Increase In Seed Yield Research Articles

Sunflower nitrogen requirement and 15N fertilizer recovery in Western Pampas, Argentina

In order to avoid nitrogen overfertilization, fertilizer rates must be adjusted to meet crop requirements. Two field experiments with sunflower ( Helianthus annuus L.) were performed in the western part of the Pampas, Argentina, to: (i) assess nitrogen fertilization effects on seed yield, grain oil content, and plant lodging, (ii) determine N requirement per unit of yield, crop recovery of fertilizer N, and whether these two parameters were affected by N and other nutrient additions. Nitrogen fertilization increased the seed yield only by 17% at one site. Crop nitrogen requirement per unit yield ( b-value) increased from 37 to 42 kg Mg −1 due to nitrogen fertilization only at the site where there was not a yield response. Therefore, if a yield response is expected, it is not necessary to use different b-values for non fertilized or fertilized crop. Reduction of seed oil content due to N addition was relatively small (2–5%), and was overcompensated by the seed yield increase at the responsive site. Recovery of fertilizer 15N was of 51%. This efficiency of absorption should be considered for making fertilizer recommendations. Application of further nutrients including P and K had no influence on seed yield.

Effect of planting method and rose water spray on seed production in onion, (Allium cepa L.)

Onion (Allium cepa L.) plants of Texas Grano 502, Local Red, and Local White cultivars were grown either from seeds in seed-to-seed method or from sets (bulbil with 1.5-2.0 cm indiameter) in set-to-seed method. The plants were sprayed three times (a week interval) with rose water (contained terpene alcohols) at the stage of opening of 5% of inflorescence flowers during 1997 and 1998 growing seasons. A wide range of insect species visited the umbels of rose water sprayed plants, mainly honeybee (Apis mellifera L.), blowfly (Caliphora vomitoria L.), and housefly (Musca domestica L.), and spraying vegetative part, inflorescence or whole plant revealed similarattractiveness to the insects. Spraying rose water also extended the touch time of the insects on the umbel from 4.5 seconds for untreated to 11.5 seconds for treated plants resulting in a higher percentage of flower set and lower number of aborted flowers in all tested cultivars. Among the plants part treated, the sprayed inflorescence had higher number of seeds (capsule-1) and higherpercentage of seed yield increase (46.1% and 43.8% for Texas Grano 502, 59.5% and 35.6% for Local Red, and 64.8% and 43.1% for Local White cultivars in 1997 and 1998 seasons respectively). A comparison between planting methods, set-to-seed produced greater seed yields compared to seed-to-seed method in all tested cultivars and may be as high as that produced from mother bulb-toseedmethod used by other authors. However, cultivars responded to the rose water spray variably and were affected by planting method. Texas Grano 502 plants had highest seed yield (634 and 1207 Kg. ha-1) when vegetative part in the set-to-seed method was sprayed; whereas spraying the inflorescence in the seed-to-seed method had the greatest seed yield. In Local White cultivar, the highest seed yield (410 and 1199 Kg. ha-1) was achieved when the inflorescence in the set-to-seed plants was treated, whereas, spraying vegetative part with rose water in the seed-to-seed method produced the highest seed yield (359 and 594 Kg. ha-1). Spraying whole plant (1997) or inflorescence (1998) of set-to-seed plants of Local Red had the highest seed yield (890 and 1160 Kg. ha-1 respectively), whereas, in the seed-to-seed method, spraying the vegetative part with rosewater produced more seed yield (562 and 502 Kg. ha-1).

