Leaf-to-stem Ratio Research Articles

Herbage Yield, Nutritional Quality of Desho Grass (<i>Pennisetum glaucifolium</i>) Mixed with Stylo and Silverleaf Desmodium at Assosa, Western Ethiopia

The study was conducted during the main cropping season of 2019/2020 at Assosa in Benishangul-Gumuz regional state. The aim of the study was to evaluate herbage dry matter yield, nutritional quality and biological compatibility of desho grass mixed with Stylo and Desmodium. The treatments included two legume species (Stylosanthes guyanensis and Desmodium unicinatum) and desho grass with four levels of seed proportions (100%, 75%, 50% and 25%) of the recommended seeding rates of the two legume forages. Randomized complete block design with four replications was used. The results revealed that number of tillers per plant (NTPP), plant height (PH) and leaf to stem ratio (LSR), plot cover and vigor score percentage, dry matter yield (DMY) tha<sup>-1</sup>, and the quality parameters such as, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent Lignin (ADL), In-vitro Dry matter Digestibility (IVDMD) and crude protein yield (CPY) tha<sup>-1</sup> were significantly (P<0.05) differed among the different seed proportions of desho grass with legume mixtures. The highest total dry matter yield (11.05 t ha<sup>-1</sup>) was obtained from the sole desho grass planted with Nitrogen fertilizer followed by sole desho grass planted without fertilizer (10.17 t ha<sup>-1 </sup>) from the mixed cropping groups mixed crop containing 75% desho grass and 25% Stylo gives a higher total dry mater yield (7.44 tha<sup>-1</sup>). On the other hand desmodium sown in pure stands had lower DMY compared to legume-grass mixtures (3.37tha<sup>-1</sup>). In terms of quality, increasing the seed proportions of both legume species in the mixture resulted in higher CP%, CPY (tha<sup>-1</sup>) and IVDMD% and lower NDF%, ADF% and ADL% contents. Relative yield total of desho grass-legume mixtures at Desho<sub>75 </sub>Stylo<sub>25 </sub>(1.43), Desho<sub>50 </sub>Desmodium <sub>50 </sub>(1.39) and Desho<sub>25 </sub>Stylo<sub>75 </sub>(1.33) were better compared to the other mixtures and pure stands. Generally, mixing of desho grass with legume species at different seed proportions of 75% desho grass: 25% stylo and 50% desho grass: 50% Stylo produced better dry matter yield, nutritional quality and compatibility in the study area when compared to the mixed cropped plants. However, the experiment should be conducted for more years at different locations to recommend the best desho grass legume mixtures for Assosa area of Benishangul-Gumuz Regional State. It is also suggested to do on animal performance trial of this result based on animal feeding practice and economic feasibility in order to come up with sound recommendations.

Registration of the Oat (Avena sativa) Variety "Walqaa" for Vertisols in the Central Highlands of Ethiopia

In this study, fifteen oat varieties including the standard checks were evaluated for agro-morphological traits, nutritional qualities, disease, and insect pest reactions during the main cropping seasons of 2015- 2018. Based on the overall performance, two best-performing oat varieties (CI-1742 and SRCPX80Ab2596) were selected and verified with the two standard checks at the Kuyu and Ginchi sub-site of Holetta Agricultural Research Center during the main cropping season of 2018. The overall mean result indicated that the released variety, Walqaa (SRCPX80Ab2596), showed the highest mean DM yield followed by the recent check (SRCPX80Ab2291) while the check variety (CI-8251) which was released earlier and commonly used for vertisol gave the lowest DM yield. Walqaa (SRCPX80Ab2596) had the highest percent increase in DM yield, CP yield, and digestible yield advantages over the standard check variety (CI-8251) which was released earlier and commonly used for vertisol conditions. Similarly, the Walqaa (SRCPX80Ab2596) had a relatively better percent increase in DM yield, CP yield, and digestible yield advantages over the recently released variety (SRCPX80Ab2291). Moreover, the Walqaa (SRCPX80Ab2596) had seeds yield advantage over the earlier released variety (CI-8251). The nutritional qualities indicated that the candidate varieties had advantages over the standard check variety (CI-8251) in terms of the leafto-stem ratio, CP, and IVDMD contents. Generally, the Walqaa (SRCPX80Ab2596) had a relatively better leaf-tostem ratio, CP, and IVDMD advantages over the standard check variety (CI-8251). The national variety releasing committee evaluated the varieties at field conditions in October 2018. Based on their evaluation result, oat variety Walqaa (SRCPX80Ab2596) was officially released in November 2019 for production in the high altitude areas and similar agro-ecologies of the country. The pre-basic and basic seeds of the released variety Walqaa (SRCPX80Ab2596) are maintained by the feeds and nutrition research program of Holetta Agricultural Research Center. Keywords: Oat, quality, variety release, variety verification, yield

Breeding Efficiency for Salt Tolerance in Alfalfa.

