Lodging Resistance In Rice Cultivars Under Rates of Nitrogen Fertilizer; Does The Main Culm Represent The General Pattern of Lodging In Primary Tiller?

Purpose Lodging resistance (LR) in rice cultivars is usually established using the main culm (MC) as a good representative of tillers on the plant. However, it remains unclear whether LR of MC represents LR of the primary tiller (PT) to guide in the selection of tillers during LR assessment in rice cultivars under rates of nitrogen fertilizer. Methods Four lodging resistant cultivars namely: NERICAs 1, 4, 6 and Moroberekan were established under three rates (0, 60, 120 kg ha-1) of nitrogen fertilizer. At 20 days after heading of each of the MC and PT, the culms were harvested for assessment of LR. Results Increasing application rates of nitrogen fertilizer increased the culm morphological traits (CMTs) such as culm wall thickness, internode and lumen diameters, bending moment and breaking strength of MC and PT with little effect on lodging index (LI). The CMTs were however, higher in the MC and with lower LI than in the PT. The higher CMTs in MC did not translate to lower LI in all the rice cultivars such as Moroberekan compared with the PT. Correlations of CMTs with LI were higher and significant in the MC than in the PT. Conclusion Main culm remains reliable for the mechanical assessment of LR in upland rice but does not represent the general pattern of lodging in the PT. There is need for consistency in selection of tiller for mechanical assessment of lodging in rice cultivars under rates of nitrogen fertilizer.

Effects of harvesting programme and sowing date on leaf growth in forage barley in Cyprus

SummaryAll combinations of four harvesting treatments and two sowing dates were compared in each of 2 years in field experiments near Nicosia. In one of the years, two levels of applied nitrogen were compared. The harvesting treatments were: (1) a milk-stage cut, (2) a boot-stage cut and a regrowth cut, (3) a grazing-stage cut and a regrowth cut, and (4) three grazing-stage cuts and a regrowth cut. The sowing dates were (1) normal (12 November) and (2) early (15 October), with sufficient irrigation to ensure establishment.Applied nitrogen had virtually no effect on leaf growth, evidently because of high reserves of available nitrogen in the soil. Early sowing increased the rates of leaf emergence, extension and expansion up to the time of the first ‘grazing’ cut (when the first node was showing) and reduced the number of leaves which died in that period. Where growth was uninterrupted to the milk stage, early sowing did not affect the number of leaves produced by a main stem or primary tiller, but increased the longevity of the later leaves. Where there were three ‘grazing’ cuts, early sowing allowed time for the production of more and larger leaf blades, with longer sheaths, between the third 'grazing’ cut and the final harvest.The ‘grazing’ cuts considerably reduced the rates of extension and expansion and the final size of the leaves which emerged soon after a cut. There was good recovery subsequently, however, in rates of extension and expansion and final leaf size, particularly with October sowing.During almost all the period of leaf production on a main stem or primary tiller, several leaves (up to six) were expanding at the same time. The stage, during the period between emergence and death, at which a leaf blade reached its full length was typically half-way between emergence and death. Where growth was uninterrupted, area per leaf blade was positively correlated with both the number of days between the emergence of successive leaves and the number of days between emergence and death.

EFFECT OF TEMPERATURE ON THE GROWTH OF WHEAT: I. MARQUILLO, KENYA FARMER, AND TWO DWARF PROGENY

Wheat varieties, Marquillo, Kenya Farmer, wheat dwarf 1 (Marquillo × Kenya Farmer), and wheat dwarf 2 (Marquillo × Kenya Farmer) were grown in growth cabinets under continuous light at an intensity of 1200 ft-c and temperatures of 16, 21, 26, and 31 °C combined in all possible combinations for 16-h and 8-h periods in a 24-h cycle.Wheat dwarf 1 elongated and produced seed only when soil and air temperature was kept at 26 °C or higher. If the plants were exposed to 21 °C or less for 8 h or longer, only a "grass-clump" habit of growth was observed. At still lower temperatures only a small primary tiller was produced. Wheat dwarf 1 plants, initially grown at 21 °C for 30 days or longer, would not grow and head when transferred to 31 °C. Plants initially grown at 31 °C did not continue to grow when transferred to 21 °C. Wheat dwarf 2 required a temperature of 21 °C or higher to induce elongation. At lower temperatures plants were dwarfed but fertile tillers were produced. Only at 16 °C was a "grass-clump" habit of growth observed.In contrast to the dwarfs, the tallest plants of Marquillo and Kenya Farmer were produced at the lowest temperatures and maximum yield of shoot and seed was obtained under a regime that would be equivalent to a continuous temperature of 17–20 °C.