جستجوی مقالات مرتبط با کلیدواژه « Seed weight » در نشریات گروه « کشاورزی »

To evaluate the effect of planting density and harvest stage on dry forage production in alfalfa, an experiment was performed during cropping years2017-2018and2018-2019 in BuAliSina University of Hamadan.The experiment was performed as strip split plots design with randomized complete block design(RCBD)in four replicates.We studied planting density at three levels and forage harvesting time at four phenological stages.The results of the mean comparison showed that forage harvest at 10% flowering stage led to a significant increase in dry forage yield in the first and second croppings and annual forage yield in the two years of the experiment.The results of mean comparison of interactions between planting density and forage harvest date in the first year of the experiment showed that increasing row spacing to 50 and 60 cm and forage harvest at 10% and 50% flowering stage led to a significant increase in dry forage yield in the second cropping and annual forage yield.In this study in both years of the experiment, the delay in the forage harvest time led to a significant increase in the plant height. Harvesting at early flowering stage leads to a significant increase in the canopy height compared to harvesting at early budding stage.Reducing crop density through increasing row spacing to 50 and 60 cm and harvesting forage at 50% flowering stage led to a significant increase in dry forage yield of first harvest.Therefore lower density planting and delay in forage harvest time up to 50% flowering is suggested aimed to increase the annual dry forage yield.

 The great importance of identifying, studying, evaluating, and protecting native ecotypes of medicinal plants as human heritage, collecting agricultural medicinal plants and ecological evaluation of their native ecotypes, and introducing their compatible ecotypes is a necessity for farmers. Considering the few studies in the field of the agricultural role of non-native plants such as Dragon's head in Iran to meet the country's nutritional needs, the present research aims to study and evaluate the performance of local medicinal and multi-purpose plant stands of urban sycamore and also to obtain new scientific materials in the case of these local masses has been done in the research farm of University of Tabriz Faculty of Agriculture. It is necessary to explain that in recent years, due to the crisis of water shortage and drought, this plant is in line with changing the cultivation pattern of the region from plants with high water requirement to plants with low water requirement or dry land has been added to the official cultivation pattern of East Azerbaijan province and is being promoted among the farmers of the region.

 To evaluate and investigate the agronomic characteristics and performance of 49 selected Dragon’s head stands from different regions of the country, an experiment was carried out in the form of a simple 7*7 square lattice design with three replications. A field experiment was carried out at the research station of the Faculty of Agriculture of University of Tabriz, located in building number 2 of the Faculty of Agriculture in Basmanj. According to meteorological maps, the climate of this region is among the steppe and semi-arid climates of the world. In this area, although rain sometimes occurs in the summer season, it generally has a dry season in the summer. The area is located at an altitude of 1360 meters above sea level, with a latitude of 38 degrees and five minutes north and a longitude of 46 degrees and 17 minutes east, and its annual rainfall is 285 millimeters. The average annual temperature is 10 degrees Celsius, the average annual maximum temperature is 16.6 degrees Celsius, and the average annual minimum temperature is 4.2 degrees Celsius.

In the comparison of the average traits, the best ecotypes in terms of yield were the ecotypes of Kolvang local population 10 and 15, Tabriz local population 3 and 4 and Ahar local population 1 respectively, simple correlation analysis, stepwise regression, and causality showed that biomass traits, number of seeds per plant, number of seeds in capsule and weight of 1000 seeds are the most important factors affecting the increase of seed yield. By analyzing it into components, the first four components explained 80.44% of the changes related to primary traits. Ecotypes Kolvang 10, Tabriz 3, and number Tabriz 4 yield 1661, 1464, and 1404 kg ha-1 respectively, and 3848, 4119, and 3848 kg ha-1 respectively. They produced 4581 kg ha-1 of biomass and were superior in most traits related to economic performance.

Taking into account the crisis of Lake Urmia and the lack of water in most regions, especially the Azerbaijan region, the medicinal plant Dragon’s head is one of the few plants that can be placed in the spring cycle in most areas of rainfed and irrigated cultivation and in improving the water balance. Lake Urmia and agriculture in the region can play a positive role. Therefore, the ecotypes of Tabriz native population 3, Kolvanagh native population 10, and Tabriz native population 4, which had more grain yield and were superior in most of the traits related to yield, can be considered the most suitable ecotypes of Dragon’s head for use in water conditions and the air of the region advised the farmers for the next crops.