Comparison of two soya bean simulation models under climate change. II. Application of climate change scenarios

The effects of climate change (for 2050 compared to ambient climate) and change in climatic variability on soya bean growth and production at 3 sites in the EU have been calculated. These calculations have been done with both a simple growth model, SOYBEANW, and a comprehensive model, CROPGRO. Comparison of the results from the 2 models indicated the sort of climate change conditions in which model results differed and may become less reliable. The effectiveness of possible management responses to climate change and the uncertainty in the model results were also evaluated with both models. Both models calculated for the climate change scenarios at Oxford a strong increase in irrigated seed yield. For Montpellier and Seville, however, CROPGRO calculated a considerable increase in irrigated yield for these scenarios, whereas SOYBEANW calculated only a slight increase. Without irrigation, the seed yield increase for the climate change scenarios was almost identical for the 2 models, i.e. considerable, slight and nil for Oxford, Montpellier and Seville, respectively. Changes in climatic variability did not result in a yield change at any site, both with and without irrigation and both for CROPGRO and SOYBEANW. With irrigation, the change in the coefficient of variation (CV) of seed yields by climate change was nil (except for decrease at Oxford) for both models and without irrigation, this change in CV was variable depending on site, climate change scenario and model. The management response analyses showed that the crop variety did not need to be changed in response to climate change, that the yield increase due to climate change was stronger for an advanced sowing date (but only without irrigation), and that irrigation requirements decreased with climate change only in the case of an early sowing date. This pointed to the need for advancing the sowing date with climate change. The uncertainty analyses showed that the yield change due to climate change was practically not affected by the used crop variety and soil type, but that this yield change may become different when a different growth model was applied or a different sowing date was chosen.

The influence of poultry manure application and plant density on the growth and yield of egusi melon (Colocynthis citrullus) on the Nsukka plains of south eastern Nigeria

A two year study, 1995 and 1996, was undertaken to assess the effects of poultry manure, plant density and their interaction on the yield and yield components of "egusi" melon (Colocynthis citrullus) under Nsukka ecological condtions of south - eastern Nigeria. It was observed that fruit production ha-1, average fruit weight, 1000 - seed weight and seed yield ha-1 increased with increase poultry manure application giving seed yield increase of 51% and 41% for 5 and 10t ha-1 rates respectively over the 0 t ha-1 rate. It was also observed that higher plant density gave higher fruit and seed yields compared with low plant density . Seed yield was increased by 31% and 39% in the 10,000 and 40,000 plants ha-1 densities compared with the 4444 plants ha-1 in 1995 and similarly by 41% and 60% in 1996. High plant density and increasd poultry manure application also enhanced plant development as was measured by days to 50% flowering, lenght of stem and number of branches/plant at 30 days after planting. Poultry manure x plant density (MxD) interaction was significant in fruit and seed production and this showed a trend of increased fruit and seed yield as poultry manure use was increased with increased plant density rates.

Physiological Changes from 58 Years of Genetic Improvement of Short‐Season Soybean Cultivars in Canada

In Canada, yield of short‐season soybean [Glycine max (L.) Merr.] cultivars has increased by approximately 0.5% per year since they were first cultivated in the early 1930s. Future yield gains may be dependent on an understanding of the changes made to soybean cultivars by breeding and selection. Our objective was to examine physiological differences associated with seed yield increase within a group of historical cultivars. At Ottawa, Ontario, we grew 14 cultivars representing seven decades of breeding and selection (1934–1992) in a randomized complete block design with four replications, across 4 years. Growth analysis provided data on leaf area and dry weight. Photosynthetic rate per leaf area was measured at several stages of development each year. Yield and harvest index were determined at maturity. The number of days to maturity and the total plant dry weight were not affected by the year of cultivar release. Seed yield, harvest index, and photosynthetic rate were found to have increased by 0.5% per year, while leaf area index decreased by 0.4% per year. The increase in seed yield with year of release was significantly correlated with an increase in harvest index, photosynthesis, and stomatal conductance and a decrease in leaf area index. Today's cultivars are more efficient at producing and allocating carbon resources to seeds than were their predecessors.

