Percentage Of Plant Survival Research Articles

Blue light sensitivity of UV-irradiated young sporophytes of Laminaria hyperborea

After damaging UV irradiation (wavelength 253.7 nm), subsequent exposure to visible light enhanced survival of young sporophytes of Laminaria hyperborea. This photoreactivation was wavelength-dependent, showing significant recovery in blue light compared with no measurable recovery either in green or red light. In white light, the effect was proportional to irradiance until saturated at ≈ 35 μmol m −2 s −1. After 12 h of various types of irradiation (10 μmol m −2 s −1 of coloured light or darkness) followed by 12 h white light (35 μmol m −2 s −1), the survival percentage of plants in 12 : 12 blue: white light was almost the same as that in continuous white light. In other cases, it was half that in continuous light. If the photoreceptor for photoreactivation were identical with that for 2-D growth of Scytosiphon lomentaria, the relative effectiveness of waveband 400–500 nm would be 3.4 times as great in blue light as in white light. In direct comparisons, when white irradiance was 3.5 times blue, survival percentages in 24 h blue, 12 : 12 blue:white and 24 h white light were found to be similar, indicating a likely involvement of the same photoreceptor. The quantum requirement of the plant for a 50% response was comparable to that for other blue light responses found in brown algae.

Response of American Ginseng to Foliar Applications of 2,4-D

Abstract Single and multiple applications of 2,4-D to American ginseng (Panax quinquefolium L.) with fully expanded leaves during a 3-year period caused no visible injury to foliage or roots. During the final 2 years of the study, percent plant survival was greater with two applications per year than with one, and percent gain in root weight decreased with increased rate of application of the herbicide. Also, terminal weight of roots decreased with increased number of years of herbicide application. Treated plants did not differ from nontreated plants in percent survival, final root weight, or percent gain in root weight. Herbicide residue was not detected (<0.02 ppm) in roots from plants that received multiple applications of the three highest 2,4-D dosages: 0.56, 1.12, or 2.24 kg·ha−1 a.i. Foliar residues were detected in plants treated once or twice per year for 3 years with 0.56 or 1.12 kg·ha−1 a.i. 2,4-D. Chemical name used: (2,4-dichlorophenoxy)acetic acid (2,4-D).

Effects of irrigation on the leaf and pod production of fluted pumpkin ( Telfairia occidentalis Hook. f.) in Southern Nigeria

Irrigation frequencies of 3, 6 and 9 days intervals were compared with no irrigation. Irrigation prolonged the productive life of the crop and enhanced leaf and pod yields. Irrigating every 6 days produced significantly (p = 0.05) higher numbers of seeds and highest water use efficiency, while irrigating every 3 days gave the best leaf and pod yield and the highest percentage of plant survival.

Breeding for Resistance to Aphanomyces euteiches Root Rot and Rhizoctonia solani Stem Rot in Peas

Abstract A modified Environmental Shift Technique based on use of a disease index (scoring) gave consistent separation between susceptible and moderately resistant pea (Pisum sativum L.) genotypes to Aphanomyces euteiches Drech. root rot in 3 tests. A moderately high association (r = −0.63 to −0.83) between disease index and percentage of plant survival was found in segregating populations. Minnesota 108, moderately resistant to A. euteiches, produced adventitious roots readily at an early stage. Root rot resistance and number of adventitious roots were inherited independently. Broad sense heritability (BSH) ranging between 0.45 and 0.57 for resistance to A. euteiches root rot, and between 0.39 and 0.44 for resistance to Rhizoctonia solani Kuehn stem rot, varied by parental combination, experiment, and method of estimation. However, heritability based on gain by selection in the F3 ranged from 0.28 to 0.46 and from 0.21 to 0.44 for resistance to A. euteiches and R. solani, respectively. Frequency distribution of resistant and susceptible plants suggested quantitative inheritance of resistance to both diseases. Recurrent selection, in which each cycle includes one intermating, selfing, and testing generation, is suggested to improve and transfer resistance.