Many agricultural lands in Guilan province of Iran, especially paddy fields, remain uncultivated in the second half of the year due to various reasons including heavy rainfall, low soil permeability (stickiness of soil particles) and inefficiency of the existing drains. Mole drainage as a low-cost drainage method, proportion for rice cultivation conditions and easier to implement than pipe drainage, can be a suitable solution in the development of second cropping. Due to the oil content of 40% of the seed, the rapeseed plant is one of the valuable oil plants and has the ability to be cultivated as a second crop in paddy fields. Nitrogen plays a key role in the performance of plants and its deficiency causes limitations in plant production. Equipping paddy fields with mole drains along with the application of appropriate level of nitrogen fertilizer can increase the quantitative and qualitative yield of rapeseed as a second crop and contribute to the food security of the country. Therefore, the development of the cultivated area of rapeseed in paddy fields after rice harvesting in Rasht region, the study of the combined effect of mole drainage and different levels of nitrogen fertilizer on yield and yield components were the aims of this project.

In order to investigate the effects of mole drainage and nitrogen fertilizer on the yield and yield components of rapeseed as a second crop in Rasht rice fields, a factorial layout based on a randomized complete block design with three replications at the research field of the Faculty of Agricultural Sciences of Guilan University was implemented in the crop year of 2022-2023. The factors included mole drainage at three levels (without drainage, without gravel and with gravel) as D0, D1 and D2 respectively, and nitrogen fertilizer as urea source at two levels (180 and 240 kg ha-1) as N1 and N2 respectively. Rapeseed plant (Brassica napus) of Delgan cultivar was selected as the second crop after rice harvest. To carry out the experiment, at first the desired land was blocked and divided into plots, then the underground drains of mole were created without gravel and with gravel with a special blade in the desired plots. To drain the drainage from the mole drains, the polyca pipe was installed at the end of each mole tunnel, then the other side of polyca pipe was connected to the sub-pipe collection and finally led to the main surface drain. This experiment was conducted in 18 plots and each one was 9 × 6 meters. The distance between plots was 1.5 m, between replications was two meters, and the distance between plants was 15 and between rows was 25 cm. To avoid the effectiveness of drainage treatments from undrained treatments, undrained plots were considered at the end of the field. Before cultivation, basic chemical fertilizers, 200 kgha-1 of potassium from potassium sulfate source and 200 kgha-1  of phosphorus from ammonium phosphate source were applied. Nitrogen fertilizer from urea source was applied at the level of 180 and 240 kgha-1  in equal amount at three stages. Just before the harvest stage, to determine the traits of the number of seed in the pods of sub-branches, the number of seed per pod, the weight of seed in sub-branches, the weight of seed in the main branch and the weight of seed per plant, ten plants were randomly selected and harvested manually from the crown area. Also, to determine the seed yield, one square meter was randomly selected from each plot, taking into account the borders, and the bushes were manually harvested from the crown area. After the moisture content of the seeds reached the desired level, the seeds were separated from the pods and weighed using a laboratory scale with an accuracy of one thousandth of a gram, and the seed yield was calculated in kgha-1. SOXTEC SYSTEM HT 1043 Extraction Unit set was used to determine oil percentage and Kjeldahl set was used to determine seed protein. Statistical analysis of the data was done using SAS software (version 9.4) and comparison of means was done using the minimum significant difference test at 5% probability level. Excel software was used to draw the graphs.

The results of variance analysis of the data showed that the interaction effects of mole drainage and nitrogen fertilizer on the traits of seed weight in the main branches, seed weight in the plant and seed yield was significant at 5% probability level, so that the highest seed weight in the main branch with 0.733 seeds in the mole drainage with gravel with a nitrogen fertilizer level of 180 kgha-1 (D2×N1) treatment was obtained and the highest seed weight in the plant with 1.443 g in the mole drainage without gravel with a nitrogen fertilizer level of 240 kgha-1 (D1×N2) treatment was obtained. Also, the highest seed yield was obtained under 3579.48 kgha-1 in the treatment of mole drainage without gravel using 240 kgha-1 of fertilizer (D1×N2) which is compared to the treatment of without drainage and drainage with gravel with the same level of fertilizer 13.63 and 2.31 percentage was higher, respectively. In addition, rapeseed plant is more important in terms of oil percentage, no significant difference was observed between drainage and nitrogen fertilizer treatments in terms of average oil percentage. Therefore, the mole drainage treatment without gravel with a fertilizer level of 240 kgha-1 (D1×N2) is the most suitable option for rapeseed cultivation as the second crop after rice harvesting.