Analysis of seed yield components in four Mediterranean annual clovers

Annual leguminous forage crops are well adapted to hay production under the climatic conditions of Mediterranean environments, but their seed yield is often reduced by high temperatures and water stress that occur during the reproductive period. Field experiments using four forage legumes, berseem ( Trifolium alexandrinum L.), crimson clover ( Trifolium incarnatum L.), Persian clover ( Trifolium resupinatum L.) and squarrosum clover ( Trifolium squarrosum L.) were conducted in Foggia (southern Italy) during 1993 and 1994 under irrigated and non-irrigated conditions, with the aim to evaluate: (i) the effects of water deficit on traits which influence seed yield and (ii) the associations among seed yield components by means of path-coefficient analysis. Seed yield varied among species: Persian and berseem clovers showed the highest and lowest values (74.0 and 27.0 g m −2, respectively). Drought stress, in all species, negatively influenced the dry matter proportion partitioned to reproductive growth and strongly reduced seed yield (about 50% on average) and seed yield components in all species. Negative associations between the principal yield components were found in all species except berseem, suggesting the existence of compensatory relationships. Path-coefficient analysis revealed that for crimson and Persian clovers, the early flowering species, a seed yield increase cannot be achieved without a suitable tiller density. For squarrosum clover, the head fertility was the most important component in determining seed yield; whereas for berseem, seeds per head, heads per tiller and seed weight, all had positive direct effects on seed yield. As the yield components that most affected seed yield were species-specific, general conclusions cannot be drawn. Among the species examined, berseem and squarrosum clover, characterized by a longer vegetative cycle, were more damaged by water stress when it occurred during seed formation and filling.

Yield response of narrow-leafed lupin plants to variations in pod number

The effect of pod number on the seed yield and components of seed yield was examined for narrow-leafed lupin (Lupinus angustifolius L.) grown at a plant density of 36 plants/m2 in both the glasshouse and the field. Diflerent numbers of pods per plant in the glasshouse-grown lupin were generated by the application of N6-benzylaminopurine (BAP) to a specific number of flowers to ensure artificially that they set pods, and the subsequent removal of the remaining untreated flowers. Pod number ranged from 6 to 65 pods/plant in the glasshouse and was naturally distributed from 2 to 22 pods/plant in the field. Increases in seed yield per plant occurred as pod number per plant increased from 2 to 30 pods. No further increases in seed yield resulted when pod number per plant increased from 30 to 55 pods. Seed yield per plant was depressed as pod number increased from 55 to 65 pods. Seed size fell as pod number per plant increased over 20 pods and was less affected once the number of seeds per pod was reduced. The reduction in seed number per pod resulted from an increase in the number of seeds that aborted during seed filling. The data suggest that at a plant density of 36 plants/m2 there is potential for improving seed yield per plant by increasing the number of pods that reach maturity, provided it does not exceed 30 pods/plant. However, if consideration is given to producing large seeds, often preferred by buyers, the number of pods per plant should not exceed 20 pods.

An evaluation of the effect of exogenous glycinebetaine on the growth and yield of soybean: timing of application, watering regimes and cultivars

Various soybean cultivars were grown under different watering regimes in the field and greenhouse in south-eastern U.S.A. (1995 and 1996), and in the field in north-eastern Western Australia (1995). Aqueous glycinebetaine was applied at different growth stages onto their foliage with the objective of ameliorating effects of water stress on photosynthesis activity, nitrogen fixation, leaf growth, biomass accumulation and seed yield. There were cultivar differences in response to drought. Trends which suggest that exogenous glycinebetaine could improve photosynthesis activity, nitrogen fixation and leaf area development, were established. The observed seed yield increase of both well-watered and drought-stressed plants was associated with greater number of seeds following the application of 3 kg ha −1 glycinebetaine. The results indicate that foliar-applied glycinebetaine possesses anti-transpirant properties and has the potential to improve drought tolerance and reduce the amount of water used for irrigation, without any significant decrease in economic yield. There is evidence that soybean could be classified as a low-accumulator of glycinebetaine.

