RESPONSE OF COTTON TO NPK FERTILIZATION – THE GREEK EXPERIENCE

Abstract                                                                         Back to Table of contents

Cotton is an economically important crop in Greece and experiments to determine the response of cotton to rates of fertilizers have always been an important part of research. The first experiments started almost 40 years ago and low rates of NPK showed a slight increase in cotton yield due to N and a lack of response to P and K fertilization.  The aim of this paper is to summarize the progress of more recent experiments.

Fifty-six experiments were conducted in eight cotton producing areas, for 12 successive years, testing five rates of N (0, 50, 100, 150, 200 Kg N per ha) and two rates of P (0,100 Kg P per ha) and K (0, 100 Kg K per ha). Data showed that N affected seed cotton yield, even at the very low application rate, while the effect of P was limited and that of K negligible. The increase in cotton yield as a result of N fertilization was related to the number of bolls and the boll weight. The maturity of cotton plants was related to N fertilization. Among the cotton fiber characteristics, only lint percentage was affected by fertilization.

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THE EFFECT OF STORAGE AND RADIATION ON COTTON SEED FOR SOME YIELD COMPONENTS

Abstract                                                                         Back to Table of contents

This research was set to study the effect of gamma irradiation (20 Kr.) on variability, heritability and the genetic advance upon selection for some economic traits and yield components. Dried seeds of three Egyptian cotton cultivars were used from Gossypium barbadense (Giza 77, Giza 80 and Giza 81). Results showed that gamma irradiation significantly increased means for the position of the first fruiting node, for the stored irradiated seeds and M2 recurrent generation in all cultivars under study, for M1 and M2 generation in Giza 77, and for M1 generation in Giza 81. There was no effect of the means for the number of bolls per plant, except the M2R generation which showed a significant decrease in Giza 81. Irradiation significantly increased mean boll weight for M2 generation in Giza 77 only. It significantly increased means of seed cotton yield per plant for the stored irradiated seeds and M2 generation of Giza 77 only. Using gamma rays significantly decreased means of lint percentage for M1 in Giza 77 and Giza 80 and M2R in Giza 81.

Heritability estimates in broad sense and the expected genetic advance upon selection were greater of all treatments for position of the first fruiting node in the three cultivars under study. These estimates were high for number of bolls per plant of the stored irradiated seeds and M1 generation in Giza 80. Boll weight was considered to be of intermediate heritability for Giza 77 and Giza 80 for all treatments, while response to selection were high values for this trait. The values obtained for all treatments indicated a high degree of heritability and response to selection for seed cotton yield per plant in Giza 77. The results showed a high degree of heritability and response to selection for lint percentage especially the stored irradiated seeds and M1 generation in Giza 80 and Giza 81.

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INFLUENCE OF SALINITY ON REPRODUCTIVE GROWTH OF THREE EGYPTIAN COTTON CULTIVARS

Abstract                                                                         Back to Table of contents

The objective of this study was to investigate to what extent salinity affects the reproductive growth of three Egyptian cotton cultivars Giza 77, Giza 75 and Giza 80. The salinity levels were 0, 2000, 4000 and 6000 ppm of either NaCl, NaCl + CaCl2 or NaCl + KCl.

Salinity delayed the appearance of first flower, reduced the number of fruiting branches, flowers and bolls and reduced the boll period (days from flowering to boll opening).  Salinity also reduced boll size, seed size and lint percentage.  As a result of these effects, salinity reduced seed cotton yield by up to 46% where 6000 ppm of NaCl was applied.

The effects of NaCl were greater than the effects of NaCl + CaCl2 or NaCl + KCl.  All cultivars had a similar response to salinity.

Conclusion

All fruiting characteristics and yield of the studied cotton cultivars were affected by saline conditions.  Higher salinity levels showed a pronounced effect and NaCl alone had a greater effect than the other mixed salts.  All three cultivars reacted similarly to salinity.

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EFFECTS OF SOAKING ON THE GERMINATION CHARACTERISTICS AND MINERAL LEAKAGE OF COTTON (GOSSYPIUM HIRSUTUM L.) SEED

Abstract                                                                         Back to Table of contents

Cotton seed (Gossypium hirsutum  L.) was tested to identify germination, seedling characteristics and growth as well as mineral leakage caused by soaking the seeds for different periods. Four cotton cultivars (BL. 644, Ç. 1518, DP. 299 and Sayar 314) were used with five different soaking periods (0, 4, 8, 16 and 24 hours).  Germination and seedling characteristics were tested in a growth cabinet at 25 ˚C.  The highest germination percentages were observed in all cotton cultivars with four and eight hours soaking, while the greatest abnormal seedlings were noted with 24 hours soaking.  Coleoptile and mesocotyl elongation and length were decreased with 24 hour treatments.  Vigour indices were decreased also with 24 hour soaking in all cultivars.  The leakage of K, P, Mn, Ca, Cu, Fe, and Zn mineral ions was increased significantly with 24 hour treatments.  The leakage of K+ and Ca++ ions was significantly correlated with the seed germination.  Zn++ was leaked less than other ions but the leakage of Zn++ was stable during other soaking periods.  Variation in seed mineral leakage was observed among the four cotton cultivars.

Conclusions

 These results indicate that soaking treatments of 4 to 6h in distilled water was helpful for better germination of cotton seeds and seedling establishment. Increasing soaking periods reduced germination. Soaked cotton seeds had leakages of K+ and Ca2+ cations, as well as Mn2+, Fe2+ and Cu2+. Similar conclusions were reported by Woodstock and Grabe (1967), Anderson et al. (1964), Cantrell, et al. (1972) and Woodstock et al. (1985).

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