Chinch Bug Control

Abstract All experiments were arranged in a randomized complete block design. The 1977 plots (Tables 1, 2, 3, 4) were located in Johnson County, Nebraska, and were one row wide, 30 ft (9.14 m) long. The 1978 plots (Tables 5, 6, 7) were located in Lancaster County, Nebraska, and were four rows wide, 30 ft (9.14 m) long. Insect and stand counts were made on the two center rows of each plot. All experiments were replicated four times. Three plants per treatment per replication were marked with flags, and insect counts were made on the same plants at each observation date. Insect counts and stand counts or percent plant survival were subjected to analysis of variance.

Penapisan Genotipe Jarak Pagar (Jatropha curcas L.) untuk Toleransi terhadap Kekeringan

The selection of Jatropha curcasfor drought tolerance is one of the key points prior to growing the species extensively on marginal lands. The objective of this study was to determine drought tolerant genotypes based on morphological and physiological characters. The research consisted of two experiments. The first experiment was aimed at determining the moisture content of the media to generate drought stress. The experiment was arranged in a split-plot design with moisture content as the main plot and genotypes as sub-plot. Four level of moisture contents were tested, i.e. 22-23%, 27-28%, 32-33%, and 37-38%. The genotypes tested (9) were Dompu-1, Gunung Tambora, Bima (representing genotypes from dry areas); Aceh Besar, IP-2P, Komering (representing genotypes from wet areas); and IP-1M, Papua, Yogyakarta (representing genotypes from moderately dry areas). The result showed that 22-23% moisture content of the media was suitable for drought tolerance test in Jatropha curcas. The second experiment was screening of genotypes using the suitable media moisture content from first experiment. Twenty three genotypes were screened for drought tolerance under 22-23% media moisture content. The result show that Dompu-2, Indralaya and China were tolerant to drought; Sukabumi-1, Sukabumi-2, Pidi, Lahat, Kupang, Lampung-2, Lampung-3, Sumba, IP-2M, and IP-2A genotypes were moderately tolerant; Curup, Bogor-1, Bogor-2, Bogor-3, Pontianak, Pagar Alam, Palembang, Saweli, Jeneponto, and Medan genotypes were sensitive to drought. Plant height, leaf water content, leaf area and percentage of plant survival can be used as indicators of drought tolerance for seedling selection using a non-destructive method.Keywords: drought tolerance, genotypes, Jatropha curcas, screening

Effects of X-irradiation of seed on X 1 and X 2 generations in Pinus banksiana Lambert

Pinus banksiana (jack pine) seed X-rayed at 1000 and 4000R was tested under commercial nursery and field planting conditions. At 4000R no seedlings survived beyond 1 yr of age. At the end of 2 yr, approximately 30 per cent of the seedlings from seed given 1000 R survived as compared to the control. A decrease in LD 50 exposure was noted as the seedlings aged; 2.25 R at 40 days, 1710 R at 130 days and 700 R at 14 months. The LD 50 determined from the survival response curves was found to be linear over the first two growing seasons permitting prediction of the dosage that would result in 50 percent plant survival at any point in the first 2 yr. Cone development and yield of X 2 seed/cone following self-pollination were reduced in the irradiated trees as compared to the controls. Seed germination, however, was higher in the seed from trees grown from the 1000 R irradiated seed than from the controls, suggesting an apparent stimulation of seed viability. Survival in the X 1 generation and the quantity and quality of X 2 seed produced on X 1 trees showed that the reproductive capacity was reduced by seed X-irradiation at 1000 R to slightly over 10 percent in cross-pollinated X 2 seed production, and to less than 5 percent after self-pollination. The results show that the effects of seed irradiation in jack pine, and probably other conifers, cannot be fully evaluated in a portion of the first generation, but that at least two generations are required.

Studies on the effect of CO 60—gamma radiation on Lupinus Termis

Seeds of Lupinus termis (variety Fayoum 45) were exposed to gamma rays resulting from Co 60 nearly 5 months prior to cultivation. The doses employed were 4, 7, 12, 16, 20 and 25 Kr respectively. The effects of radiation on the percentage of germination, plant survival, plant growth, flowering and crop yield were studied for two successive years. No clear trend of germination or survival with dose was observed. Statistical analysis showed that the applied doses of Co 60 gamma radiation had no significant effect on plant growth. No difference in the time of flowering of the irradiated plants as compared with the controls was observed; and the maximum flowering was reached at the same time as the control. From the treatments used, only the 12 Kr dose caused a significant increase in the crop yield in the second filial generation.