Lake Naivasha (Kenya,East Africa) fishery and its management together with a note on the food habits of fishes

The Lake Naivasha fishery is constituted by three introduced species, Sarotherodon leucostictus, Tilapia zillii and Micropterus salmoides. No indigenous species are now found in the lake. S. spilurus niger, another introduced species, and hybrids of S. s. niger × S. leucostictus, abundant in 1961, have almost completely disappeared.The annual catch of Sarotherodon-Tilapia and M. salmoides between 1968 and 1974 ranged from 109·2 to 1479·6 metric tons and 7·9 to 471·9 metric tons respectively.S. leucostictus is a bottom feeder (chironomid larvae 64°24%, detritus 20·58%), T. zillii feeds on aquatic macrophytes (76·62%) and M. salmoides feeds almost exclusively on crayfish (78·25%). A major portion of the fish food present in the lake is left unused.The yield, which has progressively declined since 1968, could be increased considerably by introducing certain management measures. These are discussed.     

Sunflower seed yield as influenced by some agronomic and seed characters

Summary An investigation was made to the interrelationships of agronomic and seed characters and their effect upon seed yield. Twenty genotypes of sunflower (Helianthus annuus L.) from diverse origin were studied in spring and autumn season, 1989.Most of the studied characters exhibited different relationships in spring and autumn seasons. The correlations between plant height and oil content, 100-achene weight and number of achenes per head and plant height and head diameter were, however, consistent in both seasons and across the seasons. Stepwise multiple regression analysis identified six relevant characters on which path analysis was done.Path analysis indicated that yield components like head diameter, number of achenes per head and 100-achene weight had comparatively smaller direct effects on seed yield (0.22, 0.15 and 0.23, respectively). Days to physiological maturity, plant height and oil content had relatively stronger direct effects on seed yield (0.33, 0.38 and 0.29, respectively). Days to physiological maturity, plant height and head diameter had considerable indirect effects. Head diameter, 100-achene weight and number of achenes per head were indentified as selection criteria for yield improvement.     

Substitution of mineral fertilizers with biofertilizer: an alternate to improve the growth,yield and functional biochemical properties of strawberry (Fragaria × ananassa Duch.) cv. Camarosa

Abstract

An experiment was conducted to substitute mineral fertilizers with biofertilizers in strawberry to work out the yield, quality of strawberry and soil fertility. A 25% substitution of mineral fertilizer with biofertilizer increased the number of fruits/plant along with improving Juice content (89.55%), Total soluble solids (10.35°B), total sugar (6.69%), ascorbic acid (43.80?mg 100?g^?1), anthocyanin content (81.05?mg 100?g^?1), total phenol (5.97?mg Gallic acid equiv. g^?1), flavonoids (0.12?mg g^?1) and antioxidant capacity (2.13?µmol. Trolox equiv. 100?g^?1). The available N and K content in post-harvest soils were improved significantly with 75% RDF + Azospirillium @ 2?g plant^?1 + PSB @ 2?g plant^?1 + topdressing of 25% K treatments (200.10 and 211.70?kg ha^?1, respectively). Viable count of soil microorganisms (Bacteria, actinomycetes and fungi) was also estimated maximum (4066, 190 and 11.33?×?10⁴ cfu g^?1?dry soil, respectively) with substitution of 25% of mineral fertilizer either with Azotobacter or Azospirillum.     

Effects of Mn-deficit feeding to ewes on certain amino acids and sugars in cartilage of their newborn lambs

The distribution of amino acid, amino sugar, and uronic acid in the epiphyseal cartilage of newborn lambs were examined to determine the influence of manganese (Mn) deficiency. Throughout the gestational period, one group (group I) of eight pregnant ewes was given a ration containing 60 mg of Mn/kg of feed and a second group (group II) of eight ewes was given a ration containing 5 mg of Mn/kg of feed. The neonatal lambs were killed, and the epiphyseal plates from various bones in the thoracic limb were removed and analyzed for glucosamine, galactosamine, uronic acid, and 17 amino acids. Concentrations of uronic acid and of the sulphur amino acids (methionine not significant, P greater than 0.05) were larger in the cartilage from the lambs born of group I ewes (60 mg of Mn/kg of ration) than in the cartilage from those of the Group II ewes (Mn deficiency). A tendency for higher hexosamine values was observed in the organic matrix of the group I lambs than of the group II lambs. However, concentrations of serine, histidine, and lysine were higher in the cartilage from group II lambs (Mn deficiency). Thus, the role of Mn in the prevention of joint abnormalities may be its influence on the mucopolysaccharide and protein composition of the epiphyseal plate.     

