. Frilene (conventional) subjected to similar controlled soil drought during the critical period occurring between flowering and initial seed filling. Plants were subjected to drought by watering with a fraction of water used in the evapotranspiration of control plants. Soil, pod and seed water contents, leaf water status parameters, dry matter (DM) partitioning, seed yield, yield components and water use efficiency (WUE) were measured. Although soil water content decreased in a similar way in both cultivars, leaf Ψ_w and RWC only decreased significantly in Solara. Well-watered Frilene plants produced higher shoot and pod DM, but lower seed DM. Well-watered Solara plants produced lower pod DM and higher seed DM than Frilene. Under drought, Frilene increased partitioning of total plant DM to vegetative organs, particularly roots, and decreased DM allocation to pods and seeds increasing flower abortion. By contrast, droughted Solara interrupted vegetative growth and increased leaf senescence but maintained similar partitioning of total plant DM to pods and seeds as in well-watered conditions. For both cultivars there was a close relationship between the percentage of total DM partitioned into seeds and WUE_y (water use efficiency on seed yield basis). Results demonstrate that when plants suffered the same level of drought in the soil, the reproductive response of the two cultivars was linked to differences in their WUE.     

Impact of heat stress on pod-based yield components in field pea (Pisum sativum L.)

Elevated temperatures associated with climate change result in crops being exposed to frequent spells of heat stress. Heat stress results in reduced yield in field pea (Pisum sativum L.); it is therefore important to identify cultivars with improved pod and seed retention under heat to mitigate this loss. Objectives were to investigate the effect of heat stress on phenology, yield and pod-based yield components. Sixteen pea cultivars were evaluated at normal and late (hot) seeding dates in the field in Arizona 2012 and in growth chambers with two temperature regimes (24/18°C and 35/18°C day/night temperature for 7 days) during reproductive development. We measured variation in the pattern of pod retention at four-node positions on plants, seed retention by ovule position (stylar, medial and basal) within pods and screened cultivars for pod retention, seed retention and yield. Heat stress reduced seed yield by accelerating the crop lifecycle and reducing pod number and seed size. Heat stress had the most damaging effect on younger reproductive growth (flowers and pods developed later), resulting in ovary abortion from developing flowers. Heat also accelerated seed abortion in all ovule positions within pods. Two high-yielding cultivars under control temperature, “Naparnyk” and “CDC Meadow”, maintained high yield in heat, and “MFR043” had the lowest yield. Cultivars “40-10” and “Naparnyk” retained the most ovules and seeds per pod, and “MFR043” aborted seeds when exposed to heat. In half of the cultivars, ovules at the basal peduncle end of pods were likely to abort while ovules at the medial and stylar end positions developed into seeds. For seven of the field cultivars, ovules at the medial pod position also produced mature seeds. Cultivars “40-10”, “Naparnyk” and “CDC Meadow” had greater pod and ovule retention or maintained high yield under heat stress, and were identified as heat-tolerant cultivars. Our results allow for a better understanding of pod-based yield components in field pea under heat stress and developing heat-tolerant cultivars.     

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

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

Photosynthesis is Reduced,and Seeds Fail to Set and Fill at Similar Soil Water Contents in Grass Pea (Lathyrus sativus L.) Subjected to Terminal Drought

