Water is a key limiting factor in agriculture.  Water resource shortages have become a serious threat to global food security.  The development of water-saving irrigation techniques based on crop requirements is an important strategy to resolve water scarcity in arid and semi-arid regions.  In this study, field experiments with winter wheat were performed at Wuqiao Experiment Station, China Agricultural University in two growing seasons in 2013–2015 to help develop such techniques.  Three irrigation treatments were tested: no-irrigation (i.e., no water applied after sowing), limited-irrigation (i.e., 60 mm of water applied at jointing), and sufficient-irrigation (i.e., a total of 180 mm of water applied with 60 mm at turning green, jointing and anthesis stages, respectively).  Leaf area index (LAI), light transmittance (LT), leaf angle (LA), transpiration rate (T_r), specific leaf weight, water use efficiency (WUE), and grain yield of winter wheat were measured.  The highest WUE of wheat in the irrigated treatments was found under limited-irrigation and grain yield was only reduced by a small amount in this treatment compared to the sufficient irrigation treatment.  The LAI and LA of wheat plants was lower under limited irrigation than sufficient irrigation, but canopy LT was greater.  Moreover, the specific leaf weight of winter wheat was significantly lower under sufficient than limited irrigation conditions, while the leaf T_r was significantly higher.  Correlation analysis showed that the increased LAI was associated with an increase in the leaf T_r, but the specific leaf weight had the opposite relationship with transpiration.  Optimum WUE occurred over a reasonable range in leaf T_r.  In conclusion, reduced irrigation can optimize wheat canopies and regulate water consumption, with only small reductions in final yield, ultimately leading to higher wheat WUE and water saving in arid and semi-arid regions.

To clarify the response and adaptability of peanut under salt stress, Huayu 25 was used as the material, and non-salt stress (CK), 0.15% salt stress (S1), and 0.3% salt stress (S2) were applied as three treatments.  The study analysed the effects of salt stress on photosynthetic characteristics, photosynthetic substances accumulation and distribution as well as the ecological adaptability of peanuts.  The results showed that net photosynthetic rate (P_n), SPAD value, leaf area, and peanut yield were reduced under salt stress.  P_n in CK was 13.71 and 28.72% higher than that in S1 and S2 at the 50th day after planting, respectively.  At the same growth period, the SPAD value among treatments was ranked as follows: CK>S1>S2.  The 100-pod mass, 100-kernel mass, kernel rate to pod, and pod mass per plant were reduced under salt stress, and the trend was CK>S1>S2.  The distribution proportion of dry matter in different organs of peanut plant was changed to adapt to such stress.  Roots under salt stress intensively distributed in a 0–40 cm soil layer for salt resistance.  Dry mass proportion in stems and pods increased during the vegetative stage and early period of reproductive stage, respectively.  The maximum growth rates of the pod volume, pod dry weight, and seed kernel dry weight all declined, and the pod and kernel volume at harvest were reduced, improving the seed plumpness under salt stress.  This finding could be useful in growing peanut in saline soil.

 

Somatic embryogenesis (SE) plays a vital role in genetic transformation and massive propagation of important agronomical and economical crops.  Here, we conducted a systematic assessment of the morphological, cytochemical, and cytogenetical characteristics of six culture strains with various embryogenic/regenerative potential during SE process in cotton.  Results indicated that the six cell culture strains had stable ploidy levels, and did not reveal any relationship between the cytogenetic state and their morphogenetic potential.  Moreover, the six culture strains were compared via double staining with Evans blue and Acetocarmine to efficiently distinguish embryogenic and non-embryogenic cells and determine the embryogenic nature of the calli.  In addition, the kind of auxins added in medium affected not only growth property, color, size of cell clumps but also ploidy level and regeneration ability.  By combining analysis of morphological, cytochemical, and cytogenetical characteristics of the cell cultures, we are able to obtain and maintain homogeneous cell population with high morphogenic and regeneration ability and establish efficient somatic embryogenesis and regeneration system from short-term cell cultures in upland cotton, which highlight the application of biotechnological approaches in crop breeding, and above all, to better understand totipotency of cells in higher plants.