Effects of Shade and Partial Defoliation on Carbohydrate Levels and the Growth, Fruiting and Fiber Properties of Cotton Plants.

Abstract

Carbohydrate levels in cotton plants during the fruiting period were reduced: 1. by growing the plants under muslin shades and 2. by cutting away half of each new leaf. The effects of these treatments were studied and are discussed in terms of 1. ligfht in relation to growth of the cotton plant, 2. partial defoliation and growth, 3. relative fruitfulness (bolls per 100 gm of fresh stems and leaves) and 4. changes in boll and fiber properties.The foregoing experiments were conducted along with others (partial defruiting and drought) that increased carbohydrate levels. Both of these treatments (4) increased fiber strength. Partial defruiting increased slightly and drought decreased: seed cotton per boll, fiber length, weight per inch and percent of mature fibers; but between five varieties of cotton it was found that those operating at the lowest carbohydrate levels had the strongest fibers, i.e., strength was evidently correlated with enzymatic and other growth factors that furthered carbohydrate utilization. As a further background for the results of this paper, it has been found that boll shedding is not com-. monly related to the carbohydrate or nitrogen levels in the plant (5).The shade experiment (light intensity reduced to 32% of full exposure by muslin sheeting) was repeated at a high, intermediate and low level of water supply and was started at about the time of first flowers. References were made to the findings of others on the effects of light intensities in a previous paper (6). In the partial defoliation (half-leaf) experiment, onehalf of each of the previous leaves and of each subsequent new leaf was removed weekly starting also at the time of first flowers. The work was conducted at the U. S. Cotton Field Station, Shafter, California, with the Acala p18 variety of cotton. Consideration is given in the discussion to evidence bearing on the auxin relations involved in the fruiting of the cotton plant.

Effect of Shading on Cotton Yield and Quality on Different Fruiting Branches

“…This result differed from the study of Zhao and Oosterhuis (1996), in which fiber length was not affected by shading. This viewpoint has been verified by other studies (Eaton and Ergle, 1954;Pettigrew, 1995Pettigrew, , 1996Pettigrew, , 2001, in which fiber length increased under longterm shading. This result suggests that fiber length responds to shading if shading occurs during the fiber elongation stage.…”

“…The longer duration of shading in the current study (about 2 mo compared to only 8 d in that study) may be the main reason, because fibers usually elongate to the maximum length over 20 to 25 d postanthesis ( John and Keller, 1996;Ji et al, 2002). Different from previous studies (Eaton and Ergle, 1954;Pettigrew, 1995Pettigrew, , 1996Pettigrew, , 2001Zhao and Oosterhuis, 1996, 1998b, 2000, shading in this study optimized fiber micronaire to near the premium range. This viewpoint has been verified by other studies (Eaton and Ergle, 1954;Pettigrew, 1995Pettigrew, , 1996Pettigrew, , 2001, in which fiber length increased under longterm shading.…”

Effects of different planting dates and low light on cotton fibre length formation

“…Many studies have shown that environmental factors can affect fibre development (Eaton and Ergle 1953;Pettigrew 1995Pettigrew , 2001Liaktas et al 1998;Dong et al 2006), and temperature and light often appeared as a compounding Two-way ANOVA results embedded in the figure were calculated from the data of average fibre sucrose synthase activity. ns not significant; *P \ 0.05; **P \ 0.01 (n = 6) factor in cotton production.…”

Efeito da remoção de folhas no desenvolvimento vegetativo e na produção do algodoeiro

“…De acordo com Eaton & Ercle (1965), desfolhamentos de 50% em plantas de algodão, até a formação dos frutos, resultam em redução de até 14% na produção. O algodoeiro possui crescimento seqüencial e bem definido, onde os intervalos de crescimento e florescimento vertical e horizontal são estimados em três e seis dias respectivamente, isto é, a cada três dias haverá a emissão de um novo ramo frutífero ou simpodial, e a cada seis dias haverá a emissão de uma nova estrutura frutífera (botão floral) nesse mesmo ramo (Figura 2) (Soares et al, 1999).…”