Evaluation of a Crop Simulation Model that Incorporates Gene Action

AbstractCrop simulation models are receiving increasing use in agricultural research. However, applications to plant breeding have been limited, in part due to the restricted capabilities of models to represent genetic differences. A gene‐based simulation model, GeneGro, has been developed that integrates action of seven genes into a common bean (Phaseolus vulgaris L.) model. The genes for physiological traits identified in the model include Ppd, Hr, Fin, Fd, Ssz‐1, Ssz‐2, and Ssz‐3. Evaluation of GeneGro was performed by comparison of measured field data vs. simulated data, and through a sensitivity analysis of the model. The experimental data set for model comparison was comprised of 14 field trials conducted in Canada, the USA, Mexico, and Colombia, representing 213 treatment combinations and including 39 cultivars. GeneGro explained 75% of variation in days to flower, 68% in days to maturity, and 39% in seed mass, but only 11% of variation in seed yield. Most of the variation in simulated seed yield was accounted for by the model when mean effects of site and cultivars were removed through regression analysis. This suggests that the poor simulation of seed yield was partially due to errors in simulating differences among sites rather than from simulating the response of genotypes to sites. Seed yield simulations were made for 96 genotypes that represented all expected phenotypic combinations of the seven genes included in the model. Simulations were conducted using historical weather data from Fargo, ND; Madero, Mexico; and Palmira, Colombia. GeneGro predicted that photoperiod sensitivity, conferred by Ppd and Hr, would result in zero seed yields at Fargo, a slight seed yield increase at Madero, and no effect at Palmira. Testing effects of maturity on seed yield, the genotypes fin and Fd resulted in lower seed yields due to shorter growth cycles, in agreement with field trials. The predicted effects of the three genes related to seed size varied among the sites. These results support the use of genetic information to represent cultivar differences in simulation models. They also emphasize the need for a better understanding of the physiological genetics of traits such as phenology, seed size, and growth habit.

The influence of seeding rate on weed control in small-red lentil (Lens culinaris)

Experiments were conducted at two sites for 2 yr in the Pacific Northwest dryland cropping region to determine if seeding rate of small-red lentil could enhance weed control with herbicides and increase lentil seed yield. At Pendleton, OR, and LaCrosse, WA, lentil was planted at 22 or 44 kg ha−1in one direction in all plots. In one-half of the plots, lentil was cross-seeded at right angles with an additional 22 kg ha−1to provide seeding rates of 22, 44, 22 + 22, and 44 + 22 kg ha−1. Seeding rate main plots were split into three herbicide treatments and an untreated control. Total weed density was reduced by increasing seeding rate at Pendleton both years when averaged over all herbicide treatments. Seeding rate reduced total weed density to a greater extent when herbicides did not adequately control weeds or when herbicides were not applied at Pendleton in 1992. Increased seeding rate also reduced total weed dry weight at Pendleton in 1992 and 1993 and at LaCrosse in 1993. The suppressive effect of increased seeding rate on weed dry weight was more evident when herbicides were not used or when herbicides gave only partial control. Herbicides generally reduced weed density, but the effectiveness of individual treatments was related to the weed species present and environmental conditions present in each experiment. Lentil aboveground dry weight production increased with seeding rate at both locations; however, only in 1 yr did lentil seed yield increase with seeding rate. The primary benefit from increased seeding rate in this study was to reduce weed density and dry weight.

Response of narrow-leafed lupin (Lupinus angustifolius L.) to foliar application of growth regulators in Western Australia