Alfalfa (Medicago sativa L.), one of the most extensively grown forage crops, is sensitive to saline soils. We measured the breeding efficiency for increased salt tolerance in alfalfa by comparing lines selected from BC79S, CS, and SII populations with their unselected parental means for forage mass and associated changes in stem length, leaf-to-stem ratio (LSR), number of nodes per stem, crude protein (CP) content, and neutral detergent fiber (NDF) content. The overall forage mass in the non-salt-stressed test (9562 kg ha-1) was greater (p < 0.001) than under salt stress (5783 kg ha-1), with a 40% production advantage. In the non-salt-stressed test, the BC79S and CS lines averaged at a 4% lower production than their parents, while SII lines had on average a 9% greater production. Conversely, in the salt-stressed test, all lines showed a 20% overall greater seasonal production than their parents. Some selected lines produced more forage mass in both the non-stressed and salt-stressed tests than their parents. The stem length, LSR, node number, CP content, and NDF content of the selected lines varied with respect to non-stressed vs. stressed, but they tended not to differ greatly from their respective parental means under either non- or salt-stressed conditions. The selection protocol provided a universal increase in forage mass under salt-stressed field conditions of the selected lines. Furthermore, we identified lines with forage mass values greater than their parental means under non- and salt-stressed field conditions.

Effects of Harvesting Age and Barley Varieties on Morphological Characteristics, Biomass Yield, Chemical Composition, and Economic Benefits under Hydroponic Conditions in Fogera District, Ethiopia

The objectives of this study were to evaluate the effects of harvesting age at 6, 8, 10, and 12 days and four barley varieties HB-1307, Debark-1, Tila, and local varieties on morphological characteristics, biomass yield, chemical composition, and economic benefits under hydroponics in the Fogera district at Fogera National Rice Research and Training Center of Amhara Region, Ethiopia. The interaction effects of harvesting age and barley variety significantly influenced growth parameters of plant height, shoot length, leaf length, and overall chemical composition ( P &lt; 0.05 ). All morphological characteristics were significantly different ( P &lt; 0.01 ) among harvesting ages, and the stem weight, leaf to stem ratio (LSR), and number of leaves per plant were not significantly influenced ( P &gt; 0.05 ) by the different barley varieties. The highest plant height (21.26 cm) and crude protein (CP) content (21.39%) were obtained from Debark-1 at 12 days of harvesting. The highest fresh fodder biomass yield, 203.50 t/ha, and dry matter (DM) yield, 36.21 t/ha, were obtained at 12 days of harvesting. In the case of harvesting age, all morphological parameters increased with the progress harvesting age, except for the LSR and DM content. The highest net return of 2,923,002.25 ETB/ha was obtained from Debark-1 at the 12 days harvesting age, and the lowest 941,201.13 ETB/ha was obtained for the Tila variety at the six days of harvesting age. From the study, it can be concluded that based on fresh fodder biomass yield, DM yield, CP, and economic benefits, Debark-1 was the recommended barley variety on the 12-day harvesting age, followed by HB-1307, local, and Tila barley varieties.

Comparative Evaluation of Selected Grass Species for Agronomic Performance, Forage Yield, and Chemical Composition in the Highlands of Ethiopia