The results of this study showed that mole drainage without gravel by improving soil ventilation conditions and preventing waterlogging of paddy fields along with the level of nitrogen fertilizer of 240 kgha-1 increased the yield of rapeseed compared to the condition of without drainage at the same level of nitrogen fertilizer. Therefore, rapeseed cultivation in vast paddy fields after rice harvesting can be recommended as a basic solution in order to increase the production of oilseeds and provide part of the country's oil consumption.

The practice of growing two or more crops simultaneously in the same field is called intercropping and it is a common feature in traditional farming of small landholders. It provides farmers with a variety of returns from land and labor, often increases the efficiency with which scarce resources are used, and reduces the failure risk of a single crop that is susceptible to environmental and economic fluctuation. There is another important way that without incurring additional costs and use of water and fertilizer could result in higher production. This approach is increasing agricultural production per unit area by growing more than one crop in a year. Intercropping will be successful when competition for sources is less than competition within a species. Plants in the mixture can be chosen in a way that a species benefits from environmental changes caused by other species in mixed cultures directly. Intercropping inhibits the growth and development of weeds and leads to increased production. Since the system will reduce pesticide use, environmental pollution will be also less proportionally. The objective of the present study was to study some traits of chickpea (plant height, number of pods per plant, number of seeds per plant, number of seeds per plant, 100-seed weight, and plant yield,) under application of nitrogen and planting pattern of chickpea and quinoa.

In order to study the effect of nitrogen and intercropping ratios of chickpea and quinoa on some traits of chickpeas, a factorial experiment based on randomized complete Block design (RCBD) was conducted with three replications at Gonbad Kavous University farm during the 2020-2021 growing season. Nitrogen factor was included three levels of non-application and application of 25 and 50 kg N/ha and the treatments of planting pattern were included 9 levels of sole cropping of chickpea, 67 % chickpea + 33 % quinoa, 50% chickpea + 50% quinoa, 33% chickpea + 67% quinoa, 100% chickpea + 33% quinoa, 100% chickpea + 50 % quinoa, 100% chickpea + 67% quinoa, 100% chickpea + 100% quinoa and sole cropping of quinoa. In sole cropping, the distance between the plants on the row for chickpea and quinoa was 10 cm. The operation of harvesting the entire plot was done by removing the border rows and half a meter from both sides of the middle rows. For analysis variance of data software of SAS Ver.9.1.3 was used and treatment mean differences were separated by the least significant difference (LSD) test at the 0.05 probability level.

The results of analysis variance showed that planting pattern and nitrogen had a significant effect on plant height, number of pods per plant, number of seeds per pod, number of seeds per plant, 100-seed weight, and plant yield chickpea and also plant height, number of seeds per plant, 1000-seed weight, and plant yield quinoa. Plant height in additive intercropping was more than in replacement intercropping but the number of pods per plant, number of seeds per pod, number of seeds per plant, 100-seed weight, seed weight per plant, and pods weight per plant in replacement treatments and sole cropping of chickpea was more than additive treatments. Nitrogen application increased all traits. Plant yield of quinoa in replacement intercropping of 33% quinoa instead of chickpea was greater than other treatments. However, the plant yield of chickpea in sole cropping of chickpea and replacement intercropping of 33% quinoa instead of chickpeas with 14.11 and 13.26 respectively, which was greater than other treatments.

Plant height in additive intercropping treatments was more than in replacement intercropping but the number of pods per plant, number of seeds per pod, number of seeds per plant, 100-seed weight, plant yield, and plant dry weight in replacement treatments and sole cropping of chickpea was more than additive treatments.

This experiment was conducted to investigate the effects of drought stress and foliar application of Fe and Zn on agronomical characteristics of sunflower

a farm experiment was carried out in the Fars agricultural research center in the split plots form base on a randomized complete block design with three replications during 2014. Irrigation at three levels (irrigation after 60, 120, and 180 mm of evaporation from A class evaporation pan) as the main plots and foliar application at four levels (water, iron sulfate, zinc sulfate, and iron sulfate+ zinc sulfate) were used as sub-plots.