Grass pea (Lathyrus sativus L.) is an indeterminate grain legume considered adapted to dry environments, but the mechanisms of its adaptation are not well understood. Grass pea plants were exposed to terminal drought from podding, and the development of water deficit was measured together with its effects on leaf photosynthesis, stomatal conductance, carbon remobilisation to the seeds, flower production and abortion, pod production and abortion, seed set, seed growth and the neurotoxin β‐N‐oxalyl‐L‐a, β‐diaminopropionic acid (β‐ODAP) concentration. Predawn leaf water potential (Ψ_leaf), stomatal conductance (gs), rate of leaf photosynthesis (Pn), flower production, pod production, filled pod number, seed number, seed size and yield decreased, while flower abortion, pod abortion and seed abortion increased, and the concentration of β‐ODAP was unchanged under terminal drought conditions. gs and Pn began to decrease at a higher plant‐available soil water content (PAWC) (67.2 ± 2.3 % and 62.9 ± 2.3 %) than Ψ_leaf (43.7 ± 1.1 %). Flowers and pods ceased being produced only when the PAWC decreased below 40.1 ± 4.6 % and 35.3 ± 3.0 %, respectively, but seed set and seed growth ceased when PAWC decreased below 55.5 ± 1.6 % and 58.0 ± 3.7 %, respectively. The mobilization of ¹³C labelled assimilates from the stems was greater under terminal drought than under well‐watered conditions, but the transfer to the seed was small. We conclude that seed set and seed growth decreased as the soil dried due to a reduction in current photosynthesis as a result of stomatal closure.     

Effect of Water Stress on Yield Components in Guar

This study was undertaken to measure the effect of water stress on yield and yield components in guar (Cyamopsis tetragonoloba [L.] Taub.) grown under water-stressed and water-optimal field conditions. Fifteen guar germplasms were grown in irrigated and dryland tests at Lubbock, TX on an Amarillo loam (fine-loamy, mixed thermic Aridic Paleustoll). Plants in each germplasm were hand harvested at maturity and data recorded for number of racemes/plant, pods/plant, seeds/pod, weight/100 seeds and g/seed/plant. We found differences among germplasms for yield components under both dryland and irrigated conditions. Germ-plasms responded statistically the same in both moisture levels. Among three pre-selected cultivars, water use efficiency did not differ statistically. Our analyses indicated that the component of yield most affected by water stress was number of pods/plant. Seed weight, seeds/pod, and racemes/plant each had progressively smaller effects on seed yield.     

Effects of Timing of Drought Stress on Phenology, Yield and Yield Components of Short-duration Pigeonpea

Nine short-duration pigeonpea genotypes were given adequate soil moisture throughout growth or subjected to water stress during the late vegetative and flowering (stress 1), flowering and early pod development (stress 2), or podfill (stress 3) growth stages under field conditions. The stress 1 treatment had no significant effect on the time to flowering. No stress treatment affected maturity or inter-plant flowering synchronization. The interval from a newly opened flower to a mature pod was about 30 days for all genotypes, and was unchanged in plants that were recovenng from stress 1 or undergoing stress 2. Seed yield was reduced to the greatest extent by stress 2 (by 37 %) and not significantly affected by stress 3 for all genotypes. No consistent differences were found between determinate and indeterminate genotypes in the ability to maintain seed yield under both stress 1 and stress 2. The harvest index was significantly reduced (22 %) by stress 2 but not by stress 1. However, under each soil moisture treatment, genotypic differences for seed yield were associated largely with differences in total dry matter production (TDM). For all genotypes, the number of pods m^-2 was the only yield component significantly affected by the water stress treatments. The stability of other yield components should be fully exploited to improve the stability of seed yield under drought conditions (drought resistance). Possible characteristics which may improve the drought resistance of short-duration pigeonpea include the ability to maintain TDM, low flowering synchronization, small pod size with few seeds pod^-1, and large 100-seed mass.     