Four experiments were conducted during 1991-93 in the south coastal and lakes regions of Western Australia, to test the hypothesis that foliar application of a range of growth regulators will improve the pod set and seed yield of narrow-leafed lupins (Lupinus angustifolius L.). The chemicals tested (not all in any 1 year) were: Cultar (250 g paclobutrazol/L), Pursuit (240 g imazethapyr/L), Cytokinin (21 g 6-benzyladenine/L), Legumex (400 g 2,4-DB/L), Cytolin (20 g gibberellins A4 and A7/L and 20 g 6-benzyladenine/L), Bladex (500 g cyanizine/L), Diuron 500F (500 g diuron/L), Lexone (750 g Metribuzin/kg), NAA (40 g 1-napthalene acetic acid/L), Pix (38 g mepiquat chloride/L), Gesatop 500 (500 g simazine/L), High Yield (unknown active ingredient), Lontrel (300 g clopyralid/L), a Cultar-Lontrel mix, and a Lexone-Brodal(500 g diflufenicad) mix. Chemicals were applied from as early as 6 weeks before flowering on the main stem to as late as flowering on the 1st-order branches. Any gross physical effects were visually assessed. Canopy height and components of yield were measured at some of the experimental sites. In 2 experiments, no chemical had any significant effect on seed yield (P>0.05). At the 2 remaining sites, Cultar, Lontrel, and the Lexone-Brodal mix increased seed yield of lupins by 230-250 kg/ha. Seed yield increases were related to improvements in pod set. No chemical had any significant effect (P>0.05) on dry weight production. Timing of application was critical, with application 6 weeks before flowering giving the most consistent positive responses.

Dry Matter and Seed Yield of Mediterranean Annual Legume Species

AbstractKnowledge of the effects of seeding rate, irrigation, and forage harvest management on annual legume crops is essential for their proper agronomical exploitation. Cultivars and ecotypes of berseem clover (Trifolium alexandrinum L.), common vetch (Vicia sativa L.), and fieldbean (Vicia faba L.) were compared at two seeding rates, with and without irrigation, and under two harvest managements. These experiments were conducted in Foggia (southern Italy) during 1990 and 1991. Irrigation increased and stabilized forage and seed production reducing the consequences of erratic rainfall. Mean dry matter and seed yield increases due to irrigation were, respectively: 26 and 14% in common vetch, 25 and 9% in field‐bean, and 24 and 28% in berseem clover. Berseem clover showed an increase of 48% in seed yield with forage harvest management under irrigation. Seeding rate interacted mainly with irrigation treatment and length of vegetative period. The high seeding rate under irrigation in common vetch and field‐bean increased forage production more than seed yield. The herbage and seed yield components that responded to the high seeding rate under irrigation were plant height, stems per square meter for all legumes, pods per stem, and seeds per pod for field‐bean and common vetch, and heads per stem and seeds per head for berseem. Adapted varieties and ecotypes identified within each species represent genotypes with superior genetic potential for dry matter production and seed yield under a Mediterranean environment.

Timing of Furrow Irrigation Termination for Determinate Soybean on Clay Soil

AbstractIrrigation commencing at or near beginning bloom (R1) and continuing during reproductive development of determinate soybean [Glycine max (L.) Merr.] grown in the southern USA in dry years increases seed yield. The number of irrigations between the first and last irrigation event can influence the direct costs of irrigation; however, the optimum time to stop irrigation in relation to crop maturity has not been identified. ‘Leflore’ (1987–1990) and ‘A5980’ (1988–1990) determinate cultivars were grown on Sharkey clay (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) at Stoneville, MS, to determine the effect of timing of last furrow irrigation on seed yield, yield components, yield increase, and net returns. All irrigation treatments within a cultivar were started at R1 (beginning bloom) or later. One treatment was dropped from the sequence with each successive furrow irrigation event through R6 (full seed). Irrigation applied through mid‐R5 (seed‐filling period) during a dry year produced the greatest seed yield increase of 1855 kg ha−1, which was 610 kg ha−1 greater than the yield of the treatment terminated at R4 (full pod), and equal to the yield of the treatment terminated at R6. Yield increases due to irrigation during wet years were smaller or nonexistent. In all cases, increased number of seeds was the sole contributor to increased yield. In the dry years, irrigation terminated at either mid‐ to late‐R2 or mid‐R5 produced the greatest yield increase per unit of irrigation water, but irrigation continued into the seedfill period and then terminated produced the highest net return. These results indicate that furrow irrigation of soybean grown on a cracking clay soil in dry years should be continued through mid‐R5 to achieve maximum seed yield and net returns.