The study was conducted to determine the effect of different grass species (Brachiaria mutica, Desho, and Napier) and harvesting stages on agronomic performance, forage dry matter yield, and chemical composition. The grass species used were Desho (Pennisetum pedicellatum), Brachiaria (Brachiaria mutica), and Napier (Pennisetum purpureum), and the harvesting stages considered were 60, 90, and 120 days after establishment of grasses, respectively. The data collected included the following: percent plant survival (PS), plant height (PH), number of tillers per plant (NTPP), number of leaves per plant (NLPP), leaf length per plant (LLPP), leaf width per plant (LWPP), number of nodes per plant (NNPP), leaf-to-stem ratio (LSR), dry matter yield (DMY), and chemical composition of the grass species. Samples of grass species were harvested at different ages after establishment, weighed, and dried, and then, ground subsamples were taken for determination of dry matter (DM), ash, organic matter (OM), crude protein (CP), crude protein yield (CPY), acid detergent fiber (ADF), neutral detergent fiber (NDF), and acid detergent lignin (ADL). Results showed that morphological characteristics, forage dry matter yield, and chemical composition of the forage grasses were significantly affected by interactions of species ( P &lt; 0.001 ) and harvesting dates. The highest mean PH (115.2 cm), DMY (11.8 t/ha), and %CP (11.6) were recorded from Brachiaria mutica grass which was followed by Napier grass with mean PH of 87.25 cm and mean DMY of 9.8 t/ha. The %CP content of Desho and Napier grasses declined by 24%, while %CP content of Brachiaria grass declined by 26% with increased harvesting stages. Therefore, among tested grass species, Brachiaria mutica grass was recommended followed by Napier and Desho grass for on-farm evaluation and demonstration in the study area at all harvesting ages. Farmers engaged in forage grass production could seriously consider the harvesting stage as the grasses responded differently to the chemical composition.

Assessing the nutritional quality of stored grain legume fodders: Correlations among farmers’ perceptions, sheep preferences, leaf-stem ratios and laboratory analyses

Crop residues have the potential to alleviate annual feed shortages and nutrient deficiencies experienced in the dry season in the savanna zones of West Africa. Farmers in West Africa especially value the residues of grain legumes, also known as grain legume fodders (GLFs), as animal feed. In this study, therefore, we assessed the nutritional quality of GLFs as affected by storage conditions using four different methods: farmers’ perception score (FPS), sheep preference score (SPS), leaf-to-stem ratio (LSR), and laboratory analysis of organic matter digestibility (OMD), crude protein content, neutral detergent fibre (NDF) and acid detergent fibre (ADF). We also determined correlations among these variables. The fodder of cowpea, groundnut and soybean were stored separately in three locations (rooftop, room and treefork) and with two packaging types (polythene sacks or tied with ropes) for 60, 90 and 120 days. FPS was determined by scoring the perceived quality of GLFs on a scale of 1–10 (1 = bad and 10 = good) based on physical characteristics by a group of farmers. SPS was assessed by a cafeteria feeding trial based on dry matter intake of GLFs by a flock of 12 sheep per village during a 14 hr period. LSR was determined based on the mass of the botanical fractions, i.e. leaf (leaf blade only) and stem (stem and petioles) of 200 g samples separated carefully by the hand. Laboratory analysis was done by near-infrared spectroscopy (NIRS). Results showed that all quality assessment methods successfully discriminated GLF quality differences among crops. Only farmers and sheep could distinguish quality differences among all storage conditions and packing types, whereas laboratory analyses methods could not. These findings could be due to the fact that farmers use LSR to evaluate feed quality, though colour, texture and smell of the fodder could also contribute. We also found significant correlations (ranging from 0.35 to 0.88) between all the quality assessment methods across all treatments. There were few within crop correlations between the fodder quality assessment methods, i.e. only FPS and LSR for groundnut and cowpea, FPS and CP for groundnut and all laboratory analyses parameters among each other for all crops. Hence, the differences among crops were the important determinants of the correlations. From this study, we conclude that farmers have experience and knowledge about nutritional quality of feed and livestock preference for feed. Development programmes and projects could benefit from using such knowledge when formulating and implementing interventions.

Performance Evaluation of Improved Forage Trees (Sesbania sesban) Cultivars for Animal feed and Nutritional Quality in Highlands of East Hararghe Zone, Oromia, Ethiopia

The experiment was conducted to evaluate the biomass yield and adaptability of five accession with one local check of Sesbania (Sesbania sesban) at Highland of Eastern Hararghe Zone in 2017/18 and 2018/19 G.C cropping season consecutive years on-FTC in Burka Jalala PA. The treatments evaluated were S.sesban 15019, S.sesban 10865, S.sesban 15036, S.sesban 10885, S.sesban 1238 and local check in a Randomized Complete Block Design (RCBD) with three replications. The biomass yield, plant height, stem weight, leaf to stem ratio (LSR) were taken at Annual. The analysis result indicated in Table (1) showed that there was significant (P < 0.05) variation among the accession in fresh leaf weight, fresh stem weight and percent of leaf to stem ratio. The results indicated that the maximum fresh leaf biomass yield of the accession S.sesban 1238 (7.91 ton ha -1 ), flowed by accessions S.sesban 10885 (7.23 ton ha -1 ). The results showed that the maximum leaf to stem ratio were recorded under accession S.sesban 10865(28.67%), S.sesban 15019(27.66%) and S.sesban 1238(31.33%). A significant variation (p < 0.05) among the content of total ash and Acid detergent lignin. The maximum Acid detergent lignin obtained from S.sesban 15036(22.746%), and the minimum Acid detergent lignin obtained from S.sesban 1238(14.875%) and S.sesban 10885(14.874%). It was concluded that the accessions S.sesban 1238 and S.sesban 10885 were found promising to be demonstrated under in the study areas and same agro-climatic conditions similar to study area. Keywords : Forage Trees, Quality forage, Sesbania Sesban, Tree legumes DOI: 10.7176/FSQM/106-02 Publication date: March 31 st 2021