Reproductive Abscission and Yield of Irrigated and Drought Stressed Cowpea

Two experiments were conducted under field conditions to evaluate reproductive abscission, seed yield and yield components of three cowpea [Vigna unguiculata (L.) Walp.] genotypes. In the first experiment, level of abscission and yield of two cultivars, California Blackeye Pea No. 5 (CA-5) and Speckle Purple Hull (SPH), and one experimental line (AZ-54) were studied. In the second experiment, effect of drought stress on abscission at three nodal positions, seed yield, and yield components of CA-5 were studied. Abscission in both experiments was determined by counting scars left by dropprd reproductive structures including floral buds, open flowers, and immature pods. Abscission of CA-5 and AZ-54 in the first experiment ranged between 68 and 76 % while that of SPH ranged between 86 and 89 %. CA-5 and AZ-54 retained two to three pods per peduncle, and SPH retained only one mature pod per peduncle. Average seed yields of SPH and AZ-54, respectively, were 45 and 50 % of CA-5. Drought stress in the second experiment did not affect production of floral buds Peduncle^?1 (average of 10) but significantly increased percent reproductive abscission and decreased pod retention of CA-5. Abscission in the bottom two-third nodes increased from 82 % in well-irrigated plants to 93 % in non-irrigated plants. This increase in abscission corresponded to nearly 60 % reduction in pod retention. The number of pods per peduncle in the bottom two-third nodes decreased from 1.9 in well-irrigated plants to only. 77 in non-irrigated plants. The increase in abscission and decrease in pod retention with increasing intensity of drought was greatest in the bottom one-third nodes. Drought stress did not affect abscission and pod retention in the top one-third nodes. Stress also decreased peduncles plant^?1, seeds pod^?1, and dry matter and seed yield plant^?1 but did not affect seed weight and harvest index. The decrease in seed yield was largely due to reductions in pods plant^?1 and seeds pod^?1. The reduction in the number of pods and, therefore, seed yield due to stress was because of reductions in the number of peduncles plant^?1 and increases in reproductive abscission. It is concluded external conditions that increase abscission beyond that of normal occurrence affect seed yield adversely.     

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

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

Genetic studies for seed size and grain yield traits in kabuli chickpea

Seed size, determined by 100-seed weight, is an important yield component and trade value trait in kabuli chickpea. In the present investigation, the small seeded kabuli genotype ICC 16644 was crossed with four genotypes (JGK 2, KAK 2, KRIPA and ICC 17109) and F₁, F₂ and F₃ populations were developed to study the gene action involved in seed size and other yield attributing traits. Scaling test and joint scaling test revealed the presence of epistasis for days to first flower, days to maturity, plant height, number of pods per plant, number of seeds per plant, number of seeds per pod, biological yield per plant, grain yield per plant and 100-seed weight. Additive, additive?×?additive and dominance?×?dominance effects were found to govern days to first flower. Days to maturity and plant height were under the control of both the main as well as interaction effects. Number of seeds per pod was predominantly under the control of additive and additive?×?additive effects. For grain yield per plant, additive and dominance?×?dominance effects were significant in the cross ICC 16644?×?KAK 2, whereas, additive?×?additive effects were important in the cross ICC 16644?×?JGK 2. Additive, dominance and epistatic effects influenced seed size. The study emphasized the existence of duplicate epistasis for most of the traits. To explore both additive and non-additive gene actions for phenological traits and yield traits, selection in later generations would be more effective.     

甘蓝型杂交油菜角果长度与产量构成因素的相关分析

[目的]为了研究甘蓝型杂交油菜角果长度与产量构成因素的相关关系,[方法]试验以649个甘蓝型杂交油菜组合进行田间试验、室内考种及相关分析。[结果]结果表明：甘蓝型杂交油菜角果长度平均为6.4596cm,变幅范围4.7184-8.6463cm,角果长度在5~7cm之间的材料占总数比例的96.76%,而平均角果长度≥8cm的材料只占群体比例的1.54%,小于5cm的材料也只占群体比例的1.70%,说明油菜长角果与短角果材料都较少。角果长度与千粒重(r=0.3815)、角粒数(r=0.4324)及单株产量(r=0.2347)呈极显著正相关,角果长度与单株角果数(r=0.0076)呈不显著正相关,说明在选育长角果材料的同时不仅可以提高千粒重、角粒数及单株产量,而且不会降低单株角果数。[结论]由此可知,提高油菜的角果长度,有利于提高油菜产量。     

Water Deficit during the Reproductive Period of Grass Pea (Lathyrus sativus L.) Reduced Grain Yield but Maintained Seed Size

