[Effects of partial root-zone irrigation and rational close planting on yield and water productivity of cotton in arid area.] / éƒ¨åˆ†æ ¹åŒºçŒæº‰ä¸Žåˆç†å¯†æ¤å¯¹æ—±åŒºæ£‰èŠ±äº§é‡å’Œæ°´åˆ†ç”Ÿäº§çŽ‡çš„å½±å“.

The objective of this study was to evaluate the effects and underlying physiological mecha-nisms of partial root zone irrigation (PRI) and rational close planting, as well as their interaction on yield and water productivity (WP) of cotton and to explore new alternatives of water-saving irrigation in dry land areas. A factorial field experiment with irrigation mode (normal irrigation, partial root-zone irrigation and deficient irrigation) and plant population density (135000, 180000 and 225000 plants·hm-2) was conducted in the west of Inner Mongolia to examine their effects on cotton growth, yield, water productivity and related physiological characters. The results showed that the irrigation mode and plant density as well as their interaction significantly affected the biomass, yield, yield components and harvest index. Under normal irrigation, the biomass and the number of bolls per unit area increased with the increasing of plant density, but the harvest index and boll weight significantly reduced. The yield of high plant density was comparable to that of medium plant density, both of which were increased significantly compared with that of low plant density. The content of abscisic acid (ABA) significantly increased and that of auxin (IAA) significantly reduced in cotton leaves under partial root-zone irrigation, which significantly increased the harvest index by improving the partitioning of assimilates to reproductive organs under partial root-zone irrigation. The number of bolls per unit area increased and boll mass remained unchanged with the increasing of density under partial root-zone irrigation. The yield of high density increased by 6.7% and 11.5% compared with that of medium and low density under partial root zone irrigation. The pre-frost seed cotton increased by 22.5%, the amount of irrigation reduced by 30%, and water productivity increased by 49.3% under partial root zone irrigation compared with that under normal irrigation at high plant density. Plant density did not affect photosynthetic rate (Pn) of functional leaves, but irrigation mode significantly affected Pn. Deficient irrigation significantly reduced the Pn of the main-stem functional leaves, but the Pn under partial root-zone irrigation was comparable to that of normal irrigation. The jasmonate (JA) content and the expression level of plasma membrane intrinsic protein (PIP) gene were significantly increased in the hydrated root under partial root-zone irrigation compared with those under normal irrigation. The results suggested that the increased JA content, as a signal molecule, up-regulated the expression level of PIP gene in dehydrated root and increased water uptake capacity of roots and guaranteed water balance of leaves, and then contributed to a relatively high Pn. Partial root-zone irrigation combined with relatively high plant density (225000 plants·hm-2) is an important agronomic alternative for water saving in cotton plantation in the dry land areas.

[Eco-physiology and regulation of leaf senescence and maturity performance in cotton: A review].

Senescence is a natural termination process at the plant or organ level of cotton, leading to the inevitable end of the growth and development process. Maturity performance is termed as senescence performance and results of a cotton plant during boll opening, including normal maturity, premature senescence and late-maturity in cotton. Senescence and maturity performance are influenced by genotype and environment interactions. This paper summarized and reviewed the research progress in eco-physiology and molecular biology of cotton leaf senescence. Strategies were proposed to regulate cotton growth and aging through breeding of stably-developed varieties, rational application of plant growth regulators and agronomic cultivation measures, to realize normal maturity and improve yield and quality of cotton.

[Effects of fertilization on cotton growth and nitrogen use efficiency under salinity stress].

Cotton (Gossypium hirsutum) was raised at different salinity levels (0, 0.15% and 0.30%) by irrigating with fresh- or sea-water. The effects of fertilization (N, NK, NP and NPK) on plant growth, nitrogen (N) uptake and N use efficiency were studied. The results showed that salinity and fertilization both affected the biomass, agronomic N use efficiency, N bioavailability and nitrogen accumulation of plants, and significant interaction was observed between the two factors. Fertilization could improve N use efficiency and nitrogen accumulation of plants under salinity stress, and significantly promoted the cotton yield. Among the fertilization treatments, N combined with P and K had the best effect. The benefit of fertilization was better under low salinity (0.15%) than under moderate salinity (0.3%).

[Underlying mechanisms and related techniques of stand establishment of cotton on coastal saline-alkali soil].

Stand establishment is the most difficult step for cotton planting on coastal saline-alkali soil. To establish and improve the techniques for stand establishment is the key in the production of high-yielding cotton on saline-alkali soil. Based on the previous studies and our own research progress in this field, this paper reviewed the effects and the underlying mechanisms of making unequal salt distribution in root zone, increasing soil moisture and temperature, establishing under-mulching greenhouse, and introducing seed coating agent in promoting stand establishment of cotton on saline-alkali soil. It was suggested that under the conditions of the average salt content in topsoil being not able to reduce, improving at least partial root zone environment through the induction of unequal salt distribution in the root zone and increasing soil moisture and temperature could significantly reduce salt injury and improve stand establishment. Flat seeding under plastic mulching on low-salinity soil, furrow seeding with mulching on moderate- or high-salinity soil, early mulching before sowing on rain-fed saline soil, and late sowing of short-season cotton in heat-limited area were the efficient techniques for improving the stand establishment of cotton on coastal saline-alkali soil. This review could provide full guarantee for the cotton stand establishment on coastal saline-alkali soil.

[Regulation effects of various training modes on source-sink relation of cotton].

With the removal of vegetative branches plus the maintenance of early fruiting branches as the control, the effects of various training modes on the source-sink relation of field-grown cotton were examined in 2005 and 2006. The results showed that compared with the control, either the removal of vegetative branches plus the removal of early fruiting branches (I), the maintenance of vegetative branches plus the removal of early fruiting branches (II), or the maintenance of vegetative branches plus the maintenance of early fruiting branches (III) could increase the leaf area per plant significantly, with the average maximum LAI across the two years increased by 10.3%, 28.3%, and 9.5%, respectively, and resulting in the decreases of the load per leaf area and the ratio of sink to source. I and II alleviated the leaf senescence of cotton plants as indicated by the enhanced leaf chlorophyll content and the reduced percentage of yellow leaves and C/N ratio of functional leaves, and II also induced the late-maturing of cotton plants. III had no significant effects on senescence alleviation. I produced approximately equal seed cotton, but II and III produced 6.4%-15.6% less and 6.3% more seed cotton than the control, respectively. It was concluded that either the maintenance of vegetative branches or the removal of early fruiting branches could be an effective pathway to regulate the ratio of sink to source, C/N, and maturity performance of cotton plants.