Scientific and Legislative Quality Control of Legume Inoculants for Lentil and Field Pea

Canadian research showing the agronomic benefit of superior strains of Rhizobium leguminosarum for lentil (Lens culinaris Medik.) and field pea (Pisum sativum L.) and Canadian legislated standards (The Fertilizers Act) for quality control of legume inoculants has encouraged the inoculant industry to produce high quality legume inoculants in both the USA and Canada. As a result, proper inoculation of lentil and field pea under conditions of low (< 30 Ib nitrate-N/acre) soil-available N now can predictably result in seed yield increases ol approximately 200 Ib/acre for lentil and 400 Ib/acre for field peas in Idaho and western Canada. This represents a return on investment for inoculation of approximately $17 (lentil) and $27 (pea)/acre at current market prices [...]

Effects of cycocel on growth and seed yield ofLotus uliginosusSchk. cv. Grasslands Maku

Abstract Field experiments were conducted in two successive seasons to investigate the effects of the plant growth retardant cycocel applied at 1.25 and 2.50 kg a.i./ha at different plant growth stages on the vegetative and reproductive growth, yield components, and seed yield of Lotus uliginosus Schk. cv. Grasslands Maku. Cycocel did not retard internode length or affect total dry matter, flowering pattern, or seed weight. Significant seed yield increases were recorded in both years, although responses differed with application rate and time. Cycocel at 2.50 kg/ha applied in early October before reproductive initiation, increased seed yield by 108 and 92% in 1989 and 1990 respectively. Later applications (floral bud appearance; onset of flowering) produced less-consistent results. The seed yield increases recorded were in response to increased pods per umbel and seeds per pod. Cycocel reduced pod abortion from the mid-season flowers, but abortion rates did not differ in the early- and late-season flowers.

FIELD TESTS EVALUATING PRE- AND POST-PLANT NITROGEN FERTILIZER PROGRAMS FOR MUNG BEAN PRODUCTION

Field tests were conducted in commercial mung bean (Vigna radiata) fields in 1986, 1987, and 1989. The objective of these tests were to: determine optimum nitrogen fertilizer rates; evaluate preplant, postemergence or split applications of nitrogen; and develop data to utilize petiole sampling as an analytic technique to quantify plant nitrogen status. Seed yields were significantly increased two of the three years by the addition of nitrogen fertilizers. Over three years, the addition of 40-120 pounds of nitrogen per acre resulted in an average seed yield increase of 14-37 percent, compared to an untreated control. Maximum yields were obtained with eighty pounds of nitrogen per acre. Within specific rates, there was a trend for preplant or split applications to result in the greatest yield increases. Petiole nitrate levels did not appear to be a reliable indicator of plant nitrogen status, with wide differences between rates in different years. An average for the three-year test, six weeks after crop emergence, was 1270 ppm for the control and 2340 ppm for treatments receiving 80 pounds of nitrogen per acre.

Seed yield and agronomic traits of old and modern soybean cultivars under irrigation and soil water-deficit

An understanding of how soybean [ Glycine max (L.) Merr.] cultivars of diverse yield potential respond to soil water-deficit would be valuable to soybean breeders in planning future selections. Our objectives were to evaluate differences in seed yield and agronomic trait performance under irrigation and soil water-deficit of soybean cultivars that vary in seed-yield potential. Two older, lower-yielding (‘Manchu’ and ‘Dunfield’) and two modern, higher-yielding (‘Williams 82’ and ‘Clark 63’) cultivars were drought-stressed between first flowering and harvest maturity in 1984 and 1985 on a Flanagan (Aquic Argiudoll) silt loam soil at Urbana, Illinois. Averaged over years, seed yields of Williams 82 and Clark 63 were 31 and 9% higher than those of Manchu and Dunfield under irrigation and drought stress, respectively. Relative to the irrigated conditions, the smaller seed-yield differences between the old and modern cultivars under drought stress resulted from smaller differences in pod number per branch. The old and modern cultivars did not differ in their apparent harvest index, plant number, branch number per plant, seed number per pod, and seed weight responses to soil water treatment. Leaf-area index of Williams 82 changed the most, and Manchu the least, in relation to soil water. Leaf-area duration in the lower portion of the crop canopy was increased by drought stress to a similar extent for each cultivar, while the period of reproductive development was shortened by severe soil water-deficit more for Manchu and Dunfield than for the modern cultivars. The results of this study show greater seed-yield increases with irrigation for Williams 82 and Clark 63 than for the older cultivars which were a function of a greater number of pods and increased vegetative biomass.