The results showed that the delay in irrigation from 60 to 180 mm of evaporation caused a decrease in the number of seeds per head, grain yield and biological yield by 24.8%, 37.5% and 30%, respectively. The foliar application of iron sulfate + zinc sulfate compared to the control treatment increased the number of seeds per head, 1000-seed weight and grain yield by 24.1%, 16.6 percent and 14.3 percent, respectively. The delay in irrigation, increased the water use efficiency by 50.9%. The interaction between irrigation and foliar application had a significant effect on leaf and grain iron concentration and leaf zinc concentration, so that with delay in irrigation, absorption of nutrients decreased, but foliar application under drought stress conditions increased iron and zinc absorption in sunflower

According to these results, it can be stated that with micronutrient foliar spraying, the severe drop in sunflower yield can be prevented under drought stress conditions

Quinoa, with its high nutritional value, is highly resistant to a wide range of non-biological stresses. Despite the limited resources and the increasing demand for food products in lands with low or limited fertility, it can be cultivated well and produces a good product.

This experiment was conducted with the aim of investigating the simultaneous effect of drought stress and heavy metals on the quinoa plant, in a factorial format in a completely randomized design with 3 replications. The first component involved two levels of soil (contaminated and uncontaminated), and the second factor, three levels of drought stress (100% of field capacity 60% of field capacity, and 30% of field capacity).

Interaction effect of soil type and drought stress was significant on all traits except the fresh weight of shoot and plant height. The lowest amount of fresh and dry weight of roots, dry weight of shoot and weight of thousand seeds was observed in contaminated soil with severe drought stress. Nevertheless, the weight of 1000 quinoa seeds under the influence of moderate drought stress was not significantly different from the condition without drought stress. Examining the simple effects showed that soil contamination with heavy metals caused a decrease of 13.7% in fresh weight of shoot and 30.5% decrease in dry weight of shoot compared to plants grown in uncontaminated soil.

In general, it can be stated that the increase in drought stress has significantly reduced root fresh weight and 1000 seed weight in quinoa, but the percentage and ratio of this reduction in soil contaminated with heavy metals was much higher than that of non-contaminated soil. According to the results of this research, the cultivation of quinoa can be investigated as a promising plant in soils with similar limitations.

Breeding program carried out in Horticultural Research Station of the University of Tehran in 1996 with crossing of seven good quality seeded grape cultivars as female parents (Muscat Siah, Tabraze, Dizmari, Alhaghi, Ghezelozum, Rajabi Sefid, Alibaba) and four seedless grapes as male parents (Bidane Sefid, Bidane Ghermez, Yaghouti, Askari). 223 and 276 genotypes of that crossing respectively in 2019 and 2020 with bush training were evaluated for their quantitative and qualitative traits. Blooming date and fruit and seed traits were measured and recorded. Based on the results, the highest percentage of coefficient variation was in the number of floating and sink seeds of a berry, berry color, and dry weight of seeds per berry, cluster weight, while the lowest coefficient of variation was obtained for pH juice and berry width. There was a positive correlation between berry traits and seed index. The seedless progenies were 17.93% in the first year and 9.05% in the second year. Fresh weight of seeds in a berry in classes of seedless, semi-seedless, semi-seeded and seeded were recorded 0.02, 0.05, 0.07 and 0.1 g respectively. In comparative with male parents and control groups, seedless genotypes of G135, H126, H139, H171 in 2019 and B60, D66, H124, H139 in 2020, were recognized as superior genotypes. As well as, among semi-seedless genotypes, E147, G110, C88, I67, F125 were selected as superior due to their traits. Finally, the best selected seedless genotypes of H139 with a berry weight of 2.6 g and D66 with a berry weight of 3.3 g which are highly recommended for further studies to be released as new cultivars.

This research aims to investigate the yield and yield components of safflower (Carthamus tinctorius) in intercropping with dragon head (Lallemantia iberica).