Crossbred bull selection for bigger scrotum and shorter age at puberty with potentials for better quality semen.

Shortening age at puberty of crossbred breeding bull is an important issue in the tropics. This study aimed at selecting crossbred bulls at earliest possible age with bigger scrotum and potential for donating quality semen. One hundred and 31 pre-joining crossbred bulls of Central Artificial Insemination Laboratory, Saver, Dhaka were examined. The bulls being trained by seeing semen collection from mature bulls were allowed ejaculation into the artificial vagina at homosexual mount during a 20 min time at three occasions, every three months. Eighty one of 131 bulls produced at least one ejaculate during the study and their mean +/- SD age and scrotal circumference (SC) were 20.3 +/- 4.7 months and 28.2 +/-2.7 cm, respectively. Bulls' body weight, body condition score (BCS) and SC influenced the attainment of their puberty (p < 0.05). Bull's body weight had positive effects on scrotal circumference and ejaculate volume (p < 0.05). Scrotal circumference positively influenced the percentages of normal spermatozoa (p < 0.05). Scrotal skin-fold thickness negatively influenced the proportion of spermatozoa with normal head (p < 0.05). Based on age at first ejaculate and SC, 29.6% bulls (n = 24) were selected by cluster analysis. Selected bulls had mean +/- SD age 17.9 +/- 2.2 months, body weight 287.3 +/-48.6 kg, SC 30.5 +/- 1.5 cm, ejaculate volume 3.4 +/- 1.3 ml, sperm motility 50.8 +/- 17.2%, total spermatozoa per ejaculate 2541.9 +/- 1699.2 million and normal spermatozoa 81.5 +/-14.5%. The selected pubertal bull group was different from the unselected pubertal bulls at MANOVA (p < 0.0001). About 30% of pubertal crossbred bulls can be selected with shorter age and larger scrotum at puberty under conditions prevailed in Bangladesh.     

Effect of simultaneous and sequential inoculations of <Emphasis Type="Italic">Meloidogyne incognita</Emphasis>, <Emphasis Type="Italic">Ralstonia solanacearum</Emphasis> and <Emphasis Type="Italic">Phomopsis vexans</Emphasis> on eggplant in sand mix and fly ash mix soil

Effects simultaneous and sequential inoculations of Meloidogyne incognita, Ralstonia solanacearum and Phomopsis vexans were studied on the growth, chlorophyll and carotenoid contents of eggplants grown in 25% fly ash and 25% sand mix soil. Plants grown in 25% fly ash mix soil had lesser plant growth than grown in 25% sand ash mix soil. Inoculation of M. incognita / R. solanacearum or P. vexans caused reduction in plant growth, chlorophyll and carotenoid contents in both types of soils but these pathogens in combination caused a greater reduction in than individual inoculation. Inoculation of M. incognita 20 days prior to R. solanacearum caused a greater reduction in plant growth than inoculation of M. incognita prior to P. vexans. Inoculation of P. vexans prior to R. solanacearum caused a lesser reduction in plant growth, chlorophyll and carotenoid contents than inoculation of P. vexans prior to M. incognita. Inoculation of R. solanacearum 20 days prior to M. incognita caused a greater reduction in plant growth, chlorophyll and carotenoid contents than inoculation of R. solanacearum prior to P. vexans. Galling and multiplication of M. incognita was higher in plants grown in 25% sand amended soil than with 25% fly ash soil. R. solanacearum and P. vexans had adverse effects on galling and nematode multiplication. Wilt and blight indices caused by R. solanacearum and P. vexans were 3 respectively. Wilt and blight indices were 4 when two pathogens were inoculated together.