Evaluating the effects of storage conditions on dry matter loss and nutritional quality of grain legume fodders in West Africa

Feed scarcity is a major challenge for livestock production in West Africa, especially during the dry season when grass quality and quantity on grazing lands are inadequate. In the dry season, crop residues are a key source of livestock feed. The residues of grain legumes, also known as grain legume fodders (GLFs), are stored and traded for feeding in the dry season. The objectives of our experiment were to evaluate the effects of storage conditions and duration on dry matter (DM) and nutritional quality of GLFs, and to assess the risk of aflatoxin in stored groundnut fodder. The experiment was designed as a factorial trial with 18 treatment combinations with four replicates (4 farms). The treatments included: 3 types of GLFs (cowpea, groundnut and soybean fodder), 3 types of storage locations (rooftop, room and tree-fork) and 2 types of packaging (packed in polythene sacks and unpacked but tied with rope). Over a 120 day storage period, DM quantity reduced by an average of 24 % across all storage conditions, showing a range from 14 % in the best condition (sacks and rooms) to 35 % in the worst condition (bundles tied with rope and stored on rooftops or tree-forks). Soybean fodder had no leaves, the lowest crude protein content (CP) and organic matter digestibility (OMD), and the highest content of cell wall components compared to cowpea and groundnut fodder. These nutritional quality parameters in soybean fodder hardly changed during storage. Cowpea and groundnut fodder showed a decrease in leaf-to-stem ratio (LSR), CP and OMD, and an increase in the content of cell wall components during storage, but their nutritional value remained better than that of soybean fodder. Storage in sacks resulted in less DM loss, in less reduction of LSR and in a smaller increase of the content of cell wall components than storage of bundles tied with rope. Our study shows that the DM loss, the decrease in LSR, and the increase in the content of cell wall components can be prevented partly by storing GLFs in sacks instead of tying bundles with rope, and to a minor extent by storing in rooms instead of in the open air. Aflatoxin was not detectable in the groundnut fodder samples. Our results highlight that attention to storage conditions can improve the feeding value of GLFs which are key for livestock nutrition during the dry season.

Effects of Fertilization and Harvesting Age on Yield and Quality of Desho (&amp;lt;i&amp;gt;Pennisetum pedicellatum&amp;lt;/i&amp;gt;) Grass Under Irrigation, in Dehana District, Wag Hemra Zone, Ethiopia

The experiment was conducted to evaluating the effects of fertilizer and harvesting age on agronomic performance, chemical composition and economic feasibility of Desho (Pennisetum Pedicellatum) grass under irrigation, in Ethiopia. A factorial arrangement with four fertilizer types (control, urea, compost and urea + compost), and three harvesting ages (90, 120 and 150) with three replications were used. Data on morphological characteristics of the grass were recorded. Based on the data collected, harvesting age was significantly affected the agronomic parameters of the grass. Plant height (PH), number of tillers per plant (NTPP), number of leaves per plant (NLPP), number of leaves per tiller (NLPT), dry matter yield (DMY), leaf length (LL) and leaf area (LA) were increased with increasing harvesting age, while leaf to stem ratio (LSR) showed a decreasing trend. NDF, ADF and ADL content were also increased with increasing age, while ash declined with age. Fertilizer was also significantly affected the agronomic parameter of Desho grass. A mixture of 50 kg urea (U)/ha and 6,000 kg compost/ha was provided the highest NTPP, NLPP, NLPT, and DMY, while NF (control) was the lowest in all parameters. Highest NDF, ADF, ADL and ash content were recorded at the control group. In general, using a mixture of 50 kg urea (U)/ha and 6,000 kg compost/ha fertilizer is the most important for long-term Desho grass production which provides a high benefit-cost ratio. Further research is needed in different organic and inorganic fertilizer combinations.