The grain legume grass pea (Lathyrus sativus L.) is adapted to drought‐prone environments, but the extent and mechanisms of its tolerance are not well understood. In a pot experiment, water deficit was imposed on plants by withholding water from first flowering until predawn leaf water potential (LWP_pd) was ?3.12 MPa. Water deficit reduced dry matter, seed yield, harvest index and water use efficiency by 60 %, 87 %, 67 % and 75 %, respectively, when compared with the controls. Flower production stopped when LWP_pd fell to ?1.8 MPa. At LWP_pd?1.5 MPa, only 25 % of flowers resulted in filled pods (compared with 95 % filled pods in the control) with the rest aborted as flowers (48 %) or pods (27 %). Filled pods had more aborted ovules than controls, resulting in 29 % less seeds per pod. Water deficit reduced pollen viability, germination and the number of pollen tubes reaching the ovary by 13 %, 25 % and 31 %, respectively. Emergence from seeds produced from water‐deficient plants was 21 % less than controls, but seedling shoot dry mass was 18 % higher, in accordance with the 19 % higher seed mass. The sensitivity of flowering to drought limited pod numbers but enabled plants to retain existing pods and develop near‐normal seeds with low β‐N‐oxalyl‐l ‐α‐β‐diaminopropionic acid toxin concentrations. This trait is useful for farming systems reliant on harvested seed for the next crop and in cases where seed size influences the value of the product.     

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

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

Genetic control of seed weight and calcium concentration in chickpea seed

Chickpea, Cicer arietinum L., is a staple protein source in many Asian and Middle Eastern countries. Hence, the mineral content of its seed, especially that of calcium, is of nutritional importance. Calcium is transported through plants and to legume pods almost exclusively via the xylem stream, with Ca accretion in developing seeds resulting primarily from diffusion of Ca from the adjoining pod wall. Thus, for seeds of differing surface‐to‐mass ratios, Ca concentration is expected to correlate inversely with seed weight. The relationship between seed weight and Ca concentration in chickpea seeds was studied using a range of germplasm and derivatives from crosses between types differing in seed Ca concentration. Among the cultivars tested, low seed mass was associated with high Ca concentration. However, the study of hybrid progeny indicated that seed Ca content was mainly determined by genetic factors other than grain weight genes. This finding may assist in future breeding of high nutritional quality chickpea cultivars.     

Yield Variation of Soybeans in Hawaii

In Hawaii, soybeans planted in November through January will produce yields of 25 to 50 percent compared with those planted through June. Yield components were studied for several soybean cultivars to determine which one was the most sensitive to planting dates and if there were differences between cultivars.
Soybean cultivars, Amsoy 71, Davis, Forrest, Kahala, P.I. 297,550 , and Williams were planted each month for two years. One November planting was lost, so there were 23 tests representing different environments. Each test consisted of 24 plots, six cultivars in four replications in a randomized block.
Analysis of variance of combined tests indicated significant differences between number of plants, pods per plant, seeds per pod, seed weight, yield of seed, plant height, and oil content of the seed that were due to data of planting, cultivar, and date × cultivar interaction.
Regression analysis indicated a closer relationship between pods per plant and yield during stress conditions (November through January plantings), whereas number of seeds per pod was more closely associated with yield during non-stress environments (April through June plantings).     

Variation in tolerance to radiant frost at reproductive stages in field pea germplasm