Mixed cropping was done based on increasing series, where Carthamus tinctorius is the main plant and Lallemantia iberica is the Sub plant. The basic design of the experiment was in the form of randomized complete blocks with four replications. Different cultivation patterns include pure Carthamus tinctorius cultivation, 100% Carthamus tinctorius with 15% Lallemantia iberica, 100% Carthamus tinctorius with 30% Lallemantia iberica, 100% Carthamus tinctorius cultivation with 45% Lallemantia iberica, 100% Carthamus tinctorius with 60%Lallemantia iberica, 100% Carthamus tinctorius with 75%Lallemantia iberica. In this study, Carthamus tinctorius traits included number of pods per plant, number of seeds per pod, weight of 1000 seeds, seed yield and biological yield.

The results showed that the effect of different cultivation patterns on the number of seeds per plant and seed weight was not significant, but it was significant on the number of pods per plant, seed yield and biological yield .The highest number of seeds according to the 100:30 mixed crop pattern (Lallemantia iberica- Carthamus tinctorius) and the highest seed yield and biological yield belonged to pure Carthamus tinctorius cultivation.The highest land equivalent ratio belonged to 100:30 mixed cultivation (Lallemantia iberica-Carthamus tinctorius).

100:30 intercropping pattern (Lallemantia iberica-Carthamus tinctorius) was suggested as the suitable pattern of mixed cropping due to highest grain yield, biological yield and economic benefit.

Millet (Panicum miliaceum L.) is a ,warm-season grass with a growing season of 60–100 days. It is a highly nutritious cereal grain used for human consumption, birdseed, and/or ethanol production. Millet ranks sixth among the world’s most important cereal grains, sustaining more than one-third of the world’s population. Millets are generally among the most suitable crops for sustainable agriculture and food security on marginal lands with low fertility. Millet crops are grown on marginal lands and under low-input agricultural conditions, situations in which major cereal crops often produce low yields. Foliar application of Zn brings the greatest benefit in comparison with addition to soil where they become less available. Generally, Micronutrients are essential for plant growth and play an important role in balanced crop nutrition. Micronutrients are as important to plant nutrition as primary and secondary nutrients, though plants do not require as much of them. 

To study the effect of cow manure (CM: 0, 10, 20, and 30 ton ha-1) and zinc sulfate (ZS: 0, 60, and 90 kg ha-1) application on common millet (Panicum miliaceaum L.) growth and yield, a factorial experiment based on a randomized complete block design (RCBD) with three replications was conducted in the research field of University of Birjand, Iran, in 2018 growing season. In addition, a chemical fertilizer (NPK) treatment was considered in each block, and its effect was compared with 12 other combination treatments based on a randomized complete block design.  The studied traits were plant height, number of tillers per plant, 1000-grain weight, grain yield, biological yield, harvest index, and seed zinc content. The software SAS (V9.1) and Excel were used to analyze the data and draw the figures. Means were compared using the FLSD test at a 5% probability level. 

Analysis of variance results showed that the simple effects of both experimental factors were significant on all studied traits, but none of the interaction effects were significant. Application of 60 kg ha-1 of ZS improved all growth and yield parameters of millet, while the highest zinc content in the seed was obtained by applying 90 kg ha-1. The highest seed and biological yields (2227 and 7940 kg ha-1, respectively) were obtained by 60 kg ha-1 of ZS application, which was 36 and 6.6% higher than the control treatment (no-fertilization), respectively. All studied traits showed an increasing trend with increasing the amount of CM consumption, so that their highest values ​​were obtained when 30 tons ha-1 of CM was applied. Seed yield (2564 kg ha-1) at the highest CM level was 138% more than the control treatment and ultimately led to a 14.4% increase in the harvest index. 

Millet (Panicum miliaceum L.) is a cereal plant cultivated for its grain, mostly in Asia and North America. It is a warm-season grass with a short growing season and low moisture requirement that is capable of producing food or feed where other grain crops would fail. Chemical fertilizer treatment (NPK) also improved all traits related to plant growth and yield compared to control as well as some other fertilization treatments. Modifying the physical properties of the soil and the availability of nutrients for millet plants can be a major reason for the increased yield and growth of the plant. Also, the results showed that consumption of zinc sulfate at 60 kg.ha-1 increased yield and yield components of common millet, but consumption of 90 kg.ha-1 of this fertilizer reduced the studied traits. In addition, the results of this experiment showed a significant difference between four levels of manure so that the highest grain yield of studied millet was obtained from 30 tons per hectare of manure. According to the test results, it can be stated that the application of zinc sulfate at a rate of 60 kg per hectare increased the yield and yield components of millet and therefore is introduced as the desired amount of fertilizer to achieve ideal yield.