Agronomic Performance of Forage Sorghum Genotypes as Affected by Watering Interval in Semi-arid Environment

In the latest years, scarcity of rainfall in North Kordofan of Sudan led to the search for irrigation water for cultivation of fodder crops to fill the gap in fodder production, hence the North Kordofan state characterized by a limited water situations. Therefore, efficient use of irrigation water seems to be of vital importance. This situation emphasizes the need for using earlier variety and scientifically sound methods for deciding when and how much to irrigate the crops. A field experiment was carried out during two successive seasons (2014/2015) and (2015/2016), to investigate the effect of ten genotypes and two watering intervals (seven and ten days) on growth and yield of forage sorghum. The treatments were arrange in a split plot design with three replications. The results showed that there were significant differences among watering intervals and genotypes for the most characters measured. The Watering interval of seven days significantly improved growth and forage yield of sorghum. Hybrid Pioneer was superior in plant height, leaf to stem ratio (LSR), fresh and dry forage yield (ton/ha) compared to other genotypes.

Nutritive Value Response of Native Warm-Season Forage Grasses to Harvest Intervals and Durations in Mixed Stands.

Interest in management of native warm-season grasses for multiple uses is growing in southeastern USA. Forage quality response of early-succession mixed stands of big bluestem (BB, Andropogon gerardii), indiangrass (IG, Sorghastrum nutans), and little bluestem (SG, Schizachyrium scoparium) to harvest intervals (30-, 40-, 60-, 90 or 120-d) and durations (one or two years) were assessed in crop-field buffers. Over three years, phased harvestings were initiated in May, on sets of randomized plots, ≥90 cm apart, in five replications (blocks) to produce one-, two-, and three-year-old stands, by the third year. Whole-plot regrowths were machine-harvested after collecting species (IG and LB) sample tillers for leafiness estimates. Species-specific leaf area (SLA) and leaf-to-stem ratio (LSR) were greater for early-season harvests and shorter intervals. In a similar pattern, whole-plot crude protein concentrations were greatest for the 30-d (74 g·kg−1 DM) and the least (40 g·kg−1 DM) for the 120-d interval. Corresponding neutral detergent fiber (NDF) values were the lowest (620 g·kg−1 DM) and highest (710 g·kg−1 DM), respectively. In vitro dry matter and NDF digestibility were greater for early-season harvests at shorter intervals (63 and 720 g·kg−1 DM). With strategic harvesting, similar stands may produce quality hay for beef cattle weight gain.

Fall Dormancy and Harvest Stage Effects on Alfalfa Nutritive Value in a Subtropical Climate

Alfalfa (Medicago sativa L.) annual yield is not strongly related to fall dormancy (FD) rating in regions with mild winters, but nutritive value might be, especially when accounting for harvest management. The objective of this study was to compare the forage quality of alfalfa having three FD ratings, all within the nondormant group, under the effect of two phenologically based harvest regimes in a humid subtropical climate. Cultivars with FD ratings of 7.5 (less nondormant), 8.5 (nondormant), and 10.5 (very nondormant) were seeded in April 2005 at the experimental farm of Padova University in Legnaro, northeastern Italy. Plots were harvested at early bud or early flower from 2005 to 2007 and were subsampled at each harvest for nutritive value analyses. Differences were observed between FD ratings for weighted annual average (weighted by yield) neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), crude protein (CP), ash, and ether extract (EE). For example, less nondormant cultivars had higher CP (193 g kg−1) than nondormant cultivars (190 g kg−1), and very nondormant cultivars (187 g kg−1). Harvesting more frequently improved forage nutritive value regardless of the FD rating used. Alfalfa harvested at early flower had NDF concentrations 18 g kg−1 higher than when harvested at early bud. All the chemical components studied were better correlated to the height of canopy than to the leaf to stem ratio (LSR). Results suggest that forage nutritive value was more impacted by stage of maturity than by FD rating or LSR.