Radiant frost is a major abiotic stress, particularly at the reproductive stage, in field pea (Pisum sativum L.) grown in Mediterranean environments. Here, response to frost was studied for flowering stage (FS) organs (buds, flowers and set pods) and pod development stage (PDS) organs (flat, swollen and mature pods) under controlled conditions, with plants exposed to a minimum temperature of –4.8°C for 4 h. This frost treatment adversely affected seed yield through (i) abortion of buds, flowers and set pods (ii) death of pods and (iii) reduction in seed size. FS organs were more sensitive to frost than PDS organs. Genetic variation was observed among 83 accessions collected from 34 countries worldwide for survival of FS buds, flowers and set pods. In 60 of 83 accessions, no buds, flowers or set pods survived the frost treatment. Five accessions: ATC 104 (origin: United Kingdom), ATC 377 (Estonia), ATC 968 (Italy), ATC 3992 (Kazakhstan) and ATC 4204 (China), showed the highest frost tolerance of FS organs and lowest numbers of abnormal seeds. The frost tolerant accessions identified in this study may be useful as parents for breeding field pea varieties that will be less likely to suffer yield loss due to radiant frost during the reproductive stage.     

Putrescine Increases Floral Retention, Pod Set and Seed Yield in Cold Stressed Chickpea

Chickpea (Cicer arietinum L.) is sensitive to cold stress (<8 °C) at its reproductive phase that results in flower abortion, poor pod set and thus reduced yield. Early maturing genotypes are especially more sensitive. In this crop, the metabolic causes underlying cold injury that are imperative to induce cold tolerance are not known. In the present study, the endogenous levels of putrescine (diamine), spermidine (triamine) and spermine (tetramine) were examined in early maturing chickpea genotype ICCV 96029, subjected to chilling temperatures of field (12–15/4–6 °C; average maximum and minimum temperature respectively), at flowering or early podding stage. These were compared with controls growing in warmer conditions (28/12 °C) of the glasshouse. The polyamine levels increased six to nine times because of stress. Relatively, putrescine (PUT) elevation was the highest but short-lived and its decrease appeared to match with the onset of flower and pod abscission in stressed plants. Compared with controls, chilling injury, observed as electrolyte leakage (EL), increased by 60 % while cellular respiration declined by 68 % in stressed plants. Exogenous application of 10 mm PUT to stressed plants reduced the EL by 29 % and elevated the cellular respiration by 40 %. PUT application at flowering stage resulted in increase of 30, 31, 23 and 25 % in floral retention, pod set, pod retention and fertile pods respectively. At the early podding stage, PUT treatment increased the seed yield per plant, seed number per 100 pods and individual seed weight by 50, 17 and 19 % respectively. The number of single-seeded pods per plant increased from 4.4 in stressed plants to 12.2 in PUT-treated plants while the number of double-seeded pods reduced from 6.2 to 4.3. The number of infertile pods declined from 8.2 in stressed plants to 3.1 in PUT-treated plants.     

Cultivar identification and genetic relationship among selected breeding lines and cultivars in chickpea (Cicer arietinum L.)

Twenty two RAPD and 22 ISSR markers were evaluated for their potential use in determination of genetic relationships in chickpea (Cicer arietinum L.) cultivars and breeding lines. We were able to identify six chickpea cultivars/breeding lines by cultivar-specific markers. All of the cultivars tested displayed a different phenotype generated either by the RAPD or ISSR primers. Though ISSR primers generated less markers than RAPD primers, the ISSR primers produced higher levels of polymorphism (% of polymorphic markers per primer) than RAPD primers. A high level of within cultivar homogeneity was observed in chickpea. Cultivars/breeding lines originating from a common genetic background showed closer genetic relationship. Chickpea lines with similar seed type(kabuli or desi) had a tendency to cluster together. This revised version was published online in August 2006 with corrections to the Cover Date.     

菜用大豆品种花荚粒形成的初步研究

通过对24个菜用大豆品种花荚及籽粒形成的比较,认为不同熟期类型品种间发育规律存在差异。早熟品种较晚熟品种花、荚形成发育快,时间短,脱落也快。籽粒形成主要集中在三个时期：籽粒重在中后期,荚皮重在中前期,荚重在中期。中期的生殖生长是籽粒形成的基础,也是影响产量的关键。因此在江苏徐淮地区的生态条件下,鼓粒前的花荚期长短是选择菜用大豆品种生育指标的重要因素。菜用大豆鼓粒前的花荚期以20d左右为宜。