EFFECT OF N AND P ENRICHED SUNFLOWER STALK ON CROP YIELD, OIL CONTENT AND SOIL FERTILITY

Field experiments were conducted at Agricultural Research Station, Bhavanisagar to find out the efficiency of N and P2O5 enriched sunflower stalk along with N/P2Os fertilizers on yield of sunflower (Morden). The 5% P20s enriched sunflower stalk at the rate of 60 kg P20s as basal dressing along with 40 kg N through urea recorded a seed yield increase of 18.4% over the same quantity of N and P2Os applied through inorganic fertilizers. The physical condition and fertility status of the soll were also improved by the addition of enriched sunflower stalk.

Reproductive phenology, parental balance, and supplemental mass pollination in a sitka-spruce seed-orchard

Reproductive bud phenology and seed-cone crop of a Sitka-spruce [ Picea sitchensis (Bong.) Carr.] seed-orchard were studied to assess the validity of two seed-orchard assumptions, namely panmictic equilibrium, and parental balance. Also, the impact of supplemental mass pollination as a crop-management practice was evaluated. The study revealed significant variation in reproductive bud-development timing as well as proportion of reproductive strobili. A lack of mature male cones was observed while the majority of seed cones were in their receptive stage. It was also observed that approximately 80% of the seed-cone crop was produced by only 20% of the orchard clones. Supplemental mass pollination produced a 14-fold difference in the number of filled seeds per cone compared to that produced under wind pollination. In addition to the significant increase in seed-yield, supplemental mass pollination is proposed as a management option in Sitka-spruce seed-orchards to alleviate the effect of parental imbalance and panmictic disequilibrium.

Response of Five Food Legume Crops to an Irrigation Gradient Imposed During Reproductive Growth

AbstractFood legumes, an excellent source of protein and soil fertility improvement, offer small farmers a means of intensifying cropping on rice lands in semiarid and tropical regions. Unfortunately food legume productivity is often limited by variation in the amount and distribution of rainfall. The study was conducted to compare differential responses of mungbean (Vigna radiata L.), soybean [Glycine max (L.) Merr.], cowpea [Vigna unguiculata (L.) Walp.], peanut (Arachis hypogaea L.), and pigeonpea (Cajanus cajan L.) to a soil water gradient imposed during the reproductive growth phase. Field studies were conducted on Lipa clay loam, an isohyperthemic Typic Hapludoll silt loam soil, using a line source sprinkler irrigation system at the International Rice Research Institute, Philippines, from January to May during 1985 and 1986. Among the five species, peanut yielded significantly higher across the irrigation regimes in both years. Lack of water in the driest regime (50% water deficit replacement) reduced the seed yield of mungbean, soybean, cowpea, and peanut by an average of 43, 39,34, and 32%, respectively. However, pigeonpea seed yield increased by an average of 31% in the driest regime. Seed yield increases per mm of total irrigation water plus rainfall were 3.46 and 5.61 kg ha−1 in soybean, and 3.55 to 5.67 kg ha−1 in peanut in 1985 and 1986, respectively. However, pigeonpea yield per mm of total irrigation water plus rainfall declined 1.53 and 1.27 kg ha−1 in 1985 and 1986, respectively. Peanut performed best in irrigated as well as in rainfed environments, followed by cowpea, soybean, and mungbean. Pigeonpea was suitable only for the relatively dry, rainfed environment. Results indicate the need to match the suitable food legumes to maximize the rice land use.