Relationship between Dry Matter Per Plant in First Cutting and the Yield-Related Traits in Twelve Alfalfa Varieties Introduced Overseas

Yield of alfalfa (Medicago sativa L.) is closely related to its plant characteristics and the yield in 1st cutting contributes the majority to the annual harvest with the dry matter per plant (DMPP) determining the total community yield. The relationship between dry matter per plant in 1st cutting and yield-related traits (plant height, branch characteristics and leaf to stem ratio) of 12 alfalfa varieties introduced were studied in three continuous years (the 3–5 growth years) under field condition. There was a significant positive correlation between dry matter per plant and sub-branch number (SBN) (r = 0.689), and between DMPP and internode number of sub-branch (SBIN) (r = 0.526). The 1st principal component was composed of the branch number (BN), SBN, branch internode number (BIN) and SBIN, which accounted for 58.05% of total variance. This suggests that SBN and SBIN may be considered as the main objective characteristics for alfalfa breeding selection. The plant height (PH) had no significant correlation with DMPP, but a significant negative correlation with BN and BIN (r = –0.650 and –0.637, respectively), indicating that the control of the plant height of alfalfa by filed management appropriately is beneficial to the yield. The cluster analysis for DMPP showed that the 3-year average SBN in 1st cutting for group 1 varieties (the group with the highest DMPP including Pondus and WL-414) was significantly higher than other two groups. The SBIN had no significant difference between group 1 and group 2, but showed significant difference between group 1 and group 3 (P0.05). The leaf to stem ratio (LSR) of group 1 was 6.05% higher than that of group 2 and 10.91% higher than that of group 3, and the difference was significant between group 1 and group 3 (P0.05). Among the varieties, Pondus and WL-414 had higher breeding value in yield and palatability than other varieties.

Agronomic characteristics and nutritive value of 11 grasses grown with irrigation on a saline soil in southwestern Saskatchewan

Agronomic and nutritive characteristics of 11 grasses were studied at Swift Current, Saskatchewan on a moderately saline irrigated soil: [smooth bromegrass (Bromus inermis Leyss.), meadow bromegrass (Bromus riparius Rehmann), tall wheatgrass (Elytrigia elongata (Host) Nevski), crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.), intermediate wheatgrass (Elytrigia intermedia (Host) Nevski), slender wheatgrass (Elymus trachycaulus (Linke) Gould ex Shinners), Altai wild ryegrass (Leymus angustus (Trin. Pilger), Russian wild ryegrass (Psathyrostachys junceus (Fisch.) Nevski), Dahurian wild ryegrass (Elymus dahuricus Turcz ex Grieseb), reed canarygrass (Phalaris arudinaceae L.) and creeping foxtail (Alopecurus arundinaceus Poir.)]. Grasses were clipped at threeleaf, heading and seed set. Yield, leaf-to-stem ratio (LSR), botanical composition (BC), crude protein (CP), phosphorus, fibre and in vitro dry matter digestibility (IVDMD) were determined. There were differences (P &lt; 0.05) between the grasses in yield at each growth stage with smooth bromegrass and creeping foxtail having high yields and meadow bromegrass low yields at all growth stages. The BC of most target grasses was greater than 60%. Exceptions were Dahurian wild ryegrass, crested wheatgrass, tall wheatgrass and meadow bromegrass. There were few significant differences between the grasses for LSR, except that Russian and Altai wild ryegrasses and meadow bromegrass had higher LSR (P &lt; 0.05) than the other grasses. Differences in CP, P, neutral (NDF) and acid (ADF) detergent fibres were inconsistent and small at each growth stage but CP and P declined (P &lt; 0.05) while NDF and ADF increased (P &lt; 0.05) with plant maturation. There were differences (P &lt; 0.05) between years and cuts for all traits except between years for yield, BC and LSR at seed set (P &gt; 0.05). Dry matter intake (DMI) NDF and in vivo dry matter digestibility (DMD) were determined for hay cut from each plot using sheep. The relationship between forage NDF and DMI: DMI g kg BW-1 d-1 = 86.5 – 0.09 NDF (r2 = 0.87; RSD = 1.16; P &lt; 0.001)]

Within‐ and Among‐Cultivar Genetic Variation in Alfalfa: Forage Quality, Morphology, and Yield

Alfalfa (Medicago sativa L.) cultivars are synthetic populations formed from 8 to 200 parents and thus have a broad genetic base. Within‐cultivar variation was compared with among‐cultivar variation for energy value traits, morphological traits, and dry matter yield. Eleven cultivars, each represented by 15 clones of 7 to 20 genotypes, were evaluated in field plots simulating a dense canopy at INRA (National Institute of Agronomic Research), Lusignan in France. Six harvests spanning 3 yr were analyzed. Neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), enzymatic digestibility, leaf‐to‐stem ratio (LSR), number of stems, stem height, and dry matter yield were measured. Within‐cultivar variance accounted for 31 to 70% of the genetic variance for LSR and quality traits and 57 to 100% for morphological traits and dry matter yield. Large within‐cultivar variation for yield‐related traits could impart yield stability across environments, as a result of competition in alfalfa canopies. Phenotypic and genetic correlations were relatively low in each harvest for dry matter yield and NDF content, but high for NDF content and LSR. Within‐cultivar variation could be exploited as an additional source of genetic variation in breeding programs for quality traits to achieve a higher genetic gain per breeding cycle.

