Research Notes : United States : Evaluation of soybean germplasm for stress tolerance biological efficiency : To evaluate soybean germplasm and cultivars for stress tolerance toward : Harvest index

Simultaneous investigations were conducted at experiment farms at Fort Valley State College and Maryland Eastern Shore in 1985 with 42 soybean genotypes (14 each from MG III, IV, and V) to determine seed yield efficiency (SYE) and grain yield and their relationship to other agronomic traits. The mean seed yield efficiency ranged from 34 to 51, 35 to 50, and 28 to 59% for MG III, IV, and V, respectively. The mean grain yield for three MGs was similar and ranged from 19.65 (MG III) to 22.86 (MG V) quintals/ha

Research Notes : United States : Evaluation of soybean germplasm for stress tolerance and biological efficiency : To evaluate soybean germplasm for biological efficiency in - Photosynthetic activity and translocation of photosynthates

Sixteen soybean genotypes comprising the parentage of cultivar Forrest were grown in pots in the greenhouse and under field conditions to determine whole-plant and single-leaf net photosynthesis (Pn), leaf-area index, dry-matter accumulation, photosynthate partitioning, leaf conductance, and yield uynder field conditions, the range in pN was 47.9 to 29.6 mg C02dm hr for \u27Illini\u27 and \u27Haberlandt\u27, respectively (Tables 12 and 15). Illini also had higher photosynthesis (whole-plant basis) than all other genotypes grown in pots (Table 13). The range in leaf area index was 5.8 to 3.4. \u27Volstate\u27 accumulated more dry matter (505.0 g/m2) than all the other genotypes during the vegetative stage of growth (Table 14)

Research Notes : United States : Evaluation of soybean germplasm for stress tolerance and biological efficiency towards : Harvest Index

Eighteen soybean genotypes, six each from Maturity Groups (MG) V, VI, and VII were planted in four-row (6 m long and 0.9 m wide) experimental plots in a randomized complete block, with four replications, under field conditions using standard cultural practices. The objective was to determine seed yield efficiency (SYE), phytomass accumulation and leaf area index (LAI) development and other physiological and morphological traits and their relationships to yield. Significant differences were found in most of the parameters studied

Research Notes : United States : Evaluation of soybean germplasm for stress tolerance and biological efficiency : To evaluate soybean germplasm for biological efficiency in - Photosynthetic activity and translocation of photosynthates

Sixteen soybean genotypes comprising the parentage of cultivar Forrest were grown in pots in the greenhouse and under field conditions to determine whole-plant and single-leaf net photosynthesis (Pn), leaf-area index, dry-matter accumulation, photosynthate partitioning, leaf conductance, and yield uynder field conditions, the range in pN was 47.9 to 29.6 mg C02dm hr for 'Illini' and 'Haberlandt', respectively (Tables 12 and 15). Illini also had higher photosynthesis (whole-plant basis) than all other genotypes grown in pots (Table 13). The range in leaf area index was 5.8 to 3.4. 'Volstate' accumulated more dry matter (505.0 g/m2) than all the other genotypes during the vegetative stage of growth (Table 14).</p

Growth, Gas Exchange, And Harvest Index of Field-Grown Cassava in a Subtropical Short-Season environment

Cassava ( Manihot esculenta Crantz L.) is an important food and industrial crop in the tropics and holds potential in the subtropics. Cassava productivity is similar to C4 crop plants but its single-leaf net photosynthetic rate (Pn) is lower than C4 plants. This field investigation was conducted from 1982 to 1984 with seven cassava genotypes to study growth and gas exchange in a short-season environment. The Pn was determined on fully mature and attached leaves in an open system and canopy photosynthesis (CPn) was determined in a closed system between 1100 and 1500 hr using a portable plexiglass chamber. Leaf area index (LAI) of all cassava genotypes was similar except for Aug 1983 sampling and ranged from 2.40 to 6.16. The stomatal density was about ten times higher on the abaxial than the adaxial surface of cassava leaves. The abaxial stomatal conductance of water ranged from 0.23 cm s-1 to 1.94 cm s-1. Canopy photosynthesis differed significantly only during 1983 and varied from 1.31 to 1.97 mg CO2 m-2s-1. The Pn ranged from 0.48 to 1.21 mg CO2 m-2 s-1. ‘Senorita’ and ‘M Ven 218’, the two semi-forking genotypes, had generally higher HI than the forking genotypes. The HI was significantly correlated with CPn (r= 0.76*) and storage root yield (r=0.92*) during 1984. Cassava HI in a short season environment in the subtopics is similar to that in tropics. The relatively high productivity of cassava may be attributed to its high HI

Research Notes : United States : Evaluation of soybean germplasm for stress tolerance biological efficiency : To evaluate soybean germplasm and cultivars for stress tolerance toward : Harvest index

Simultaneous investigations were conducted at experiment farms at Fort Valley State College and Maryland Eastern Shore in 1985 with 42 soybean genotypes (14 each from MG III, IV, and V) to determine seed yield efficiency (SYE) and grain yield and their relationship to other agronomic traits. The mean seed yield efficiency ranged from 34 to 51, 35 to 50, and 28 to 59% for MG III, IV, and V, respectively. The mean grain yield for three MGs was similar and ranged from 19.65 (MG III) to 22.86 (MG V) quintals/ha.</p

Research Notes : United States : Evaluation of soybean germplasm for stress tolerance and biological efficiency towards : Harvest Index

Eighteen soybean genotypes, six each from Maturity Groups (MG) V, VI, and VII were planted in four-row (6 m long and 0.9 m wide) experimental plots in a randomized complete block, with four replications, under field conditions using standard cultural practices. The objective was to determine seed yield efficiency (SYE), phytomass accumulation and leaf area index (LAI) development and other physiological and morphological traits and their relationships to yield. Significant differences were found in most of the parameters studied.</p

Ability of systemic insecticide dimethoate to prevent aphid colonisation and the spread of aphid transmitted viruses in Solanum tuberosum Lin.

Seven potato (Solanum tuberosum Lin.) varieties previously indexed against potato leaf roll virus (PLRV), potato virus Y (PVY), potato virus S (PVS) and potato virus X (PVX) were grown in the fieid for two seasons at Namulonge representing warm, mid-altitude tropics and, for one season at Kalengyere representing cool highland areas. One set of the seven potato varieties was sprayed with dimethoate at a rate of 1.19 kg a.i. ha-1 at weekly intervals to prevent aphid infestation and spread of aphid transmitted viruses. The second set was not treated. Seed tuber indexing before planting showed the absence of aphid transmitted viruses (PLRV, PVY and PVS) in seed potato obtained from Kalengyere during both seasons. Weekly collection of aphids at both sites showcrl a predominance of Myzus persicae (Sul.), the principle vector of most potato viruses. Dimethoate controlled aphids at Kalengyere but not at Namulonge. As a result, seed potatoes obtained from Kalengyere and grown at Namulonge acquired the aphid-transmitled PLRV in the fint season of growth whether they were treated with the insecticide or not. However, all the varieties were free from PVY and PVS. At Kaleogyere, all the varieties grown in the field were free from aphid-borne viruses irrespective of the insecticide fre:ltment. These results indicate that there·is probably M. persicae resistance to dimethoate at Namulonge.Key words: Dimethoate, virus latent infection, aphid-borne viruses, Myzus persicae, ELlSA

Effect of mother plant applied nitrogen and potassium on the sowing value of true potato seed

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