Five varieties of Phalaenopsis (Nottingham, Dubrovnik, Andorra, Memphis, Bucharest) were self-pollinated and crossed with each either as the male or the female parents. The five self-pollination and 20 cross-pollination states were evaluated for six phenological and morphological characteristics. Pollination was performed using an orchid pollination syringe in a greenhouse with a temperature of 20-27 ◦C, the humidity of 80% and light of 2500 lx during the 2018-2019 growing season. Nottingham under self-pollination conditions was better than other varieties and was superior to all crosses for all traits under investigation. The differences among males, females and their crosses were significant for all traits, except the time to the first pollination signs in which the effect of the female factor was not significant. In general, Nottingham was the superior variety in almost all traits and Dubrovnik was the worst variety in most traits either as male or female parents. Cross-pollination also had different outcomes in different traits. For example, for the time until swelling of the capsule, crosses Memphis × Nottingham and Nottingham × Memphis caused the capsule to fill later than the Nottingham parent. The cross Dubrovnik × Nottingham caused the capsule to fill earlier than the Dubrovnik parent. In the Dubrovnik × Nottingham cross, the weight of seeds per capsule, as an important trait, was higher than the Dubrovnik parent under self-fertilization conditions. Also, the cross-pollination was not suitable for increasing the weight of seeds per capsule in the Nottingham × Andorra cross. As an example for the capsule length, the Nottingham × Bucharest cross had smaller capsules than the self-pollination conditions of Nottingham and Bucharest. Therefore, depending on the importance of the traits under consideration in commercial production, cross-pollination can be used as a method, in addition to producing flowers with colors and shapes different from the parents, for improving the desired traits relative to one parent or both parents in self-pollination conditions.

Selection of wheat cultivars with stable seed yield and seed yield components in different climatic conditions was  aim of this research.

To evaluate the seed yield  and seed  yield  components stability of 20 spring wheat lines, this experiment  was done using RCBD with two replications under  five conditions for three years(2010-2013) in Islamic Azad University research  stations( Tabriz and Mianeh).

Due to significant Genotype X Environment interaction (G X E), stability analysis for seed yield and seed yield  components was done using AMMI method (Additive Main effects and Multiplicative Interaction)  and the results showed that the lines N-75-4, N-75-5 ,N-75-17 and N=75-1 are the stable for 1000KW, respectively , the lines N-75-6 ,N-75-4 , N-75-1, N-75-9 and N-75-14 are the most stable for number of seed per spike , the lines N-75-6 ,N-75-16 , N-75-1 and N-75-5 have stability of producing spike per square, respectively, and the lines N-75-6 , N-75-5, N-75-1  and N-75-17 have stable seed yield, respectively.

According to the results of AMMI method the lines N-75-1(Tajan), N-75-5 (Yang87-158) and N-75-6 (Rayan 89) with the seed yield of 6.475 , 5.623 and 4.083 t/ha had the most stability respectively, so on the basis of having the stable yield and seed yield more than average of total lines, those lines can be used as a parental lines  in wheat breeding program and secondary can be cultivated in the spring
in cold regions of East Azerbaijan and similar places also.

In order to determine the critical nitrogen concentration of canola leaf and studying the correlation of yield and yield components of this plant with leaf nitrogen concentration, 35 farms were managed in the same way of Varamin plain and in the dominant soil serie (Varamin), were selected during 2016. Leaf samples were pick up from these farms at flowering stage and were prepared for analysis. In harvest season, all 35 fields were harvested and the mean grain yield was determined. The critical nitrogen concentration in dry leaves was determined at 3% by using Kate and Nelson's graphical method, for 90% relative yield. There was a significant correlation between the content of canola leaf nitrogen as independent variable (X) with other traits, including grain yield and yield components as dependent variables (Y) at the 35 studied farms. The results of the studies showed that canola seed yield was affected by leaf nitrogen content. The content of nitrogen in canola leaves was significantly correlated with grain yield. This correlation was followed by a quadratic function with a coefficient of explanation of 0.97. Relative yield of canola seed increased only to 4.36% nitrogen concentration of leaves, and since then, the increase in leaf nitrogen did not affect grain yield.