Heritabilities and Interrelationships of Water‐Use Efficiency and Agronomic Traits in Irrigated Alfalfa

Improvements in alfalfa (Medicago sativa L.) water‐use efficiency (WUE), the amount of forage and root biomass produced per unit of water transpired, could benefit irrigated production environments. Correlations between important agronomic traits and key physiological traits associated with WUE must be determined if benefits from improved WUE are to be realized. This study characterized genetic correlations among carbon isotope discrimination (Δ), canopy temperature, ash concentration, specific leaf mass (SLM), dry matter yield, forage maturity, and leaf‐to‐stem ratio (LSR) in irrigated alfalfa. Heritabilities of the traits on a progeny mean basis were also determined. Twenty‐eight half‐sib families possessing moderate fall dormancy were evaluated in seeded plots that were irrigated every 14 d during 2 yr near Las Cruces, NM. An increase in dry matter yield was associated with higher Δ (r = 0.39; P ≤ 0.05) and reduced LSR (r = −0.75; P ≤ 0.01). Carbon isotope discrimination was negatively correlated with specific leaf mass (r = −0.43; P ≤ 0.05) but was not correlated with canopy temperature or ash concentration. Ash concentration, Δ, LSR, and yield were moderately heritable (h2 = 0.44 to 0.61) indicating that these traits could be altered through breeding and selection. A positive relationship between A and forage yield indicated that both traits should be evaluated when characterizing alfalfa for high WUE to minimize potential yield reductions that may result from selection based only on Δ. The magnitude of the positive correlation between Δ and forage yield indicated that opportunities may exist to simultaneously improve both traits in irrigated environments. Moderate to low correlations between Δ and SLM, canopy temperature, and ash concentration indicated that none of these traits provided highly reliable estimates of Δ in irrigated alfalfa.

Heritabilities of Water‐Use Efficiency Traits and Correlations with Agronomic Traits in Water‐Stressed Alfalfa

Inadequate supplies of surface water limit forage production in the southern Great Plains and western United States. Alfalfa (Medicago sativa L.) production in this region may benefit from improvements in water‐use efficiency (WUE), the amount of forage and root biomass produced per unit of water transpired. If benefits from improved WUE are to be realized, correlations between important agronomic traits and key physiological traits associated with WUE must be determined under water‐limited conditions. This study characterized genetic correlations among C isotope discrimination (Δ), canopy temperature, ash concentration, dry‐matter yield, forage maturity, and leaf‐to‐stem ratio (LSR) in alfalfa grown under water‐stressed field conditions. Heritabilities of the traits on a progeny mean basis were also determined. Thirty semidormant half‐sib families were evaluated in seeded plots that were irrigated every 30 d during 2 yr near Las Cruces, NM. Carbon isotope discrimination was negatively correlated with canopy temperature and ash content. An increase in dry‐matter yield was associated with higher Δ, lower canopy temperatures, low ash concentration, taller shoots, earlier maturity, and reduced LSR. Carbon isotope discrimination, ash concentration, and yield were moderately heritable (h2 = 0.4–0.56) indicating that these traits could be altered through breeding and selection. The positive relationship between Δ and shoot yield suggests that germplasms should be evaluated for both Δ and yield when characterizing alfalfa for high WUE to minimize potential yield reductions that may result from selection based only on Δ. Moderate correlations between Δ and canopy temperature or ash content indicated that neither trait provided highly reliable estimates of Δ in water‐stressed alfalfa.

