Climate Change and Agriculture in the United States: Effects and Adaptation

Strawberry fruit quality attributes after application of plant growth stimulating compounds

http://dadun.unav.edu/bitstream/10171/22642/1/Remote%20Sensing%20of%20Environment%20114%20286%20a%20298.pdf

Detecting water stress effects on fruit quality in orchards with time-series PRI airborne imagery

Summary The yield-enhancing effects of some pesticides may change the focus of their use in crop production, from crop protection to crop enhancement While such beneficial uses of pesticides are specifically en vogue for fungicides and seed treatments, the use of herbicides for crop enhancement has not yet been realised The potential for improving crop production by low-dose, stimulatory effects of herbicides has been proposed, and reports of 10–25% efficiency of improving certain plant traits under field conditions seem promising However, past attempts to make use of herbicide hormesis, the term for this effect, have been largely unsuccessful The reasons for this may be manifold, but the lack of understanding of the principles and mechanisms of this low-dose phenomenon in plants may have contributed to the often claimed lack of adequate predictability for commercial use Thanks to the research progress recently made in this area, we are now better able to understand the principles of herbicide hormesis and its potential for crop enhancement Therefore, this review highlights the potential of phytotoxins to induce plant hormesis and the factors influencing its expression Based on this, possible practical constraints and consequences for the portfolio of uses for herbicides are discussed, along with undesired but apparent hormetic side effects of herbicides

Herbicide hormesis - can it be useful in crop production?

Plant biostimulants are under investigation as innovative products to improve plant production and fruit quality, without resulting in environmental and food contaminations. Here, the effects of the application of Expando, a biostimulant based on seaweed and yeast extracts, on plant productivity, fruit ripening times, and fruit quality of Solanum lycopersicum var. Micro-Tom were evaluated. After biostimulant treatment, a two-week reduction of ripening times and a concomitant enhancement of the production percentage during the earliest ripening times, in terms of both fruit yield (+110%) and size (+85%), were observed. Concerning fruit quality, proximate analysis showed that tomatoes treated with the biostimulant had better nutritional composition compared to untreated samples, since both the quality of unsatured fatty acids (C16:3ω3: +328%; C18:2ω6: -23%) and micronutrients essential for human health (Fe: +14%; Cu: +21%; Zn: +24%) were increased. From a nutraceutical point of view, despite strong changes in bioactive compound profile not being observed, an increase of the antioxidant properties was recorded in fruits harvested by plants treated with the biostimulant (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS): +38%; 2,2-diphenyl-1-picrylhydrazyl (DPPH): +11%). In conclusion, the biostimulant application was able to reduce the ripening times and fruit size, while slightly increasing nutritional and nutraceutical values, leading to more marketable tomato fruits.

https://www.mdpi.com/2218-273X/10/12/1662/pdf

The application of a plant biostimulant based on seaweed and yeast extract improved tomato fruit development and quality

The importance of fruit size as a parameter of quality of citrus fruits has increased markedly in recent times. The consumer’s marked preference for large fruit causes huge differences in price between large and small fruit to the point that the income from the smaller fruit is often less than picking and hauling costs. Fruit size has become as important as yield in the determination of the profitability of citrus plantings, and an economic premium is usually obtained through the increase in fruit size even at the expense of a reduction in crop yield. This applies not only to the small fruited mandarins and hybrids but also to large fruit species such as lemons, oranges and grapefruit. To increase fruit size beyond the limits which may be obtained through the optimization of the standard cultural practices (fertilization, irrigation, pruning), several techniques have been tried such as hand thinning [80], chemical and hormone thinning [49, 77] and the hormonal stimulation of fruit growth rate by synthetic auxins [69, 70, 71]. The earlier investigations on this subject were reviewed extensively by Coggins and Hield [12], Monselise [57] and Wilson [78], which pointed out some drawbacks encountered with the use of these techniques in practice. Particularly, the application of synthetic auxins to increase fruit size often resulted in too erratic results to justify the use of these compounds by the growers [57]. An exception was the successful use of NAA and, in recent times, IZAA (5-chloroindazol-8-acetic acid; ethylcholozate) to thin satsuma mandarins in Japan [49, 50]. This success resulted from a nation wide research in which the physiological aspects of the response to these compounds were carefully characterised. In the present report, we summarise the most recent developments and our present knowledge on the way fruit size is determined and the different approaches to increase it through the use of plant growth regulators. Understanding the mode of action of the applied bioregulators shall ensure more reliable results from their application and has resulted already in the formulation of some general recommendations on their use. Some aspects on the regulation of fruit size and the response to synthetic auxins have been reviewed recently [38, 46]. Recent research carriedout in Japan has been summarised by Iwahori [54] and Yamashita [79].

J.L. Guardiola

Papers

Increasing fruit size in Citrus. Thinning and stimulation of fruit growth