Variation for Yield, Water‐Use Efficiency, and Canopy Morphology among Nine Alfalfa Germplasm

Alfalfa (Medicago sativa L.) production under irrigated and rainfed conditions may benefit from improvements in water‐use efficiency (WUE), the amount of forage and root biomass produced per unit of water transpired. If benefits from improved WUE are to be realized, correlations between important agronomic traits and key physiological traits associated with WUE must be determined. This study characterized variation for dry matter yield, forage maturity, leaf‐to‐stem ratio (LSR), carbon isotope discrimination (Δ), canopy temperature, ash content, and specific leaf mass (SLM) in alfalfa. Associations between traits were also determined. Nine alfalfa germplasms representing eight of the nine historical genetic diversity groups, and a very fall‐dormant (YFD) population, were established in seeded, irrigated plots for 2 yr near Las Cruces, NM. Significant variation (P ≤ 0.10) was detected for all traits and was greatest for Δ and maturity, intermediate for yield, canopy temperature, ash content, and LSR, and least for SLM. The African, Peruvian, and Indian germplasms exhibited a higher Δ than either the Turkistan, YFD, M. varia Martyn., or Ladak germplasms. Carbon isotope discrimination was positively correlated with forage yield (r = 0.64; P ≤ 0.10; n = 9) and forage maturity (r = 0.66; P ≤ 0.05; n = 9). No association was detected between Δ and either canopy temperature, ash content, SLM, or LSR. The results indicate that differences in stomatal conductance or photosynthetic capacity exist among the nine populations, and that germplasms with low Δ tended to have slower growth and development rates under irrigated conditions. Neither canopy temperature, ash content, nor SLM provided suitable alternate measurements of A among the nine alfalfa germplasms.

Water‐Deficit Effects on Alfalfa at Various Growth Stages

AbstractStudies of water‐deficit effects on forage quality of alfalfa (Medicago sativa L.) have generally considered water stress throughout plant growth. This experiment was conducted to compare, with an unstressed control, the effects of short‐term soil‐water deficits occurring at three growth stages. Plants were grown in 100‐L containers set into the ground and protected with an automatic rain‐out shelter. Control treatments were watered weekly or twice weekly to raise the soil‐water level to field capacity. Watering was excluded during the third or fourth week of regrowth for plants that were stressed at vegetative and bud stages, respectively. For plants stressed at the flower stage, watering was excluded during the sixth or seventh week. Plants were harvested at five weekly intervals beginning 21 d after an initial defoliation. Stress at the bud or flower stages reduced leaf‐to‐stem ratio (LSR) by 25 and 38% of control, respectively. Stress at the vegetative stage did not affect LSR. As a result of lower LSR, in vitro digestible dry matter (IVDDM) in plants stressed at the bud or flower stages was 4% less than that of the control. The IVDDM of herbage in plants stressed at the vegetative stage was not different from the control. Crude protein (CP) concentration in stems increased by up to 8% of the control when plants were stressed at the vegetative or bud stages. Concentration of CP in leaves of stressed plants was 5 to 11% less than that of the control. Herbage CP concentration was up to 12% less than that of the control with stress at the bud or flower stages. Cell wall (CW) concentration in stems and total herbage was generally lower in plants stressed at the vegetative and bud stages. After rewatering, forage quality recovered in plants stressed at the bud stage. Most of the decline in forage quality due to stress at the bud or flower stages was caused by reduction in LSR and deterioration of leaf quality.

Water‐Stress Effects on Alfalfa Forage Quality After Adjustment for Maturity Differences

AbstractForage quality of alfalfa (Medicago sativa L.) often is higher in water‐deficit‐stressed plants than in nonstressed plants. At least part of the improvement could result from a delay in plant development due to the water stress. The objective of this study was to determine forage quality response of alfalfa to water stress and to relate this to corresponding changes in plant maturity, phonological development, and growth. ‘Apollo II’ alfalfa was grown in 100‐L containers set into the ground and protected by a movable rain shelter. Plants were watered either weekly or twice weekly to 112,100, 88, 76, and 64% of field capacity during 2 yr. Regrowth herbage was harvested at five weekly intervals beginning 3 wk after the initial cut. Plants were divided into stem bases (portion of stems below and including the sixth node), stem tops, and leaves before forage quality analyses were conducted. Plant maturity decreased linearly with increasing water stress. Averaged over the harvests, leaf‐to‐stem ratio (LSR) increased from 0.60 in the well‐watered treatments to 0.72 in the most severely stressed treatment. Delayed plant maturity and node number did not account fully for the increase in LSR under water stress. In vitro digestible dry matter (IVDDM) in stems, which increased by about 9% under water stress, was largely accounted for by delayed plant maturity. In stem bases, crude protein (CP) concentration increased by 11% with increasing water stress, even after accounting for differences in plant maturity. Cellulose concentration, expressed on a cell‐wall (CW) basis, decreased whereas CW hemicellulose concentration increased with water stress in both leaves and stems, and these changes were not entirely attributable to differences in plant maturity and growth. Thus, the slowing of plant maturation and growth during water stress accounted for much, but not all, of the changes in forage quality.